Anemia

SAN ANTONIO – Clinicians don’t appear to mind too much when their red blood cell orders are flagged for review by a best practice alert system, and alert fatigue doesn’t seem to hamper patient blood management efforts, investigators in a single-center study reported.

Neil Osterweil/MDedge News

At the Medical University of South Carolina, Charleston (MUSC), if clinicians order RBC transfusions for patients with hemoglobin levels over 7.0 g/dL or for patients who did not have a hemoglobin determination over the past 24 hours, they receive a best practice alert. They must acknowledge it and cancel the order, or override it and document a reason in the medical record.

Although approximately 70% of alerts were overridden, the reasons for the overrides “were consistent over time and appropriate,” reported Jerry E. Squires, MD, PhD, and colleagues from MUSC in a poster presentation at the annual meeting of AABB, the group formerly known as the American Association of Blood Banks.

The goal of the study was to find out if the effectiveness of the alert was wearing out after months of active use by clinicians. “Is it true that they’re clicking too much and they’re inundated with other [best practice alerts], and are they even paying attention?” said coauthor Heather Toeppner, RN, also from MUSC, in an interview. “All in all, we found that the alert is making a lasting impression in our institution,” she said.

Transfusion clinical decision support systems that produce automated alerts for clinicians can improve usage and reduce waste of RBCs, but whether the effect is sustained over time was unknown, Ms. Toeppner said, prompting the investigators to study the effect of the RBC best practice alert over 10 months.

As noted, the alert is triggered when providers order RBCs for patients with hemoglobin levels over 7.0 g/dL or when there is no record of a hemoglobin test in the chart within the past 24 hours. Before the alert is triggered, however, the system reviews the record and excludes alerts for patients with specific conditions, such as concurrent surgery or sickle cell disease.

The authors found that the alert was triggered an average of 195 times per month over the 10 months studied. On average, 16% of the alerts resulted in a cancellation of the RBC order, and 71% of alerts were overridden.

“Most importantly, there was no trend suggesting that either cancellation of the RBC order or overriding the alert became more frequent over time,” the investigators wrote. “Similarly, reasons for overriding the alert were consistent over time, with ‘preparation for an invasive procedure’ and ‘active bleeding’ being the most common reasons for overriding the alert (32% and 23% of all overrides, respectively).”

Other common reasons for overrides included tachycardia, shortness of breath, hypotension, onset of chest pain, and acute coronary syndrome.

Interestingly, but perhaps not surprisingly, they found that overrides dropped sharply and changed orders rose by the same magnitude in July, when new residents started their rotations.

The investigators wrote that the relatively small number of alerts may be attributable to their institution’s robust patient blood management program and the intentional exclusion of orders for patients with specific diagnostic codes, including intraoperative patients, those with sickle cell disease, and all patients aged younger than 18 years.

The study was internally funded. The authors reported having no conflicts of interest.

SAN ANTONIO – Clinicians don’t appear to mind too much when their red blood cell orders are flagged for review by a best practice alert system, and alert fatigue doesn’t seem to hamper patient blood management efforts, investigators in a single-center study reported.

Neil Osterweil/MDedge News

At the Medical University of South Carolina, Charleston (MUSC), if clinicians order RBC transfusions for patients with hemoglobin levels over 7.0 g/dL or for patients who did not have a hemoglobin determination over the past 24 hours, they receive a best practice alert. They must acknowledge it and cancel the order, or override it and document a reason in the medical record.

Although approximately 70% of alerts were overridden, the reasons for the overrides “were consistent over time and appropriate,” reported Jerry E. Squires, MD, PhD, and colleagues from MUSC in a poster presentation at the annual meeting of AABB, the group formerly known as the American Association of Blood Banks.

The goal of the study was to find out if the effectiveness of the alert was wearing out after months of active use by clinicians. “Is it true that they’re clicking too much and they’re inundated with other [best practice alerts], and are they even paying attention?” said coauthor Heather Toeppner, RN, also from MUSC, in an interview. “All in all, we found that the alert is making a lasting impression in our institution,” she said.

Transfusion clinical decision support systems that produce automated alerts for clinicians can improve usage and reduce waste of RBCs, but whether the effect is sustained over time was unknown, Ms. Toeppner said, prompting the investigators to study the effect of the RBC best practice alert over 10 months.

As noted, the alert is triggered when providers order RBCs for patients with hemoglobin levels over 7.0 g/dL or when there is no record of a hemoglobin test in the chart within the past 24 hours. Before the alert is triggered, however, the system reviews the record and excludes alerts for patients with specific conditions, such as concurrent surgery or sickle cell disease.

The authors found that the alert was triggered an average of 195 times per month over the 10 months studied. On average, 16% of the alerts resulted in a cancellation of the RBC order, and 71% of alerts were overridden.

“Most importantly, there was no trend suggesting that either cancellation of the RBC order or overriding the alert became more frequent over time,” the investigators wrote. “Similarly, reasons for overriding the alert were consistent over time, with ‘preparation for an invasive procedure’ and ‘active bleeding’ being the most common reasons for overriding the alert (32% and 23% of all overrides, respectively).”

Other common reasons for overrides included tachycardia, shortness of breath, hypotension, onset of chest pain, and acute coronary syndrome.

Interestingly, but perhaps not surprisingly, they found that overrides dropped sharply and changed orders rose by the same magnitude in July, when new residents started their rotations.

The investigators wrote that the relatively small number of alerts may be attributable to their institution’s robust patient blood management program and the intentional exclusion of orders for patients with specific diagnostic codes, including intraoperative patients, those with sickle cell disease, and all patients aged younger than 18 years.

The study was internally funded. The authors reported having no conflicts of interest.

SAN ANTONIO – Clinicians don’t appear to mind too much when their red blood cell orders are flagged for review by a best practice alert system, and alert fatigue doesn’t seem to hamper patient blood management efforts, investigators in a single-center study reported.

Neil Osterweil/MDedge News

At the Medical University of South Carolina, Charleston (MUSC), if clinicians order RBC transfusions for patients with hemoglobin levels over 7.0 g/dL or for patients who did not have a hemoglobin determination over the past 24 hours, they receive a best practice alert. They must acknowledge it and cancel the order, or override it and document a reason in the medical record.

Although approximately 70% of alerts were overridden, the reasons for the overrides “were consistent over time and appropriate,” reported Jerry E. Squires, MD, PhD, and colleagues from MUSC in a poster presentation at the annual meeting of AABB, the group formerly known as the American Association of Blood Banks.

The goal of the study was to find out if the effectiveness of the alert was wearing out after months of active use by clinicians. “Is it true that they’re clicking too much and they’re inundated with other [best practice alerts], and are they even paying attention?” said coauthor Heather Toeppner, RN, also from MUSC, in an interview. “All in all, we found that the alert is making a lasting impression in our institution,” she said.

Transfusion clinical decision support systems that produce automated alerts for clinicians can improve usage and reduce waste of RBCs, but whether the effect is sustained over time was unknown, Ms. Toeppner said, prompting the investigators to study the effect of the RBC best practice alert over 10 months.

As noted, the alert is triggered when providers order RBCs for patients with hemoglobin levels over 7.0 g/dL or when there is no record of a hemoglobin test in the chart within the past 24 hours. Before the alert is triggered, however, the system reviews the record and excludes alerts for patients with specific conditions, such as concurrent surgery or sickle cell disease.

The authors found that the alert was triggered an average of 195 times per month over the 10 months studied. On average, 16% of the alerts resulted in a cancellation of the RBC order, and 71% of alerts were overridden.

“Most importantly, there was no trend suggesting that either cancellation of the RBC order or overriding the alert became more frequent over time,” the investigators wrote. “Similarly, reasons for overriding the alert were consistent over time, with ‘preparation for an invasive procedure’ and ‘active bleeding’ being the most common reasons for overriding the alert (32% and 23% of all overrides, respectively).”

Other common reasons for overrides included tachycardia, shortness of breath, hypotension, onset of chest pain, and acute coronary syndrome.

Interestingly, but perhaps not surprisingly, they found that overrides dropped sharply and changed orders rose by the same magnitude in July, when new residents started their rotations.

The investigators wrote that the relatively small number of alerts may be attributable to their institution’s robust patient blood management program and the intentional exclusion of orders for patients with specific diagnostic codes, including intraoperative patients, those with sickle cell disease, and all patients aged younger than 18 years.

The study was internally funded. The authors reported having no conflicts of interest.

