Alejandro Recio-Boiles, MD

Introduction

Pancreatic ductal adenocarcinoma is a challenging disease with a poor prognosis, with 5-year survival rates in the single digits (~8%).¹ Survival rates in pancreatic cancer are low in part because most patients have advanced disease at the time of diagnosis and early development of systemic metastatic disease is common, with approximately 52% of patients with newly diagnosed pancreatic cancer having metastatic disease at diagnosis.¹ Surgical resection with negative margins is the cornerstone of potentially curative therapy for localized disease, but only 15% to 20% of patients are eligible for resection at the time of initial diagnosis. Patients with unresectable and metastatic disease are offered palliative chemotherapy. Unfortunately, early recurrence is common in patients with resectable tumors who achieve a complete resection and are treated with adjuvant therapy (5-year recurrence rate ~80%).^2,3 This article reviews the management of patients with unresectable and/or metastatic pancreatic cancer. A previous article reviewed the diagnosis and staging of pancreatic cancer and the approach to neoadjuvant and adjuvant therapy in patients with resectable and borderline-resectable disease.⁴

First-Line Systemic Treatment

Case Presentation

A 72-year-old man who underwent treatment for pancreatic adenocarcinoma 18 months ago presents to the emergency department after developing poor appetite, weight loss, and abdominal discomfort and fullness without diarrhea, which has been constant for the past 2 weeks even though he has been taking analgesics and pancreatic enzymes.

The patient was diagnosed with pancreatic cancer 18 months ago after presenting with yellowish skin and sclera color; abdominal and pelvis computed tomography (CT) with intravenous contrast showed a pancreatic head mass measuring 2.6 × 2.3 cm minimally abutting the anterior surface of the superior mesenteric vein. Endoscopic ultrasound confirmed an irregular mass at the head of the pancreas and sonographic evidence suggested invasion into the portal vein. Examination of a tissue sample obtained during the procedure showed that the mass was consistent with pancreatic adenocarcinoma. Magnetic resonance imaging (MRI) performed to define venous vasculature involvement revealed a pancreatic head mass measuring 3.0 × 2.7 cm without arterial or venous vasculature invasion. The mass was abutting the portal vein and superior mesenteric veins, and a nonspecific 8-mm aortocaval lymph node was noted. The tumor was deemed to be borderline resectable, and the patient received neoadjuvant therapy with gemcitabine and nab-paclitaxel. After 4 cycles, his carbohydrate antigen (CA) 19-9 level decreased, and MRI revealed a smaller head mass (1.3 × 1.4 cm) with stable effacement of the superior mesenteric vein and no portal vein involvement; the aortocaval lymph node remained stable. He was treated with gemcitabine chemoradiotherapy prior to undergoing an uncomplicated partial pancreaticoduodenectomy. Analysis of a surgical pathology specimen revealed T3N0 disease with a closest margin of 0.1 cm. Postsurgery, the patient completed 4 cycles of adjuvant chemotherapy with gemcitabine plus capecitabine.

At his current presentation, MRI of the abdomen and pelvis reveals a new liver mass and peritoneal thickness. Serology testing reveals a CA 19-9 level of 240 U/mL, and other liver function tests are within normal limits. Biopsy of the mass confirms recurrence.

• What systemic chemotherapy would you recommend for this patient with metastatic pancreatic adenocarcinoma?

Most cases of pancreatic cancer are unresectable and/or metastatic at the time of diagnosis. Identifying treatment endpoints and the patient’s goals of care is a critical step in management. Systemic chemotherapy can provide significant survival benefit in first-line and second-line treatment compared to best supportive care. Palliative interventions also include systemic therapy, which often improves pain control and other cancer related–symptoms and hence quality of life. Participation in clinical trials should be offered to all patients. Therapy selection depends on the patient’s performance status, comorbidities, and liver profile and the results of biomarker testing and mutation analysis.

Several single-agents, including fluoropyrimidines, gemcitabine, irinotecan, platinum compounds, and taxanes, have minor objective response rates (< 10%) and a minimal survival benefit (~2 weeks) in metastatic pancreatic adenocarcinoma. Conversely, multi-agent therapies provide higher response rates and can extend overall survival (OS). Two combinations, nab-paclitaxel plus gemcitabine and FOLFIRINOX (oxaliplatin, irinotecan, leucovorin, and flourouracil), have significantly prolonged survival compared to best single-agent gemcitabine, as demonstrated in the MPACT (Metastatic Pancreatic Adenocarcinoma Clinical Trial) and PRODIGE 4/ACCORD 11 trials.^5,6 Because both multi-agent regimens are also associated with a more toxic adverse effect profile, gemcitabine monotherapy continues to be a front-line therapy for patients with multiple comorbidities, elderly frail patients (> 80 years of age), or patients who cannot tolerate other combinations.⁷

Gemcitabine-Based Therapy

Gemcitabine became a standard of care treatment for pancreatic cancer in the mid-1990s, and was tested as a second-line therapy in a multicenter phase 2 clinical trial that accrued 74 patients with metastatic pancreatic cancer who had progressed on fluorouracil therapy. In this trial, 27% of patients treated with gemcitabine achieved a clinical benefit response and the median OS was 3.85 months.⁸ The agent was generally well-tolerated with a low incidence of grade 3 or 4 toxicities. Subsequently, a randomized clinical trial compared gemcitabine to fluorouracil in the front-line setting in 126 patients with newly diagnosed advanced pancreatic cancer.⁹ Patients were randomly assigned to receive single-agent intravenous fluorouracil administered without leucovorin as a short-term infusion (600 mg/m² once weekly) or gemcitabine (1000 mg/m² weekly for up to 7 weeks followed by 1 week of rest, and then weekly for 3 out of every 4 weeks thereafter). A higher proportion of patients treated with gemcitabine had a clinical benefit response (23.8% versus 4.8%), with an improvement in a composite measure of pain (pain intensity and analgesic consumption) and performance status. Clinical responses assessed by a secondary measure, weight gain, were below 10% in both arms, but the median OS was significantly longer for the gemcitabine arm (5.65 months versus 4.4 months, P = 0.0025) and the 1-year OS rate also favored the gemcitabine arm (18% versus 2%). Grade 3/4 neutropenia was reported more frequently in the gemcitabine arm (23% versus 5%). There is no evidence that increasing the dose intensity of the fixed-dose rate of gemcitabine (1000 mg/m² per week administered as a 30-minute infusion) leads to improved antitumor activity.

Following publication of the trial conducted by Burris and colleagues,⁹ a plethora of clinical trials have tried to outperform gemcitabine monotherapy, with all trials studying gemcitabine monotherapy compared with gemcitabine plus another agent (fluorouracil, cisplatin, oxaliplatin, irinotecan, pemetrexed, novel biologics including cetuximab, bevacizumab, axitinib, sorafenib, aflibercept). These combinations have failed to significantly extend OS compared to single-agent gemcitabine, although some showed a marginal clinical benefit:

• Capecitabine¹⁰ (hazard ratio [HR] 0.86 [95% confidence interval {CI} 0.75 to 0.98])
• Erlotinib¹¹ (HR 0.81 [95% CI 0.69 to 0.99])
• Cisplatin, epirubicin, fluorouracil, gemcitabine¹² (HR 0.65 [95% CI 0.43 to 0.99])

The best outcomes were obtained with gemcitabine plus nab-paclitaxel compared to gemcitabine monotherapy. The gemcitabine/nab-paclitaxel combination has not been compared to FOLFIRINOX in the front-line setting, as the ACCORD 11 and MPACT trials were ongoing simultaneously. However, a large retrospective trial that compared use of the regimens in the US Oncology Network in the United States demonstrated similar efficacy, although more patients treated with FOLFIRINOX needed white blood cell growth factor administration.¹³

Gemcitabine/nab-paclitaxel was studied in a phase 1/2 clinical trial with 67 untreated metastatic pancreatic cancer patients.¹⁴ Patients received nab-paclitaxel at doses of 100, 125, or 150 mg/m² followed by gemcitabine 1000 mg/m² on days 1, 8, and 15 every 28 days. The maximum tolerated dose (MTD) was 1000 mg/m² of gemcitabine plus 125 mg/m² of nab-paclitaxel once a week for 3 weeks every 28 days. Dose-limiting toxicities were sepsis and neutropenia. Patients who received the MTD had a response rate of 48%, median OS of 12.2 months, and a 1-year survival rate of 48%.

The landmark phase 3 MPACT trial confirmed that adding nab-paclitaxel to gemcitabine prolongs survival compared with gemcitabine monotherapy.⁵ This multinational randomized study included 861 treatment-naive patients with a Karnofsky performance score of 70 or higher. The median OS in the nab-paclitaxel/gemcitabine group was 8.5 months, as compared to 6.7 months in the gemcitabine monotherapy group (HR for death 0.72 [95% CI 0.62 to 0.83], P < 0.001). The survival rate was 35% in the nab-paclitaxel/gemcitabine group versus 22% in the gemcitabine group at 1 year, and 9% versus 4% at 2 years. Median progression-free survival (PFS) was 5.5 months in the nab-paclitaxel/gemcitabine group, compared to 3.7 months in the gemcitabine group (HR for disease progression or death 0.69 [95% CI 0.58 to 0.82], P < 0.001). The overall response rate according to independent review was 23% compared with 7% in the 2 groups, respectively (P < 0.001). The most common adverse events of grade 3 or higher were neutropenia (38% in the nab-paclitaxel/gemcitabine group versus 27% in the gemcitabine group), fatigue (17% versus 7%), and neuropathy (17% versus 1%). Febrile neutropenia occurred in 3% of the combination group versus 1% of the montherapy group. In the nab-paclitaxel/gemcitabine group, neuropathy of grade 3 or higher improved to grade 1 or lower a median of 29 days after discontinuation of nab-paclitaxel. In 2013, nab-paclitaxel in combination with gemcitabine received U.S. Food and Drug Administration (FDA) approval as first-line therapy for metastatic pancreatic cancer.

A pilot phase 1b/2 trial that added cisplatin to nab-paclitaxel and gemcitabine in treating 24 treatment-naive metastatic pancreatic adenocarcinoma patients showed impressive tumor response (complete response 8.3%, partial response 62.5%, stable disease 16.7%, progressive disease 12.5%) and extended median OS to 16.5 months.¹⁵ A phase 1b trial conducted in Europe added capecitabine to the cisplatin, nab-paclitaxel, and gemcitabine regimen, albeit with a different schedule and doses, in 24 patients with locally advanced and metastatic disease.¹⁶ This trial demonstrated an impressive overall response rate of 67%, with 43% of patients achieving a complete metabolic response on positron emission tomography scan and the CA 19-9 level decreasing by ≥ 49% in all 19 patients who had an elevated basal value. Moreover, PFS at 6 months was 96%. After chemotherapy 17 patients remained unresectable and 7 patients were taken to surgery; of the latter group, only 1 was determined to be unresectable at the time of surgery. This regimen is being explored in a larger study in patients with stage III and IV disease.

FOLFIRINOX

A randomized phase 2 clinical trial comparing FOLFIRINOX to gemcitabine monotherapy in 88 patients with treatment-naive metastatic pancreatic cancer revealed a high response rate for FOLFIRINOX (39% versus 11%, respectively) with a tolerable toxicity profile.¹⁷ FOLFIRINOX became the front-line standard of care therapy in pancreatic adenocarcinoma after the results of the subsequent phase 3 ACCORD 11 study preplanned interim analysis showed an unprecedented significantly improved OS benefit.⁶ The ACCORD 11 trial randomly assigned 342 patients with an Eastern Cooperative Oncology Group (ECOG) score of 0 or 1 and a serum bilirubin level less than 1.5 times the upper limit of normal to receive FOLFIRINOX (oxaliplatin 85 mg/m², irinotecan 180 mg/m², leucovorin 400 mg/m², and fluorouracil 400 mg/m² given as a bolus followed by 2400 mg/m² given as a 46-hour continuous infusion, every 2 weeks) or gemcitabine at a dose of 1000 mg/m² weekly for 7 of 8 weeks and then weekly for 3 of 4 weeks. The median OS in the FOLFIRINOX group was 11.1 months as compared with 6.8 months in the gemcitabine group (HR 0.57 [95% CI 0.45 to 0.73], P < 0.001). The FOLFIRINOX group also had a longer median PFS (6.4 months versus 3.3 months, HR 0.47 [95% CI 0.37 to 0.59], P < 0.001) and higher objective response rate (31.6% versus 9.4%, P < 0.001). More adverse events were noted in the FOLFIRINOX group, including grade 3 or 4 neutropenia (46% versus 21%), febrile neutropenia (5.4% versus 1.2%), thrombocytopenia (9.1% versus 3.6%), sensory neuropathy (9% versus 0%), vomiting (15% versus 8%), fatigue (23% versus 18%), and diarrhea (13% versus 2%). Despite the greater toxicity, only 31% of the FOLFIRINOX group had a definitive degradation of quality of life, as compared to 66% in the gemcitabine group (HR 0.47 [95% CI 0.30 to 0.70], P < 0.001), thus indicating an improvement in quality of life.

Of note, combinations containing irinotecan require adequate biliary function for excretion of its active glucuronide metabolite, SN-38. Approximately 10% of patients in the United States are homozygous for the UGT1A1*28 allele polymorphism, which causes increased SN-38 bioavailability and hence a potential for severe toxicities (eg, life threatening-refractory diarrhea).¹⁸ Therefore, it is recommended that physicians start with a lower dose of irinotecan or choose a different regimen altogether in such patients.

Current Approach and Future Directions

Based on results of the ACCORD 11 and MPACT trials, both front-line regimens (nab-paclitaxel/gemcitabine and FOLFIRINOX) can be considered appropriate treatment options for treatment-naive patients with good performance status who have locally advanced unresectable or metastatic pancreatic adenocarcinoma. FOLFIRINOX has a higher objective response rate than nab-paclitaxel-gemcitabine (32% versus 23%, respectively), but the adverse effect profile favors the nab-paclitaxel/gemcitabine combination, acknowledging this conclusion is limited due to lack of a comparative trial. Modifications to both regimens have been presented at American Society of Clinical Oncology symposiums, with preliminary data showing an extended median OS and a more tolerable toxicity profile.^19,20 In a recent retrospective observational cohort comparative analysis of nab-paclitaxel/gemcitabine versus FOLFIRINOX, results showed no statistical difference in median OS. The real-world data showed that gemcitabine-based therapy is being offered commonly to elderly patients and patients with poor performance status.¹³ There is no current research proposal for conducting a direct head-to-head comparison between these 2 regimens. Based on extrapolated data from the prior mentioned trials and retrospective analysis reviews, current guidelines recommend offering younger (< 65 years old), healthier (no comorbidity contraindication) patients with excellent performance status (ECOG 0) first-line FOLFIRINOX or gemcitabine/nab-paclitaxel. Elderly patients with stable comorbidities and good performance status (ECOG 1 or 2, Karnofsky performance status ≥ 70) could be preferably considered for treatment with nab-paclitaxel/gemcitabine as first-line or modified FOLFIRINOX if performance status is excellent. Patients with poor performance status (ECOG ≥ 2), advanced age, and significant comorbidities could still be considered candidates for gemcitabine monotherapy. However, there are promising indications that the combination of gemcitabine, nab-paclitaxel, and cisplatin could be a frontline therapy in advanced pancreaticobilliary malignancies in the future.

Second-Line Systemic Treatment

Case Continued

The patient and oncologist opt to begin treatment with modified FOLFIRINOX therapy, and after the patient completes 10 cycles CT scan shows progression of disease. His oncologist decides to refer the patient to a comprehensive cancer center for evaluation for participation in clinical trials, as his performance status remains very good (ECOG 1) and he would like to seek a novel therapy. His liver mass biopsy and blood liquid biopsy are sent for tumor mutational profile evaluation; results show a high tumor mutational burden and microsatellite instability.

• What are second-line treatment options for metastatic pancreatic cancer?

Second-line regimen recommendations for metastatic pancreatic cancer depend on which agents were used in first-line therapy and the patient’s performance status and comorbidities. Patients who progressed on first-line FOLFIRINOX and continue to have a good performance status (ECOG 0 or 1) may be considered for gemcitabine/nab-paclitaxel therapy; otherwise, they may be candidates for gemcitabine plus capecitabine or gemcitabine monotherapy based on performance status and goals of care. Patients who progressed on front-line gemcitabine/nab-paclitaxel may opt for FOLFIRINOX (or an oxaliplatin-based regimen [FOLFOX] or irinotecan-based regimen [FOLFIRI] if FOLFIRINOX is not tolerable), nanoliposomal irinotecan/fluorouracil/leucovorin, or a short-term infusional fluorouracil and leucovorin regimen. The preferences for second-line treatment are not well established, and patients should be encouraged to participate in clinical trials. Chemotherapy should be offered only to those patients who maintain good performance status after progression on first-line therapy. For patients with poor performance status (ECOG 3 or 4) or multiple comorbidities, a discussion about goals of care and palliative therapy is warranted.

Gemcitabine-Based Therapy

An AGEO prospective multicenter cohort assigned 57 patients with metastatic pancreatic adenocarcinoma who had disease progression on FOLFIRINOX therapy to receive gemcitabine/nab-paclitaxel (dose as per MPACT trial).²¹ The median OS was 8.8 months and median PFS was 5.1 months after FOLFIRINOX. There were reported manageable grade 3/4 toxicities in 40% of patients, which included neutropenia (12.5%), neurotoxicity (12.5%), asthenia (9%), and thrombocytopenia (6.5%). A phase 2 clinical trial that evaluated gemcitabine monotherapy in 74 patients with metastatic pancreatic cancer who had progressed on fluorouracil showed a 3.85-month survival benefit.²²

Irinotecan-Based Regimens

The NAPOLI-1 (NAnoliPOsomaL Irinotecan) trial evaluated nanoliposomal irinotecan (MM-398, nal-IRI) and fluorouracil/leucovorin in patients with metastatic pancreatic cancer refractory to gemcitabine-based therapy.²³ This global, open-label phase 3 trial initially randomly assigned and stratified 417 patients in a 1:1 fashion to receive either nanoliposomal irinotecan monotherapy (120 mg/m² every 3 weeks, equivalent to 100 mg/m² of irinotecan base) or fluorouracil/leucovorin combination. A third treatment arm consisting of nanoliposomal irinotecan (80 mg/m², equivalent to 70 mg/m² of irinotecan base) with fluorouracil and leucovorin every 2 weeks was added later in a 1:1:1 fashion. Patients assigned to nanoliposomal irinotecan plus fluorouracil/leucovorin had a significantly improved OS of 6.1 months compared to 4.2 months with fluorouracil/leucovorin (HR 0.67 [95% CI 0.49 to 0.92], P = 0.012). The results of an intention-to-treat analysis favored the nanoliposomal irinotecan regimen, with a median OS of 8.9 months compared with 5.1 months (HR 0.57, P = 0.011). In addition, median PFS was improved in the nanoliposomal irinotecan arm (3.1 months versus 1.5 months; HR 0.56, P < 0.001), and median OS did not differ between patients treated with nanoliposomal irinotecan monotherapy and those treated with fluorouracil/leucovorin (4.9 months versus 4.2 months; HR 0.99 [95% CI 0.77 to 1.28], P = 0.94). The grade 3/4 adverse events that occurred most frequently in the 117 patients assigned to nanoliposomal irinotecan plus fluorouracil/leucovorin were neutropenia (27%), diarrhea (13%), vomiting (11%), and fatigue (14%). Nanoliposomal irinotecan combination provides another second-line treatment option for patients with metastatic pancreatic adenocarcinoma who have progressed on gemcitabine-based therapy but are not candidates for FOLFIRINOX.

Oxaliplatin-Based Regimens

Regimens that combine oxaliplatin with fluorouracil and leucovorin or capecitabine have shown superiority to fluorouracil/leucovorin or best supportive care (BSC). The CONKO study group compared oxaliplatin plus fluorouracil/leucovorin to BSC as second-line therapy in patients with advanced pancreatic cancer who progressed while on gemcitabine therapy (CONKO-003).²⁴ In this phase 3 trial, patients were randomly assigned (1:1) and stratified based on duration of first-line therapy, performance status, and tumor stage to receive BSC alone or the OFF regimen, which consisted of oxaliplatin (85 mg/m² on days 8 and 22) plus short-term infusional fluorouracil (2000 mg/m² over 24 hours) and leucovorin (200 mg/m² over 30 minutes), both given on days 1, 8, 15, and 22 of a 6-week cycle. This trial was terminated early according to predefined protocol regulations because of insufficient accrual (lack of acceptance of BSC by patients and physicians). Median second-line survival was 4.82 months for patients who received OFF treatment and 2.30 months for those who received BSC (HR 0.45 [95% CI 0.24 to 0.83], P = 0.008).  Neurotoxicity (grade 1/2) and nausea, emesis, and diarrhea (grade 2/3) were worse in the chemotherapy arm; otherwise, the regimen was well tolerated.

A later modification of the CONKO-003 trial changed the comparison arm from BSC to fluorouracil/leucovorin.²⁵ The median OS in the OFF group was 5.9 months versus 3.3 months in the fluorouracil/leucovorin group (HR 0.66 [95% CI 0.48 to 0.91], log-rank P = 0.010). Time to progression was significantly extended with OFF (2.9 months) as compared with fluorouracil/leucovorin (2.0 months; HR 0.68 [95% CI 0.50 to 0.94], log-rank P = 0.019). Rates of adverse events were similar between the treatment arms, with the exception of grades 1/2 neurotoxicity, which were reported in 38.2% and 7.1% of patients in the OFF and fluorouracil/leucovorin groups, respectively (P < 0.001).

The phase 3 PANCREOX trial failed to show superiority of modified FOLFOX6 (mFOLFOX6; infusional fluorouracil, leucovorin, and oxaliplatin) over fluorouracil/leucovorin.²⁶ A phase 2 trial of oxaliplatin plus capecitabine for second-line therapy in gemcitabine-treated advanced pancreatic cancer patients with dose adjustments for performance status (ECOG 2) and age (> 65 years) showed a median OS of 5.7 months without a comparison.²⁷ A modified oxaliplatin regimen may be a reasonable second-line therapy option for gemcitabine-treated patients who are not candidates for an irinotecan-based regimen (eg, elevated bilirubin) and continue to have an acceptable performance status.

Targeted Therapies

A variety of targeted therapies have failed to demonstrate major activity in metastatic pancreatic cancer, including bevacizumab targeting vascular endothelial growth factor, cetuximab targeting epidermal growth factor receptor, ruxolitinib targeting JAK pathway signaling, saridegib targeting the hedgehog pathway, and MK-0646 targeting insulin-like growth factor 1 receptor (IGFR). Other novel agents against targetable pathways that had promising early-phase results are currently being studied in ongoing clinical trials; these include JAK-2, PI3K, MEK, and BRAF inhibitors and immunotherapy.

Recent research efforts have focused on targeted testing of advanced pancreatic cancers for mismatch repair deficiency (dMMR) and high microsatellite instability (MSI-H) and for the germline and somatic BRCA1/2 or PALB2 mutations to determine potential eligibility for immunotherapy. Patients with these tumor characteristics and/or mutations might also be more sensitive to platinum-based chemotherapy agents or poly (ADP-ribose) polymerase (PARP) inhibitors. Germline mutations in BRCA 1/2 are present in 5% to 8% of patients with pancreatic cancer (up to 10%–15% in Ashkenazi Jewish population).²⁸ A superior median OS was retrospectively observed for patients with advanced stage BRCA 1/2-associated pancreatic adenocarcinoma who were treated with platinum-based chemotherapy agents versus those treated with non-platinum-based agents (22 versus 9 months; P = 0.039).²² PARP inhibitors have shown activity in germline BRCA1/2-associated breast (off label) and ovarian cancers (approved by the FDA). The efficacy and safety of PARP inhibitors were evaluated in a phase 2 study of a spectrum of BRCA1/2-associated cancers, including pancreatic cancer. The results revealed a tumor response rate of 21.7% (5 of 23 patients with pancreatic cancer [95% CI 7.5 to 43.7]), and 35% of patients had stable disease for a duration of 8 weeks or more (95% CI 16.4 to 57.3) with good tolerability.²⁹ Three novel PARP inhibitors are currently under clinical trial investigation in patients with germline BRCA 1/2- and PALB2-mutated metastatic pancreatic cancer: maintenance olaparib (NCT02184195) and rucaparib (NCT03140670) are both being studied as monotherapy in patients whose disease has not progressed on first-line platinum-based chemotherapy, and veliparib is being evaluated in a 3-arm study that includes gemcitabine and cisplatin with or without veliparib and single-agent maintenance veliparib (NCT01585805).