The National Institutes of Health and the Bill & Melinda Gates Foundation have announced that they plan to invest $100 million each over the next 4 years to develop affordable, gene-based cures for sickle cell disease (SCD) and HIV.

The initiative follows an announcement from President Trump that set a goal of ending the HIV epidemic in the United States in the next 10 years, seeking to reduce the number of diagnoses by 90% by 2030. The Trump administration has also identified SCD as an “intractable health challenge with the potential for dramatic advances in the coming years,” the NIH said in a statement.

Gene-based therapy has become a reality in recent years thanks to dramatic advances, but the cost is prohibitive in many parts of the world. “The collaboration between the NIH and the Gates Foundation sets out a bold goal of advancing safe, effective, and durable gene-based cures to clinical trials in the United States and relevant countries in sub-Saharan Africa within the next 7-10 years. The ultimate goal is to scale and implement these treatments globally in areas hardest hit by these diseases,” the NIH said.

Both diseases are a significant burden on low- and middle-income countries, as 95% of the 38 million people living with HIV globally are in the developing world, with 67% living in sub-Saharan Africa; about half of the HIV-infected population receives no treatment for the disease. An estimated 15 million children will be born with SCD over the next 30 years, with three-quarters of those births occurring in sub-Saharan Africa. About 50%-90% of children born with SCD will die before age 5 years.

The collaboration will focus on coordination in two areas: identifying potential candidate cures for SCD and HIV for preclinical and clinical evaluation, and defining long-term opportunities to work together and with African partners on advancing promising candidates to late-phase clinical trials, with funding to be determined as candidates progress.

“In recent years, gene-based treatments have been groundbreaking for rare genetic disorders and infectious diseases. While these treatments are exciting, people in low- and middle-income countries do not have access to these breakthroughs. By working with the NIH and scientists across Africa, we aim to ensure these approaches will improve the lives of those most in need and bring the incredible promise of gene-based treatments to the world of public health,” said Trevor Mundel, MD, PhD, president of the global health program at the Bill & Melinda Gates Foundation.

[email protected]

The National Institutes of Health and the Bill & Melinda Gates Foundation have announced that they plan to invest $100 million each over the next 4 years to develop affordable, gene-based cures for sickle cell disease (SCD) and HIV.

The initiative follows an announcement from President Trump that set a goal of ending the HIV epidemic in the United States in the next 10 years, seeking to reduce the number of diagnoses by 90% by 2030. The Trump administration has also identified SCD as an “intractable health challenge with the potential for dramatic advances in the coming years,” the NIH said in a statement.

Gene-based therapy has become a reality in recent years thanks to dramatic advances, but the cost is prohibitive in many parts of the world. “The collaboration between the NIH and the Gates Foundation sets out a bold goal of advancing safe, effective, and durable gene-based cures to clinical trials in the United States and relevant countries in sub-Saharan Africa within the next 7-10 years. The ultimate goal is to scale and implement these treatments globally in areas hardest hit by these diseases,” the NIH said.

Both diseases are a significant burden on low- and middle-income countries, as 95% of the 38 million people living with HIV globally are in the developing world, with 67% living in sub-Saharan Africa; about half of the HIV-infected population receives no treatment for the disease. An estimated 15 million children will be born with SCD over the next 30 years, with three-quarters of those births occurring in sub-Saharan Africa. About 50%-90% of children born with SCD will die before age 5 years.

The collaboration will focus on coordination in two areas: identifying potential candidate cures for SCD and HIV for preclinical and clinical evaluation, and defining long-term opportunities to work together and with African partners on advancing promising candidates to late-phase clinical trials, with funding to be determined as candidates progress.

“In recent years, gene-based treatments have been groundbreaking for rare genetic disorders and infectious diseases. While these treatments are exciting, people in low- and middle-income countries do not have access to these breakthroughs. By working with the NIH and scientists across Africa, we aim to ensure these approaches will improve the lives of those most in need and bring the incredible promise of gene-based treatments to the world of public health,” said Trevor Mundel, MD, PhD, president of the global health program at the Bill & Melinda Gates Foundation.

[email protected]

The National Institutes of Health and the Bill & Melinda Gates Foundation have announced that they plan to invest $100 million each over the next 4 years to develop affordable, gene-based cures for sickle cell disease (SCD) and HIV.

The initiative follows an announcement from President Trump that set a goal of ending the HIV epidemic in the United States in the next 10 years, seeking to reduce the number of diagnoses by 90% by 2030. The Trump administration has also identified SCD as an “intractable health challenge with the potential for dramatic advances in the coming years,” the NIH said in a statement.

Gene-based therapy has become a reality in recent years thanks to dramatic advances, but the cost is prohibitive in many parts of the world. “The collaboration between the NIH and the Gates Foundation sets out a bold goal of advancing safe, effective, and durable gene-based cures to clinical trials in the United States and relevant countries in sub-Saharan Africa within the next 7-10 years. The ultimate goal is to scale and implement these treatments globally in areas hardest hit by these diseases,” the NIH said.

Both diseases are a significant burden on low- and middle-income countries, as 95% of the 38 million people living with HIV globally are in the developing world, with 67% living in sub-Saharan Africa; about half of the HIV-infected population receives no treatment for the disease. An estimated 15 million children will be born with SCD over the next 30 years, with three-quarters of those births occurring in sub-Saharan Africa. About 50%-90% of children born with SCD will die before age 5 years.

The collaboration will focus on coordination in two areas: identifying potential candidate cures for SCD and HIV for preclinical and clinical evaluation, and defining long-term opportunities to work together and with African partners on advancing promising candidates to late-phase clinical trials, with funding to be determined as candidates progress.

“In recent years, gene-based treatments have been groundbreaking for rare genetic disorders and infectious diseases. While these treatments are exciting, people in low- and middle-income countries do not have access to these breakthroughs. By working with the NIH and scientists across Africa, we aim to ensure these approaches will improve the lives of those most in need and bring the incredible promise of gene-based treatments to the world of public health,” said Trevor Mundel, MD, PhD, president of the global health program at the Bill & Melinda Gates Foundation.

[email protected]

Autoimmune hemolytic anemia (AIHA) is mediated by antibodies, and in most cases immunoglobulin (Ig) G is the mediating antibody. This type of AIHA is referred to as "warm" AIHA because IgG antibodies bind best at body temperature. "Cold" AIHA is mediated by IgM antibodies, which bind maximally at temperatures below 37°C. AIHA caused by a drug reaction is rare, with an estimated annual incidence of 1:1,000,000 for severe drug-related AIHA.¹ This article reviews the management of the more common types of AIHA, with a focus on warm, cold, and drug-induced AIHA; the evaluation and diagnosis of AIHA is reviewed in a separate article.

Warm Autoimmune Hemolytic Anemia

In AIHA, hemolysis is mediated by antibodies that bind to the surface of red blood cells. AIHA in which IgG antibodies are the offending antibodies is referred to as warm AIHA. “Warm” refers to the fact that the antibody binds best at body temperature (37°C). In warm AIHA, testing will show IgG molecules attached to the surface of the red cells, with 50% of patients also showing C3. Between 50% and 90% of AIHA cases are due to warm antibodies.^2,3 The incidence of warm AIHA varies by series but is approximately 1 case per 100,000 patients per year; this form of hemolysis affects women more frequently than men.^4,5

Therapeutic Options

First Line

Steroids. The goal of therapy in warm AIHA can be hard to define. However, most would agree that a hematocrit above 30% (or higher to prevent symptoms) with a minimal increase in the reticulocyte count—reflective of a significantly slowed hemolytic process—is a reasonable goal. Initial management of warm AIHA is prednisone at a standard dose of 1 mg/kg daily (Table 1).^6,7 Patients should be also started on proton-pump inhibitors to prevent ulcers. It can take up to 3 weeks for patients to respond to prednisone therapy. Once the patient’s hematocrit is above 30%, the prednisone is slowly tapered. Although approximately 80% of patients will respond to steroids, only 30% can be fully tapered off steroids. For patients who can be maintained on a daily steroid dose of 10 mg or less, steroids may be the most reasonable long-term therapy. In addition, because active hemolysis leads to an increased demand for folic acid, patients with warm AIHA are often prescribed folic acid 1 mg daily to prevent megaloblastic anemia due to folic acid deficiency.