In 2017, the FDA granted accelerated approval to pembrolizumab for treatment of patients with unresectable or metastatic MSI-H or dMMR solid tumors whose disease progressed on prior treatments, making it the first oncology drug to be approved based on the genetic features of the tumor rather than its location in the body. This first tissue/site-agnostic approval was based on results from 5 single-arm trials involving 149 patients, including 5 patients with pancreatic cancer.³⁰ The objective response rate with pembrolizumab was 39.6% (95% CI 31.7 to 47.9), including a 7.4% complete response rate and a 32.2% partial response rate. The median duration of response was not reached at the time of publication (range, 1.6+ months to 22.7+ months).

Palliative and Supportive Care

Case Continued

The patient opts to participate in a novel immunotherapy clinical trial and is currently on his second cycle. He continues to have right upper quadrant pain despite opioid analgesia, has not gained any weight, and noticed new right lower extremity swelling after a recent holiday vacation to Florida.

• What supportive measures should be in place for patients with metastatic adenocarcinoma?

Most patients with advanced pancreatic adenocarcinoma will require a palliative intervention. All new unresectable pancreatic cancer patients should have an early psychosocial evaluation; identification of symptoms and implementation of preventive interventions that would improve quality of life and reduce suffering are paramount. A multidisciplinary team including physician/nursing staff, nutritionist/dietitian, palliative service, a social worker, and a case manager should be involved in patient care. More than two-thirds of patients can develop symptomatic biliary obstruction.³¹ Bile duct obstruction due to locally advanced pancreatic adenocarcinoma causes hyperbilirubinemia, which requires endoscopic placement of a metallic or plastic stent; plastic stents have a higher rate of re-occlusion.³² Appropriate bile flow allows treatment with irinotecan-based regimens. Percutaneous biliary drainage may be necessary if endoscopic intervention is not feasible.

Approximately one quarter of patients may present with gastric outlet obstruction due to duodenal obstruction.³¹ Endoscopic placement of an enteral expandable metal stent is preferred. Alternatively, percutaneous endoscopic gastrostomy tube placement may give symptomatic relief. Palliative surgical interventions are reserved for patients with greater life expectancy and in whom all other interventions have failed or are not feasible.

Almost all patients with pancreatic adenocarcinoma will experience cancer-associated pain. Intractable pain should be treated with a celiac plexus block. Radiation therapy may be considered as an adjunct therapy for pain, bleeding, and/or local obstruction. The National Comprehensive Cancer Network guidelines recommend that patients who undergo a laparotomy for potentially resectable disease but are found to have unresectable disease at the time of surgery should undergo stenting, open biliary-enteric bypass with or without gastrojejunostomy, and/or celiac plexus neurolysis.³³

Pancreatic exocrine enzyme insufficiency due to tumor extension, duct blockage, or surgical removal may cause malabsoprtive steatorrhea, contributing to cancer cachexia syndrome. Nutritional evaluation and daily oral pancreatic enzyme supplementation are recommended.³⁴

Patients diagnosed with pancreatic adenocarcinoma have a venous thromboembolism (VTE) incidence of 20 per 100 person-years (5%–60% of patients) and are considered at very high risk for VTE based on the Khorana score.³⁵ The preferred VTE treatment is low-molecular-weight heparin rather than warfarin based on the results of the CLOT study.³⁶ There is no current evidence for routine prophylactic therapy or the use of direct oral anticoagulants.

Finally, a cancer diagnosis, particularly pancreatic cancer, causes a significant amount of psychosocial stress and requires active support and counseling from a professional.

Conclusion

Pancreatic adenocarcinoma is the most lethal of all the gastrointestinal malignancies. FOLFIRINOX and gemcitabine/nab-paclitaxel are superior to gemcitabine monotherapy for patients with advanced unresectable and/or metastatic pancreatic cancer who are candidates for more aggressive therapy and are considered first-line therapies. Early data on the gemcitabine, nab-paclitaxel, and cisplatin combination appears to show superior efficacy. Second-line therapies are selected based on the patient’s performance status, first-line regimen, and residual toxicities from the prior regimen; options include gemcitabine/nab-paclitaxel, FOLFIRINOX (± oxaliplatin or irinotecan), single-agent gemcitabine (elderly frail patients), fluorouracil and liposomal-irinotecan, or referral for a clinical trial. The main challenge with pancreatic cancer is the development of stroma around the tumor, which abrogates drug delivery, allows for tumor growth in a hypoxic microenvironment, alters the metabolomics, and causes an immunosuppressive microenvironment. Drugs that target the microenvironments, such as hedgehog pathway inhibitors, have failed to show any clinical benefit, and we hope to see more efficacious microenvironment-targeted novel drugs in the future. In addition, immunotherapy has not shown any significant efficacy in clinical trials and many trials are still ongoing.

Introduction

Pancreatic ductal adenocarcinoma is a challenging disease with a poor prognosis, with 5-year survival rates in the single digits (~8%).¹ Survival rates in pancreatic cancer are low in part because most patients have advanced disease at the time of diagnosis and early development of systemic metastatic disease is common, with approximately 52% of patients with newly diagnosed pancreatic cancer having metastatic disease at diagnosis.¹ Surgical resection with negative margins is the cornerstone of potentially curative therapy for localized disease, but only 15% to 20% of patients are eligible for resection at the time of initial diagnosis. Patients with unresectable and metastatic disease are offered palliative chemotherapy. Unfortunately, early recurrence is common in patients with resectable tumors who achieve a complete resection and are treated with adjuvant therapy (5-year recurrence rate ~80%).^2,3 This article reviews the management of patients with unresectable and/or metastatic pancreatic cancer. A previous article reviewed the diagnosis and staging of pancreatic cancer and the approach to neoadjuvant and adjuvant therapy in patients with resectable and borderline-resectable disease.⁴

First-Line Systemic Treatment

Case Presentation

A 72-year-old man who underwent treatment for pancreatic adenocarcinoma 18 months ago presents to the emergency department after developing poor appetite, weight loss, and abdominal discomfort and fullness without diarrhea, which has been constant for the past 2 weeks even though he has been taking analgesics and pancreatic enzymes.

The patient was diagnosed with pancreatic cancer 18 months ago after presenting with yellowish skin and sclera color; abdominal and pelvis computed tomography (CT) with intravenous contrast showed a pancreatic head mass measuring 2.6 × 2.3 cm minimally abutting the anterior surface of the superior mesenteric vein. Endoscopic ultrasound confirmed an irregular mass at the head of the pancreas and sonographic evidence suggested invasion into the portal vein. Examination of a tissue sample obtained during the procedure showed that the mass was consistent with pancreatic adenocarcinoma. Magnetic resonance imaging (MRI) performed to define venous vasculature involvement revealed a pancreatic head mass measuring 3.0 × 2.7 cm without arterial or venous vasculature invasion. The mass was abutting the portal vein and superior mesenteric veins, and a nonspecific 8-mm aortocaval lymph node was noted. The tumor was deemed to be borderline resectable, and the patient received neoadjuvant therapy with gemcitabine and nab-paclitaxel. After 4 cycles, his carbohydrate antigen (CA) 19-9 level decreased, and MRI revealed a smaller head mass (1.3 × 1.4 cm) with stable effacement of the superior mesenteric vein and no portal vein involvement; the aortocaval lymph node remained stable. He was treated with gemcitabine chemoradiotherapy prior to undergoing an uncomplicated partial pancreaticoduodenectomy. Analysis of a surgical pathology specimen revealed T3N0 disease with a closest margin of 0.1 cm. Postsurgery, the patient completed 4 cycles of adjuvant chemotherapy with gemcitabine plus capecitabine.

At his current presentation, MRI of the abdomen and pelvis reveals a new liver mass and peritoneal thickness. Serology testing reveals a CA 19-9 level of 240 U/mL, and other liver function tests are within normal limits. Biopsy of the mass confirms recurrence.

• What systemic chemotherapy would you recommend for this patient with metastatic pancreatic adenocarcinoma?

Most cases of pancreatic cancer are unresectable and/or metastatic at the time of diagnosis. Identifying treatment endpoints and the patient’s goals of care is a critical step in management. Systemic chemotherapy can provide significant survival benefit in first-line and second-line treatment compared to best supportive care. Palliative interventions also include systemic therapy, which often improves pain control and other cancer related–symptoms and hence quality of life. Participation in clinical trials should be offered to all patients. Therapy selection depends on the patient’s performance status, comorbidities, and liver profile and the results of biomarker testing and mutation analysis.

Several single-agents, including fluoropyrimidines, gemcitabine, irinotecan, platinum compounds, and taxanes, have minor objective response rates (< 10%) and a minimal survival benefit (~2 weeks) in metastatic pancreatic adenocarcinoma. Conversely, multi-agent therapies provide higher response rates and can extend overall survival (OS). Two combinations, nab-paclitaxel plus gemcitabine and FOLFIRINOX (oxaliplatin, irinotecan, leucovorin, and flourouracil), have significantly prolonged survival compared to best single-agent gemcitabine, as demonstrated in the MPACT (Metastatic Pancreatic Adenocarcinoma Clinical Trial) and PRODIGE 4/ACCORD 11 trials.^5,6 Because both multi-agent regimens are also associated with a more toxic adverse effect profile, gemcitabine monotherapy continues to be a front-line therapy for patients with multiple comorbidities, elderly frail patients (> 80 years of age), or patients who cannot tolerate other combinations.⁷

Gemcitabine-Based Therapy

Gemcitabine became a standard of care treatment for pancreatic cancer in the mid-1990s, and was tested as a second-line therapy in a multicenter phase 2 clinical trial that accrued 74 patients with metastatic pancreatic cancer who had progressed on fluorouracil therapy. In this trial, 27% of patients treated with gemcitabine achieved a clinical benefit response and the median OS was 3.85 months.⁸ The agent was generally well-tolerated with a low incidence of grade 3 or 4 toxicities. Subsequently, a randomized clinical trial compared gemcitabine to fluorouracil in the front-line setting in 126 patients with newly diagnosed advanced pancreatic cancer.⁹ Patients were randomly assigned to receive single-agent intravenous fluorouracil administered without leucovorin as a short-term infusion (600 mg/m² once weekly) or gemcitabine (1000 mg/m² weekly for up to 7 weeks followed by 1 week of rest, and then weekly for 3 out of every 4 weeks thereafter). A higher proportion of patients treated with gemcitabine had a clinical benefit response (23.8% versus 4.8%), with an improvement in a composite measure of pain (pain intensity and analgesic consumption) and performance status. Clinical responses assessed by a secondary measure, weight gain, were below 10% in both arms, but the median OS was significantly longer for the gemcitabine arm (5.65 months versus 4.4 months, P = 0.0025) and the 1-year OS rate also favored the gemcitabine arm (18% versus 2%). Grade 3/4 neutropenia was reported more frequently in the gemcitabine arm (23% versus 5%). There is no evidence that increasing the dose intensity of the fixed-dose rate of gemcitabine (1000 mg/m² per week administered as a 30-minute infusion) leads to improved antitumor activity.

Following publication of the trial conducted by Burris and colleagues,⁹ a plethora of clinical trials have tried to outperform gemcitabine monotherapy, with all trials studying gemcitabine monotherapy compared with gemcitabine plus another agent (fluorouracil, cisplatin, oxaliplatin, irinotecan, pemetrexed, novel biologics including cetuximab, bevacizumab, axitinib, sorafenib, aflibercept). These combinations have failed to significantly extend OS compared to single-agent gemcitabine, although some showed a marginal clinical benefit:

• Capecitabine¹⁰ (hazard ratio [HR] 0.86 [95% confidence interval {CI} 0.75 to 0.98])
• Erlotinib¹¹ (HR 0.81 [95% CI 0.69 to 0.99])
• Cisplatin, epirubicin, fluorouracil, gemcitabine¹² (HR 0.65 [95% CI 0.43 to 0.99])

The best outcomes were obtained with gemcitabine plus nab-paclitaxel compared to gemcitabine monotherapy. The gemcitabine/nab-paclitaxel combination has not been compared to FOLFIRINOX in the front-line setting, as the ACCORD 11 and MPACT trials were ongoing simultaneously. However, a large retrospective trial that compared use of the regimens in the US Oncology Network in the United States demonstrated similar efficacy, although more patients treated with FOLFIRINOX needed white blood cell growth factor administration.¹³

Gemcitabine/nab-paclitaxel was studied in a phase 1/2 clinical trial with 67 untreated metastatic pancreatic cancer patients.¹⁴ Patients received nab-paclitaxel at doses of 100, 125, or 150 mg/m² followed by gemcitabine 1000 mg/m² on days 1, 8, and 15 every 28 days. The maximum tolerated dose (MTD) was 1000 mg/m² of gemcitabine plus 125 mg/m² of nab-paclitaxel once a week for 3 weeks every 28 days. Dose-limiting toxicities were sepsis and neutropenia. Patients who received the MTD had a response rate of 48%, median OS of 12.2 months, and a 1-year survival rate of 48%.

The landmark phase 3 MPACT trial confirmed that adding nab-paclitaxel to gemcitabine prolongs survival compared with gemcitabine monotherapy.⁵ This multinational randomized study included 861 treatment-naive patients with a Karnofsky performance score of 70 or higher. The median OS in the nab-paclitaxel/gemcitabine group was 8.5 months, as compared to 6.7 months in the gemcitabine monotherapy group (HR for death 0.72 [95% CI 0.62 to 0.83], P < 0.001). The survival rate was 35% in the nab-paclitaxel/gemcitabine group versus 22% in the gemcitabine group at 1 year, and 9% versus 4% at 2 years. Median progression-free survival (PFS) was 5.5 months in the nab-paclitaxel/gemcitabine group, compared to 3.7 months in the gemcitabine group (HR for disease progression or death 0.69 [95% CI 0.58 to 0.82], P < 0.001). The overall response rate according to independent review was 23% compared with 7% in the 2 groups, respectively (P < 0.001). The most common adverse events of grade 3 or higher were neutropenia (38% in the nab-paclitaxel/gemcitabine group versus 27% in the gemcitabine group), fatigue (17% versus 7%), and neuropathy (17% versus 1%). Febrile neutropenia occurred in 3% of the combination group versus 1% of the montherapy group. In the nab-paclitaxel/gemcitabine group, neuropathy of grade 3 or higher improved to grade 1 or lower a median of 29 days after discontinuation of nab-paclitaxel. In 2013, nab-paclitaxel in combination with gemcitabine received U.S. Food and Drug Administration (FDA) approval as first-line therapy for metastatic pancreatic cancer.

A pilot phase 1b/2 trial that added cisplatin to nab-paclitaxel and gemcitabine in treating 24 treatment-naive metastatic pancreatic adenocarcinoma patients showed impressive tumor response (complete response 8.3%, partial response 62.5%, stable disease 16.7%, progressive disease 12.5%) and extended median OS to 16.5 months.¹⁵ A phase 1b trial conducted in Europe added capecitabine to the cisplatin, nab-paclitaxel, and gemcitabine regimen, albeit with a different schedule and doses, in 24 patients with locally advanced and metastatic disease.¹⁶ This trial demonstrated an impressive overall response rate of 67%, with 43% of patients achieving a complete metabolic response on positron emission tomography scan and the CA 19-9 level decreasing by ≥ 49% in all 19 patients who had an elevated basal value. Moreover, PFS at 6 months was 96%. After chemotherapy 17 patients remained unresectable and 7 patients were taken to surgery; of the latter group, only 1 was determined to be unresectable at the time of surgery. This regimen is being explored in a larger study in patients with stage III and IV disease.

FOLFIRINOX

A randomized phase 2 clinical trial comparing FOLFIRINOX to gemcitabine monotherapy in 88 patients with treatment-naive metastatic pancreatic cancer revealed a high response rate for FOLFIRINOX (39% versus 11%, respectively) with a tolerable toxicity profile.¹⁷ FOLFIRINOX became the front-line standard of care therapy in pancreatic adenocarcinoma after the results of the subsequent phase 3 ACCORD 11 study preplanned interim analysis showed an unprecedented significantly improved OS benefit.⁶ The ACCORD 11 trial randomly assigned 342 patients with an Eastern Cooperative Oncology Group (ECOG) score of 0 or 1 and a serum bilirubin level less than 1.5 times the upper limit of normal to receive FOLFIRINOX (oxaliplatin 85 mg/m², irinotecan 180 mg/m², leucovorin 400 mg/m², and fluorouracil 400 mg/m² given as a bolus followed by 2400 mg/m² given as a 46-hour continuous infusion, every 2 weeks) or gemcitabine at a dose of 1000 mg/m² weekly for 7 of 8 weeks and then weekly for 3 of 4 weeks. The median OS in the FOLFIRINOX group was 11.1 months as compared with 6.8 months in the gemcitabine group (HR 0.57 [95% CI 0.45 to 0.73], P < 0.001). The FOLFIRINOX group also had a longer median PFS (6.4 months versus 3.3 months, HR 0.47 [95% CI 0.37 to 0.59], P < 0.001) and higher objective response rate (31.6% versus 9.4%, P < 0.001). More adverse events were noted in the FOLFIRINOX group, including grade 3 or 4 neutropenia (46% versus 21%), febrile neutropenia (5.4% versus 1.2%), thrombocytopenia (9.1% versus 3.6%), sensory neuropathy (9% versus 0%), vomiting (15% versus 8%), fatigue (23% versus 18%), and diarrhea (13% versus 2%). Despite the greater toxicity, only 31% of the FOLFIRINOX group had a definitive degradation of quality of life, as compared to 66% in the gemcitabine group (HR 0.47 [95% CI 0.30 to 0.70], P < 0.001), thus indicating an improvement in quality of life.

Of note, combinations containing irinotecan require adequate biliary function for excretion of its active glucuronide metabolite, SN-38. Approximately 10% of patients in the United States are homozygous for the UGT1A1*28 allele polymorphism, which causes increased SN-38 bioavailability and hence a potential for severe toxicities (eg, life threatening-refractory diarrhea).¹⁸ Therefore, it is recommended that physicians start with a lower dose of irinotecan or choose a different regimen altogether in such patients.

Current Approach and Future Directions

Based on results of the ACCORD 11 and MPACT trials, both front-line regimens (nab-paclitaxel/gemcitabine and FOLFIRINOX) can be considered appropriate treatment options for treatment-naive patients with good performance status who have locally advanced unresectable or metastatic pancreatic adenocarcinoma. FOLFIRINOX has a higher objective response rate than nab-paclitaxel-gemcitabine (32% versus 23%, respectively), but the adverse effect profile favors the nab-paclitaxel/gemcitabine combination, acknowledging this conclusion is limited due to lack of a comparative trial. Modifications to both regimens have been presented at American Society of Clinical Oncology symposiums, with preliminary data showing an extended median OS and a more tolerable toxicity profile.^19,20 In a recent retrospective observational cohort comparative analysis of nab-paclitaxel/gemcitabine versus FOLFIRINOX, results showed no statistical difference in median OS. The real-world data showed that gemcitabine-based therapy is being offered commonly to elderly patients and patients with poor performance status.¹³ There is no current research proposal for conducting a direct head-to-head comparison between these 2 regimens. Based on extrapolated data from the prior mentioned trials and retrospective analysis reviews, current guidelines recommend offering younger (< 65 years old), healthier (no comorbidity contraindication) patients with excellent performance status (ECOG 0) first-line FOLFIRINOX or gemcitabine/nab-paclitaxel. Elderly patients with stable comorbidities and good performance status (ECOG 1 or 2, Karnofsky performance status ≥ 70) could be preferably considered for treatment with nab-paclitaxel/gemcitabine as first-line or modified FOLFIRINOX if performance status is excellent. Patients with poor performance status (ECOG ≥ 2), advanced age, and significant comorbidities could still be considered candidates for gemcitabine monotherapy. However, there are promising indications that the combination of gemcitabine, nab-paclitaxel, and cisplatin could be a frontline therapy in advanced pancreaticobilliary malignancies in the future.

Second-Line Systemic Treatment

Case Continued

The patient and oncologist opt to begin treatment with modified FOLFIRINOX therapy, and after the patient completes 10 cycles CT scan shows progression of disease. His oncologist decides to refer the patient to a comprehensive cancer center for evaluation for participation in clinical trials, as his performance status remains very good (ECOG 1) and he would like to seek a novel therapy. His liver mass biopsy and blood liquid biopsy are sent for tumor mutational profile evaluation; results show a high tumor mutational burden and microsatellite instability.

• What are second-line treatment options for metastatic pancreatic cancer?

Second-line regimen recommendations for metastatic pancreatic cancer depend on which agents were used in first-line therapy and the patient’s performance status and comorbidities. Patients who progressed on first-line FOLFIRINOX and continue to have a good performance status (ECOG 0 or 1) may be considered for gemcitabine/nab-paclitaxel therapy; otherwise, they may be candidates for gemcitabine plus capecitabine or gemcitabine monotherapy based on performance status and goals of care. Patients who progressed on front-line gemcitabine/nab-paclitaxel may opt for FOLFIRINOX (or an oxaliplatin-based regimen [FOLFOX] or irinotecan-based regimen [FOLFIRI] if FOLFIRINOX is not tolerable), nanoliposomal irinotecan/fluorouracil/leucovorin, or a short-term infusional fluorouracil and leucovorin regimen. The preferences for second-line treatment are not well established, and patients should be encouraged to participate in clinical trials. Chemotherapy should be offered only to those patients who maintain good performance status after progression on first-line therapy. For patients with poor performance status (ECOG 3 or 4) or multiple comorbidities, a discussion about goals of care and palliative therapy is warranted.

Gemcitabine-Based Therapy

An AGEO prospective multicenter cohort assigned 57 patients with metastatic pancreatic adenocarcinoma who had disease progression on FOLFIRINOX therapy to receive gemcitabine/nab-paclitaxel (dose as per MPACT trial).²¹ The median OS was 8.8 months and median PFS was 5.1 months after FOLFIRINOX. There were reported manageable grade 3/4 toxicities in 40% of patients, which included neutropenia (12.5%), neurotoxicity (12.5%), asthenia (9%), and thrombocytopenia (6.5%). A phase 2 clinical trial that evaluated gemcitabine monotherapy in 74 patients with metastatic pancreatic cancer who had progressed on fluorouracil showed a 3.85-month survival benefit.²²

Irinotecan-Based Regimens

The NAPOLI-1 (NAnoliPOsomaL Irinotecan) trial evaluated nanoliposomal irinotecan (MM-398, nal-IRI) and fluorouracil/leucovorin in patients with metastatic pancreatic cancer refractory to gemcitabine-based therapy.²³ This global, open-label phase 3 trial initially randomly assigned and stratified 417 patients in a 1:1 fashion to receive either nanoliposomal irinotecan monotherapy (120 mg/m² every 3 weeks, equivalent to 100 mg/m² of irinotecan base) or fluorouracil/leucovorin combination. A third treatment arm consisting of nanoliposomal irinotecan (80 mg/m², equivalent to 70 mg/m² of irinotecan base) with fluorouracil and leucovorin every 2 weeks was added later in a 1:1:1 fashion. Patients assigned to nanoliposomal irinotecan plus fluorouracil/leucovorin had a significantly improved OS of 6.1 months compared to 4.2 months with fluorouracil/leucovorin (HR 0.67 [95% CI 0.49 to 0.92], P = 0.012). The results of an intention-to-treat analysis favored the nanoliposomal irinotecan regimen, with a median OS of 8.9 months compared with 5.1 months (HR 0.57, P = 0.011). In addition, median PFS was improved in the nanoliposomal irinotecan arm (3.1 months versus 1.5 months; HR 0.56, P < 0.001), and median OS did not differ between patients treated with nanoliposomal irinotecan monotherapy and those treated with fluorouracil/leucovorin (4.9 months versus 4.2 months; HR 0.99 [95% CI 0.77 to 1.28], P = 0.94). The grade 3/4 adverse events that occurred most frequently in the 117 patients assigned to nanoliposomal irinotecan plus fluorouracil/leucovorin were neutropenia (27%), diarrhea (13%), vomiting (11%), and fatigue (14%). Nanoliposomal irinotecan combination provides another second-line treatment option for patients with metastatic pancreatic adenocarcinoma who have progressed on gemcitabine-based therapy but are not candidates for FOLFIRINOX.