Rituximab. Increasingly, rituximab (anti-CD20) therapy is added to the initial steroids. Two clinical trials showed both increased long-term and short-term responses with the use of rituximab.^8,9 An important consideration is that most patients respond gradually to rituximab over weeks, so a rapid response should not be expected. Most studies have used the traditional dosing of 375 mg/m² weekly for 4 weeks. These responses appear to be durable, but as in immune thrombocytopenia (ITP), repeat treatment with rituximab is effective.

The major side effects of rituximab are infusion reactions, which are often worse with the first dose. These reactions can be controlled with antihistamines, steroids, and, for severe rigors, meperidine. Rarely, patients can develop neutropenia (approximately 1:500) that appears to be autoimmune in nature. Infections appear to be only minimally increased with the use of rituximab.¹⁰ One group at risk is chronic carriers of hepatitis B virus, who may experience a reactivation of the virus that can be fatal. Thus, patients being considered for rituximab need to be screened for hepatitis B virus carrier state.¹¹ Patients receiving rituximab are at very slight risk for progressive multifocal leukoencephalopathy, which is more common in patients with cancer and in heavily immunosuppressed patients. The overall risk is unknown but is less than 1:50,000.

Second Line

Splenectomy. For patients who cannot be weaned from steroids or in whom steroid therapy fails, there is no standard therapy. Currently, the 2 main choices are splenectomy or rituximab (anti-CD20) therapy if the patient did not receive it first line. Splenectomy is the classic therapy for warm AIHA. Reported response rates in the literature range from 50% to 80%, with 50% to 60% remaining in remission.^12-16 Timing of the procedure is a balance between allowing time for the steroids to work and the risk of toxicity of steroids. In a patient who has low presurgical risk and has either refractory disease or cannot be weaned from high doses of steroids, splenectomy should be done sooner. Splenectomy can be delayed or other therapy tried first in patients who require lower doses of steroids or have medical risk factors for surgery. Most splenectomies are performed via laparoscopy. The small incisions allow for quicker healing, and the laparoscopic approach provides better visualization of the abdomen to find and remove accessory spleens. When splenectomy is performed by experienced surgeons, the mortality rate is low (< 0.5%).¹⁷

The most concerning complication of splenectomy is overwhelming post-splenectomy infection (OPSI).¹⁸ In adults, the spleen appears to play a minimal role in immunity except for protecting against certain encap-sulated organisms. Splenectomized patients infected with an encapsulated organism (eg, Pneumococcus) will develop overwhelming sepsis within hours. These patients will often have disseminated intravascular coagulation and will rapidly progress to purpura fulminans. Approximately 40% to 50% of patients will die of sepsis even when the infection is detected early. The overall lifetime risk of sepsis may be as high as 1:500. The organism that most commonly causes sepsis in splenectomized patients is Streptococcus pneumoniae, reported in over 50% of cases. Neisseria meningitidis and Haemophilus influenzae have also been implicated in many cases.¹⁹ Overwhelming sepsis after dog bites has been reported due to Capnocytophaga canimorsus infections. Patients are also at increased risk of developing severe malaria and severe babesiosis.¹⁸

Patients who have undergone splenectomy need to be warned about the risk of OPSI and instructed to report to the emergency department readily if they develop a fever greater than 101°F (38.3°C) or shaking chills. Once in the emergency department, blood cultures should be obtained rapidly and the patient started on antibiotic coverage with vancomycin and ceftriaxone (or levofloxacin if allergic to beta-lactams).²⁰ For patients in remote areas, some physicians will prescribe prophylactic antibiotics to take while they are traveling to a health care provider or even recommend a “standby” antibiotic dose to take while traveling to health care.⁵ This usually consists of amoxicillin or a macrolide for penicillin-allergic patients.

Patients in whom splenectomy is being planned or considered should be vaccinated for pneumococcal, meningococcal, and influenza infections (Table 2).¹⁸ If there is a plan to treat with rituximab, patients should first be vaccinated since they will not be able to mount an immune response after being treated with rituximab.

Third Line

The therapeutic options for patients who do not respond to either splenectomy or rituximab are much less certain.^5,6 Although intravenous immune globulin is a standard therapy for ITP, response rates are low in warm AIHA.¹⁷ Numerous therapies have been reported in small series, but no clear approach has emerged. Options include azathioprine, cyclophosphamide, mycophenolate, cyclosporine, danazol, and alemtuzumab. Our approach has been to use mycophenolate for patients requiring high doses of steroids or transfusions. Patients who respond to lower doses of steroids may be good candidates for danazol to help wean them off steroids.

Warm AIHA can complicate several diseases. Patients with systemic lupus erythematosus (SLE) can develop warm AIHA as part of their disease complex. The initial treatment approach is the same, but data suggest that splenectomy may not be as effective.^13,17 Also, many SLE patients have complex medical conditions, making surgeries riskier. For SLE patients who are refractory or cannot be weaned from steroids, rituximab may be the better choice. Babesiosis, particularly in asplenic patients, has been associated with the development of AIHA.^21,22

Of the malignances associated with AIHA, chronic lymphocytic leukemia (CLL) has the strongest association.^4,23 Series show that 5% to 10% of patients with CLL will have warm AIHA. AIHA can appear concurrent with CLL or develop during the course of the disease. The introduction of purine analogs such as fludarabine led to a dramatic increase in the incidence of warm AIHA in treated patients.²⁴ It is speculated that these powerful agents reduce the number and effectiveness of T cells that hold in check the autoantibody response, leading to warm AIHA.²⁵ However, when these purine analogs are used in com-bination with agents such as cyclophosphamide or rituximab (with their immunosuppressive effects), the rates of warm AIHA have been lower.²³

The approach to patients with CLL and warm AIHA depends on the state of their CLL.²³ For patients who have low-stage CLL that does not need treatment, the standard approach to warm AIHA should be steroids, splenectomy, and rituximab.²⁴ For patients with higher-stage CLL, the treatment for the leukemia will often provide therapy for the warm AIHA. The combination of rituximab-cyclophosphamide-dexamethasone has been reported to be effective for both the AIHA and CLL components.²⁶ The use of ibrutinib has also been reported to be effective.²⁷

A rare but important variant of warm AIHA is Evans syndrome.^28,29 This is the combination of AIHA and ITP. Approximately 1% to 3% of AIHA cases are the Evans variant. The ITP can precede, be concurrent with, or develop after the AIHA. The diagnosis of Evans syndrome should raise concern for underlying disorders. In young adults, immunodeficiency disorders such as autoimmune lymphoproliferative disease (ALPS) need to be considered. In older patients, Evans syndrome is often associated with T cell lymphomas. The sparse literature on Evans syndrome suggests that it can be more refractory to standard therapy, with response rates to splenectomy in the 50% range.^28,30 In patients with lymphoma, antineoplastic therapy is crucial. There is increasing data showing that mycophenolate or sirolimus may be effective for patients with ALPS in whom splenectomy or rituximab therapy is unsuccessful.³¹

Warm AIHA with IgA or IgM Antibodies

In rare patients with warm AIHA, IgA or IgM is the implicated antibody. The literature suggests that patients with IgA AIHA may have more severe hemolysis.³² Patients with IgM AIHA often have a severe course with a fatal outcome.³³ In such cases, the patient’s plasma may show spontaneous hemolysis and agglutination. The DAT may not be strongly positive or may show C3 reactivity only. The clinical clues are C3 reactivity with no cold agglutinins and severe hemolysis, sometimes with an intravascular component. Treatment is the same as for warm AIHA, including the use of rituximab.³⁴

In cold AIHA, the hemolysis is mediated by IgM antibodies directed against red cells.³⁵ As discussed earlier, the term “cold” refers to the fact that the antibody binds maximally at temperatures below 37°C. The most efficient temperature for binding is called the “thermal amplitude,” and, in theory, the higher the thermal amplitude, the more virulent the antibody. An antibody titer can be calculated at each reaction temperature from 4°C to 37°C by serial dilutions of the patient’s serum prior to incubating with reagent red cells. Rarely, the IgM can fix complement rapidly, leading to intravascular hemolysis. In most patients, complement is fixed through C3, and the C3-coated red cells are taken up by macrophages in the mononuclear phagocyte system, primarily in the liver.³