Oxaliplatin-Based Regimens

Regimens that combine oxaliplatin with fluorouracil and leucovorin or capecitabine have shown superiority to fluorouracil/leucovorin or best supportive care (BSC). The CONKO study group compared oxaliplatin plus fluorouracil/leucovorin to BSC as second-line therapy in patients with advanced pancreatic cancer who progressed while on gemcitabine therapy (CONKO-003).²⁴ In this phase 3 trial, patients were randomly assigned (1:1) and stratified based on duration of first-line therapy, performance status, and tumor stage to receive BSC alone or the OFF regimen, which consisted of oxaliplatin (85 mg/m² on days 8 and 22) plus short-term infusional fluorouracil (2000 mg/m² over 24 hours) and leucovorin (200 mg/m² over 30 minutes), both given on days 1, 8, 15, and 22 of a 6-week cycle. This trial was terminated early according to predefined protocol regulations because of insufficient accrual (lack of acceptance of BSC by patients and physicians). Median second-line survival was 4.82 months for patients who received OFF treatment and 2.30 months for those who received BSC (HR 0.45 [95% CI 0.24 to 0.83], P = 0.008).  Neurotoxicity (grade 1/2) and nausea, emesis, and diarrhea (grade 2/3) were worse in the chemotherapy arm; otherwise, the regimen was well tolerated.

A later modification of the CONKO-003 trial changed the comparison arm from BSC to fluorouracil/leucovorin.²⁵ The median OS in the OFF group was 5.9 months versus 3.3 months in the fluorouracil/leucovorin group (HR 0.66 [95% CI 0.48 to 0.91], log-rank P = 0.010). Time to progression was significantly extended with OFF (2.9 months) as compared with fluorouracil/leucovorin (2.0 months; HR 0.68 [95% CI 0.50 to 0.94], log-rank P = 0.019). Rates of adverse events were similar between the treatment arms, with the exception of grades 1/2 neurotoxicity, which were reported in 38.2% and 7.1% of patients in the OFF and fluorouracil/leucovorin groups, respectively (P < 0.001).

The phase 3 PANCREOX trial failed to show superiority of modified FOLFOX6 (mFOLFOX6; infusional fluorouracil, leucovorin, and oxaliplatin) over fluorouracil/leucovorin.²⁶ A phase 2 trial of oxaliplatin plus capecitabine for second-line therapy in gemcitabine-treated advanced pancreatic cancer patients with dose adjustments for performance status (ECOG 2) and age (> 65 years) showed a median OS of 5.7 months without a comparison.²⁷ A modified oxaliplatin regimen may be a reasonable second-line therapy option for gemcitabine-treated patients who are not candidates for an irinotecan-based regimen (eg, elevated bilirubin) and continue to have an acceptable performance status.

Targeted Therapies

A variety of targeted therapies have failed to demonstrate major activity in metastatic pancreatic cancer, including bevacizumab targeting vascular endothelial growth factor, cetuximab targeting epidermal growth factor receptor, ruxolitinib targeting JAK pathway signaling, saridegib targeting the hedgehog pathway, and MK-0646 targeting insulin-like growth factor 1 receptor (IGFR). Other novel agents against targetable pathways that had promising early-phase results are currently being studied in ongoing clinical trials; these include JAK-2, PI3K, MEK, and BRAF inhibitors and immunotherapy.

Recent research efforts have focused on targeted testing of advanced pancreatic cancers for mismatch repair deficiency (dMMR) and high microsatellite instability (MSI-H) and for the germline and somatic BRCA1/2 or PALB2 mutations to determine potential eligibility for immunotherapy. Patients with these tumor characteristics and/or mutations might also be more sensitive to platinum-based chemotherapy agents or poly (ADP-ribose) polymerase (PARP) inhibitors. Germline mutations in BRCA 1/2 are present in 5% to 8% of patients with pancreatic cancer (up to 10%–15% in Ashkenazi Jewish population).²⁸ A superior median OS was retrospectively observed for patients with advanced stage BRCA 1/2-associated pancreatic adenocarcinoma who were treated with platinum-based chemotherapy agents versus those treated with non-platinum-based agents (22 versus 9 months; P = 0.039).²² PARP inhibitors have shown activity in germline BRCA1/2-associated breast (off label) and ovarian cancers (approved by the FDA). The efficacy and safety of PARP inhibitors were evaluated in a phase 2 study of a spectrum of BRCA1/2-associated cancers, including pancreatic cancer. The results revealed a tumor response rate of 21.7% (5 of 23 patients with pancreatic cancer [95% CI 7.5 to 43.7]), and 35% of patients had stable disease for a duration of 8 weeks or more (95% CI 16.4 to 57.3) with good tolerability.²⁹ Three novel PARP inhibitors are currently under clinical trial investigation in patients with germline BRCA 1/2- and PALB2-mutated metastatic pancreatic cancer: maintenance olaparib (NCT02184195) and rucaparib (NCT03140670) are both being studied as monotherapy in patients whose disease has not progressed on first-line platinum-based chemotherapy, and veliparib is being evaluated in a 3-arm study that includes gemcitabine and cisplatin with or without veliparib and single-agent maintenance veliparib (NCT01585805).

In 2017, the FDA granted accelerated approval to pembrolizumab for treatment of patients with unresectable or metastatic MSI-H or dMMR solid tumors whose disease progressed on prior treatments, making it the first oncology drug to be approved based on the genetic features of the tumor rather than its location in the body. This first tissue/site-agnostic approval was based on results from 5 single-arm trials involving 149 patients, including 5 patients with pancreatic cancer.³⁰ The objective response rate with pembrolizumab was 39.6% (95% CI 31.7 to 47.9), including a 7.4% complete response rate and a 32.2% partial response rate. The median duration of response was not reached at the time of publication (range, 1.6+ months to 22.7+ months).

Palliative and Supportive Care

Case Continued

The patient opts to participate in a novel immunotherapy clinical trial and is currently on his second cycle. He continues to have right upper quadrant pain despite opioid analgesia, has not gained any weight, and noticed new right lower extremity swelling after a recent holiday vacation to Florida.

• What supportive measures should be in place for patients with metastatic adenocarcinoma?

Most patients with advanced pancreatic adenocarcinoma will require a palliative intervention. All new unresectable pancreatic cancer patients should have an early psychosocial evaluation; identification of symptoms and implementation of preventive interventions that would improve quality of life and reduce suffering are paramount. A multidisciplinary team including physician/nursing staff, nutritionist/dietitian, palliative service, a social worker, and a case manager should be involved in patient care. More than two-thirds of patients can develop symptomatic biliary obstruction.³¹ Bile duct obstruction due to locally advanced pancreatic adenocarcinoma causes hyperbilirubinemia, which requires endoscopic placement of a metallic or plastic stent; plastic stents have a higher rate of re-occlusion.³² Appropriate bile flow allows treatment with irinotecan-based regimens. Percutaneous biliary drainage may be necessary if endoscopic intervention is not feasible.

Approximately one quarter of patients may present with gastric outlet obstruction due to duodenal obstruction.³¹ Endoscopic placement of an enteral expandable metal stent is preferred. Alternatively, percutaneous endoscopic gastrostomy tube placement may give symptomatic relief. Palliative surgical interventions are reserved for patients with greater life expectancy and in whom all other interventions have failed or are not feasible.

Almost all patients with pancreatic adenocarcinoma will experience cancer-associated pain. Intractable pain should be treated with a celiac plexus block. Radiation therapy may be considered as an adjunct therapy for pain, bleeding, and/or local obstruction. The National Comprehensive Cancer Network guidelines recommend that patients who undergo a laparotomy for potentially resectable disease but are found to have unresectable disease at the time of surgery should undergo stenting, open biliary-enteric bypass with or without gastrojejunostomy, and/or celiac plexus neurolysis.³³

Pancreatic exocrine enzyme insufficiency due to tumor extension, duct blockage, or surgical removal may cause malabsoprtive steatorrhea, contributing to cancer cachexia syndrome. Nutritional evaluation and daily oral pancreatic enzyme supplementation are recommended.³⁴

Patients diagnosed with pancreatic adenocarcinoma have a venous thromboembolism (VTE) incidence of 20 per 100 person-years (5%–60% of patients) and are considered at very high risk for VTE based on the Khorana score.³⁵ The preferred VTE treatment is low-molecular-weight heparin rather than warfarin based on the results of the CLOT study.³⁶ There is no current evidence for routine prophylactic therapy or the use of direct oral anticoagulants.

Finally, a cancer diagnosis, particularly pancreatic cancer, causes a significant amount of psychosocial stress and requires active support and counseling from a professional.

Conclusion

Pancreatic adenocarcinoma is the most lethal of all the gastrointestinal malignancies. FOLFIRINOX and gemcitabine/nab-paclitaxel are superior to gemcitabine monotherapy for patients with advanced unresectable and/or metastatic pancreatic cancer who are candidates for more aggressive therapy and are considered first-line therapies. Early data on the gemcitabine, nab-paclitaxel, and cisplatin combination appears to show superior efficacy. Second-line therapies are selected based on the patient’s performance status, first-line regimen, and residual toxicities from the prior regimen; options include gemcitabine/nab-paclitaxel, FOLFIRINOX (± oxaliplatin or irinotecan), single-agent gemcitabine (elderly frail patients), fluorouracil and liposomal-irinotecan, or referral for a clinical trial. The main challenge with pancreatic cancer is the development of stroma around the tumor, which abrogates drug delivery, allows for tumor growth in a hypoxic microenvironment, alters the metabolomics, and causes an immunosuppressive microenvironment. Drugs that target the microenvironments, such as hedgehog pathway inhibitors, have failed to show any clinical benefit, and we hope to see more efficacious microenvironment-targeted novel drugs in the future. In addition, immunotherapy has not shown any significant efficacy in clinical trials and many trials are still ongoing.

Introduction

Pancreatic ductal adenocarcinoma is a challenging disease with a poor prognosis, with 5-year survival rates in the single digits (~8%).¹ Survival rates in pancreatic cancer are low in part because most patients have advanced disease at the time of diagnosis and early development of systemic metastatic disease is common, with approximately 52% of patients with newly diagnosed pancreatic cancer having metastatic disease at diagnosis.¹ Surgical resection with negative margins is the cornerstone of potentially curative therapy for localized disease, but only 15% to 20% of patients are eligible for resection at the time of initial diagnosis. Patients with unresectable and metastatic disease are offered palliative chemotherapy. Unfortunately, early recurrence is common in patients with resectable tumors who achieve a complete resection and are treated with adjuvant therapy (5-year recurrence rate ~80%).^2,3 This article reviews the management of patients with unresectable and/or metastatic pancreatic cancer. A previous article reviewed the diagnosis and staging of pancreatic cancer and the approach to neoadjuvant and adjuvant therapy in patients with resectable and borderline-resectable disease.⁴

First-Line Systemic Treatment

Case Presentation

A 72-year-old man who underwent treatment for pancreatic adenocarcinoma 18 months ago presents to the emergency department after developing poor appetite, weight loss, and abdominal discomfort and fullness without diarrhea, which has been constant for the past 2 weeks even though he has been taking analgesics and pancreatic enzymes.

The patient was diagnosed with pancreatic cancer 18 months ago after presenting with yellowish skin and sclera color; abdominal and pelvis computed tomography (CT) with intravenous contrast showed a pancreatic head mass measuring 2.6 × 2.3 cm minimally abutting the anterior surface of the superior mesenteric vein. Endoscopic ultrasound confirmed an irregular mass at the head of the pancreas and sonographic evidence suggested invasion into the portal vein. Examination of a tissue sample obtained during the procedure showed that the mass was consistent with pancreatic adenocarcinoma. Magnetic resonance imaging (MRI) performed to define venous vasculature involvement revealed a pancreatic head mass measuring 3.0 × 2.7 cm without arterial or venous vasculature invasion. The mass was abutting the portal vein and superior mesenteric veins, and a nonspecific 8-mm aortocaval lymph node was noted. The tumor was deemed to be borderline resectable, and the patient received neoadjuvant therapy with gemcitabine and nab-paclitaxel. After 4 cycles, his carbohydrate antigen (CA) 19-9 level decreased, and MRI revealed a smaller head mass (1.3 × 1.4 cm) with stable effacement of the superior mesenteric vein and no portal vein involvement; the aortocaval lymph node remained stable. He was treated with gemcitabine chemoradiotherapy prior to undergoing an uncomplicated partial pancreaticoduodenectomy. Analysis of a surgical pathology specimen revealed T3N0 disease with a closest margin of 0.1 cm. Postsurgery, the patient completed 4 cycles of adjuvant chemotherapy with gemcitabine plus capecitabine.

At his current presentation, MRI of the abdomen and pelvis reveals a new liver mass and peritoneal thickness. Serology testing reveals a CA 19-9 level of 240 U/mL, and other liver function tests are within normal limits. Biopsy of the mass confirms recurrence.

• What systemic chemotherapy would you recommend for this patient with metastatic pancreatic adenocarcinoma?

Most cases of pancreatic cancer are unresectable and/or metastatic at the time of diagnosis. Identifying treatment endpoints and the patient’s goals of care is a critical step in management. Systemic chemotherapy can provide significant survival benefit in first-line and second-line treatment compared to best supportive care. Palliative interventions also include systemic therapy, which often improves pain control and other cancer related–symptoms and hence quality of life. Participation in clinical trials should be offered to all patients. Therapy selection depends on the patient’s performance status, comorbidities, and liver profile and the results of biomarker testing and mutation analysis.

Several single-agents, including fluoropyrimidines, gemcitabine, irinotecan, platinum compounds, and taxanes, have minor objective response rates (< 10%) and a minimal survival benefit (~2 weeks) in metastatic pancreatic adenocarcinoma. Conversely, multi-agent therapies provide higher response rates and can extend overall survival (OS). Two combinations, nab-paclitaxel plus gemcitabine and FOLFIRINOX (oxaliplatin, irinotecan, leucovorin, and flourouracil), have significantly prolonged survival compared to best single-agent gemcitabine, as demonstrated in the MPACT (Metastatic Pancreatic Adenocarcinoma Clinical Trial) and PRODIGE 4/ACCORD 11 trials.^5,6 Because both multi-agent regimens are also associated with a more toxic adverse effect profile, gemcitabine monotherapy continues to be a front-line therapy for patients with multiple comorbidities, elderly frail patients (> 80 years of age), or patients who cannot tolerate other combinations.⁷

Gemcitabine-Based Therapy

Gemcitabine became a standard of care treatment for pancreatic cancer in the mid-1990s, and was tested as a second-line therapy in a multicenter phase 2 clinical trial that accrued 74 patients with metastatic pancreatic cancer who had progressed on fluorouracil therapy. In this trial, 27% of patients treated with gemcitabine achieved a clinical benefit response and the median OS was 3.85 months.⁸ The agent was generally well-tolerated with a low incidence of grade 3 or 4 toxicities. Subsequently, a randomized clinical trial compared gemcitabine to fluorouracil in the front-line setting in 126 patients with newly diagnosed advanced pancreatic cancer.⁹ Patients were randomly assigned to receive single-agent intravenous fluorouracil administered without leucovorin as a short-term infusion (600 mg/m² once weekly) or gemcitabine (1000 mg/m² weekly for up to 7 weeks followed by 1 week of rest, and then weekly for 3 out of every 4 weeks thereafter). A higher proportion of patients treated with gemcitabine had a clinical benefit response (23.8% versus 4.8%), with an improvement in a composite measure of pain (pain intensity and analgesic consumption) and performance status. Clinical responses assessed by a secondary measure, weight gain, were below 10% in both arms, but the median OS was significantly longer for the gemcitabine arm (5.65 months versus 4.4 months, P = 0.0025) and the 1-year OS rate also favored the gemcitabine arm (18% versus 2%). Grade 3/4 neutropenia was reported more frequently in the gemcitabine arm (23% versus 5%). There is no evidence that increasing the dose intensity of the fixed-dose rate of gemcitabine (1000 mg/m² per week administered as a 30-minute infusion) leads to improved antitumor activity.

Following publication of the trial conducted by Burris and colleagues,⁹ a plethora of clinical trials have tried to outperform gemcitabine monotherapy, with all trials studying gemcitabine monotherapy compared with gemcitabine plus another agent (fluorouracil, cisplatin, oxaliplatin, irinotecan, pemetrexed, novel biologics including cetuximab, bevacizumab, axitinib, sorafenib, aflibercept). These combinations have failed to significantly extend OS compared to single-agent gemcitabine, although some showed a marginal clinical benefit:

• Capecitabine¹⁰ (hazard ratio [HR] 0.86 [95% confidence interval {CI} 0.75 to 0.98])
• Erlotinib¹¹ (HR 0.81 [95% CI 0.69 to 0.99])
• Cisplatin, epirubicin, fluorouracil, gemcitabine¹² (HR 0.65 [95% CI 0.43 to 0.99])

The best outcomes were obtained with gemcitabine plus nab-paclitaxel compared to gemcitabine monotherapy. The gemcitabine/nab-paclitaxel combination has not been compared to FOLFIRINOX in the front-line setting, as the ACCORD 11 and MPACT trials were ongoing simultaneously. However, a large retrospective trial that compared use of the regimens in the US Oncology Network in the United States demonstrated similar efficacy, although more patients treated with FOLFIRINOX needed white blood cell growth factor administration.¹³

Gemcitabine/nab-paclitaxel was studied in a phase 1/2 clinical trial with 67 untreated metastatic pancreatic cancer patients.¹⁴ Patients received nab-paclitaxel at doses of 100, 125, or 150 mg/m² followed by gemcitabine 1000 mg/m² on days 1, 8, and 15 every 28 days. The maximum tolerated dose (MTD) was 1000 mg/m² of gemcitabine plus 125 mg/m² of nab-paclitaxel once a week for 3 weeks every 28 days. Dose-limiting toxicities were sepsis and neutropenia. Patients who received the MTD had a response rate of 48%, median OS of 12.2 months, and a 1-year survival rate of 48%.

The landmark phase 3 MPACT trial confirmed that adding nab-paclitaxel to gemcitabine prolongs survival compared with gemcitabine monotherapy.⁵ This multinational randomized study included 861 treatment-naive patients with a Karnofsky performance score of 70 or higher. The median OS in the nab-paclitaxel/gemcitabine group was 8.5 months, as compared to 6.7 months in the gemcitabine monotherapy group (HR for death 0.72 [95% CI 0.62 to 0.83], P < 0.001). The survival rate was 35% in the nab-paclitaxel/gemcitabine group versus 22% in the gemcitabine group at 1 year, and 9% versus 4% at 2 years. Median progression-free survival (PFS) was 5.5 months in the nab-paclitaxel/gemcitabine group, compared to 3.7 months in the gemcitabine group (HR for disease progression or death 0.69 [95% CI 0.58 to 0.82], P < 0.001). The overall response rate according to independent review was 23% compared with 7% in the 2 groups, respectively (P < 0.001). The most common adverse events of grade 3 or higher were neutropenia (38% in the nab-paclitaxel/gemcitabine group versus 27% in the gemcitabine group), fatigue (17% versus 7%), and neuropathy (17% versus 1%). Febrile neutropenia occurred in 3% of the combination group versus 1% of the montherapy group. In the nab-paclitaxel/gemcitabine group, neuropathy of grade 3 or higher improved to grade 1 or lower a median of 29 days after discontinuation of nab-paclitaxel. In 2013, nab-paclitaxel in combination with gemcitabine received U.S. Food and Drug Administration (FDA) approval as first-line therapy for metastatic pancreatic cancer.

A pilot phase 1b/2 trial that added cisplatin to nab-paclitaxel and gemcitabine in treating 24 treatment-naive metastatic pancreatic adenocarcinoma patients showed impressive tumor response (complete response 8.3%, partial response 62.5%, stable disease 16.7%, progressive disease 12.5%) and extended median OS to 16.5 months.¹⁵ A phase 1b trial conducted in Europe added capecitabine to the cisplatin, nab-paclitaxel, and gemcitabine regimen, albeit with a different schedule and doses, in 24 patients with locally advanced and metastatic disease.¹⁶ This trial demonstrated an impressive overall response rate of 67%, with 43% of patients achieving a complete metabolic response on positron emission tomography scan and the CA 19-9 level decreasing by ≥ 49% in all 19 patients who had an elevated basal value. Moreover, PFS at 6 months was 96%. After chemotherapy 17 patients remained unresectable and 7 patients were taken to surgery; of the latter group, only 1 was determined to be unresectable at the time of surgery. This regimen is being explored in a larger study in patients with stage III and IV disease.

FOLFIRINOX

A randomized phase 2 clinical trial comparing FOLFIRINOX to gemcitabine monotherapy in 88 patients with treatment-naive metastatic pancreatic cancer revealed a high response rate for FOLFIRINOX (39% versus 11%, respectively) with a tolerable toxicity profile.¹⁷ FOLFIRINOX became the front-line standard of care therapy in pancreatic adenocarcinoma after the results of the subsequent phase 3 ACCORD 11 study preplanned interim analysis showed an unprecedented significantly improved OS benefit.⁶ The ACCORD 11 trial randomly assigned 342 patients with an Eastern Cooperative Oncology Group (ECOG) score of 0 or 1 and a serum bilirubin level less than 1.5 times the upper limit of normal to receive FOLFIRINOX (oxaliplatin 85 mg/m², irinotecan 180 mg/m², leucovorin 400 mg/m², and fluorouracil 400 mg/m² given as a bolus followed by 2400 mg/m² given as a 46-hour continuous infusion, every 2 weeks) or gemcitabine at a dose of 1000 mg/m² weekly for 7 of 8 weeks and then weekly for 3 of 4 weeks. The median OS in the FOLFIRINOX group was 11.1 months as compared with 6.8 months in the gemcitabine group (HR 0.57 [95% CI 0.45 to 0.73], P < 0.001). The FOLFIRINOX group also had a longer median PFS (6.4 months versus 3.3 months, HR 0.47 [95% CI 0.37 to 0.59], P < 0.001) and higher objective response rate (31.6% versus 9.4%, P < 0.001). More adverse events were noted in the FOLFIRINOX group, including grade 3 or 4 neutropenia (46% versus 21%), febrile neutropenia (5.4% versus 1.2%), thrombocytopenia (9.1% versus 3.6%), sensory neuropathy (9% versus 0%), vomiting (15% versus 8%), fatigue (23% versus 18%), and diarrhea (13% versus 2%). Despite the greater toxicity, only 31% of the FOLFIRINOX group had a definitive degradation of quality of life, as compared to 66% in the gemcitabine group (HR 0.47 [95% CI 0.30 to 0.70], P < 0.001), thus indicating an improvement in quality of life.

Of note, combinations containing irinotecan require adequate biliary function for excretion of its active glucuronide metabolite, SN-38. Approximately 10% of patients in the United States are homozygous for the UGT1A1*28 allele polymorphism, which causes increased SN-38 bioavailability and hence a potential for severe toxicities (eg, life threatening-refractory diarrhea).¹⁸ Therefore, it is recommended that physicians start with a lower dose of irinotecan or choose a different regimen altogether in such patients.

Current Approach and Future Directions

Based on results of the ACCORD 11 and MPACT trials, both front-line regimens (nab-paclitaxel/gemcitabine and FOLFIRINOX) can be considered appropriate treatment options for treatment-naive patients with good performance status who have locally advanced unresectable or metastatic pancreatic adenocarcinoma. FOLFIRINOX has a higher objective response rate than nab-paclitaxel-gemcitabine (32% versus 23%, respectively), but the adverse effect profile favors the nab-paclitaxel/gemcitabine combination, acknowledging this conclusion is limited due to lack of a comparative trial. Modifications to both regimens have been presented at American Society of Clinical Oncology symposiums, with preliminary data showing an extended median OS and a more tolerable toxicity profile.^19,20 In a recent retrospective observational cohort comparative analysis of nab-paclitaxel/gemcitabine versus FOLFIRINOX, results showed no statistical difference in median OS. The real-world data showed that gemcitabine-based therapy is being offered commonly to elderly patients and patients with poor performance status.¹³ There is no current research proposal for conducting a direct head-to-head comparison between these 2 regimens. Based on extrapolated data from the prior mentioned trials and retrospective analysis reviews, current guidelines recommend offering younger (< 65 years old), healthier (no comorbidity contraindication) patients with excellent performance status (ECOG 0) first-line FOLFIRINOX or gemcitabine/nab-paclitaxel. Elderly patients with stable comorbidities and good performance status (ECOG 1 or 2, Karnofsky performance status ≥ 70) could be preferably considered for treatment with nab-paclitaxel/gemcitabine as first-line or modified FOLFIRINOX if performance status is excellent. Patients with poor performance status (ECOG ≥ 2), advanced age, and significant comorbidities could still be considered candidates for gemcitabine monotherapy. However, there are promising indications that the combination of gemcitabine, nab-paclitaxel, and cisplatin could be a frontline therapy in advanced pancreaticobilliary malignancies in the future.

Second-Line Systemic Treatment

Case Continued

The patient and oncologist opt to begin treatment with modified FOLFIRINOX therapy, and after the patient completes 10 cycles CT scan shows progression of disease. His oncologist decides to refer the patient to a comprehensive cancer center for evaluation for participation in clinical trials, as his performance status remains very good (ECOG 1) and he would like to seek a novel therapy. His liver mass biopsy and blood liquid biopsy are sent for tumor mutational profile evaluation; results show a high tumor mutational burden and microsatellite instability.