The DAT in patients with cold AIHA will show cells coated with C3. The blood smear will often show ag-glutination of the blood, and if the blood cools before being analyzed, the agglutination will interfere with the analysis. Titers of cold agglutinin can range from 1:1000 to over 1 million. The IgM autoantibodies are most often directed against the I/i antigens on the red blood cell membrane, with 90% against I antigen.³⁵ The I antigen specificity is typical with primary cold agglutinin disease and after Mycoplasma infection. The i antigen specificity is most typical of Epstein-Barr virus and cytomegalovirus infections in children. In young patients, cold AIHA often occurs following an infection, including viral and Mycoplasma infections, and the course is self-limited.^35,36 The hemolysis usually starts 2 to 3 weeks after the illness and will last for 4 to 6 weeks. In older patients, the etiology in over 90% of cases is a B-cell lymphoproliferative disorder, usually with monoclonal kappa B-cells.³⁷ The most common disorders are marginal zone lymphoma, small lymphocytic lymphoma, and lymphoplasmacytic lymphoma.³

Therapeutic Options

It is important to diagnose cold AIHA because the standard therapy for warm AIHA (steroids) is ineffective in cold AIHA. Because C3-coated red cells are taken up primarily in the liver, removing the spleen is also an ineffective therapy. Simple measures to help with cold AIHA should be employed.³⁷ Patients should be kept in a warm environment and should try to avoid the cold. If transfusions are needed, they should be infused via blood warmers to prevent hemolysis. In rare patients with severe hemolysis, therapeutic plasma exchange (TPE) can be considered.³⁸ Given that the culprit antibody is IgM—mostly intravascular—use of TPE may slow the hemolysis to give time for other therapies to take effect.

Treatment of cold AIHA remains difficult (Table 3). Because most patients with primary AIHA have underlying lymphoproliferative diseases, chlorambucil has been used in the past to treat cold AIHA. However, responses were rare and the drug could worsen the anemia.³⁸ Currently, the drug of choice is rituximab. Response is seen in 45% to 75% of patients, but is almost always a partial response and retreatment is often necessary.^17,37,39 As with other autoimmune hematologic diseases, there can be a delay in response that ranges from 2 weeks to 4 months (median time, 1.5 months).³⁷ Given the lack of robust response (complete and durable) with rituximab, the Berentsen group has explored adding bendamustine to rituximab.⁴⁰ In a prospective trial, 71% of patients responded with a 40% complete response rate. Therapy was well tolerated, with only 29% of patients needing dose reduction Although more toxic, this combination can be considered in patients with aggressive disease. A small study of the use of bortezomib showed a good response in one-third of patients.⁴¹ There is increasing use of the C5 complement inhibitor eculizumab to halt the hemolysis, but further study of this agent is also required.^36,42,43 Blockers of C1s complement, which block hemolysis by preventing complement activation, are currently being studied in clinical trials.⁴⁴

Since most patients with cold AIHA are older, a frequent issue that must be considered is cardiac surgery. The concern is that the hypothermia involved with most heart bypass procedures will lead to agglutination and hemolysis. The development of normothermic bypass has expanded treatment options. A recommended approach in patients who have known cold agglutinins is to measure the thermal amplitude of the antibody preoperatively. If the thermal amplitude is above 18°C, normothermic bypass should be done, if feasible.⁴⁵ If not feasible, preoperative TPE should be considered.

Paroxysmal Cold Hemoglobinuria

A unique cold AIHA is paroxysmal cold hemoglobinuria (PCH).^3,46 This cold hemolytic syndrome most often occurs in children following a viral infection, but in the past it complicated any stage of syphilis.⁴⁷ The mediating antibody in PCH is an IgG antibody directed against the P antigen on the red blood cell. This antibody binds best at temperatures below 37°C, fixing complement at cold temperatures, but then activates the complement cascade at body temperature.⁴⁸ Because this antibody can fix complement, hemolysis can be rapid and severe, leading to extreme anemia. The DAT is often weakly positive but can be negative. The diagnostic test for PCH is the Donath–Landsteiner test. This complex test is performed by incubating 3 blood samples, 1 at 0° to 4°C, another at 37°C, and a third at 0° to 4°C and then at 37°C. The diagnosis of PCH is made if only the third tube shows hemolysis.³⁵ PCH can persist for 1 to 3 months but is almost always self-limiting. In severe case, steroids may be of benefit.

Drug-Induced Hemolytic Anemia

AIHA caused by a drug reaction is rare, with a lower incidence than drug-related ITP. The rate of severe drug-related AIHA is estimated at 1:1,000,000, but less severe cases may be missed.¹ Most patients will have a positive DAT without signs of hemolysis, but in rare cases patients will have relentless hemolysis resulting in death.

Mechanisms

Multiple mechanisms for drug-induced immune hemolysis have been proposed, including drug-absorption (hapten-induced) and immune complex mechanisms.^1,49 The hapten mechanism is most often associated with the use of high-dose penicillin.⁵⁰ High doses of penicillin or similar drugs such as piperacillin lead to incorporation of the drug into the red cell membrane by binding to proteins. Patients will manifest a positive DAT with IgG antibody but not complement.⁵¹ The patient’s plasma will be reactive only with penicillin-coated red cells and not with normal cells. As mentioned, very few patients will have hemolysis, and if they have hemolysis, it will resolve in a few days after discontinuation of the offending drug.⁵²

Binding of a drug-antibody complex to the red cell membrane may cause hemolysis via the immune com-plex mechanism.⁵³ Again, most often the patient will have just a positive DAT, but rarely patients will have life-threatening hemolysis upon exposure or reexposure to the drug. The onset of hemolysis is rapid, with signs of acute illness and intravascular hemolysis. The paradigm drug is quinine, but many other drugs have been implicated. Testing shows a positive Coombs test with anti-complement but not anti-IgG.⁵⁰ This pattern is due to the effectiveness of the tertiary complex at fixing complement. The patient’s plasma reacts with red cells only when the drug is added.

A form of immune complex hemolysis associated with both disseminated intravascular coagulation (DIC) and brisk hemolysis has been recognized. Patients who receive certain second- and third-generation cephalosporins (especially cefotetan and ceftriaxone.^53,54) have developed this syndrome.^50,55-59 The clinical symptoms start 7 to 10 days after the drug is administered; often the patient has only received the antibiotic for surgical prophylaxis. Immune hemolysis with acute hematocrit drop, hypotension, and DIC ensues. The patients are often believed to have sepsis and are often reexposed to the cephalosporin, resulting in worsening of the clinical status. The outcome is often fatal due to massive hemolysis and thrombosis.^56,60,62

Finally, 8% to 36% of patients taking methyldopa will develop a positive DAT after 6 months of therapy, with less than 1% showing hemolysis.^52,63 The hemolysis in these patients is indistinguishable from warm AIHA, consistent with the notion that methyldopa induces an AIHA. The hemolysis often resolves rapidly after the methyldopa is stopped, but the Coombs test may remain positive for months.⁶³ This type of drug-induced hemolytic anemia has been reported with levodopa, procainamide, and chlorpromazine, but fludarabine is the most common cause currently. This form of AIHA is now being seen with increased use of checkpoint inhibitors.⁶⁴

Diagnosis

In many patients, the first clue to the presence of drug AIHA is the finding of a positive DAT. Rarely, patients will have severe hemolysis, but in many patients the hemolytic process is mild and may be wrongly assumed to be part of the underlying illness. Finding the offending drug can be a challenge, unless a patient has recently started a new drug; in a hospitalized patient on multiple agents, identifying the problem drug is difficult. Patients recently started on “suspect drugs,” especially the most common agents cefotetan, ceftriaxone, and piperacillin, should have these agents stopped (Table 4).^1,49,65 Specialty laboratories such as the Blood Center of Wisconsin or the Los Angeles Red Cross can perform in vitro studies of drug interactions that can confirm the clinical diagnosis of drug-induced AIHA.

Treatment

Therapy for patients with positive DAT without signs of hemolysis is uncertain. If the drug is essential, then the patient can be observed. If the patient has hemolysis, the drug needs to be stopped and the patient observed for signs of end-organ damage. It is doubtful that steroids or other autoimmune-directed therapy is effective. For patients with the DIC-hemolysis syndrome, there are anecdotal reports that TPE may be helpful.¹

Summary

AIHA can range from an abnormal laboratory test (positive DAT and signs of hemolysis) to an acute, life-threatening illness. Treatment is guided by the laboratory work-up and evaluation of the patient’s clinical status. While rituximab is promising for many patients, the lack of robust clinical trials hinders the treatment of patients who fail standard therapies.

Autoimmune hemolytic anemia (AIHA) is mediated by antibodies, and in most cases immunoglobulin (Ig) G is the mediating antibody. This type of AIHA is referred to as "warm" AIHA because IgG antibodies bind best at body temperature. "Cold" AIHA is mediated by IgM antibodies, which bind maximally at temperatures below 37°C. AIHA caused by a drug reaction is rare, with an estimated annual incidence of 1:1,000,000 for severe drug-related AIHA.¹ This article reviews the management of the more common types of AIHA, with a focus on warm, cold, and drug-induced AIHA; the evaluation and diagnosis of AIHA is reviewed in a separate article.

Warm Autoimmune Hemolytic Anemia

In AIHA, hemolysis is mediated by antibodies that bind to the surface of red blood cells. AIHA in which IgG antibodies are the offending antibodies is referred to as warm AIHA. “Warm” refers to the fact that the antibody binds best at body temperature (37°C). In warm AIHA, testing will show IgG molecules attached to the surface of the red cells, with 50% of patients also showing C3. Between 50% and 90% of AIHA cases are due to warm antibodies.^2,3 The incidence of warm AIHA varies by series but is approximately 1 case per 100,000 patients per year; this form of hemolysis affects women more frequently than men.^4,5

Therapeutic Options

First Line

Steroids. The goal of therapy in warm AIHA can be hard to define. However, most would agree that a hematocrit above 30% (or higher to prevent symptoms) with a minimal increase in the reticulocyte count—reflective of a significantly slowed hemolytic process—is a reasonable goal. Initial management of warm AIHA is prednisone at a standard dose of 1 mg/kg daily (Table 1).^6,7 Patients should be also started on proton-pump inhibitors to prevent ulcers. It can take up to 3 weeks for patients to respond to prednisone therapy. Once the patient’s hematocrit is above 30%, the prednisone is slowly tapered. Although approximately 80% of patients will respond to steroids, only 30% can be fully tapered off steroids. For patients who can be maintained on a daily steroid dose of 10 mg or less, steroids may be the most reasonable long-term therapy. In addition, because active hemolysis leads to an increased demand for folic acid, patients with warm AIHA are often prescribed folic acid 1 mg daily to prevent megaloblastic anemia due to folic acid deficiency.

Rituximab. Increasingly, rituximab (anti-CD20) therapy is added to the initial steroids. Two clinical trials showed both increased long-term and short-term responses with the use of rituximab.^8,9 An important consideration is that most patients respond gradually to rituximab over weeks, so a rapid response should not be expected. Most studies have used the traditional dosing of 375 mg/m² weekly for 4 weeks. These responses appear to be durable, but as in immune thrombocytopenia (ITP), repeat treatment with rituximab is effective.

The major side effects of rituximab are infusion reactions, which are often worse with the first dose. These reactions can be controlled with antihistamines, steroids, and, for severe rigors, meperidine. Rarely, patients can develop neutropenia (approximately 1:500) that appears to be autoimmune in nature. Infections appear to be only minimally increased with the use of rituximab.¹⁰ One group at risk is chronic carriers of hepatitis B virus, who may experience a reactivation of the virus that can be fatal. Thus, patients being considered for rituximab need to be screened for hepatitis B virus carrier state.¹¹ Patients receiving rituximab are at very slight risk for progressive multifocal leukoencephalopathy, which is more common in patients with cancer and in heavily immunosuppressed patients. The overall risk is unknown but is less than 1:50,000.

Second Line

Splenectomy. For patients who cannot be weaned from steroids or in whom steroid therapy fails, there is no standard therapy. Currently, the 2 main choices are splenectomy or rituximab (anti-CD20) therapy if the patient did not receive it first line. Splenectomy is the classic therapy for warm AIHA. Reported response rates in the literature range from 50% to 80%, with 50% to 60% remaining in remission.^12-16 Timing of the procedure is a balance between allowing time for the steroids to work and the risk of toxicity of steroids. In a patient who has low presurgical risk and has either refractory disease or cannot be weaned from high doses of steroids, splenectomy should be done sooner. Splenectomy can be delayed or other therapy tried first in patients who require lower doses of steroids or have medical risk factors for surgery. Most splenectomies are performed via laparoscopy. The small incisions allow for quicker healing, and the laparoscopic approach provides better visualization of the abdomen to find and remove accessory spleens. When splenectomy is performed by experienced surgeons, the mortality rate is low (< 0.5%).¹⁷

The most concerning complication of splenectomy is overwhelming post-splenectomy infection (OPSI).¹⁸ In adults, the spleen appears to play a minimal role in immunity except for protecting against certain encap-sulated organisms. Splenectomized patients infected with an encapsulated organism (eg, Pneumococcus) will develop overwhelming sepsis within hours. These patients will often have disseminated intravascular coagulation and will rapidly progress to purpura fulminans. Approximately 40% to 50% of patients will die of sepsis even when the infection is detected early. The overall lifetime risk of sepsis may be as high as 1:500. The organism that most commonly causes sepsis in splenectomized patients is Streptococcus pneumoniae, reported in over 50% of cases. Neisseria meningitidis and Haemophilus influenzae have also been implicated in many cases.¹⁹ Overwhelming sepsis after dog bites has been reported due to Capnocytophaga canimorsus infections. Patients are also at increased risk of developing severe malaria and severe babesiosis.¹⁸

Patients who have undergone splenectomy need to be warned about the risk of OPSI and instructed to report to the emergency department readily if they develop a fever greater than 101°F (38.3°C) or shaking chills. Once in the emergency department, blood cultures should be obtained rapidly and the patient started on antibiotic coverage with vancomycin and ceftriaxone (or levofloxacin if allergic to beta-lactams).²⁰ For patients in remote areas, some physicians will prescribe prophylactic antibiotics to take while they are traveling to a health care provider or even recommend a “standby” antibiotic dose to take while traveling to health care.⁵ This usually consists of amoxicillin or a macrolide for penicillin-allergic patients.

Patients in whom splenectomy is being planned or considered should be vaccinated for pneumococcal, meningococcal, and influenza infections (Table 2).¹⁸ If there is a plan to treat with rituximab, patients should first be vaccinated since they will not be able to mount an immune response after being treated with rituximab.

Third Line

The therapeutic options for patients who do not respond to either splenectomy or rituximab are much less certain.^5,6 Although intravenous immune globulin is a standard therapy for ITP, response rates are low in warm AIHA.¹⁷ Numerous therapies have been reported in small series, but no clear approach has emerged. Options include azathioprine, cyclophosphamide, mycophenolate, cyclosporine, danazol, and alemtuzumab. Our approach has been to use mycophenolate for patients requiring high doses of steroids or transfusions. Patients who respond to lower doses of steroids may be good candidates for danazol to help wean them off steroids.

Warm AIHA can complicate several diseases. Patients with systemic lupus erythematosus (SLE) can develop warm AIHA as part of their disease complex. The initial treatment approach is the same, but data suggest that splenectomy may not be as effective.^13,17 Also, many SLE patients have complex medical conditions, making surgeries riskier. For SLE patients who are refractory or cannot be weaned from steroids, rituximab may be the better choice. Babesiosis, particularly in asplenic patients, has been associated with the development of AIHA.^21,22

Of the malignances associated with AIHA, chronic lymphocytic leukemia (CLL) has the strongest association.^4,23 Series show that 5% to 10% of patients with CLL will have warm AIHA. AIHA can appear concurrent with CLL or develop during the course of the disease. The introduction of purine analogs such as fludarabine led to a dramatic increase in the incidence of warm AIHA in treated patients.²⁴ It is speculated that these powerful agents reduce the number and effectiveness of T cells that hold in check the autoantibody response, leading to warm AIHA.²⁵ However, when these purine analogs are used in com-bination with agents such as cyclophosphamide or rituximab (with their immunosuppressive effects), the rates of warm AIHA have been lower.²³

The approach to patients with CLL and warm AIHA depends on the state of their CLL.²³ For patients who have low-stage CLL that does not need treatment, the standard approach to warm AIHA should be steroids, splenectomy, and rituximab.²⁴ For patients with higher-stage CLL, the treatment for the leukemia will often provide therapy for the warm AIHA. The combination of rituximab-cyclophosphamide-dexamethasone has been reported to be effective for both the AIHA and CLL components.²⁶ The use of ibrutinib has also been reported to be effective.²⁷