• What are second-line treatment options for metastatic pancreatic cancer?

Second-line regimen recommendations for metastatic pancreatic cancer depend on which agents were used in first-line therapy and the patient’s performance status and comorbidities. Patients who progressed on first-line FOLFIRINOX and continue to have a good performance status (ECOG 0 or 1) may be considered for gemcitabine/nab-paclitaxel therapy; otherwise, they may be candidates for gemcitabine plus capecitabine or gemcitabine monotherapy based on performance status and goals of care. Patients who progressed on front-line gemcitabine/nab-paclitaxel may opt for FOLFIRINOX (or an oxaliplatin-based regimen [FOLFOX] or irinotecan-based regimen [FOLFIRI] if FOLFIRINOX is not tolerable), nanoliposomal irinotecan/fluorouracil/leucovorin, or a short-term infusional fluorouracil and leucovorin regimen. The preferences for second-line treatment are not well established, and patients should be encouraged to participate in clinical trials. Chemotherapy should be offered only to those patients who maintain good performance status after progression on first-line therapy. For patients with poor performance status (ECOG 3 or 4) or multiple comorbidities, a discussion about goals of care and palliative therapy is warranted.

Gemcitabine-Based Therapy

An AGEO prospective multicenter cohort assigned 57 patients with metastatic pancreatic adenocarcinoma who had disease progression on FOLFIRINOX therapy to receive gemcitabine/nab-paclitaxel (dose as per MPACT trial).²¹ The median OS was 8.8 months and median PFS was 5.1 months after FOLFIRINOX. There were reported manageable grade 3/4 toxicities in 40% of patients, which included neutropenia (12.5%), neurotoxicity (12.5%), asthenia (9%), and thrombocytopenia (6.5%). A phase 2 clinical trial that evaluated gemcitabine monotherapy in 74 patients with metastatic pancreatic cancer who had progressed on fluorouracil showed a 3.85-month survival benefit.²²

Irinotecan-Based Regimens

The NAPOLI-1 (NAnoliPOsomaL Irinotecan) trial evaluated nanoliposomal irinotecan (MM-398, nal-IRI) and fluorouracil/leucovorin in patients with metastatic pancreatic cancer refractory to gemcitabine-based therapy.²³ This global, open-label phase 3 trial initially randomly assigned and stratified 417 patients in a 1:1 fashion to receive either nanoliposomal irinotecan monotherapy (120 mg/m² every 3 weeks, equivalent to 100 mg/m² of irinotecan base) or fluorouracil/leucovorin combination. A third treatment arm consisting of nanoliposomal irinotecan (80 mg/m², equivalent to 70 mg/m² of irinotecan base) with fluorouracil and leucovorin every 2 weeks was added later in a 1:1:1 fashion. Patients assigned to nanoliposomal irinotecan plus fluorouracil/leucovorin had a significantly improved OS of 6.1 months compared to 4.2 months with fluorouracil/leucovorin (HR 0.67 [95% CI 0.49 to 0.92], P = 0.012). The results of an intention-to-treat analysis favored the nanoliposomal irinotecan regimen, with a median OS of 8.9 months compared with 5.1 months (HR 0.57, P = 0.011). In addition, median PFS was improved in the nanoliposomal irinotecan arm (3.1 months versus 1.5 months; HR 0.56, P < 0.001), and median OS did not differ between patients treated with nanoliposomal irinotecan monotherapy and those treated with fluorouracil/leucovorin (4.9 months versus 4.2 months; HR 0.99 [95% CI 0.77 to 1.28], P = 0.94). The grade 3/4 adverse events that occurred most frequently in the 117 patients assigned to nanoliposomal irinotecan plus fluorouracil/leucovorin were neutropenia (27%), diarrhea (13%), vomiting (11%), and fatigue (14%). Nanoliposomal irinotecan combination provides another second-line treatment option for patients with metastatic pancreatic adenocarcinoma who have progressed on gemcitabine-based therapy but are not candidates for FOLFIRINOX.

Oxaliplatin-Based Regimens

Regimens that combine oxaliplatin with fluorouracil and leucovorin or capecitabine have shown superiority to fluorouracil/leucovorin or best supportive care (BSC). The CONKO study group compared oxaliplatin plus fluorouracil/leucovorin to BSC as second-line therapy in patients with advanced pancreatic cancer who progressed while on gemcitabine therapy (CONKO-003).²⁴ In this phase 3 trial, patients were randomly assigned (1:1) and stratified based on duration of first-line therapy, performance status, and tumor stage to receive BSC alone or the OFF regimen, which consisted of oxaliplatin (85 mg/m² on days 8 and 22) plus short-term infusional fluorouracil (2000 mg/m² over 24 hours) and leucovorin (200 mg/m² over 30 minutes), both given on days 1, 8, 15, and 22 of a 6-week cycle. This trial was terminated early according to predefined protocol regulations because of insufficient accrual (lack of acceptance of BSC by patients and physicians). Median second-line survival was 4.82 months for patients who received OFF treatment and 2.30 months for those who received BSC (HR 0.45 [95% CI 0.24 to 0.83], P = 0.008).  Neurotoxicity (grade 1/2) and nausea, emesis, and diarrhea (grade 2/3) were worse in the chemotherapy arm; otherwise, the regimen was well tolerated.

A later modification of the CONKO-003 trial changed the comparison arm from BSC to fluorouracil/leucovorin.²⁵ The median OS in the OFF group was 5.9 months versus 3.3 months in the fluorouracil/leucovorin group (HR 0.66 [95% CI 0.48 to 0.91], log-rank P = 0.010). Time to progression was significantly extended with OFF (2.9 months) as compared with fluorouracil/leucovorin (2.0 months; HR 0.68 [95% CI 0.50 to 0.94], log-rank P = 0.019). Rates of adverse events were similar between the treatment arms, with the exception of grades 1/2 neurotoxicity, which were reported in 38.2% and 7.1% of patients in the OFF and fluorouracil/leucovorin groups, respectively (P < 0.001).

The phase 3 PANCREOX trial failed to show superiority of modified FOLFOX6 (mFOLFOX6; infusional fluorouracil, leucovorin, and oxaliplatin) over fluorouracil/leucovorin.²⁶ A phase 2 trial of oxaliplatin plus capecitabine for second-line therapy in gemcitabine-treated advanced pancreatic cancer patients with dose adjustments for performance status (ECOG 2) and age (> 65 years) showed a median OS of 5.7 months without a comparison.²⁷ A modified oxaliplatin regimen may be a reasonable second-line therapy option for gemcitabine-treated patients who are not candidates for an irinotecan-based regimen (eg, elevated bilirubin) and continue to have an acceptable performance status.

Targeted Therapies

A variety of targeted therapies have failed to demonstrate major activity in metastatic pancreatic cancer, including bevacizumab targeting vascular endothelial growth factor, cetuximab targeting epidermal growth factor receptor, ruxolitinib targeting JAK pathway signaling, saridegib targeting the hedgehog pathway, and MK-0646 targeting insulin-like growth factor 1 receptor (IGFR). Other novel agents against targetable pathways that had promising early-phase results are currently being studied in ongoing clinical trials; these include JAK-2, PI3K, MEK, and BRAF inhibitors and immunotherapy.

Recent research efforts have focused on targeted testing of advanced pancreatic cancers for mismatch repair deficiency (dMMR) and high microsatellite instability (MSI-H) and for the germline and somatic BRCA1/2 or PALB2 mutations to determine potential eligibility for immunotherapy. Patients with these tumor characteristics and/or mutations might also be more sensitive to platinum-based chemotherapy agents or poly (ADP-ribose) polymerase (PARP) inhibitors. Germline mutations in BRCA 1/2 are present in 5% to 8% of patients with pancreatic cancer (up to 10%–15% in Ashkenazi Jewish population).²⁸ A superior median OS was retrospectively observed for patients with advanced stage BRCA 1/2-associated pancreatic adenocarcinoma who were treated with platinum-based chemotherapy agents versus those treated with non-platinum-based agents (22 versus 9 months; P = 0.039).²² PARP inhibitors have shown activity in germline BRCA1/2-associated breast (off label) and ovarian cancers (approved by the FDA). The efficacy and safety of PARP inhibitors were evaluated in a phase 2 study of a spectrum of BRCA1/2-associated cancers, including pancreatic cancer. The results revealed a tumor response rate of 21.7% (5 of 23 patients with pancreatic cancer [95% CI 7.5 to 43.7]), and 35% of patients had stable disease for a duration of 8 weeks or more (95% CI 16.4 to 57.3) with good tolerability.²⁹ Three novel PARP inhibitors are currently under clinical trial investigation in patients with germline BRCA 1/2- and PALB2-mutated metastatic pancreatic cancer: maintenance olaparib (NCT02184195) and rucaparib (NCT03140670) are both being studied as monotherapy in patients whose disease has not progressed on first-line platinum-based chemotherapy, and veliparib is being evaluated in a 3-arm study that includes gemcitabine and cisplatin with or without veliparib and single-agent maintenance veliparib (NCT01585805).

In 2017, the FDA granted accelerated approval to pembrolizumab for treatment of patients with unresectable or metastatic MSI-H or dMMR solid tumors whose disease progressed on prior treatments, making it the first oncology drug to be approved based on the genetic features of the tumor rather than its location in the body. This first tissue/site-agnostic approval was based on results from 5 single-arm trials involving 149 patients, including 5 patients with pancreatic cancer.³⁰ The objective response rate with pembrolizumab was 39.6% (95% CI 31.7 to 47.9), including a 7.4% complete response rate and a 32.2% partial response rate. The median duration of response was not reached at the time of publication (range, 1.6+ months to 22.7+ months).

Palliative and Supportive Care

Case Continued

The patient opts to participate in a novel immunotherapy clinical trial and is currently on his second cycle. He continues to have right upper quadrant pain despite opioid analgesia, has not gained any weight, and noticed new right lower extremity swelling after a recent holiday vacation to Florida.

• What supportive measures should be in place for patients with metastatic adenocarcinoma?

Most patients with advanced pancreatic adenocarcinoma will require a palliative intervention. All new unresectable pancreatic cancer patients should have an early psychosocial evaluation; identification of symptoms and implementation of preventive interventions that would improve quality of life and reduce suffering are paramount. A multidisciplinary team including physician/nursing staff, nutritionist/dietitian, palliative service, a social worker, and a case manager should be involved in patient care. More than two-thirds of patients can develop symptomatic biliary obstruction.³¹ Bile duct obstruction due to locally advanced pancreatic adenocarcinoma causes hyperbilirubinemia, which requires endoscopic placement of a metallic or plastic stent; plastic stents have a higher rate of re-occlusion.³² Appropriate bile flow allows treatment with irinotecan-based regimens. Percutaneous biliary drainage may be necessary if endoscopic intervention is not feasible.

Approximately one quarter of patients may present with gastric outlet obstruction due to duodenal obstruction.³¹ Endoscopic placement of an enteral expandable metal stent is preferred. Alternatively, percutaneous endoscopic gastrostomy tube placement may give symptomatic relief. Palliative surgical interventions are reserved for patients with greater life expectancy and in whom all other interventions have failed or are not feasible.

Almost all patients with pancreatic adenocarcinoma will experience cancer-associated pain. Intractable pain should be treated with a celiac plexus block. Radiation therapy may be considered as an adjunct therapy for pain, bleeding, and/or local obstruction. The National Comprehensive Cancer Network guidelines recommend that patients who undergo a laparotomy for potentially resectable disease but are found to have unresectable disease at the time of surgery should undergo stenting, open biliary-enteric bypass with or without gastrojejunostomy, and/or celiac plexus neurolysis.³³

Pancreatic exocrine enzyme insufficiency due to tumor extension, duct blockage, or surgical removal may cause malabsoprtive steatorrhea, contributing to cancer cachexia syndrome. Nutritional evaluation and daily oral pancreatic enzyme supplementation are recommended.³⁴

Patients diagnosed with pancreatic adenocarcinoma have a venous thromboembolism (VTE) incidence of 20 per 100 person-years (5%–60% of patients) and are considered at very high risk for VTE based on the Khorana score.³⁵ The preferred VTE treatment is low-molecular-weight heparin rather than warfarin based on the results of the CLOT study.³⁶ There is no current evidence for routine prophylactic therapy or the use of direct oral anticoagulants.

Finally, a cancer diagnosis, particularly pancreatic cancer, causes a significant amount of psychosocial stress and requires active support and counseling from a professional.

Conclusion

Pancreatic adenocarcinoma is the most lethal of all the gastrointestinal malignancies. FOLFIRINOX and gemcitabine/nab-paclitaxel are superior to gemcitabine monotherapy for patients with advanced unresectable and/or metastatic pancreatic cancer who are candidates for more aggressive therapy and are considered first-line therapies. Early data on the gemcitabine, nab-paclitaxel, and cisplatin combination appears to show superior efficacy. Second-line therapies are selected based on the patient’s performance status, first-line regimen, and residual toxicities from the prior regimen; options include gemcitabine/nab-paclitaxel, FOLFIRINOX (± oxaliplatin or irinotecan), single-agent gemcitabine (elderly frail patients), fluorouracil and liposomal-irinotecan, or referral for a clinical trial. The main challenge with pancreatic cancer is the development of stroma around the tumor, which abrogates drug delivery, allows for tumor growth in a hypoxic microenvironment, alters the metabolomics, and causes an immunosuppressive microenvironment. Drugs that target the microenvironments, such as hedgehog pathway inhibitors, have failed to show any clinical benefit, and we hope to see more efficacious microenvironment-targeted novel drugs in the future. In addition, immunotherapy has not shown any significant efficacy in clinical trials and many trials are still ongoing.

Introduction

Exocrine pancreatic cancer refers to pancreatic adenocarcinomas that arise from ductal epithelial cells. Pancreatic ductal adenocarcinoma is a highly lethal malignancy, ranking as the fourth most common cause of cancer-related death in the United States¹ and the eighth most common worldwide.² In the United States, the pancreas is the second most common site of gastrointestinal malignancy after the colon.¹ The only potentially curative modality for pancreatic adenocarcinomas is complete resection, followed by adjuvant therapy; unfortunately, only around 20% of patients are surgical candidates at the time of presentation due to delayed development of symptoms and consequently diagnosis.³ Most symptomatic patients with pancreatic cancer have locally advanced disease at diagnosis, and only a select group of patients with good performance status and borderline resectable disease can be offered neoadjuvant therapy. Adjuvant chemotherapy is typically recommended for patients who undergo potentially curative resection for pancreatic cancer.

Epidemiology

In the United States, pancreatic cancer has an annual estimated incidence of 55,440 new cases.¹ It causes an estimated 44,330 deaths per year, with a 5-year overall survival (OS) rate of 8.2%.¹ Worldwide an estimated 138,100 men and 127,900 women die of pancreatic cancer each year.² In general, pancreatic cancers occur more commonly in persons living in Western/industrialized countries, older persons (age > 60 years), males (ratio 1.3:1 female), and African-Americans and native Hawaiians.⁴

Etiology

The major preventable environmental risk factor for pancreatic cancer is cigarette smoking, which accounts for 25% of all cases.⁵ A prospective study that estimated the excess incidence of pancreatic cancer among cigarette smokers and assessed the influence of smoking cessation on the risk for pancreatic cancer showed that persons who quit smoking reduced their risk of pancreatic cancer by 48% after 2 years of cessation, compared with smokers who did not quit, and reduced their risk to near the level of a never smoker after 10 years of cessation.⁵ Risk is higher for heavy smokers and those with homozygous deletions of the glutathione S-transferase theta 1 gene (GSTT1), which results in the absence of the carcinogen-metabolizing function of the glutathione S-transferase enzyme. High body mass index and sedentary lifestyle have been linked to pancreatic cancer.⁶ Data regarding aspirin, diet, coffee, and excess alcohol consumption are insufficient, inconclusive, and even conflicting, and thus the effect of these factors on risk for pancreatic cancer remains unclear. Infectious risk factors such as Helicobacter pylori and hepatitis B and C virus have weak associations with pancreatic cancer. Chronic pancreatitis and pancreatic cysts (eg, intraductal papillary mucinous neoplasm [IPMN] of the pancreas) carry a risk for malignant transformation, and hence may require surveillance. Multiple epidemiologic studies have shown a strong association between pancreatic cancer and recently diagnosed diabetes mellitus (relative risk [RR] 1.97 [95% confidence interval {CI} 1.78 to 2.18]); the presence of diabetes also may be a long-term predisposing factor for pancreatic cancer, and cancer screening needs to be considered for selected patients.⁷

A predisposing genetic anomaly accounts for 15% of all cases of pancreatic cancer.⁸ Hereditary risk factors are divided into 2 broad categories: defined genetic syndromes and familial pancreatic cancer. Familial predispositions that do not meet genetic syndrome criteria account for approximately 5% to 10% of all cases associated with hereditary factors; in one study, 29% of tested kindreds with an incident pancreatic cancer had a germline BRCA2 mutation.⁹ Other predisposing genetic syndromes that have been linked to pancreatic cancer include:

• Peutz-Jeghers syndrome with germline STK11 mutations (RR 132);
• Hereditary pancreatitis with germline PRSS1, SPINK1, and CFTR mutations (RR 26–87);
• Familial atypical multiple mole melanoma syndrome with CDKN2A mutations (RR 20–40);
• Familial breast and ovarian cancer with BRCA2 (RR 10) and BRCA1 (RR 2.8) mutations;
• Hereditary nonpolyposis colorectal cancer (HNPCC, Lynch II syndrome) with MLH1, MSH2, MSH6, and PMS2 mutations (RR 9–11); and
• Familial adenomatous polyposis with APC mutations (RR 5).¹⁰

Other gene mutations with unknown relative risk for pancreatic cancer include mutations affecting PALB2, ATM, and TP53.

The International Cancer of the Pancreas Screening consortium consensus on screening for pancreatic cancer in patients with increased risk for familial pancreatic cancer recommends screening those at high risk: first-degree relatives (FDRs) of patients with pancreatic cancer from a familial pancreatic kindred with at least 2 affected FDRs; patients with Peutz-Jeghers syndrome; and p16, BRCA2, and HNPCC mutation carriers with 1 or more affected FDRs and hereditary pancreatitis. The guidelines emphasize that screening should be done only in those who are surgical candidates and are evaluated at an experienced multidisciplinary center.⁸

Deleterious germline mutations in pancreatic cancer can account for 33% of patients with apparent sporadic cancers and no hereditary risk. These include germline mutations affecting BRCA1/2, PALB2, ATM, MLH1, CHK-2, CDKN2A, and TP53.¹¹

Pathogenesis

Pancreatic neoplasms can be benign or malignant and thus a tissue histologic diagnosis is paramount. Pancreatic adenocarcinomas with exocrine features represent more than 95% of all pancreatic neoplasms, with only 5% arising from the endocrine pancreas (ie, neuroendocrine tumors). Pancreatic neuroendocrine tumors and pancreatic adenocarcinoma must be distinguished histologically because treatment of the 2 neoplasms is completely different. Other malignant pancreatic tumors are signet ring cell carcinoma, adenosquamous carcinoma, undifferentiated (anaplastic) carcinoma, and mucinous noncystic (colloid) carcinoma; the latter tumor has a better prognosis.¹² It is essential to characterize and distinguish among benign cystic neoplasms, as some require surgical resection due to the risk of malignant transformation. IPMN, pancreatic intraepithelial neoplasia, and mucinous cystic neoplasms are thought to be premalignant lesions of invasive ductal adenocarcinomas, and the pathological report should highlight the degree of dysplasia for adequate risk stratification.¹³ This information could be the deciding factor in whether a pancreatectomy is recommended by a multidisciplinary team.

Most pancreatic cancers harbor activating or silencing genetic mutations, and multiple combinations of altered genes can be detected by next-generation sequencing (average of 63 genetic alterations per cancer).¹⁴ Mutational activated KRAS is the most frequent (> 90%) genetic alteration in pancreatic cancer, even in early neoplastic precursors (IPMN > 75%). KRAS is a highly complex, dynamic proto-oncogene involved in signaling of various receptor kinases such as the epidermal growth factor receptor and the insulin-like growth factor receptor-I. It also engages in canonical downstream effector pathways, mainly Raf/MEK/ERK, PI3K/PDK1/Akt, and the Ral guanine nucleotide exchange factor pathway, which drive much of the pathogenesis of malignancy. These pathways lead to sustained proliferation, metabolic reprogramming, anti-apoptosis, remodeling of the tumor microenvironment, evasion of the immune response, cell migration, and metastasis. An activating point mutation in codon G12 is the most common (98%) locus of KRAS mutation in pancreatic adenocarcinoma, but all drugs targeting this mutation have failed in clinical practice.¹⁵ Additionally, inactivation of tumor suppressor genes such as p53, DPC4 (SMAD4/MADH4), CDKN2A (p16/MTS1), and BRCA2 can be found in 75%, 30%, 35%, and 4% of pancreatic adenocarcinoma cases, respectively.¹⁴ Another pancreatic cancer hallmark is inactivation of DNA damage repair genes, which include MLH1 and MSH2.¹⁶

Diagnosis and Staging

Case Presentation

A 71-year-old male veteran with no significant past medical history other than hypertension and hyperlipidemia and an excellent performance status presents to the emergency department after noticing a yellowish skin and sclera color. He denies weight loss, abdominal pain, or any other pertinent symptom or sign. Physical examination reveals a healthy developed man with yellowish discoloration of the skin and sclera and a soft, nontender benign abdomen; physical examination is otherwise unremarkable. Laboratory evaluation reveals a direct bilirubin level of 4.5 mg/dL and normal values for complete blood count and renal, liver, and coagulation panels. Abdominal and pelvis computed tomography (CT) with intravenous contrast shows a pancreatic head mass measuring 2.6 × 2.3 cm minimally abutting the anterior surface of the superior mesenteric vein, which remains patent. Follow-up endoscopic ultrasound (EUS) confirms an irregular mass at the head of the pancreas measuring 3.2 × 2.6 cm with sonographic evidence suggesting invasion into the portal vein. During the procedure, the bile duct is successfully stented, the mass is biopsied, and bile duct brushing is performed. Pathology report is consistent with pancreatic adenocarcinoma.

• What is the typical presentation of pancreatic cancer?

The most common symptoms of pancreatic cancer at the time of presentation include weight loss (85%), asthenia/anorexia (86%), and/or abdominal pain (79%).¹⁷ The most frequent signs are jaundice (55%), hepatomegaly (39%), and cachexia (13%). Courvoisier sign, a nontender but palpable distended gallbladder at the right costal margin, is neither sensitive nor specific for pancreatic cancer (13% of cases). Trousseau syndrome, a superficial thrombophlebitis, is another classic sign that reflects the hypercoagulable nature of pancreatic cancer (3% of cases).¹⁷ The pathophysiology of this syndrome is not completely understood, but it may occur secondary to the release of cancer microparticles in the blood stream which in turn stimulate the coagulation cascade. Other nonspecific symptoms are dark urine, nausea, vomiting, diarrhea, steatorrhea, and epigastric and back pain. Because symptoms early in the course of the disease are nonspecific, pancreatic cancer is typically diagnosed late, after the cancer has invaded local structures or metastasized. The initial presentation varies depending on tumor location, with 70% of pancreatic head malignancies presenting with jaundice and pain correlating to an advanced stage.¹⁸ Although data supporting an association between new-onset diabetes mellitus and pancreatic cancer are inconclusive, pancreatic cancer should still be a consideration in patients with new-onset diabetes mellitus and other symptoms such as pain and weight loss. Early signs of incurable disease include a palpable mass, ascites, lymphadenopathy (classic Virchow node), and an umbilical mass (Sister Mary Joseph node). Incidentally discovered pancreatic masses on imaging are rare, but the incidence is increasing due to frequent imaging for other reasons and improved diagnostic techniques.

• What is the approach to diagnosis and staging?

History and physical examination findings are not sufficiently sensitive or specific to diagnose pancreatic cancer. High clinical suspicion in a patient with risk factors can lead to a comprehensive evaluation and potential early diagnosis. In general, an initial diagnostic work-up for suspected pancreatic cancer will include serologic evaluation (liver function test, lipase, tumor markers) and abdominal imaging (ultrasound, CT scans, or magnetic resonance imaging [MRI]). Ultrasound is a first-line diagnostic tool with a sensitivity of 90% and specificity of 98.8% for pancreatic cancer, but it is investigator-dependent and is less accurate in detecting tumors smaller than 3 cm in diameter.¹⁹ Multiphasic helical CT of the abdomen has better sensitivity (100%) and specificity (100%) for detecting tumors larger than 2 cm, but this modality is less accurate in detecting pancreatic masses smaller than 2 cm (77%).²⁰ Percutaneous fine-needle aspiration (FNA) performed by ultrasound or CT guidance is avoided due to theoretical concerns about intraperitoneal seeding and bleeding.