A rare but important variant of warm AIHA is Evans syndrome.^28,29 This is the combination of AIHA and ITP. Approximately 1% to 3% of AIHA cases are the Evans variant. The ITP can precede, be concurrent with, or develop after the AIHA. The diagnosis of Evans syndrome should raise concern for underlying disorders. In young adults, immunodeficiency disorders such as autoimmune lymphoproliferative disease (ALPS) need to be considered. In older patients, Evans syndrome is often associated with T cell lymphomas. The sparse literature on Evans syndrome suggests that it can be more refractory to standard therapy, with response rates to splenectomy in the 50% range.^28,30 In patients with lymphoma, antineoplastic therapy is crucial. There is increasing data showing that mycophenolate or sirolimus may be effective for patients with ALPS in whom splenectomy or rituximab therapy is unsuccessful.³¹

Warm AIHA with IgA or IgM Antibodies

In rare patients with warm AIHA, IgA or IgM is the implicated antibody. The literature suggests that patients with IgA AIHA may have more severe hemolysis.³² Patients with IgM AIHA often have a severe course with a fatal outcome.³³ In such cases, the patient’s plasma may show spontaneous hemolysis and agglutination. The DAT may not be strongly positive or may show C3 reactivity only. The clinical clues are C3 reactivity with no cold agglutinins and severe hemolysis, sometimes with an intravascular component. Treatment is the same as for warm AIHA, including the use of rituximab.³⁴

In cold AIHA, the hemolysis is mediated by IgM antibodies directed against red cells.³⁵ As discussed earlier, the term “cold” refers to the fact that the antibody binds maximally at temperatures below 37°C. The most efficient temperature for binding is called the “thermal amplitude,” and, in theory, the higher the thermal amplitude, the more virulent the antibody. An antibody titer can be calculated at each reaction temperature from 4°C to 37°C by serial dilutions of the patient’s serum prior to incubating with reagent red cells. Rarely, the IgM can fix complement rapidly, leading to intravascular hemolysis. In most patients, complement is fixed through C3, and the C3-coated red cells are taken up by macrophages in the mononuclear phagocyte system, primarily in the liver.³

The DAT in patients with cold AIHA will show cells coated with C3. The blood smear will often show ag-glutination of the blood, and if the blood cools before being analyzed, the agglutination will interfere with the analysis. Titers of cold agglutinin can range from 1:1000 to over 1 million. The IgM autoantibodies are most often directed against the I/i antigens on the red blood cell membrane, with 90% against I antigen.³⁵ The I antigen specificity is typical with primary cold agglutinin disease and after Mycoplasma infection. The i antigen specificity is most typical of Epstein-Barr virus and cytomegalovirus infections in children. In young patients, cold AIHA often occurs following an infection, including viral and Mycoplasma infections, and the course is self-limited.^35,36 The hemolysis usually starts 2 to 3 weeks after the illness and will last for 4 to 6 weeks. In older patients, the etiology in over 90% of cases is a B-cell lymphoproliferative disorder, usually with monoclonal kappa B-cells.³⁷ The most common disorders are marginal zone lymphoma, small lymphocytic lymphoma, and lymphoplasmacytic lymphoma.³

Therapeutic Options

It is important to diagnose cold AIHA because the standard therapy for warm AIHA (steroids) is ineffective in cold AIHA. Because C3-coated red cells are taken up primarily in the liver, removing the spleen is also an ineffective therapy. Simple measures to help with cold AIHA should be employed.³⁷ Patients should be kept in a warm environment and should try to avoid the cold. If transfusions are needed, they should be infused via blood warmers to prevent hemolysis. In rare patients with severe hemolysis, therapeutic plasma exchange (TPE) can be considered.³⁸ Given that the culprit antibody is IgM—mostly intravascular—use of TPE may slow the hemolysis to give time for other therapies to take effect.

Treatment of cold AIHA remains difficult (Table 3). Because most patients with primary AIHA have underlying lymphoproliferative diseases, chlorambucil has been used in the past to treat cold AIHA. However, responses were rare and the drug could worsen the anemia.³⁸ Currently, the drug of choice is rituximab. Response is seen in 45% to 75% of patients, but is almost always a partial response and retreatment is often necessary.^17,37,39 As with other autoimmune hematologic diseases, there can be a delay in response that ranges from 2 weeks to 4 months (median time, 1.5 months).³⁷ Given the lack of robust response (complete and durable) with rituximab, the Berentsen group has explored adding bendamustine to rituximab.⁴⁰ In a prospective trial, 71% of patients responded with a 40% complete response rate. Therapy was well tolerated, with only 29% of patients needing dose reduction Although more toxic, this combination can be considered in patients with aggressive disease. A small study of the use of bortezomib showed a good response in one-third of patients.⁴¹ There is increasing use of the C5 complement inhibitor eculizumab to halt the hemolysis, but further study of this agent is also required.^36,42,43 Blockers of C1s complement, which block hemolysis by preventing complement activation, are currently being studied in clinical trials.⁴⁴

Since most patients with cold AIHA are older, a frequent issue that must be considered is cardiac surgery. The concern is that the hypothermia involved with most heart bypass procedures will lead to agglutination and hemolysis. The development of normothermic bypass has expanded treatment options. A recommended approach in patients who have known cold agglutinins is to measure the thermal amplitude of the antibody preoperatively. If the thermal amplitude is above 18°C, normothermic bypass should be done, if feasible.⁴⁵ If not feasible, preoperative TPE should be considered.

Paroxysmal Cold Hemoglobinuria

A unique cold AIHA is paroxysmal cold hemoglobinuria (PCH).^3,46 This cold hemolytic syndrome most often occurs in children following a viral infection, but in the past it complicated any stage of syphilis.⁴⁷ The mediating antibody in PCH is an IgG antibody directed against the P antigen on the red blood cell. This antibody binds best at temperatures below 37°C, fixing complement at cold temperatures, but then activates the complement cascade at body temperature.⁴⁸ Because this antibody can fix complement, hemolysis can be rapid and severe, leading to extreme anemia. The DAT is often weakly positive but can be negative. The diagnostic test for PCH is the Donath–Landsteiner test. This complex test is performed by incubating 3 blood samples, 1 at 0° to 4°C, another at 37°C, and a third at 0° to 4°C and then at 37°C. The diagnosis of PCH is made if only the third tube shows hemolysis.³⁵ PCH can persist for 1 to 3 months but is almost always self-limiting. In severe case, steroids may be of benefit.

Drug-Induced Hemolytic Anemia

AIHA caused by a drug reaction is rare, with a lower incidence than drug-related ITP. The rate of severe drug-related AIHA is estimated at 1:1,000,000, but less severe cases may be missed.¹ Most patients will have a positive DAT without signs of hemolysis, but in rare cases patients will have relentless hemolysis resulting in death.

Mechanisms

Multiple mechanisms for drug-induced immune hemolysis have been proposed, including drug-absorption (hapten-induced) and immune complex mechanisms.^1,49 The hapten mechanism is most often associated with the use of high-dose penicillin.⁵⁰ High doses of penicillin or similar drugs such as piperacillin lead to incorporation of the drug into the red cell membrane by binding to proteins. Patients will manifest a positive DAT with IgG antibody but not complement.⁵¹ The patient’s plasma will be reactive only with penicillin-coated red cells and not with normal cells. As mentioned, very few patients will have hemolysis, and if they have hemolysis, it will resolve in a few days after discontinuation of the offending drug.⁵²

Binding of a drug-antibody complex to the red cell membrane may cause hemolysis via the immune com-plex mechanism.⁵³ Again, most often the patient will have just a positive DAT, but rarely patients will have life-threatening hemolysis upon exposure or reexposure to the drug. The onset of hemolysis is rapid, with signs of acute illness and intravascular hemolysis. The paradigm drug is quinine, but many other drugs have been implicated. Testing shows a positive Coombs test with anti-complement but not anti-IgG.⁵⁰ This pattern is due to the effectiveness of the tertiary complex at fixing complement. The patient’s plasma reacts with red cells only when the drug is added.

A form of immune complex hemolysis associated with both disseminated intravascular coagulation (DIC) and brisk hemolysis has been recognized. Patients who receive certain second- and third-generation cephalosporins (especially cefotetan and ceftriaxone.^53,54) have developed this syndrome.^50,55-59 The clinical symptoms start 7 to 10 days after the drug is administered; often the patient has only received the antibiotic for surgical prophylaxis. Immune hemolysis with acute hematocrit drop, hypotension, and DIC ensues. The patients are often believed to have sepsis and are often reexposed to the cephalosporin, resulting in worsening of the clinical status. The outcome is often fatal due to massive hemolysis and thrombosis.^56,60,62

Finally, 8% to 36% of patients taking methyldopa will develop a positive DAT after 6 months of therapy, with less than 1% showing hemolysis.^52,63 The hemolysis in these patients is indistinguishable from warm AIHA, consistent with the notion that methyldopa induces an AIHA. The hemolysis often resolves rapidly after the methyldopa is stopped, but the Coombs test may remain positive for months.⁶³ This type of drug-induced hemolytic anemia has been reported with levodopa, procainamide, and chlorpromazine, but fludarabine is the most common cause currently. This form of AIHA is now being seen with increased use of checkpoint inhibitors.⁶⁴

Diagnosis

In many patients, the first clue to the presence of drug AIHA is the finding of a positive DAT. Rarely, patients will have severe hemolysis, but in many patients the hemolytic process is mild and may be wrongly assumed to be part of the underlying illness. Finding the offending drug can be a challenge, unless a patient has recently started a new drug; in a hospitalized patient on multiple agents, identifying the problem drug is difficult. Patients recently started on “suspect drugs,” especially the most common agents cefotetan, ceftriaxone, and piperacillin, should have these agents stopped (Table 4).^1,49,65 Specialty laboratories such as the Blood Center of Wisconsin or the Los Angeles Red Cross can perform in vitro studies of drug interactions that can confirm the clinical diagnosis of drug-induced AIHA.

Treatment

Therapy for patients with positive DAT without signs of hemolysis is uncertain. If the drug is essential, then the patient can be observed. If the patient has hemolysis, the drug needs to be stopped and the patient observed for signs of end-organ damage. It is doubtful that steroids or other autoimmune-directed therapy is effective. For patients with the DIC-hemolysis syndrome, there are anecdotal reports that TPE may be helpful.¹

Summary

AIHA can range from an abnormal laboratory test (positive DAT and signs of hemolysis) to an acute, life-threatening illness. Treatment is guided by the laboratory work-up and evaluation of the patient’s clinical status. While rituximab is promising for many patients, the lack of robust clinical trials hinders the treatment of patients who fail standard therapies.

Autoimmune hemolytic anemia (AIHA) is mediated by antibodies, and in most cases immunoglobulin (Ig) G is the mediating antibody. This type of AIHA is referred to as "warm" AIHA because IgG antibodies bind best at body temperature. "Cold" AIHA is mediated by IgM antibodies, which bind maximally at temperatures below 37°C. AIHA caused by a drug reaction is rare, with an estimated annual incidence of 1:1,000,000 for severe drug-related AIHA.¹ This article reviews the management of the more common types of AIHA, with a focus on warm, cold, and drug-induced AIHA; the evaluation and diagnosis of AIHA is reviewed in a separate article.

Warm Autoimmune Hemolytic Anemia

In AIHA, hemolysis is mediated by antibodies that bind to the surface of red blood cells. AIHA in which IgG antibodies are the offending antibodies is referred to as warm AIHA. “Warm” refers to the fact that the antibody binds best at body temperature (37°C). In warm AIHA, testing will show IgG molecules attached to the surface of the red cells, with 50% of patients also showing C3. Between 50% and 90% of AIHA cases are due to warm antibodies.^2,3 The incidence of warm AIHA varies by series but is approximately 1 case per 100,000 patients per year; this form of hemolysis affects women more frequently than men.^4,5

Therapeutic Options

First Line

Steroids. The goal of therapy in warm AIHA can be hard to define. However, most would agree that a hematocrit above 30% (or higher to prevent symptoms) with a minimal increase in the reticulocyte count—reflective of a significantly slowed hemolytic process—is a reasonable goal. Initial management of warm AIHA is prednisone at a standard dose of 1 mg/kg daily (Table 1).^6,7 Patients should be also started on proton-pump inhibitors to prevent ulcers. It can take up to 3 weeks for patients to respond to prednisone therapy. Once the patient’s hematocrit is above 30%, the prednisone is slowly tapered. Although approximately 80% of patients will respond to steroids, only 30% can be fully tapered off steroids. For patients who can be maintained on a daily steroid dose of 10 mg or less, steroids may be the most reasonable long-term therapy. In addition, because active hemolysis leads to an increased demand for folic acid, patients with warm AIHA are often prescribed folic acid 1 mg daily to prevent megaloblastic anemia due to folic acid deficiency.

Rituximab. Increasingly, rituximab (anti-CD20) therapy is added to the initial steroids. Two clinical trials showed both increased long-term and short-term responses with the use of rituximab.^8,9 An important consideration is that most patients respond gradually to rituximab over weeks, so a rapid response should not be expected. Most studies have used the traditional dosing of 375 mg/m² weekly for 4 weeks. These responses appear to be durable, but as in immune thrombocytopenia (ITP), repeat treatment with rituximab is effective.

The major side effects of rituximab are infusion reactions, which are often worse with the first dose. These reactions can be controlled with antihistamines, steroids, and, for severe rigors, meperidine. Rarely, patients can develop neutropenia (approximately 1:500) that appears to be autoimmune in nature. Infections appear to be only minimally increased with the use of rituximab.¹⁰ One group at risk is chronic carriers of hepatitis B virus, who may experience a reactivation of the virus that can be fatal. Thus, patients being considered for rituximab need to be screened for hepatitis B virus carrier state.¹¹ Patients receiving rituximab are at very slight risk for progressive multifocal leukoencephalopathy, which is more common in patients with cancer and in heavily immunosuppressed patients. The overall risk is unknown but is less than 1:50,000.

Second Line

Splenectomy. For patients who cannot be weaned from steroids or in whom steroid therapy fails, there is no standard therapy. Currently, the 2 main choices are splenectomy or rituximab (anti-CD20) therapy if the patient did not receive it first line. Splenectomy is the classic therapy for warm AIHA. Reported response rates in the literature range from 50% to 80%, with 50% to 60% remaining in remission.^12-16 Timing of the procedure is a balance between allowing time for the steroids to work and the risk of toxicity of steroids. In a patient who has low presurgical risk and has either refractory disease or cannot be weaned from high doses of steroids, splenectomy should be done sooner. Splenectomy can be delayed or other therapy tried first in patients who require lower doses of steroids or have medical risk factors for surgery. Most splenectomies are performed via laparoscopy. The small incisions allow for quicker healing, and the laparoscopic approach provides better visualization of the abdomen to find and remove accessory spleens. When splenectomy is performed by experienced surgeons, the mortality rate is low (< 0.5%).¹⁷

The most concerning complication of splenectomy is overwhelming post-splenectomy infection (OPSI).¹⁸ In adults, the spleen appears to play a minimal role in immunity except for protecting against certain encap-sulated organisms. Splenectomized patients infected with an encapsulated organism (eg, Pneumococcus) will develop overwhelming sepsis within hours. These patients will often have disseminated intravascular coagulation and will rapidly progress to purpura fulminans. Approximately 40% to 50% of patients will die of sepsis even when the infection is detected early. The overall lifetime risk of sepsis may be as high as 1:500. The organism that most commonly causes sepsis in splenectomized patients is Streptococcus pneumoniae, reported in over 50% of cases. Neisseria meningitidis and Haemophilus influenzae have also been implicated in many cases.¹⁹ Overwhelming sepsis after dog bites has been reported due to Capnocytophaga canimorsus infections. Patients are also at increased risk of developing severe malaria and severe babesiosis.¹⁸

Patients who have undergone splenectomy need to be warned about the risk of OPSI and instructed to report to the emergency department readily if they develop a fever greater than 101°F (38.3°C) or shaking chills. Once in the emergency department, blood cultures should be obtained rapidly and the patient started on antibiotic coverage with vancomycin and ceftriaxone (or levofloxacin if allergic to beta-lactams).²⁰ For patients in remote areas, some physicians will prescribe prophylactic antibiotics to take while they are traveling to a health care provider or even recommend a “standby” antibiotic dose to take while traveling to health care.⁵ This usually consists of amoxicillin or a macrolide for penicillin-allergic patients.

Patients in whom splenectomy is being planned or considered should be vaccinated for pneumococcal, meningococcal, and influenza infections (Table 2).¹⁸ If there is a plan to treat with rituximab, patients should first be vaccinated since they will not be able to mount an immune response after being treated with rituximab.