If a pancreatic mass is detected by ultrasound or CT, additional interventions may be indicated depending on the clinical scenario. EUS-guided biopsy can provide histological confirmation and is currently utilized frequently for diagnosis and early resectability staging. Endoscopic retrograde cholangiopancreatography (ERCP) is indicated for patients with biliary obstruction requiring stent placement, and this procedure may provide tissue confirmation by forceps biopsy or brush cytology (lower accuracy than EUS). In a meta-analysis that evaluated the diagnostic value of tests for pancreatic cancer, ERCP had the highest sensitivity (92%) and specificity (96%) compared to ultrasound and CT,²¹ but this modality carries a risk for pancreatitis, bleeding, and cholangitis. Magnetic resonance cholangiopancreatography has not replaced ERCP, but it but may be an alternative for patients who cannot undergo ERCP (eg, gastric outlet obstruction, duodenal stenosis, anatomical surgical disruption, unsuccessful ERCP). ERCP is used frequently because many patients present with obstructive jaundice due to pancreatic mass compression, specifically if the mass is located in the head, and must undergo ERCP and stenting of the common bile duct.

The carbohydrate antigen (CA) 19-9 level has variable sensitivity and specificity in pancreatic cancer, as levels can be elevated in many benign pancreaticobiliary disorders. Elevated CA 19-9, in the appropriate clinical scenario (ie, a suspicious pancreatic mass and a value greater than 37 U/mL) demonstrated a sensitivity of 77% and specificity of 87% when differentiating pancreaticobiliary cancer from benign clinical conditions such as acute cholangitis or cholestasis.²² CA 19-9 level has prognostic value, as it may predict occult disease and correlates with survival rates, but no specific cutoff value has been established to guide perioperative therapy for high-risk resectable tumors.²³

The American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) tumor, node, metastasis (TNM) system is the preferred method for staging pancreatic cancer (Table 1). 

Positron emission tomography with CT scan is occasionally utilized in practice to assess tumor burden by evaluating anatomical structures and assessing physiologic uptake, which aids in establishing the extent of disease in equivocal cases. Staging laparoscopy with or without peritoneal biopsy is sometimes used to establish appropriate staging in cases that are questionable for occult metastatic disease. This procedure helps avoid unnecessary morbid surgeries.

Neoadjuvant Therapy

Case Continued

The patient is referred to oncology. Blood work reveals a CA 19-9 level of 100 U/mL (reference range < 35 U/mL) and a staging CT scan of the chest reveals a benign-appearing 3-mm nodule (no prior imaging for comparison). CT scan of the abdomen and pelvis does not define venous vasculature involvement appropriately and hence MRI of the abdomen and pelvis is performed. MRI reveals a pancreatic head mass measuring 3.0 × 2.7 cm, without arterial or venous vasculature invasion. However, the mass is abutting the portal vein and superior mesenteric vein and there is a new nonspecific 8-mm aortocaval lymph node.

• What are the current approaches to treating patients with resectable, unresectable, and metastatic disease?

Accurate staging and assessment of surgical resectability in pancreatic cancer are paramount as these steps prevent a futile morbid Whipple procedure in patients with advanced disease and a high risk of recurrence. Conversely, it allows patients with low-volume disease to undergo a potentially curative surgery. Approximately 20% of patients present with resectable disease, 40% present with locally advanced unresectable tumors (eg, involvement of critical vascular structures), and 40% present with metastatic disease.³ Treatment for resectable pancreatic cancer continues to be upfront surgery, although neoadjuvant therapy with either chemoradiation, radiation alone, or chemotherapy is an option per guidelines from the American Society of Clinical Oncology (ASCO),²⁸ the NCCN,²⁶ and the European Society for Medical Oncology (ESMO),²⁹ particularly for patients with borderline resectable tumors (Table 3). 

Systemic chemotherapy is recommended for fit candidates with locally advanced unresectable or metastatic disease, with an emphasis on supportive palliative measures. Palliative interventions include biliary stenting, duodenal stent for relieving gastric-outlet obstruction, and celiac axis nerve blocks, when indicated. Routine preoperative biliary stent placement/drainage in patients undergoing subsequent surgery for pancreatic cancer located in the head is associated with an increased risk of surgical complications when compared with up-front surgery without prior biliary drainage, and thus stent placement/drainage is not recommended.²⁶ Aggressive supportive management of symptoms, such as cancer-associated pain, anorexia-cachexia syndromes, and anxiety-depression disorders, should remain a primary palliative focus.

Case Continued

A multidisciplinary tumor board discusses the patient’s case and deems the cancer borderline resectable; neoadjuvant therapy is recommended. The patient is started on treatment with gemcitabine and nab-paclitaxel as first-line neoadjuvant therapy. After 4 cycles, the CA 19-9 level drops to 14 U/mL, and MRI reveals a smaller head mass of 1.3 × 1.4 cm with stable effacement of the superior mesenteric vein and no portal vein involvement; the aortocaval lymph node remains stable. At tumor board, it is evident that the patient has responded to therapy and the recommendation is to treat with gemcitabine chemoradiotherapy before surgery.

• What neoadjuvant therapy strategies are used in the treatment of pancreatic adenocarcinoma?

There are no established evidence-based recommendations for neoadjuvant therapy in patients with borderline resectable pancreatic cancer or patients with unresectable locally advanced pancreatic cancer. However, there are ongoing trials to investigate this treatment approach, and it is offered off-label in specific clinical scenarios, such as in the case patient described here. In patients with borderline resectable disease, preoperative chemotherapy followed by chemoradiation is a routine practice in most cancer centers,³² and ongoing clinical trials are an option for this cohort of patients (eg, Southwest Oncology Group Trial 1505, NCT02562716). The definitions of borderline resectable and unresectable pancreatic cancer have been described by the NCCN,²⁶ although most surgeons consider involvement of the major upper abdominal blood vessels the main unresectability criterion; oncologists also consider other parameters such as suspicious lesions on scans, worsening performance status, and a significantly elevated CA 19-9 level suggestive of disseminated disease.²⁸ The goal of a conversion approach by chemotherapy with or without radiation for borderline and unresectable cancers is to deliver a tolerable regimen leading to tumor downstaging, allowing for surgical resection. No randomized clinical trial has shown a survival advantage of this approach. Enrollment in clinical trials is preferred for patients with borderline and unresectable cancer, and there are trials that are currently enrolling patients.

The main treatment strategies for patients with locally advanced borderline and unresectable pancreatic cancer outside of a clinical trial are primary radiotherapy, systemic chemotherapy, and chemoradiation therapy. Guidelines from ASCO, NCCN, and ESMO recommend induction chemotherapy followed by restaging and consolidation chemoradiotherapy in the absence of progression.^26,28,29 There is no standard chemoradiation regimen and the role of chemotherapy sensitizers, including fluorouracil, gemcitabine, and capecitabine (an oral fluoropyrimidine substitute), and targeted agents in combination with different radiation modalities is now being investigated.

Fluorouracil is a radio-sensitizer that has been used in locally advanced pancreatic cancer based on experience in other gastrointestinal malignancies; data shows conflicting results with this drug. Capecitabine and tegafur/gimeracil/oteracil (S-1) are oral prodrugs that can safely replace infusional fluorouracil. Gemcitabine, a more potent radiation sensitizer, is very toxic, even at low-doses twice weekly, and does not provide a survival benefit, as demonstrated in the Cancer and Leukemia Group B (CALGB) 89805 trial, a phase 2 study of patients with surgically staged locally advanced pancreatic cancer.³³ Gemcitabine-based chemoradiotherapy was also evaluated in the Eastern Cooperative Group (ECOG) E4201 trial, which randomly assigned patients to receive gemcitabine alone (at 1000 mg/m²/wk for weeks 1 through 6, followed by 1 week rest, then weekly for 3 out of 4 weeks) or gemcitabine (600 mg/m²/wk for weeks 1 to 5, then 4 weeks later 1000 mg/m² for 3 out of 4 weeks) plus radiotherapy (starting on day 1, 1.8 Gy/fraction for total of 50.4 Gy).³⁴ Patients with locally advanced unresectable pancreatic cancer had a better OS outcome with gemcitabine in combination with radiation therapy (11.1 months) as compared with patients who received gemcitabine alone (9.2 months). Although there was a greater incidence of grade 4 and 5 treatment-related toxicities in the combination arm, no statistical differences in quality-of-life measurements were reported. Gemcitabine-based and capecitabine-based chemoradiotherapy were compared in the open-label phase 2 multicenter randomized SCALOP trial.³⁵ Patients with locally advanced pancreatic cancer were assigned to receive 3 cycles of induction with gemcitabine 1000 mg/m² days 1, 8, and 15 and capecitabine 830 mg/m² days 1 to 21 every 28 days; patients who had stable or responding disease were randomly assigned to receive a fourth cycle followed by capecitabine (830 mg/m² twice daily on weekdays only) or gemcitabine (300 mg/m² weekly) with radiation (50.4 Gy over 28 fractions). Patients treated with capecitabine-based chemoradiotherapy had higher nonsignificant median OS (17.6 months) and median progression-free survival (12 months) compared to those treated with gemcitabine (14.6 months and 10.4 months, respectively).

The benefit of radiation therapy in the treatment of locally advanced pancreatic cancer was further explored by the Fédération Francophone de Cancérologie Digestive 2000-01 phase 3 trial. This study compared induction chemoradiotherapy (60 Gy, 2 Gy/fraction; concomitant fluorouracil infusion, 300 mg/m²/day, days 1–5 for 6 weeks; cisplatin, 20 mg/m²/day, days 1–5 during weeks 1 and 5) to gemcitabine alone (1000 mg/m² weekly for 7 weeks) followed by maintenance gemcitabine in both arms.³⁶ Unexpectedly, the median OS was significantly shorter in the chemoradiotherapy arm than in the chemotherapy alone arm (8.6 months versus 13 months, respectively, P = 0.03) and the combination arm had more toxicities. The phase 3 open-label LAP07 study explored the role of radiation therapy in patients with locally advanced pancreatic cancer who had controlled disease after 4 months of induction therapy.³⁷ LAP07 had 2 randomizations: first, patients with locally advanced pancreatic cancer were assigned to receive weekly gemcitabine alone (1000 mg/m²) or this same dose of gemcitabine plus erlotinib 100 mg/day; second, patients with progression-free disease (61% of initial cohort) after 4 months of therapy were assigned to receive 2 months of the same chemotherapy or chemoradiotherapy (54 Gy plus capecitabine). This study showed that the addition of erlotinib to gemcitabine did not improve survival and in fact affected survival adversely. Of note, no survival benefit was observed after the first randomization from chemotherapy to consolidating chemoradiotherapy. Chemoradiotherapy achieved better locoregional tumor control with significantly less local tumor progression (32% versus 46%, P < 0.03) and no increase in toxicity. Based on prior moderate-quality evidence, guidelines recommend consolidative chemoradiotherapy only for surgical resection candidates following induction chemotherapy; for those who are not surgical candidates, guidelines recommend continuing systemic therapy.^26,28,29

Gemcitabine and fluorouracil-based chemotherapies were the standard induction regimens until evidence from studies of metastatic systemic treatment protocols with FOLFIRINOX (ACCORD trial³⁸) and nanoparticle albumin-bound paclitaxel (nab-paclitaxel) plus gemcitabine (MPACT trial³⁹) was extrapolated to clinical practice. These regimens were shown to achieve higher objective response rates when compared to single-agent gemcitabine in patients with metastatic pancreatic cancer. Due to the broad heterogeneity of results in small retrospective series with neoadjuvant trials in borderline resectable pancreatic cancer, the quality of the evidence is low and any recommendation is limited. Many individual series have demonstrated improved complete resection rates and promising survival rates. In the largest single-institution retrospective review of patients with borderline resectable pancreatic adenocarcinoma who completed neoadjuvant gemcitabine-based chemoradiotherapy (50 Gy in 28 fractions or 30 Gy in 10 fractions), 94% achieved a margin-negative pancreatectomy; the median OS in those who completed preoperative therapy and had surgery was 40 months, with a 5-year OS of 36%.⁴⁰ A meta-analysis by Andriulli and colleagues included 20 prospective studies of patients with initially resectable (366 lesions) or unresectable (341 lesions) disease who were treated with neoadjuvant/preoperative gemcitabine with or without radiotherapy.⁴¹ In the group with initially unresectable disease, 39% underwent surgery after restaging and 68% of explored patients were resected; the R0 resection rate was 60%. After restaging, 91% of patients with resectable disease underwent surgery, with 82% of explored patients undergoing surgical resection and 89% of these achieving R0 resection. The estimated 1- and 2-year survival probabilities after resection among patients with initially unresectable disease were 86.3% and 54.2%.⁴¹

The largest single-institution retrospective review of FOLFIRINOX (fluorouracil, oxaliplatin, irinotecan, and leucovorin), an alternative to gemcitabine, for neoadjuvant induction therapy for patients with locally advanced unresectable disease was conducted at Memorial Sloan Kettering Cancer Center. In this study (n = 101), 31% of patients initially deemed unresectable who completed FOLFIRINOX induction therapy with or without chemoradiation underwent resection. The R0 resection rate in these patients was 55%, and patients who did not progress during induction FOLFIRINOX therapy had a median OS of 26 months.⁴² A systematic review and meta-analysis of FOLFIRINOX chemotherapy with or without radiotherapy in patients with locally advanced unresectable pancreatic cancer reported that 25.9% of patients underwent resection after FOLFIRINOX therapy, and the R0 resection rate in these patients was 78.4%.⁴³ The median OS in this study was 24.2 months, which was longer than the previously reported median OS rates for gemcitabine.

There is no strong evidence published for the use of combination nab-paclitaxel plus gemcitabine in the neoadjuvant setting, but it is used in clinical practice based on evidence from the MPACT trial, which showed the combination improved OS and progression-free survival in patients with metastatic pancreatic cancer.³⁹ An early-phase 1-arm clinical trial of neoadjuvant gemcitabine, docetaxel, and capecitabine (GTX) followed by radiotherapy showed an increased response rate and survival for locally advanced disease; however, the NCCN expert panel has reached a consensus but not a uniform recommendation regarding this regimen due to significant toxicities and low patient accrual.²⁶ Selected patients with pancreatic cancer with BRCA1/2 mutations are more sensitive to platinum-based chemotherapy. Although studies of neoadjuvant platinum-based chemotherapy in this population have not been reported, the NCCN guidelines list it as an alternative option based on extrapolated data.²⁶ A clinical trial of gemcitabine, nab-paclitaxel, and cisplatin in the neoadjuvant setting in patients with resectable pancreatic cancer is currently enrolling patients (NGC triple regimen NCT0339257).

Summary

Chemotherapy alone or followed by chemoradiotherapy may be used as initial treatment for patients with borderline and unresectable pancreatic adenocarcinoma without distant metastases who are potential surgical candidates. Chemoradiotherapy remains a preferred treatment option for patients with poorly controlled pain from local tumor invasion, in view of the well-documented analgesic palliative effect of radiation therapy. FOLFIRINOX with or without radiation therapy may offer the highest documented response rates, but it also results in higher rates of treatment-related toxicities. FOLFIRINOX can be offered to selected fit patients (< 65 years old, no comorbidity contraindication, good functional status [ECOG 0–1]) who can tolerate triple therapy with a more toxic adverse-effect profile. A clinical trial evaluating neoadjuvant FOLFIRINOX with or without preoperative chemoradiotherapy in patients with borderline resectable pancreatic cancer is ongoing (PANDAS-PRODIGE 44, NCT02676349). Gemcitabine with or without radiation therapy is a tolerable combination, although it is potentially more toxic when combined with radiation. The addition of nab-paclitaxel to gemcitabine without radiation may emerge as a preferred neoadjuvant treatment for selected patients; a clinical trial investigating this modality in patients with resectable and borderline resectable disease is ongoing (NCT02723331).

Adjuvant Therapy

Case Continued

Prior to the planned surgical resection and after undergoing chemoradiation therapy, the patient has an excellent performance status and repeat MRI shows a 1.3 × 1.4 cm head mass with no further vasculature involvement, no evidence of lymphadenopathy, and no distant metastasis. The CA 19-9 level is stable at 18 U/mL. The patient undergoes an uncomplicated partial pancreaticoduodenectomy, and analysis of a surgical pathology specimen reveals T3N0 disease with closest margin of 0.1 cm.

• Would the patient benefit from adjuvant therapy?

Adjuvant chemotherapy for 6 months after pancreatic cancer resection should be offered to all patients based on mature data. Gemcitabine and capecitabine are the current standard of care in adjuvant therapy; alternatively, single-agent gemcitabine can be offered to patients with poor performance status or patients who cannot tolerate the toxicities associated with this combination.²⁸ Adjuvant treatment should be initiated within approximately 8 weeks of surgical resection. The value of radiation therapy remains controversial, but it can be offered within the context of a clinical trial or to patients with positive margins after surgical resection and/or lymph node–positive disease. Based on low-quality supportive evidence, it is strongly recommended that patients who receive neoadjuvant therapy complete a total of 6 months of chemotherapy, factoring in the duration of the preoperative regimen.²⁸ Different adjuvant strategies have been investigated, including chemotherapy alone with a fluoropyrimidine and/or gemcitabine with or without combined chemoradiation therapy.

The European Study Group for Pancreatic Cancer 1 (ESPAC)-1 trial was a randomized clinical trial that evaluated several adjuvant strategies in pancreatic cancer treatment. This trial assigned patients who underwent pancreatic adenocarcinoma resection to adjuvant chemotherapy alone (intravenous fluorouracil 425 mg/m² and leucovorin 20 mg/m² daily for 5 days, monthly for 6 months), chemoradiotherapy (20 Gy in 10 daily fractions over 2 weeks with 500 mg/m² intravenous fluorouracil on days 1–3, repeated after 2 weeks), both chemotherapy and chemoradiation, and observation.⁴⁴ The results showed no added benefit for adjuvant chemoradiotherapy, with a median OS of 15.5 months in the chemoradiotherapy cohort, as compared to a median OS of 16.1 months in the chemotherapy-alone cohort (hazard ratio [HR] 1.18 [95% CI 0.90 to 1.55], P = 0.24). In addition, there was evidence of a survival benefit for the chemotherapy-alone arm when compared to the combined modality arm, with a median OS of 19.7 versus 14.0 months, respectively (HR 0.66 [95% CI 0.52 to 0.83], P = 0.0005). Although ESPAC-1 has been criticized for being underpowered to perform statistical comparison, it is still considered a landmark trial demonstrating benefit with single-agent chemotherapy alone. A follow-up analysis of ESPAC-1 showed that adjuvant chemotherapy alone conferred a significant 5-year survival benefit while the combined modality had a deleterious effect on survival. ⁴⁵ Hence, adjuvant chemotherapy alone became the standard of care in the United States following resection.

The results of the multicenter randomized controlled phase 3 CONKO-001 (CharitéOnkologie 001) trial, which were reported in 2007, supported the use of adjuvant gemcitabine for 6 months in patients with resected pancreatic adenocarcinoma. In this study, patients treated with adjuvant gemcitabine (1000 mg/m² days 1, 8, and 15 every 4 weeks for 6 months) had superior disease-free survival compared with those who received surgery alone.³⁰ A long-term outcome update of this study demonstrated a significant improvement in 5-year OS for patients treated with adjuvant gemcitabine (20.7% [95% CI 14.7% to 26.6%]) compared to those who received surgical resection alone (10.4% [95% CI 5.9% to 15.0%]). This benefit persisted at 10-year follow-up, with an OS of 12.2% (95% CI 7.3% to 17.2%) in the adjuvant gemcitabine group, as compared to 7.7% (95% CI 3.6% to 11.8%) in the resection alone group.³¹

Fluorouracil and gemcitabine remained equivalent adjuvant treatment options until the results of the ESPAC-3 trial were reported in 2010.³² This large phase 3 trial, conducted mainly in the United Kingdom, compared weekly gemcitabine (1000 mg/m² weekly for 3 of every 4 weeks) to leucovorin-modulated fluorouracil (Mayo Clinic regimen: leucovorin 20 mg/m² followed by fluorouracil 425 mg/m² intravenous bolus days 1 through 5 every 28 days) as adjuvant therapy in resected pancreatic adenocarcinoma. After a median follow-up of 34.2 months, the median OS was similar in the 2 groups (fluorouracil/leucovorin 23.0 months versus gemcitabine 23.6 months; P = 0.39). However, the fluorouracil/leucovorin group experienced more grade 3/4 treatment-related toxicities (mucositis, stomatitis, diarrhea, and hosptializations; 14% versus 7.5%; P < 0.001).⁴⁶ Following this trial, gemcitabine became the standard of care for adjuvant chemotherapy for resected pancreatic cancer.

The U.S. Radiation Therapy Oncology Group (RTOG) 9704 trial was conducted to investigate the potential benefit of adding radiation therapy to gemcitabine. This trial demonstrated an improved trend among patients with pancreatic head tumors (but not with cancers of the pancreatic body or tail) who received adjuvant gemcitabine followed by chemoradiotherapy (50.4 Gy in 1.8 Gy daily fractions for 5.5 weeks with concurrent infusional fluorouracil 250 mg/m² daily) and subsequent gemcitabine monotherapy compared to postoperative fluorouracil-based chemoradiotherapy. Results showed a 5-year OS of 22% versus 18%, respectively, although this improvement was not statistically significant (P = 0.08). This trial failed to show a benefit of adding radiotherapy to gemcitabine.⁴⁷

The ESPAC-4 trial, reported in 2017, evaluated the combination of gemcitabine and capecitabine compared to gemcitabine alone as adjuvant therapy for resected pancreatic adenocarcinoma.⁴⁸ Patients were randomly assigned after surgical resection, regardless of margin or node status, to 6 months of gemcitabine alone (1000 mg/m²/day on days 1, 8, and 15 of each 28-day cycle) or gemcitabine plus capecitabine (1660 mg/m²/day on days 1 through 21 of each 28-day cycle). Combination therapy had a significant survival benefit compared to single therapy, with median OS durations of 28 months and 25.5 months, respectively (HR for death 0.82 [95% CI 0.68 to 0.98]). The 5-year OS for patients who received combination treatment was 29 months (95% CI 22.9 to 35.2) versus 16 months (95% CI 10.2 to 23.7) for those in the monotherapy group. As expected, grade 3 or 4 treatment-related toxicities (diarrhea, hand-foot syndrome, and neutropenia) were significantly more common with combined therapy, although there were no significant differences in the rates of serious adverse events. The adjuvant combination of gemcitabine and capecitabine became the current and preferred new standard of care following resection of pancreatic ductal adenocarcinoma,²⁸ but single-agent gemcitabine and fluorouracil/leucovorin continue to be viable options,^26,28,29 particularly for elderly patients, patients with borderline performance status, or patients with multiple comorbidities.

Evidence showing that a more intensive regimen can improve outcome in the adjuvant setting remains elusive. The phase 3 APACT study (Adjuvant Therapy for Patients with Resected Pancreatic Cancer, NCT01964430) comparing gemcitabine alone to gemcitabine plus nab-paclitaxel in patients with surgically resected pancreatic adenocarcinoma has concluded, with the results projected to be released in 2018. Another phase 3 trial investigating the efficacy of FOLFIRINOX versus gemcitabine alone as adjuvant therapy is underway in France and Canada (PRODIGE24/ACCORD24, NCT01526135). Other strategies with newer targeted therapies and immunotherapy are in the development phase.

Follow-Up and Surveillance

Case Conclusion

After recovery from surgery, the patient is offered and completes 4 cycles of adjuvant chemotherapy with gemcitabine plus capecitabine. He is started on surveillance at 3 and 6 months, and he maintains an excellent performance status. He develops clinical evidence of pancreatic enzyme insufficiency and is placed on oral replacement therapy. He has no other complaints, and there is no evidence of recurrence on MRI and CA 19-9 levels.

• What is the recommended duration of surveillance following curative resection?

Surveillance after curative resection of pancreatic adenocarcinoma is recommended by NCCN guidelines.²⁶ However, pancreatic adenocarcinoma has a poor prognosis, and surveillance after curative surgical resection with or without perioperative therapy has not been shown to impact survival. Most recurrences will occur within 2 years after treatment. Surveillance recommendations differ among expert groups.^26,28,29 NCCN guidelines recommend evaluating patients by history and physical examination every 3 to 6 months for the first 2 years, then every 6 to 12 months for 3 years. CA 19-9 level and CT scan should be obtained every 3 to 6 months for 2 years and then every 6 to 12 months for 3 years. Follow-up with CA 19-9 levels and CT scans after 5 years is not routinely performed unless guided by signs, symptoms, or laboratory findings that raise suspicion for recurrence. Follow-up visits should also include evaluation of treatment-related toxicities, symptom management, nutrition support of pancreatic insufficiency, and psychosocial support.

Conclusion

Pancreatic cancer is a leading cause of cancer-related death that frequently presents with locally advanced or metastatic disease due to nonspecific symptoms and lack of a screening modality. Histological tissue biopsy confirmation and accurate resectability staging guide treatment planning and prognosis. The only potentially curative therapy is surgical resection plus adjuvant therapy for those with resectable disease. Surgical candidates with borderline resectable and unresectable disease can be offered induction preoperative chemotherapy followed by consolidation chemoradiation, based on clinical consensus practice. Enrollment in clinical trials should be encouraged for all patients, as evidence from clinical trials is essential to making progress in pancreatic cancer treatment.

Introduction

Exocrine pancreatic cancer refers to pancreatic adenocarcinomas that arise from ductal epithelial cells. Pancreatic ductal adenocarcinoma is a highly lethal malignancy, ranking as the fourth most common cause of cancer-related death in the United States¹ and the eighth most common worldwide.² In the United States, the pancreas is the second most common site of gastrointestinal malignancy after the colon.¹ The only potentially curative modality for pancreatic adenocarcinomas is complete resection, followed by adjuvant therapy; unfortunately, only around 20% of patients are surgical candidates at the time of presentation due to delayed development of symptoms and consequently diagnosis.³ Most symptomatic patients with pancreatic cancer have locally advanced disease at diagnosis, and only a select group of patients with good performance status and borderline resectable disease can be offered neoadjuvant therapy. Adjuvant chemotherapy is typically recommended for patients who undergo potentially curative resection for pancreatic cancer.

Epidemiology

In the United States, pancreatic cancer has an annual estimated incidence of 55,440 new cases.¹ It causes an estimated 44,330 deaths per year, with a 5-year overall survival (OS) rate of 8.2%.¹ Worldwide an estimated 138,100 men and 127,900 women die of pancreatic cancer each year.² In general, pancreatic cancers occur more commonly in persons living in Western/industrialized countries, older persons (age > 60 years), males (ratio 1.3:1 female), and African-Americans and native Hawaiians.⁴

Etiology

The major preventable environmental risk factor for pancreatic cancer is cigarette smoking, which accounts for 25% of all cases.⁵ A prospective study that estimated the excess incidence of pancreatic cancer among cigarette smokers and assessed the influence of smoking cessation on the risk for pancreatic cancer showed that persons who quit smoking reduced their risk of pancreatic cancer by 48% after 2 years of cessation, compared with smokers who did not quit, and reduced their risk to near the level of a never smoker after 10 years of cessation.⁵ Risk is higher for heavy smokers and those with homozygous deletions of the glutathione S-transferase theta 1 gene (GSTT1), which results in the absence of the carcinogen-metabolizing function of the glutathione S-transferase enzyme. High body mass index and sedentary lifestyle have been linked to pancreatic cancer.⁶ Data regarding aspirin, diet, coffee, and excess alcohol consumption are insufficient, inconclusive, and even conflicting, and thus the effect of these factors on risk for pancreatic cancer remains unclear. Infectious risk factors such as Helicobacter pylori and hepatitis B and C virus have weak associations with pancreatic cancer. Chronic pancreatitis and pancreatic cysts (eg, intraductal papillary mucinous neoplasm [IPMN] of the pancreas) carry a risk for malignant transformation, and hence may require surveillance. Multiple epidemiologic studies have shown a strong association between pancreatic cancer and recently diagnosed diabetes mellitus (relative risk [RR] 1.97 [95% confidence interval {CI} 1.78 to 2.18]); the presence of diabetes also may be a long-term predisposing factor for pancreatic cancer, and cancer screening needs to be considered for selected patients.⁷

A predisposing genetic anomaly accounts for 15% of all cases of pancreatic cancer.⁸ Hereditary risk factors are divided into 2 broad categories: defined genetic syndromes and familial pancreatic cancer. Familial predispositions that do not meet genetic syndrome criteria account for approximately 5% to 10% of all cases associated with hereditary factors; in one study, 29% of tested kindreds with an incident pancreatic cancer had a germline BRCA2 mutation.⁹ Other predisposing genetic syndromes that have been linked to pancreatic cancer include:

• Peutz-Jeghers syndrome with germline STK11 mutations (RR 132);
• Hereditary pancreatitis with germline PRSS1, SPINK1, and CFTR mutations (RR 26–87);
• Familial atypical multiple mole melanoma syndrome with CDKN2A mutations (RR 20–40);
• Familial breast and ovarian cancer with BRCA2 (RR 10) and BRCA1 (RR 2.8) mutations;
• Hereditary nonpolyposis colorectal cancer (HNPCC, Lynch II syndrome) with MLH1, MSH2, MSH6, and PMS2 mutations (RR 9–11); and
• Familial adenomatous polyposis with APC mutations (RR 5).¹⁰

Other gene mutations with unknown relative risk for pancreatic cancer include mutations affecting PALB2, ATM, and TP53.

The International Cancer of the Pancreas Screening consortium consensus on screening for pancreatic cancer in patients with increased risk for familial pancreatic cancer recommends screening those at high risk: first-degree relatives (FDRs) of patients with pancreatic cancer from a familial pancreatic kindred with at least 2 affected FDRs; patients with Peutz-Jeghers syndrome; and p16, BRCA2, and HNPCC mutation carriers with 1 or more affected FDRs and hereditary pancreatitis. The guidelines emphasize that screening should be done only in those who are surgical candidates and are evaluated at an experienced multidisciplinary center.⁸

Deleterious germline mutations in pancreatic cancer can account for 33% of patients with apparent sporadic cancers and no hereditary risk. These include germline mutations affecting BRCA1/2, PALB2, ATM, MLH1, CHK-2, CDKN2A, and TP53.¹¹

Pathogenesis

Pancreatic neoplasms can be benign or malignant and thus a tissue histologic diagnosis is paramount. Pancreatic adenocarcinomas with exocrine features represent more than 95% of all pancreatic neoplasms, with only 5% arising from the endocrine pancreas (ie, neuroendocrine tumors). Pancreatic neuroendocrine tumors and pancreatic adenocarcinoma must be distinguished histologically because treatment of the 2 neoplasms is completely different. Other malignant pancreatic tumors are signet ring cell carcinoma, adenosquamous carcinoma, undifferentiated (anaplastic) carcinoma, and mucinous noncystic (colloid) carcinoma; the latter tumor has a better prognosis.¹² It is essential to characterize and distinguish among benign cystic neoplasms, as some require surgical resection due to the risk of malignant transformation. IPMN, pancreatic intraepithelial neoplasia, and mucinous cystic neoplasms are thought to be premalignant lesions of invasive ductal adenocarcinomas, and the pathological report should highlight the degree of dysplasia for adequate risk stratification.¹³ This information could be the deciding factor in whether a pancreatectomy is recommended by a multidisciplinary team.

Most pancreatic cancers harbor activating or silencing genetic mutations, and multiple combinations of altered genes can be detected by next-generation sequencing (average of 63 genetic alterations per cancer).¹⁴ Mutational activated KRAS is the most frequent (> 90%) genetic alteration in pancreatic cancer, even in early neoplastic precursors (IPMN > 75%). KRAS is a highly complex, dynamic proto-oncogene involved in signaling of various receptor kinases such as the epidermal growth factor receptor and the insulin-like growth factor receptor-I. It also engages in canonical downstream effector pathways, mainly Raf/MEK/ERK, PI3K/PDK1/Akt, and the Ral guanine nucleotide exchange factor pathway, which drive much of the pathogenesis of malignancy. These pathways lead to sustained proliferation, metabolic reprogramming, anti-apoptosis, remodeling of the tumor microenvironment, evasion of the immune response, cell migration, and metastasis. An activating point mutation in codon G12 is the most common (98%) locus of KRAS mutation in pancreatic adenocarcinoma, but all drugs targeting this mutation have failed in clinical practice.¹⁵ Additionally, inactivation of tumor suppressor genes such as p53, DPC4 (SMAD4/MADH4), CDKN2A (p16/MTS1), and BRCA2 can be found in 75%, 30%, 35%, and 4% of pancreatic adenocarcinoma cases, respectively.¹⁴ Another pancreatic cancer hallmark is inactivation of DNA damage repair genes, which include MLH1 and MSH2.¹⁶

Diagnosis and Staging

Case Presentation

A 71-year-old male veteran with no significant past medical history other than hypertension and hyperlipidemia and an excellent performance status presents to the emergency department after noticing a yellowish skin and sclera color. He denies weight loss, abdominal pain, or any other pertinent symptom or sign. Physical examination reveals a healthy developed man with yellowish discoloration of the skin and sclera and a soft, nontender benign abdomen; physical examination is otherwise unremarkable. Laboratory evaluation reveals a direct bilirubin level of 4.5 mg/dL and normal values for complete blood count and renal, liver, and coagulation panels. Abdominal and pelvis computed tomography (CT) with intravenous contrast shows a pancreatic head mass measuring 2.6 × 2.3 cm minimally abutting the anterior surface of the superior mesenteric vein, which remains patent. Follow-up endoscopic ultrasound (EUS) confirms an irregular mass at the head of the pancreas measuring 3.2 × 2.6 cm with sonographic evidence suggesting invasion into the portal vein. During the procedure, the bile duct is successfully stented, the mass is biopsied, and bile duct brushing is performed. Pathology report is consistent with pancreatic adenocarcinoma.

• What is the typical presentation of pancreatic cancer?

The most common symptoms of pancreatic cancer at the time of presentation include weight loss (85%), asthenia/anorexia (86%), and/or abdominal pain (79%).¹⁷ The most frequent signs are jaundice (55%), hepatomegaly (39%), and cachexia (13%). Courvoisier sign, a nontender but palpable distended gallbladder at the right costal margin, is neither sensitive nor specific for pancreatic cancer (13% of cases). Trousseau syndrome, a superficial thrombophlebitis, is another classic sign that reflects the hypercoagulable nature of pancreatic cancer (3% of cases).¹⁷ The pathophysiology of this syndrome is not completely understood, but it may occur secondary to the release of cancer microparticles in the blood stream which in turn stimulate the coagulation cascade. Other nonspecific symptoms are dark urine, nausea, vomiting, diarrhea, steatorrhea, and epigastric and back pain. Because symptoms early in the course of the disease are nonspecific, pancreatic cancer is typically diagnosed late, after the cancer has invaded local structures or metastasized. The initial presentation varies depending on tumor location, with 70% of pancreatic head malignancies presenting with jaundice and pain correlating to an advanced stage.¹⁸ Although data supporting an association between new-onset diabetes mellitus and pancreatic cancer are inconclusive, pancreatic cancer should still be a consideration in patients with new-onset diabetes mellitus and other symptoms such as pain and weight loss. Early signs of incurable disease include a palpable mass, ascites, lymphadenopathy (classic Virchow node), and an umbilical mass (Sister Mary Joseph node). Incidentally discovered pancreatic masses on imaging are rare, but the incidence is increasing due to frequent imaging for other reasons and improved diagnostic techniques.

• What is the approach to diagnosis and staging?

History and physical examination findings are not sufficiently sensitive or specific to diagnose pancreatic cancer. High clinical suspicion in a patient with risk factors can lead to a comprehensive evaluation and potential early diagnosis. In general, an initial diagnostic work-up for suspected pancreatic cancer will include serologic evaluation (liver function test, lipase, tumor markers) and abdominal imaging (ultrasound, CT scans, or magnetic resonance imaging [MRI]). Ultrasound is a first-line diagnostic tool with a sensitivity of 90% and specificity of 98.8% for pancreatic cancer, but it is investigator-dependent and is less accurate in detecting tumors smaller than 3 cm in diameter.¹⁹ Multiphasic helical CT of the abdomen has better sensitivity (100%) and specificity (100%) for detecting tumors larger than 2 cm, but this modality is less accurate in detecting pancreatic masses smaller than 2 cm (77%).²⁰ Percutaneous fine-needle aspiration (FNA) performed by ultrasound or CT guidance is avoided due to theoretical concerns about intraperitoneal seeding and bleeding.

If a pancreatic mass is detected by ultrasound or CT, additional interventions may be indicated depending on the clinical scenario. EUS-guided biopsy can provide histological confirmation and is currently utilized frequently for diagnosis and early resectability staging. Endoscopic retrograde cholangiopancreatography (ERCP) is indicated for patients with biliary obstruction requiring stent placement, and this procedure may provide tissue confirmation by forceps biopsy or brush cytology (lower accuracy than EUS). In a meta-analysis that evaluated the diagnostic value of tests for pancreatic cancer, ERCP had the highest sensitivity (92%) and specificity (96%) compared to ultrasound and CT,²¹ but this modality carries a risk for pancreatitis, bleeding, and cholangitis. Magnetic resonance cholangiopancreatography has not replaced ERCP, but it but may be an alternative for patients who cannot undergo ERCP (eg, gastric outlet obstruction, duodenal stenosis, anatomical surgical disruption, unsuccessful ERCP). ERCP is used frequently because many patients present with obstructive jaundice due to pancreatic mass compression, specifically if the mass is located in the head, and must undergo ERCP and stenting of the common bile duct.

The carbohydrate antigen (CA) 19-9 level has variable sensitivity and specificity in pancreatic cancer, as levels can be elevated in many benign pancreaticobiliary disorders. Elevated CA 19-9, in the appropriate clinical scenario (ie, a suspicious pancreatic mass and a value greater than 37 U/mL) demonstrated a sensitivity of 77% and specificity of 87% when differentiating pancreaticobiliary cancer from benign clinical conditions such as acute cholangitis or cholestasis.²² CA 19-9 level has prognostic value, as it may predict occult disease and correlates with survival rates, but no specific cutoff value has been established to guide perioperative therapy for high-risk resectable tumors.²³

The American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) tumor, node, metastasis (TNM) system is the preferred method for staging pancreatic cancer (Table 1). 

Positron emission tomography with CT scan is occasionally utilized in practice to assess tumor burden by evaluating anatomical structures and assessing physiologic uptake, which aids in establishing the extent of disease in equivocal cases. Staging laparoscopy with or without peritoneal biopsy is sometimes used to establish appropriate staging in cases that are questionable for occult metastatic disease. This procedure helps avoid unnecessary morbid surgeries.

Neoadjuvant Therapy

Case Continued

The patient is referred to oncology. Blood work reveals a CA 19-9 level of 100 U/mL (reference range < 35 U/mL) and a staging CT scan of the chest reveals a benign-appearing 3-mm nodule (no prior imaging for comparison). CT scan of the abdomen and pelvis does not define venous vasculature involvement appropriately and hence MRI of the abdomen and pelvis is performed. MRI reveals a pancreatic head mass measuring 3.0 × 2.7 cm, without arterial or venous vasculature invasion. However, the mass is abutting the portal vein and superior mesenteric vein and there is a new nonspecific 8-mm aortocaval lymph node.

• What are the current approaches to treating patients with resectable, unresectable, and metastatic disease?

Accurate staging and assessment of surgical resectability in pancreatic cancer are paramount as these steps prevent a futile morbid Whipple procedure in patients with advanced disease and a high risk of recurrence. Conversely, it allows patients with low-volume disease to undergo a potentially curative surgery. Approximately 20% of patients present with resectable disease, 40% present with locally advanced unresectable tumors (eg, involvement of critical vascular structures), and 40% present with metastatic disease.³ Treatment for resectable pancreatic cancer continues to be upfront surgery, although neoadjuvant therapy with either chemoradiation, radiation alone, or chemotherapy is an option per guidelines from the American Society of Clinical Oncology (ASCO),²⁸ the NCCN,²⁶ and the European Society for Medical Oncology (ESMO),²⁹ particularly for patients with borderline resectable tumors (Table 3). 

Systemic chemotherapy is recommended for fit candidates with locally advanced unresectable or metastatic disease, with an emphasis on supportive palliative measures. Palliative interventions include biliary stenting, duodenal stent for relieving gastric-outlet obstruction, and celiac axis nerve blocks, when indicated. Routine preoperative biliary stent placement/drainage in patients undergoing subsequent surgery for pancreatic cancer located in the head is associated with an increased risk of surgical complications when compared with up-front surgery without prior biliary drainage, and thus stent placement/drainage is not recommended.²⁶ Aggressive supportive management of symptoms, such as cancer-associated pain, anorexia-cachexia syndromes, and anxiety-depression disorders, should remain a primary palliative focus.

Case Continued

A multidisciplinary tumor board discusses the patient’s case and deems the cancer borderline resectable; neoadjuvant therapy is recommended. The patient is started on treatment with gemcitabine and nab-paclitaxel as first-line neoadjuvant therapy. After 4 cycles, the CA 19-9 level drops to 14 U/mL, and MRI reveals a smaller head mass of 1.3 × 1.4 cm with stable effacement of the superior mesenteric vein and no portal vein involvement; the aortocaval lymph node remains stable. At tumor board, it is evident that the patient has responded to therapy and the recommendation is to treat with gemcitabine chemoradiotherapy before surgery.

• What neoadjuvant therapy strategies are used in the treatment of pancreatic adenocarcinoma?

There are no established evidence-based recommendations for neoadjuvant therapy in patients with borderline resectable pancreatic cancer or patients with unresectable locally advanced pancreatic cancer. However, there are ongoing trials to investigate this treatment approach, and it is offered off-label in specific clinical scenarios, such as in the case patient described here. In patients with borderline resectable disease, preoperative chemotherapy followed by chemoradiation is a routine practice in most cancer centers,³² and ongoing clinical trials are an option for this cohort of patients (eg, Southwest Oncology Group Trial 1505, NCT02562716). The definitions of borderline resectable and unresectable pancreatic cancer have been described by the NCCN,²⁶ although most surgeons consider involvement of the major upper abdominal blood vessels the main unresectability criterion; oncologists also consider other parameters such as suspicious lesions on scans, worsening performance status, and a significantly elevated CA 19-9 level suggestive of disseminated disease.²⁸ The goal of a conversion approach by chemotherapy with or without radiation for borderline and unresectable cancers is to deliver a tolerable regimen leading to tumor downstaging, allowing for surgical resection. No randomized clinical trial has shown a survival advantage of this approach. Enrollment in clinical trials is preferred for patients with borderline and unresectable cancer, and there are trials that are currently enrolling patients.

The main treatment strategies for patients with locally advanced borderline and unresectable pancreatic cancer outside of a clinical trial are primary radiotherapy, systemic chemotherapy, and chemoradiation therapy. Guidelines from ASCO, NCCN, and ESMO recommend induction chemotherapy followed by restaging and consolidation chemoradiotherapy in the absence of progression.^26,28,29 There is no standard chemoradiation regimen and the role of chemotherapy sensitizers, including fluorouracil, gemcitabine, and capecitabine (an oral fluoropyrimidine substitute), and targeted agents in combination with different radiation modalities is now being investigated.

Fluorouracil is a radio-sensitizer that has been used in locally advanced pancreatic cancer based on experience in other gastrointestinal malignancies; data shows conflicting results with this drug. Capecitabine and tegafur/gimeracil/oteracil (S-1) are oral prodrugs that can safely replace infusional fluorouracil. Gemcitabine, a more potent radiation sensitizer, is very toxic, even at low-doses twice weekly, and does not provide a survival benefit, as demonstrated in the Cancer and Leukemia Group B (CALGB) 89805 trial, a phase 2 study of patients with surgically staged locally advanced pancreatic cancer.³³ Gemcitabine-based chemoradiotherapy was also evaluated in the Eastern Cooperative Group (ECOG) E4201 trial, which randomly assigned patients to receive gemcitabine alone (at 1000 mg/m²/wk for weeks 1 through 6, followed by 1 week rest, then weekly for 3 out of 4 weeks) or gemcitabine (600 mg/m²/wk for weeks 1 to 5, then 4 weeks later 1000 mg/m² for 3 out of 4 weeks) plus radiotherapy (starting on day 1, 1.8 Gy/fraction for total of 50.4 Gy).³⁴ Patients with locally advanced unresectable pancreatic cancer had a better OS outcome with gemcitabine in combination with radiation therapy (11.1 months) as compared with patients who received gemcitabine alone (9.2 months). Although there was a greater incidence of grade 4 and 5 treatment-related toxicities in the combination arm, no statistical differences in quality-of-life measurements were reported. Gemcitabine-based and capecitabine-based chemoradiotherapy were compared in the open-label phase 2 multicenter randomized SCALOP trial.³⁵ Patients with locally advanced pancreatic cancer were assigned to receive 3 cycles of induction with gemcitabine 1000 mg/m² days 1, 8, and 15 and capecitabine 830 mg/m² days 1 to 21 every 28 days; patients who had stable or responding disease were randomly assigned to receive a fourth cycle followed by capecitabine (830 mg/m² twice daily on weekdays only) or gemcitabine (300 mg/m² weekly) with radiation (50.4 Gy over 28 fractions). Patients treated with capecitabine-based chemoradiotherapy had higher nonsignificant median OS (17.6 months) and median progression-free survival (12 months) compared to those treated with gemcitabine (14.6 months and 10.4 months, respectively).

The benefit of radiation therapy in the treatment of locally advanced pancreatic cancer was further explored by the Fédération Francophone de Cancérologie Digestive 2000-01 phase 3 trial. This study compared induction chemoradiotherapy (60 Gy, 2 Gy/fraction; concomitant fluorouracil infusion, 300 mg/m²/day, days 1–5 for 6 weeks; cisplatin, 20 mg/m²/day, days 1–5 during weeks 1 and 5) to gemcitabine alone (1000 mg/m² weekly for 7 weeks) followed by maintenance gemcitabine in both arms.³⁶ Unexpectedly, the median OS was significantly shorter in the chemoradiotherapy arm than in the chemotherapy alone arm (8.6 months versus 13 months, respectively, P = 0.03) and the combination arm had more toxicities. The phase 3 open-label LAP07 study explored the role of radiation therapy in patients with locally advanced pancreatic cancer who had controlled disease after 4 months of induction therapy.³⁷ LAP07 had 2 randomizations: first, patients with locally advanced pancreatic cancer were assigned to receive weekly gemcitabine alone (1000 mg/m²) or this same dose of gemcitabine plus erlotinib 100 mg/day; second, patients with progression-free disease (61% of initial cohort) after 4 months of therapy were assigned to receive 2 months of the same chemotherapy or chemoradiotherapy (54 Gy plus capecitabine). This study showed that the addition of erlotinib to gemcitabine did not improve survival and in fact affected survival adversely. Of note, no survival benefit was observed after the first randomization from chemotherapy to consolidating chemoradiotherapy. Chemoradiotherapy achieved better locoregional tumor control with significantly less local tumor progression (32% versus 46%, P < 0.03) and no increase in toxicity. Based on prior moderate-quality evidence, guidelines recommend consolidative chemoradiotherapy only for surgical resection candidates following induction chemotherapy; for those who are not surgical candidates, guidelines recommend continuing systemic therapy.^26,28,29

Gemcitabine and fluorouracil-based chemotherapies were the standard induction regimens until evidence from studies of metastatic systemic treatment protocols with FOLFIRINOX (ACCORD trial³⁸) and nanoparticle albumin-bound paclitaxel (nab-paclitaxel) plus gemcitabine (MPACT trial³⁹) was extrapolated to clinical practice. These regimens were shown to achieve higher objective response rates when compared to single-agent gemcitabine in patients with metastatic pancreatic cancer. Due to the broad heterogeneity of results in small retrospective series with neoadjuvant trials in borderline resectable pancreatic cancer, the quality of the evidence is low and any recommendation is limited. Many individual series have demonstrated improved complete resection rates and promising survival rates. In the largest single-institution retrospective review of patients with borderline resectable pancreatic adenocarcinoma who completed neoadjuvant gemcitabine-based chemoradiotherapy (50 Gy in 28 fractions or 30 Gy in 10 fractions), 94% achieved a margin-negative pancreatectomy; the median OS in those who completed preoperative therapy and had surgery was 40 months, with a 5-year OS of 36%.⁴⁰ A meta-analysis by Andriulli and colleagues included 20 prospective studies of patients with initially resectable (366 lesions) or unresectable (341 lesions) disease who were treated with neoadjuvant/preoperative gemcitabine with or without radiotherapy.⁴¹ In the group with initially unresectable disease, 39% underwent surgery after restaging and 68% of explored patients were resected; the R0 resection rate was 60%. After restaging, 91% of patients with resectable disease underwent surgery, with 82% of explored patients undergoing surgical resection and 89% of these achieving R0 resection. The estimated 1- and 2-year survival probabilities after resection among patients with initially unresectable disease were 86.3% and 54.2%.⁴¹

The largest single-institution retrospective review of FOLFIRINOX (fluorouracil, oxaliplatin, irinotecan, and leucovorin), an alternative to gemcitabine, for neoadjuvant induction therapy for patients with locally advanced unresectable disease was conducted at Memorial Sloan Kettering Cancer Center. In this study (n = 101), 31% of patients initially deemed unresectable who completed FOLFIRINOX induction therapy with or without chemoradiation underwent resection. The R0 resection rate in these patients was 55%, and patients who did not progress during induction FOLFIRINOX therapy had a median OS of 26 months.⁴² A systematic review and meta-analysis of FOLFIRINOX chemotherapy with or without radiotherapy in patients with locally advanced unresectable pancreatic cancer reported that 25.9% of patients underwent resection after FOLFIRINOX therapy, and the R0 resection rate in these patients was 78.4%.⁴³ The median OS in this study was 24.2 months, which was longer than the previously reported median OS rates for gemcitabine.

There is no strong evidence published for the use of combination nab-paclitaxel plus gemcitabine in the neoadjuvant setting, but it is used in clinical practice based on evidence from the MPACT trial, which showed the combination improved OS and progression-free survival in patients with metastatic pancreatic cancer.³⁹ An early-phase 1-arm clinical trial of neoadjuvant gemcitabine, docetaxel, and capecitabine (GTX) followed by radiotherapy showed an increased response rate and survival for locally advanced disease; however, the NCCN expert panel has reached a consensus but not a uniform recommendation regarding this regimen due to significant toxicities and low patient accrual.²⁶ Selected patients with pancreatic cancer with BRCA1/2 mutations are more sensitive to platinum-based chemotherapy. Although studies of neoadjuvant platinum-based chemotherapy in this population have not been reported, the NCCN guidelines list it as an alternative option based on extrapolated data.²⁶ A clinical trial of gemcitabine, nab-paclitaxel, and cisplatin in the neoadjuvant setting in patients with resectable pancreatic cancer is currently enrolling patients (NGC triple regimen NCT0339257).

Summary

Chemotherapy alone or followed by chemoradiotherapy may be used as initial treatment for patients with borderline and unresectable pancreatic adenocarcinoma without distant metastases who are potential surgical candidates. Chemoradiotherapy remains a preferred treatment option for patients with poorly controlled pain from local tumor invasion, in view of the well-documented analgesic palliative effect of radiation therapy. FOLFIRINOX with or without radiation therapy may offer the highest documented response rates, but it also results in higher rates of treatment-related toxicities. FOLFIRINOX can be offered to selected fit patients (< 65 years old, no comorbidity contraindication, good functional status [ECOG 0–1]) who can tolerate triple therapy with a more toxic adverse-effect profile. A clinical trial evaluating neoadjuvant FOLFIRINOX with or without preoperative chemoradiotherapy in patients with borderline resectable pancreatic cancer is ongoing (PANDAS-PRODIGE 44, NCT02676349). Gemcitabine with or without radiation therapy is a tolerable combination, although it is potentially more toxic when combined with radiation. The addition of nab-paclitaxel to gemcitabine without radiation may emerge as a preferred neoadjuvant treatment for selected patients; a clinical trial investigating this modality in patients with resectable and borderline resectable disease is ongoing (NCT02723331).

Adjuvant Therapy

Case Continued

Prior to the planned surgical resection and after undergoing chemoradiation therapy, the patient has an excellent performance status and repeat MRI shows a 1.3 × 1.4 cm head mass with no further vasculature involvement, no evidence of lymphadenopathy, and no distant metastasis. The CA 19-9 level is stable at 18 U/mL. The patient undergoes an uncomplicated partial pancreaticoduodenectomy, and analysis of a surgical pathology specimen reveals T3N0 disease with closest margin of 0.1 cm.

• Would the patient benefit from adjuvant therapy?

Adjuvant chemotherapy for 6 months after pancreatic cancer resection should be offered to all patients based on mature data. Gemcitabine and capecitabine are the current standard of care in adjuvant therapy; alternatively, single-agent gemcitabine can be offered to patients with poor performance status or patients who cannot tolerate the toxicities associated with this combination.²⁸ Adjuvant treatment should be initiated within approximately 8 weeks of surgical resection. The value of radiation therapy remains controversial, but it can be offered within the context of a clinical trial or to patients with positive margins after surgical resection and/or lymph node–positive disease. Based on low-quality supportive evidence, it is strongly recommended that patients who receive neoadjuvant therapy complete a total of 6 months of chemotherapy, factoring in the duration of the preoperative regimen.²⁸ Different adjuvant strategies have been investigated, including chemotherapy alone with a fluoropyrimidine and/or gemcitabine with or without combined chemoradiation therapy.

The European Study Group for Pancreatic Cancer 1 (ESPAC)-1 trial was a randomized clinical trial that evaluated several adjuvant strategies in pancreatic cancer treatment. This trial assigned patients who underwent pancreatic adenocarcinoma resection to adjuvant chemotherapy alone (intravenous fluorouracil 425 mg/m² and leucovorin 20 mg/m² daily for 5 days, monthly for 6 months), chemoradiotherapy (20 Gy in 10 daily fractions over 2 weeks with 500 mg/m² intravenous fluorouracil on days 1–3, repeated after 2 weeks), both chemotherapy and chemoradiation, and observation.⁴⁴ The results showed no added benefit for adjuvant chemoradiotherapy, with a median OS of 15.5 months in the chemoradiotherapy cohort, as compared to a median OS of 16.1 months in the chemotherapy-alone cohort (hazard ratio [HR] 1.18 [95% CI 0.90 to 1.55], P = 0.24). In addition, there was evidence of a survival benefit for the chemotherapy-alone arm when compared to the combined modality arm, with a median OS of 19.7 versus 14.0 months, respectively (HR 0.66 [95% CI 0.52 to 0.83], P = 0.0005). Although ESPAC-1 has been criticized for being underpowered to perform statistical comparison, it is still considered a landmark trial demonstrating benefit with single-agent chemotherapy alone. A follow-up analysis of ESPAC-1 showed that adjuvant chemotherapy alone conferred a significant 5-year survival benefit while the combined modality had a deleterious effect on survival. ⁴⁵ Hence, adjuvant chemotherapy alone became the standard of care in the United States following resection.

The results of the multicenter randomized controlled phase 3 CONKO-001 (CharitéOnkologie 001) trial, which were reported in 2007, supported the use of adjuvant gemcitabine for 6 months in patients with resected pancreatic adenocarcinoma. In this study, patients treated with adjuvant gemcitabine (1000 mg/m² days 1, 8, and 15 every 4 weeks for 6 months) had superior disease-free survival compared with those who received surgery alone.³⁰ A long-term outcome update of this study demonstrated a significant improvement in 5-year OS for patients treated with adjuvant gemcitabine (20.7% [95% CI 14.7% to 26.6%]) compared to those who received surgical resection alone (10.4% [95% CI 5.9% to 15.0%]). This benefit persisted at 10-year follow-up, with an OS of 12.2% (95% CI 7.3% to 17.2%) in the adjuvant gemcitabine group, as compared to 7.7% (95% CI 3.6% to 11.8%) in the resection alone group.³¹

Fluorouracil and gemcitabine remained equivalent adjuvant treatment options until the results of the ESPAC-3 trial were reported in 2010.³² This large phase 3 trial, conducted mainly in the United Kingdom, compared weekly gemcitabine (1000 mg/m² weekly for 3 of every 4 weeks) to leucovorin-modulated fluorouracil (Mayo Clinic regimen: leucovorin 20 mg/m² followed by fluorouracil 425 mg/m² intravenous bolus days 1 through 5 every 28 days) as adjuvant therapy in resected pancreatic adenocarcinoma. After a median follow-up of 34.2 months, the median OS was similar in the 2 groups (fluorouracil/leucovorin 23.0 months versus gemcitabine 23.6 months; P = 0.39). However, the fluorouracil/leucovorin group experienced more grade 3/4 treatment-related toxicities (mucositis, stomatitis, diarrhea, and hosptializations; 14% versus 7.5%; P < 0.001).⁴⁶ Following this trial, gemcitabine became the standard of care for adjuvant chemotherapy for resected pancreatic cancer.

The U.S. Radiation Therapy Oncology Group (RTOG) 9704 trial was conducted to investigate the potential benefit of adding radiation therapy to gemcitabine. This trial demonstrated an improved trend among patients with pancreatic head tumors (but not with cancers of the pancreatic body or tail) who received adjuvant gemcitabine followed by chemoradiotherapy (50.4 Gy in 1.8 Gy daily fractions for 5.5 weeks with concurrent infusional fluorouracil 250 mg/m² daily) and subsequent gemcitabine monotherapy compared to postoperative fluorouracil-based chemoradiotherapy. Results showed a 5-year OS of 22% versus 18%, respectively, although this improvement was not statistically significant (P = 0.08). This trial failed to show a benefit of adding radiotherapy to gemcitabine.⁴⁷

The ESPAC-4 trial, reported in 2017, evaluated the combination of gemcitabine and capecitabine compared to gemcitabine alone as adjuvant therapy for resected pancreatic adenocarcinoma.⁴⁸ Patients were randomly assigned after surgical resection, regardless of margin or node status, to 6 months of gemcitabine alone (1000 mg/m²/day on days 1, 8, and 15 of each 28-day cycle) or gemcitabine plus capecitabine (1660 mg/m²/day on days 1 through 21 of each 28-day cycle). Combination therapy had a significant survival benefit compared to single therapy, with median OS durations of 28 months and 25.5 months, respectively (HR for death 0.82 [95% CI 0.68 to 0.98]). The 5-year OS for patients who received combination treatment was 29 months (95% CI 22.9 to 35.2) versus 16 months (95% CI 10.2 to 23.7) for those in the monotherapy group. As expected, grade 3 or 4 treatment-related toxicities (diarrhea, hand-foot syndrome, and neutropenia) were significantly more common with combined therapy, although there were no significant differences in the rates of serious adverse events. The adjuvant combination of gemcitabine and capecitabine became the current and preferred new standard of care following resection of pancreatic ductal adenocarcinoma,²⁸ but single-agent gemcitabine and fluorouracil/leucovorin continue to be viable options,^26,28,29 particularly for elderly patients, patients with borderline performance status, or patients with multiple comorbidities.

Evidence showing that a more intensive regimen can improve outcome in the adjuvant setting remains elusive. The phase 3 APACT study (Adjuvant Therapy for Patients with Resected Pancreatic Cancer, NCT01964430) comparing gemcitabine alone to gemcitabine plus nab-paclitaxel in patients with surgically resected pancreatic adenocarcinoma has concluded, with the results projected to be released in 2018. Another phase 3 trial investigating the efficacy of FOLFIRINOX versus gemcitabine alone as adjuvant therapy is underway in France and Canada (PRODIGE24/ACCORD24, NCT01526135). Other strategies with newer targeted therapies and immunotherapy are in the development phase.

Follow-Up and Surveillance

Case Conclusion

After recovery from surgery, the patient is offered and completes 4 cycles of adjuvant chemotherapy with gemcitabine plus capecitabine. He is started on surveillance at 3 and 6 months, and he maintains an excellent performance status. He develops clinical evidence of pancreatic enzyme insufficiency and is placed on oral replacement therapy. He has no other complaints, and there is no evidence of recurrence on MRI and CA 19-9 levels.

• What is the recommended duration of surveillance following curative resection?

Surveillance after curative resection of pancreatic adenocarcinoma is recommended by NCCN guidelines.²⁶ However, pancreatic adenocarcinoma has a poor prognosis, and surveillance after curative surgical resection with or without perioperative therapy has not been shown to impact survival. Most recurrences will occur within 2 years after treatment. Surveillance recommendations differ among expert groups.^26,28,29 NCCN guidelines recommend evaluating patients by history and physical examination every 3 to 6 months for the first 2 years, then every 6 to 12 months for 3 years. CA 19-9 level and CT scan should be obtained every 3 to 6 months for 2 years and then every 6 to 12 months for 3 years. Follow-up with CA 19-9 levels and CT scans after 5 years is not routinely performed unless guided by signs, symptoms, or laboratory findings that raise suspicion for recurrence. Follow-up visits should also include evaluation of treatment-related toxicities, symptom management, nutrition support of pancreatic insufficiency, and psychosocial support.

Conclusion

Pancreatic cancer is a leading cause of cancer-related death that frequently presents with locally advanced or metastatic disease due to nonspecific symptoms and lack of a screening modality. Histological tissue biopsy confirmation and accurate resectability staging guide treatment planning and prognosis. The only potentially curative therapy is surgical resection plus adjuvant therapy for those with resectable disease. Surgical candidates with borderline resectable and unresectable disease can be offered induction preoperative chemotherapy followed by consolidation chemoradiation, based on clinical consensus practice. Enrollment in clinical trials should be encouraged for all patients, as evidence from clinical trials is essential to making progress in pancreatic cancer treatment.

Introduction

Exocrine pancreatic cancer refers to pancreatic adenocarcinomas that arise from ductal epithelial cells. Pancreatic ductal adenocarcinoma is a highly lethal malignancy, ranking as the fourth most common cause of cancer-related death in the United States¹ and the eighth most common worldwide.² In the United States, the pancreas is the second most common site of gastrointestinal malignancy after the colon.¹ The only potentially curative modality for pancreatic adenocarcinomas is complete resection, followed by adjuvant therapy; unfortunately, only around 20% of patients are surgical candidates at the time of presentation due to delayed development of symptoms and consequently diagnosis.³ Most symptomatic patients with pancreatic cancer have locally advanced disease at diagnosis, and only a select group of patients with good performance status and borderline resectable disease can be offered neoadjuvant therapy. Adjuvant chemotherapy is typically recommended for patients who undergo potentially curative resection for pancreatic cancer.

Epidemiology

In the United States, pancreatic cancer has an annual estimated incidence of 55,440 new cases.¹ It causes an estimated 44,330 deaths per year, with a 5-year overall survival (OS) rate of 8.2%.¹ Worldwide an estimated 138,100 men and 127,900 women die of pancreatic cancer each year.² In general, pancreatic cancers occur more commonly in persons living in Western/industrialized countries, older persons (age > 60 years), males (ratio 1.3:1 female), and African-Americans and native Hawaiians.⁴

Etiology

The major preventable environmental risk factor for pancreatic cancer is cigarette smoking, which accounts for 25% of all cases.⁵ A prospective study that estimated the excess incidence of pancreatic cancer among cigarette smokers and assessed the influence of smoking cessation on the risk for pancreatic cancer showed that persons who quit smoking reduced their risk of pancreatic cancer by 48% after 2 years of cessation, compared with smokers who did not quit, and reduced their risk to near the level of a never smoker after 10 years of cessation.⁵ Risk is higher for heavy smokers and those with homozygous deletions of the glutathione S-transferase theta 1 gene (GSTT1), which results in the absence of the carcinogen-metabolizing function of the glutathione S-transferase enzyme. High body mass index and sedentary lifestyle have been linked to pancreatic cancer.⁶ Data regarding aspirin, diet, coffee, and excess alcohol consumption are insufficient, inconclusive, and even conflicting, and thus the effect of these factors on risk for pancreatic cancer remains unclear. Infectious risk factors such as Helicobacter pylori and hepatitis B and C virus have weak associations with pancreatic cancer. Chronic pancreatitis and pancreatic cysts (eg, intraductal papillary mucinous neoplasm [IPMN] of the pancreas) carry a risk for malignant transformation, and hence may require surveillance. Multiple epidemiologic studies have shown a strong association between pancreatic cancer and recently diagnosed diabetes mellitus (relative risk [RR] 1.97 [95% confidence interval {CI} 1.78 to 2.18]); the presence of diabetes also may be a long-term predisposing factor for pancreatic cancer, and cancer screening needs to be considered for selected patients.⁷

A predisposing genetic anomaly accounts for 15% of all cases of pancreatic cancer.⁸ Hereditary risk factors are divided into 2 broad categories: defined genetic syndromes and familial pancreatic cancer. Familial predispositions that do not meet genetic syndrome criteria account for approximately 5% to 10% of all cases associated with hereditary factors; in one study, 29% of tested kindreds with an incident pancreatic cancer had a germline BRCA2 mutation.⁹ Other predisposing genetic syndromes that have been linked to pancreatic cancer include:

• Peutz-Jeghers syndrome with germline STK11 mutations (RR 132);
• Hereditary pancreatitis with germline PRSS1, SPINK1, and CFTR mutations (RR 26–87);
• Familial atypical multiple mole melanoma syndrome with CDKN2A mutations (RR 20–40);
• Familial breast and ovarian cancer with BRCA2 (RR 10) and BRCA1 (RR 2.8) mutations;
• Hereditary nonpolyposis colorectal cancer (HNPCC, Lynch II syndrome) with MLH1, MSH2, MSH6, and PMS2 mutations (RR 9–11); and
• Familial adenomatous polyposis with APC mutations (RR 5).¹⁰

Other gene mutations with unknown relative risk for pancreatic cancer include mutations affecting PALB2, ATM, and TP53.

The International Cancer of the Pancreas Screening consortium consensus on screening for pancreatic cancer in patients with increased risk for familial pancreatic cancer recommends screening those at high risk: first-degree relatives (FDRs) of patients with pancreatic cancer from a familial pancreatic kindred with at least 2 affected FDRs; patients with Peutz-Jeghers syndrome; and p16, BRCA2, and HNPCC mutation carriers with 1 or more affected FDRs and hereditary pancreatitis. The guidelines emphasize that screening should be done only in those who are surgical candidates and are evaluated at an experienced multidisciplinary center.⁸

Deleterious germline mutations in pancreatic cancer can account for 33% of patients with apparent sporadic cancers and no hereditary risk. These include germline mutations affecting BRCA1/2, PALB2, ATM, MLH1, CHK-2, CDKN2A, and TP53.¹¹

Pathogenesis

Pancreatic neoplasms can be benign or malignant and thus a tissue histologic diagnosis is paramount. Pancreatic adenocarcinomas with exocrine features represent more than 95% of all pancreatic neoplasms, with only 5% arising from the endocrine pancreas (ie, neuroendocrine tumors). Pancreatic neuroendocrine tumors and pancreatic adenocarcinoma must be distinguished histologically because treatment of the 2 neoplasms is completely different. Other malignant pancreatic tumors are signet ring cell carcinoma, adenosquamous carcinoma, undifferentiated (anaplastic) carcinoma, and mucinous noncystic (colloid) carcinoma; the latter tumor has a better prognosis.¹² It is essential to characterize and distinguish among benign cystic neoplasms, as some require surgical resection due to the risk of malignant transformation. IPMN, pancreatic intraepithelial neoplasia, and mucinous cystic neoplasms are thought to be premalignant lesions of invasive ductal adenocarcinomas, and the pathological report should highlight the degree of dysplasia for adequate risk stratification.¹³ This information could be the deciding factor in whether a pancreatectomy is recommended by a multidisciplinary team.

Most pancreatic cancers harbor activating or silencing genetic mutations, and multiple combinations of altered genes can be detected by next-generation sequencing (average of 63 genetic alterations per cancer).¹⁴ Mutational activated KRAS is the most frequent (> 90%) genetic alteration in pancreatic cancer, even in early neoplastic precursors (IPMN > 75%). KRAS is a highly complex, dynamic proto-oncogene involved in signaling of various receptor kinases such as the epidermal growth factor receptor and the insulin-like growth factor receptor-I. It also engages in canonical downstream effector pathways, mainly Raf/MEK/ERK, PI3K/PDK1/Akt, and the Ral guanine nucleotide exchange factor pathway, which drive much of the pathogenesis of malignancy. These pathways lead to sustained proliferation, metabolic reprogramming, anti-apoptosis, remodeling of the tumor microenvironment, evasion of the immune response, cell migration, and metastasis. An activating point mutation in codon G12 is the most common (98%) locus of KRAS mutation in pancreatic adenocarcinoma, but all drugs targeting this mutation have failed in clinical practice.¹⁵ Additionally, inactivation of tumor suppressor genes such as p53, DPC4 (SMAD4/MADH4), CDKN2A (p16/MTS1), and BRCA2 can be found in 75%, 30%, 35%, and 4% of pancreatic adenocarcinoma cases, respectively.¹⁴ Another pancreatic cancer hallmark is inactivation of DNA damage repair genes, which include MLH1 and MSH2.¹⁶

Diagnosis and Staging

Case Presentation

A 71-year-old male veteran with no significant past medical history other than hypertension and hyperlipidemia and an excellent performance status presents to the emergency department after noticing a yellowish skin and sclera color. He denies weight loss, abdominal pain, or any other pertinent symptom or sign. Physical examination reveals a healthy developed man with yellowish discoloration of the skin and sclera and a soft, nontender benign abdomen; physical examination is otherwise unremarkable. Laboratory evaluation reveals a direct bilirubin level of 4.5 mg/dL and normal values for complete blood count and renal, liver, and coagulation panels. Abdominal and pelvis computed tomography (CT) with intravenous contrast shows a pancreatic head mass measuring 2.6 × 2.3 cm minimally abutting the anterior surface of the superior mesenteric vein, which remains patent. Follow-up endoscopic ultrasound (EUS) confirms an irregular mass at the head of the pancreas measuring 3.2 × 2.6 cm with sonographic evidence suggesting invasion into the portal vein. During the procedure, the bile duct is successfully stented, the mass is biopsied, and bile duct brushing is performed. Pathology report is consistent with pancreatic adenocarcinoma.

• What is the typical presentation of pancreatic cancer?

The most common symptoms of pancreatic cancer at the time of presentation include weight loss (85%), asthenia/anorexia (86%), and/or abdominal pain (79%).¹⁷ The most frequent signs are jaundice (55%), hepatomegaly (39%), and cachexia (13%). Courvoisier sign, a nontender but palpable distended gallbladder at the right costal margin, is neither sensitive nor specific for pancreatic cancer (13% of cases). Trousseau syndrome, a superficial thrombophlebitis, is another classic sign that reflects the hypercoagulable nature of pancreatic cancer (3% of cases).¹⁷ The pathophysiology of this syndrome is not completely understood, but it may occur secondary to the release of cancer microparticles in the blood stream which in turn stimulate the coagulation cascade. Other nonspecific symptoms are dark urine, nausea, vomiting, diarrhea, steatorrhea, and epigastric and back pain. Because symptoms early in the course of the disease are nonspecific, pancreatic cancer is typically diagnosed late, after the cancer has invaded local structures or metastasized. The initial presentation varies depending on tumor location, with 70% of pancreatic head malignancies presenting with jaundice and pain correlating to an advanced stage.¹⁸ Although data supporting an association between new-onset diabetes mellitus and pancreatic cancer are inconclusive, pancreatic cancer should still be a consideration in patients with new-onset diabetes mellitus and other symptoms such as pain and weight loss. Early signs of incurable disease include a palpable mass, ascites, lymphadenopathy (classic Virchow node), and an umbilical mass (Sister Mary Joseph node). Incidentally discovered pancreatic masses on imaging are rare, but the incidence is increasing due to frequent imaging for other reasons and improved diagnostic techniques.

• What is the approach to diagnosis and staging?

History and physical examination findings are not sufficiently sensitive or specific to diagnose pancreatic cancer. High clinical suspicion in a patient with risk factors can lead to a comprehensive evaluation and potential early diagnosis. In general, an initial diagnostic work-up for suspected pancreatic cancer will include serologic evaluation (liver function test, lipase, tumor markers) and abdominal imaging (ultrasound, CT scans, or magnetic resonance imaging [MRI]). Ultrasound is a first-line diagnostic tool with a sensitivity of 90% and specificity of 98.8% for pancreatic cancer, but it is investigator-dependent and is less accurate in detecting tumors smaller than 3 cm in diameter.¹⁹ Multiphasic helical CT of the abdomen has better sensitivity (100%) and specificity (100%) for detecting tumors larger than 2 cm, but this modality is less accurate in detecting pancreatic masses smaller than 2 cm (77%).²⁰ Percutaneous fine-needle aspiration (FNA) performed by ultrasound or CT guidance is avoided due to theoretical concerns about intraperitoneal seeding and bleeding.

If a pancreatic mass is detected by ultrasound or CT, additional interventions may be indicated depending on the clinical scenario. EUS-guided biopsy can provide histological confirmation and is currently utilized frequently for diagnosis and early resectability staging. Endoscopic retrograde cholangiopancreatography (ERCP) is indicated for patients with biliary obstruction requiring stent placement, and this procedure may provide tissue confirmation by forceps biopsy or brush cytology (lower accuracy than EUS). In a meta-analysis that evaluated the diagnostic value of tests for pancreatic cancer, ERCP had the highest sensitivity (92%) and specificity (96%) compared to ultrasound and CT,²¹ but this modality carries a risk for pancreatitis, bleeding, and cholangitis. Magnetic resonance cholangiopancreatography has not replaced ERCP, but it but may be an alternative for patients who cannot undergo ERCP (eg, gastric outlet obstruction, duodenal stenosis, anatomical surgical disruption, unsuccessful ERCP). ERCP is used frequently because many patients present with obstructive jaundice due to pancreatic mass compression, specifically if the mass is located in the head, and must undergo ERCP and stenting of the common bile duct.

The carbohydrate antigen (CA) 19-9 level has variable sensitivity and specificity in pancreatic cancer, as levels can be elevated in many benign pancreaticobiliary disorders. Elevated CA 19-9, in the appropriate clinical scenario (ie, a suspicious pancreatic mass and a value greater than 37 U/mL) demonstrated a sensitivity of 77% and specificity of 87% when differentiating pancreaticobiliary cancer from benign clinical conditions such as acute cholangitis or cholestasis.²² CA 19-9 level has prognostic value, as it may predict occult disease and correlates with survival rates, but no specific cutoff value has been established to guide perioperative therapy for high-risk resectable tumors.²³

The American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) tumor, node, metastasis (TNM) system is the preferred method for staging pancreatic cancer (Table 1). 

Positron emission tomography with CT scan is occasionally utilized in practice to assess tumor burden by evaluating anatomical structures and assessing physiologic uptake, which aids in establishing the extent of disease in equivocal cases. Staging laparoscopy with or without peritoneal biopsy is sometimes used to establish appropriate staging in cases that are questionable for occult metastatic disease. This procedure helps avoid unnecessary morbid surgeries.

Neoadjuvant Therapy

Case Continued

The patient is referred to oncology. Blood work reveals a CA 19-9 level of 100 U/mL (reference range < 35 U/mL) and a staging CT scan of the chest reveals a benign-appearing 3-mm nodule (no prior imaging for comparison). CT scan of the abdomen and pelvis does not define venous vasculature involvement appropriately and hence MRI of the abdomen and pelvis is performed. MRI reveals a pancreatic head mass measuring 3.0 × 2.7 cm, without arterial or venous vasculature invasion. However, the mass is abutting the portal vein and superior mesenteric vein and there is a new nonspecific 8-mm aortocaval lymph node.

• What are the current approaches to treating patients with resectable, unresectable, and metastatic disease?

Accurate staging and assessment of surgical resectability in pancreatic cancer are paramount as these steps prevent a futile morbid Whipple procedure in patients with advanced disease and a high risk of recurrence. Conversely, it allows patients with low-volume disease to undergo a potentially curative surgery. Approximately 20% of patients present with resectable disease, 40% present with locally advanced unresectable tumors (eg, involvement of critical vascular structures), and 40% present with metastatic disease.³ Treatment for resectable pancreatic cancer continues to be upfront surgery, although neoadjuvant therapy with either chemoradiation, radiation alone, or chemotherapy is an option per guidelines from the American Society of Clinical Oncology (ASCO),²⁸ the NCCN,²⁶ and the European Society for Medical Oncology (ESMO),²⁹ particularly for patients with borderline resectable tumors (Table 3). 

Systemic chemotherapy is recommended for fit candidates with locally advanced unresectable or metastatic disease, with an emphasis on supportive palliative measures. Palliative interventions include biliary stenting, duodenal stent for relieving gastric-outlet obstruction, and celiac axis nerve blocks, when indicated. Routine preoperative biliary stent placement/drainage in patients undergoing subsequent surgery for pancreatic cancer located in the head is associated with an increased risk of surgical complications when compared with up-front surgery without prior biliary drainage, and thus stent placement/drainage is not recommended.²⁶ Aggressive supportive management of symptoms, such as cancer-associated pain, anorexia-cachexia syndromes, and anxiety-depression disorders, should remain a primary palliative focus.

Case Continued

A multidisciplinary tumor board discusses the patient’s case and deems the cancer borderline resectable; neoadjuvant therapy is recommended. The patient is started on treatment with gemcitabine and nab-paclitaxel as first-line neoadjuvant therapy. After 4 cycles, the CA 19-9 level drops to 14 U/mL, and MRI reveals a smaller head mass of 1.3 × 1.4 cm with stable effacement of the superior mesenteric vein and no portal vein involvement; the aortocaval lymph node remains stable. At tumor board, it is evident that the patient has responded to therapy and the recommendation is to treat with gemcitabine chemoradiotherapy before surgery.

• What neoadjuvant therapy strategies are used in the treatment of pancreatic adenocarcinoma?

There are no established evidence-based recommendations for neoadjuvant therapy in patients with borderline resectable pancreatic cancer or patients with unresectable locally advanced pancreatic cancer. However, there are ongoing trials to investigate this treatment approach, and it is offered off-label in specific clinical scenarios, such as in the case patient described here. In patients with borderline resectable disease, preoperative chemotherapy followed by chemoradiation is a routine practice in most cancer centers,³² and ongoing clinical trials are an option for this cohort of patients (eg, Southwest Oncology Group Trial 1505, NCT02562716). The definitions of borderline resectable and unresectable pancreatic cancer have been described by the NCCN,²⁶ although most surgeons consider involvement of the major upper abdominal blood vessels the main unresectability criterion; oncologists also consider other parameters such as suspicious lesions on scans, worsening performance status, and a significantly elevated CA 19-9 level suggestive of disseminated disease.²⁸ The goal of a conversion approach by chemotherapy with or without radiation for borderline and unresectable cancers is to deliver a tolerable regimen leading to tumor downstaging, allowing for surgical resection. No randomized clinical trial has shown a survival advantage of this approach. Enrollment in clinical trials is preferred for patients with borderline and unresectable cancer, and there are trials that are currently enrolling patients.

The main treatment strategies for patients with locally advanced borderline and unresectable pancreatic cancer outside of a clinical trial are primary radiotherapy, systemic chemotherapy, and chemoradiation therapy. Guidelines from ASCO, NCCN, and ESMO recommend induction chemotherapy followed by restaging and consolidation chemoradiotherapy in the absence of progression.^26,28,29 There is no standard chemoradiation regimen and the role of chemotherapy sensitizers, including fluorouracil, gemcitabine, and capecitabine (an oral fluoropyrimidine substitute), and targeted agents in combination with different radiation modalities is now being investigated.

Fluorouracil is a radio-sensitizer that has been used in locally advanced pancreatic cancer based on experience in other gastrointestinal malignancies; data shows conflicting results with this drug. Capecitabine and tegafur/gimeracil/oteracil (S-1) are oral prodrugs that can safely replace infusional fluorouracil. Gemcitabine, a more potent radiation sensitizer, is very toxic, even at low-doses twice weekly, and does not provide a survival benefit, as demonstrated in the Cancer and Leukemia Group B (CALGB) 89805 trial, a phase 2 study of patients with surgically staged locally advanced pancreatic cancer.³³ Gemcitabine-based chemoradiotherapy was also evaluated in the Eastern Cooperative Group (ECOG) E4201 trial, which randomly assigned patients to receive gemcitabine alone (at 1000 mg/m²/wk for weeks 1 through 6, followed by 1 week rest, then weekly for 3 out of 4 weeks) or gemcitabine (600 mg/m²/wk for weeks 1 to 5, then 4 weeks later 1000 mg/m² for 3 out of 4 weeks) plus radiotherapy (starting on day 1, 1.8 Gy/fraction for total of 50.4 Gy).³⁴ Patients with locally advanced unresectable pancreatic cancer had a better OS outcome with gemcitabine in combination with radiation therapy (11.1 months) as compared with patients who received gemcitabine alone (9.2 months). Although there was a greater incidence of grade 4 and 5 treatment-related toxicities in the combination arm, no statistical differences in quality-of-life measurements were reported. Gemcitabine-based and capecitabine-based chemoradiotherapy were compared in the open-label phase 2 multicenter randomized SCALOP trial.³⁵ Patients with locally advanced pancreatic cancer were assigned to receive 3 cycles of induction with gemcitabine 1000 mg/m² days 1, 8, and 15 and capecitabine 830 mg/m² days 1 to 21 every 28 days; patients who had stable or responding disease were randomly assigned to receive a fourth cycle followed by capecitabine (830 mg/m² twice daily on weekdays only) or gemcitabine (300 mg/m² weekly) with radiation (50.4 Gy over 28 fractions). Patients treated with capecitabine-based chemoradiotherapy had higher nonsignificant median OS (17.6 months) and median progression-free survival (12 months) compared to those treated with gemcitabine (14.6 months and 10.4 months, respectively).

The benefit of radiation therapy in the treatment of locally advanced pancreatic cancer was further explored by the Fédération Francophone de Cancérologie Digestive 2000-01 phase 3 trial. This study compared induction chemoradiotherapy (60 Gy, 2 Gy/fraction; concomitant fluorouracil infusion, 300 mg/m²/day, days 1–5 for 6 weeks; cisplatin, 20 mg/m²/day, days 1–5 during weeks 1 and 5) to gemcitabine alone (1000 mg/m² weekly for 7 weeks) followed by maintenance gemcitabine in both arms.³⁶ Unexpectedly, the median OS was significantly shorter in the chemoradiotherapy arm than in the chemotherapy alone arm (8.6 months versus 13 months, respectively, P = 0.03) and the combination arm had more toxicities. The phase 3 open-label LAP07 study explored the role of radiation therapy in patients with locally advanced pancreatic cancer who had controlled disease after 4 months of induction therapy.³⁷ LAP07 had 2 randomizations: first, patients with locally advanced pancreatic cancer were assigned to receive weekly gemcitabine alone (1000 mg/m²) or this same dose of gemcitabine plus erlotinib 100 mg/day; second, patients with progression-free disease (61% of initial cohort) after 4 months of therapy were assigned to receive 2 months of the same chemotherapy or chemoradiotherapy (54 Gy plus capecitabine). This study showed that the addition of erlotinib to gemcitabine did not improve survival and in fact affected survival adversely. Of note, no survival benefit was observed after the first randomization from chemotherapy to consolidating chemoradiotherapy. Chemoradiotherapy achieved better locoregional tumor control with significantly less local tumor progression (32% versus 46%, P < 0.03) and no increase in toxicity. Based on prior moderate-quality evidence, guidelines recommend consolidative chemoradiotherapy only for surgical resection candidates following induction chemotherapy; for those who are not surgical candidates, guidelines recommend continuing systemic therapy.^26,28,29

Gemcitabine and fluorouracil-based chemotherapies were the standard induction regimens until evidence from studies of metastatic systemic treatment protocols with FOLFIRINOX (ACCORD trial³⁸) and nanoparticle albumin-bound paclitaxel (nab-paclitaxel) plus gemcitabine (MPACT trial³⁹) was extrapolated to clinical practice. These regimens were shown to achieve higher objective response rates when compared to single-agent gemcitabine in patients with metastatic pancreatic cancer. Due to the broad heterogeneity of results in small retrospective series with neoadjuvant trials in borderline resectable pancreatic cancer, the quality of the evidence is low and any recommendation is limited. Many individual series have demonstrated improved complete resection rates and promising survival rates. In the largest single-institution retrospective review of patients with borderline resectable pancreatic adenocarcinoma who completed neoadjuvant gemcitabine-based chemoradiotherapy (50 Gy in 28 fractions or 30 Gy in 10 fractions), 94% achieved a margin-negative pancreatectomy; the median OS in those who completed preoperative therapy and had surgery was 40 months, with a 5-year OS of 36%.⁴⁰ A meta-analysis by Andriulli and colleagues included 20 prospective studies of patients with initially resectable (366 lesions) or unresectable (341 lesions) disease who were treated with neoadjuvant/preoperative gemcitabine with or without radiotherapy.⁴¹ In the group with initially unresectable disease, 39% underwent surgery after restaging and 68% of explored patients were resected; the R0 resection rate was 60%. After restaging, 91% of patients with resectable disease underwent surgery, with 82% of explored patients undergoing surgical resection and 89% of these achieving R0 resection. The estimated 1- and 2-year survival probabilities after resection among patients with initially unresectable disease were 86.3% and 54.2%.⁴¹

The largest single-institution retrospective review of FOLFIRINOX (fluorouracil, oxaliplatin, irinotecan, and leucovorin), an alternative to gemcitabine, for neoadjuvant induction therapy for patients with locally advanced unresectable disease was conducted at Memorial Sloan Kettering Cancer Center. In this study (n = 101), 31% of patients initially deemed unresectable who completed FOLFIRINOX induction therapy with or without chemoradiation underwent resection. The R0 resection rate in these patients was 55%, and patients who did not progress during induction FOLFIRINOX therapy had a median OS of 26 months.⁴² A systematic review and meta-analysis of FOLFIRINOX chemotherapy with or without radiotherapy in patients with locally advanced unresectable pancreatic cancer reported that 25.9% of patients underwent resection after FOLFIRINOX therapy, and the R0 resection rate in these patients was 78.4%.⁴³ The median OS in this study was 24.2 months, which was longer than the previously reported median OS rates for gemcitabine.

There is no strong evidence published for the use of combination nab-paclitaxel plus gemcitabine in the neoadjuvant setting, but it is used in clinical practice based on evidence from the MPACT trial, which showed the combination improved OS and progression-free survival in patients with metastatic pancreatic cancer.³⁹ An early-phase 1-arm clinical trial of neoadjuvant gemcitabine, docetaxel, and capecitabine (GTX) followed by radiotherapy showed an increased response rate and survival for locally advanced disease; however, the NCCN expert panel has reached a consensus but not a uniform recommendation regarding this regimen due to significant toxicities and low patient accrual.²⁶ Selected patients with pancreatic cancer with BRCA1/2 mutations are more sensitive to platinum-based chemotherapy. Although studies of neoadjuvant platinum-based chemotherapy in this population have not been reported, the NCCN guidelines list it as an alternative option based on extrapolated data.²⁶ A clinical trial of gemcitabine, nab-paclitaxel, and cisplatin in the neoadjuvant setting in patients with resectable pancreatic cancer is currently enrolling patients (NGC triple regimen NCT0339257).

Summary

Chemotherapy alone or followed by chemoradiotherapy may be used as initial treatment for patients with borderline and unresectable pancreatic adenocarcinoma without distant metastases who are potential surgical candidates. Chemoradiotherapy remains a preferred treatment option for patients with poorly controlled pain from local tumor invasion, in view of the well-documented analgesic palliative effect of radiation therapy. FOLFIRINOX with or without radiation therapy may offer the highest documented response rates, but it also results in higher rates of treatment-related toxicities. FOLFIRINOX can be offered to selected fit patients (< 65 years old, no comorbidity contraindication, good functional status [ECOG 0–1]) who can tolerate triple therapy with a more toxic adverse-effect profile. A clinical trial evaluating neoadjuvant FOLFIRINOX with or without preoperative chemoradiotherapy in patients with borderline resectable pancreatic cancer is ongoing (PANDAS-PRODIGE 44, NCT02676349). Gemcitabine with or without radiation therapy is a tolerable combination, although it is potentially more toxic when combined with radiation. The addition of nab-paclitaxel to gemcitabine without radiation may emerge as a preferred neoadjuvant treatment for selected patients; a clinical trial investigating this modality in patients with resectable and borderline resectable disease is ongoing (NCT02723331).

Adjuvant Therapy

Case Continued

Prior to the planned surgical resection and after undergoing chemoradiation therapy, the patient has an excellent performance status and repeat MRI shows a 1.3 × 1.4 cm head mass with no further vasculature involvement, no evidence of lymphadenopathy, and no distant metastasis. The CA 19-9 level is stable at 18 U/mL. The patient undergoes an uncomplicated partial pancreaticoduodenectomy, and analysis of a surgical pathology specimen reveals T3N0 disease with closest margin of 0.1 cm.

• Would the patient benefit from adjuvant therapy?

Adjuvant chemotherapy for 6 months after pancreatic cancer resection should be offered to all patients based on mature data. Gemcitabine and capecitabine are the current standard of care in adjuvant therapy; alternatively, single-agent gemcitabine can be offered to patients with poor performance status or patients who cannot tolerate the toxicities associated with this combination.²⁸ Adjuvant treatment should be initiated within approximately 8 weeks of surgical resection. The value of radiation therapy remains controversial, but it can be offered within the context of a clinical trial or to patients with positive margins after surgical resection and/or lymph node–positive disease. Based on low-quality supportive evidence, it is strongly recommended that patients who receive neoadjuvant therapy complete a total of 6 months of chemotherapy, factoring in the duration of the preoperative regimen.²⁸ Different adjuvant strategies have been investigated, including chemotherapy alone with a fluoropyrimidine and/or gemcitabine with or without combined chemoradiation therapy.

The European Study Group for Pancreatic Cancer 1 (ESPAC)-1 trial was a randomized clinical trial that evaluated several adjuvant strategies in pancreatic cancer treatment. This trial assigned patients who underwent pancreatic adenocarcinoma resection to adjuvant chemotherapy alone (intravenous fluorouracil 425 mg/m² and leucovorin 20 mg/m² daily for 5 days, monthly for 6 months), chemoradiotherapy (20 Gy in 10 daily fractions over 2 weeks with 500 mg/m² intravenous fluorouracil on days 1–3, repeated after 2 weeks), both chemotherapy and chemoradiation, and observation.⁴⁴ The results showed no added benefit for adjuvant chemoradiotherapy, with a median OS of 15.5 months in the chemoradiotherapy cohort, as compared to a median OS of 16.1 months in the chemotherapy-alone cohort (hazard ratio [HR] 1.18 [95% CI 0.90 to 1.55], P = 0.24). In addition, there was evidence of a survival benefit for the chemotherapy-alone arm when compared to the combined modality arm, with a median OS of 19.7 versus 14.0 months, respectively (HR 0.66 [95% CI 0.52 to 0.83], P = 0.0005). Although ESPAC-1 has been criticized for being underpowered to perform statistical comparison, it is still considered a landmark trial demonstrating benefit with single-agent chemotherapy alone. A follow-up analysis of ESPAC-1 showed that adjuvant chemotherapy alone conferred a significant 5-year survival benefit while the combined modality had a deleterious effect on survival. ⁴⁵ Hence, adjuvant chemotherapy alone became the standard of care in the United States following resection.

The results of the multicenter randomized controlled phase 3 CONKO-001 (CharitéOnkologie 001) trial, which were reported in 2007, supported the use of adjuvant gemcitabine for 6 months in patients with resected pancreatic adenocarcinoma. In this study, patients treated with adjuvant gemcitabine (1000 mg/m² days 1, 8, and 15 every 4 weeks for 6 months) had superior disease-free survival compared with those who received surgery alone.³⁰ A long-term outcome update of this study demonstrated a significant improvement in 5-year OS for patients treated with adjuvant gemcitabine (20.7% [95% CI 14.7% to 26.6%]) compared to those who received surgical resection alone (10.4% [95% CI 5.9% to 15.0%]). This benefit persisted at 10-year follow-up, with an OS of 12.2% (95% CI 7.3% to 17.2%) in the adjuvant gemcitabine group, as compared to 7.7% (95% CI 3.6% to 11.8%) in the resection alone group.³¹

Fluorouracil and gemcitabine remained equivalent adjuvant treatment options until the results of the ESPAC-3 trial were reported in 2010.³² This large phase 3 trial, conducted mainly in the United Kingdom, compared weekly gemcitabine (1000 mg/m² weekly for 3 of every 4 weeks) to leucovorin-modulated fluorouracil (Mayo Clinic regimen: leucovorin 20 mg/m² followed by fluorouracil 425 mg/m² intravenous bolus days 1 through 5 every 28 days) as adjuvant therapy in resected pancreatic adenocarcinoma. After a median follow-up of 34.2 months, the median OS was similar in the 2 groups (fluorouracil/leucovorin 23.0 months versus gemcitabine 23.6 months; P = 0.39). However, the fluorouracil/leucovorin group experienced more grade 3/4 treatment-related toxicities (mucositis, stomatitis, diarrhea, and hosptializations; 14% versus 7.5%; P < 0.001).⁴⁶ Following this trial, gemcitabine became the standard of care for adjuvant chemotherapy for resected pancreatic cancer.

The U.S. Radiation Therapy Oncology Group (RTOG) 9704 trial was conducted to investigate the potential benefit of adding radiation therapy to gemcitabine. This trial demonstrated an improved trend among patients with pancreatic head tumors (but not with cancers of the pancreatic body or tail) who received adjuvant gemcitabine followed by chemoradiotherapy (50.4 Gy in 1.8 Gy daily fractions for 5.5 weeks with concurrent infusional fluorouracil 250 mg/m² daily) and subsequent gemcitabine monotherapy compared to postoperative fluorouracil-based chemoradiotherapy. Results showed a 5-year OS of 22% versus 18%, respectively, although this improvement was not statistically significant (P = 0.08). This trial failed to show a benefit of adding radiotherapy to gemcitabine.⁴⁷

The ESPAC-4 trial, reported in 2017, evaluated the combination of gemcitabine and capecitabine compared to gemcitabine alone as adjuvant therapy for resected pancreatic adenocarcinoma.⁴⁸ Patients were randomly assigned after surgical resection, regardless of margin or node status, to 6 months of gemcitabine alone (1000 mg/m²/day on days 1, 8, and 15 of each 28-day cycle) or gemcitabine plus capecitabine (1660 mg/m²/day on days 1 through 21 of each 28-day cycle). Combination therapy had a significant survival benefit compared to single therapy, with median OS durations of 28 months and 25.5 months, respectively (HR for death 0.82 [95% CI 0.68 to 0.98]). The 5-year OS for patients who received combination treatment was 29 months (95% CI 22.9 to 35.2) versus 16 months (95% CI 10.2 to 23.7) for those in the monotherapy group. As expected, grade 3 or 4 treatment-related toxicities (diarrhea, hand-foot syndrome, and neutropenia) were significantly more common with combined therapy, although there were no significant differences in the rates of serious adverse events. The adjuvant combination of gemcitabine and capecitabine became the current and preferred new standard of care following resection of pancreatic ductal adenocarcinoma,²⁸ but single-agent gemcitabine and fluorouracil/leucovorin continue to be viable options,^26,28,29 particularly for elderly patients, patients with borderline performance status, or patients with multiple comorbidities.

Evidence showing that a more intensive regimen can improve outcome in the adjuvant setting remains elusive. The phase 3 APACT study (Adjuvant Therapy for Patients with Resected Pancreatic Cancer, NCT01964430) comparing gemcitabine alone to gemcitabine plus nab-paclitaxel in patients with surgically resected pancreatic adenocarcinoma has concluded, with the results projected to be released in 2018. Another phase 3 trial investigating the efficacy of FOLFIRINOX versus gemcitabine alone as adjuvant therapy is underway in France and Canada (PRODIGE24/ACCORD24, NCT01526135). Other strategies with newer targeted therapies and immunotherapy are in the development phase.

Follow-Up and Surveillance

Case Conclusion

After recovery from surgery, the patient is offered and completes 4 cycles of adjuvant chemotherapy with gemcitabine plus capecitabine. He is started on surveillance at 3 and 6 months, and he maintains an excellent performance status. He develops clinical evidence of pancreatic enzyme insufficiency and is placed on oral replacement therapy. He has no other complaints, and there is no evidence of recurrence on MRI and CA 19-9 levels.

• What is the recommended duration of surveillance following curative resection?

Surveillance after curative resection of pancreatic adenocarcinoma is recommended by NCCN guidelines.²⁶ However, pancreatic adenocarcinoma has a poor prognosis, and surveillance after curative surgical resection with or without perioperative therapy has not been shown to impact survival. Most recurrences will occur within 2 years after treatment. Surveillance recommendations differ among expert groups.^26,28,29 NCCN guidelines recommend evaluating patients by history and physical examination every 3 to 6 months for the first 2 years, then every 6 to 12 months for 3 years. CA 19-9 level and CT scan should be obtained every 3 to 6 months for 2 years and then every 6 to 12 months for 3 years. Follow-up with CA 19-9 levels and CT scans after 5 years is not routinely performed unless guided by signs, symptoms, or laboratory findings that raise suspicion for recurrence. Follow-up visits should also include evaluation of treatment-related toxicities, symptom management, nutrition support of pancreatic insufficiency, and psychosocial support.

Conclusion

Pancreatic cancer is a leading cause of cancer-related death that frequently presents with locally advanced or metastatic disease due to nonspecific symptoms and lack of a screening modality. Histological tissue biopsy confirmation and accurate resectability staging guide treatment planning and prognosis. The only potentially curative therapy is surgical resection plus adjuvant therapy for those with resectable disease. Surgical candidates with borderline resectable and unresectable disease can be offered induction preoperative chemotherapy followed by consolidation chemoradiation, based on clinical consensus practice. Enrollment in clinical trials should be encouraged for all patients, as evidence from clinical trials is essential to making progress in pancreatic cancer treatment.