Third Line

The therapeutic options for patients who do not respond to either splenectomy or rituximab are much less certain.^5,6 Although intravenous immune globulin is a standard therapy for ITP, response rates are low in warm AIHA.¹⁷ Numerous therapies have been reported in small series, but no clear approach has emerged. Options include azathioprine, cyclophosphamide, mycophenolate, cyclosporine, danazol, and alemtuzumab. Our approach has been to use mycophenolate for patients requiring high doses of steroids or transfusions. Patients who respond to lower doses of steroids may be good candidates for danazol to help wean them off steroids.

Warm AIHA can complicate several diseases. Patients with systemic lupus erythematosus (SLE) can develop warm AIHA as part of their disease complex. The initial treatment approach is the same, but data suggest that splenectomy may not be as effective.^13,17 Also, many SLE patients have complex medical conditions, making surgeries riskier. For SLE patients who are refractory or cannot be weaned from steroids, rituximab may be the better choice. Babesiosis, particularly in asplenic patients, has been associated with the development of AIHA.^21,22

Of the malignances associated with AIHA, chronic lymphocytic leukemia (CLL) has the strongest association.^4,23 Series show that 5% to 10% of patients with CLL will have warm AIHA. AIHA can appear concurrent with CLL or develop during the course of the disease. The introduction of purine analogs such as fludarabine led to a dramatic increase in the incidence of warm AIHA in treated patients.²⁴ It is speculated that these powerful agents reduce the number and effectiveness of T cells that hold in check the autoantibody response, leading to warm AIHA.²⁵ However, when these purine analogs are used in com-bination with agents such as cyclophosphamide or rituximab (with their immunosuppressive effects), the rates of warm AIHA have been lower.²³

The approach to patients with CLL and warm AIHA depends on the state of their CLL.²³ For patients who have low-stage CLL that does not need treatment, the standard approach to warm AIHA should be steroids, splenectomy, and rituximab.²⁴ For patients with higher-stage CLL, the treatment for the leukemia will often provide therapy for the warm AIHA. The combination of rituximab-cyclophosphamide-dexamethasone has been reported to be effective for both the AIHA and CLL components.²⁶ The use of ibrutinib has also been reported to be effective.²⁷

A rare but important variant of warm AIHA is Evans syndrome.^28,29 This is the combination of AIHA and ITP. Approximately 1% to 3% of AIHA cases are the Evans variant. The ITP can precede, be concurrent with, or develop after the AIHA. The diagnosis of Evans syndrome should raise concern for underlying disorders. In young adults, immunodeficiency disorders such as autoimmune lymphoproliferative disease (ALPS) need to be considered. In older patients, Evans syndrome is often associated with T cell lymphomas. The sparse literature on Evans syndrome suggests that it can be more refractory to standard therapy, with response rates to splenectomy in the 50% range.^28,30 In patients with lymphoma, antineoplastic therapy is crucial. There is increasing data showing that mycophenolate or sirolimus may be effective for patients with ALPS in whom splenectomy or rituximab therapy is unsuccessful.³¹

Warm AIHA with IgA or IgM Antibodies

In rare patients with warm AIHA, IgA or IgM is the implicated antibody. The literature suggests that patients with IgA AIHA may have more severe hemolysis.³² Patients with IgM AIHA often have a severe course with a fatal outcome.³³ In such cases, the patient’s plasma may show spontaneous hemolysis and agglutination. The DAT may not be strongly positive or may show C3 reactivity only. The clinical clues are C3 reactivity with no cold agglutinins and severe hemolysis, sometimes with an intravascular component. Treatment is the same as for warm AIHA, including the use of rituximab.³⁴

In cold AIHA, the hemolysis is mediated by IgM antibodies directed against red cells.³⁵ As discussed earlier, the term “cold” refers to the fact that the antibody binds maximally at temperatures below 37°C. The most efficient temperature for binding is called the “thermal amplitude,” and, in theory, the higher the thermal amplitude, the more virulent the antibody. An antibody titer can be calculated at each reaction temperature from 4°C to 37°C by serial dilutions of the patient’s serum prior to incubating with reagent red cells. Rarely, the IgM can fix complement rapidly, leading to intravascular hemolysis. In most patients, complement is fixed through C3, and the C3-coated red cells are taken up by macrophages in the mononuclear phagocyte system, primarily in the liver.³

The DAT in patients with cold AIHA will show cells coated with C3. The blood smear will often show ag-glutination of the blood, and if the blood cools before being analyzed, the agglutination will interfere with the analysis. Titers of cold agglutinin can range from 1:1000 to over 1 million. The IgM autoantibodies are most often directed against the I/i antigens on the red blood cell membrane, with 90% against I antigen.³⁵ The I antigen specificity is typical with primary cold agglutinin disease and after Mycoplasma infection. The i antigen specificity is most typical of Epstein-Barr virus and cytomegalovirus infections in children. In young patients, cold AIHA often occurs following an infection, including viral and Mycoplasma infections, and the course is self-limited.^35,36 The hemolysis usually starts 2 to 3 weeks after the illness and will last for 4 to 6 weeks. In older patients, the etiology in over 90% of cases is a B-cell lymphoproliferative disorder, usually with monoclonal kappa B-cells.³⁷ The most common disorders are marginal zone lymphoma, small lymphocytic lymphoma, and lymphoplasmacytic lymphoma.³

Therapeutic Options

It is important to diagnose cold AIHA because the standard therapy for warm AIHA (steroids) is ineffective in cold AIHA. Because C3-coated red cells are taken up primarily in the liver, removing the spleen is also an ineffective therapy. Simple measures to help with cold AIHA should be employed.³⁷ Patients should be kept in a warm environment and should try to avoid the cold. If transfusions are needed, they should be infused via blood warmers to prevent hemolysis. In rare patients with severe hemolysis, therapeutic plasma exchange (TPE) can be considered.³⁸ Given that the culprit antibody is IgM—mostly intravascular—use of TPE may slow the hemolysis to give time for other therapies to take effect.

Treatment of cold AIHA remains difficult (Table 3). Because most patients with primary AIHA have underlying lymphoproliferative diseases, chlorambucil has been used in the past to treat cold AIHA. However, responses were rare and the drug could worsen the anemia.³⁸ Currently, the drug of choice is rituximab. Response is seen in 45% to 75% of patients, but is almost always a partial response and retreatment is often necessary.^17,37,39 As with other autoimmune hematologic diseases, there can be a delay in response that ranges from 2 weeks to 4 months (median time, 1.5 months).³⁷ Given the lack of robust response (complete and durable) with rituximab, the Berentsen group has explored adding bendamustine to rituximab.⁴⁰ In a prospective trial, 71% of patients responded with a 40% complete response rate. Therapy was well tolerated, with only 29% of patients needing dose reduction Although more toxic, this combination can be considered in patients with aggressive disease. A small study of the use of bortezomib showed a good response in one-third of patients.⁴¹ There is increasing use of the C5 complement inhibitor eculizumab to halt the hemolysis, but further study of this agent is also required.^36,42,43 Blockers of C1s complement, which block hemolysis by preventing complement activation, are currently being studied in clinical trials.⁴⁴

Since most patients with cold AIHA are older, a frequent issue that must be considered is cardiac surgery. The concern is that the hypothermia involved with most heart bypass procedures will lead to agglutination and hemolysis. The development of normothermic bypass has expanded treatment options. A recommended approach in patients who have known cold agglutinins is to measure the thermal amplitude of the antibody preoperatively. If the thermal amplitude is above 18°C, normothermic bypass should be done, if feasible.⁴⁵ If not feasible, preoperative TPE should be considered.

Paroxysmal Cold Hemoglobinuria

A unique cold AIHA is paroxysmal cold hemoglobinuria (PCH).^3,46 This cold hemolytic syndrome most often occurs in children following a viral infection, but in the past it complicated any stage of syphilis.⁴⁷ The mediating antibody in PCH is an IgG antibody directed against the P antigen on the red blood cell. This antibody binds best at temperatures below 37°C, fixing complement at cold temperatures, but then activates the complement cascade at body temperature.⁴⁸ Because this antibody can fix complement, hemolysis can be rapid and severe, leading to extreme anemia. The DAT is often weakly positive but can be negative. The diagnostic test for PCH is the Donath–Landsteiner test. This complex test is performed by incubating 3 blood samples, 1 at 0° to 4°C, another at 37°C, and a third at 0° to 4°C and then at 37°C. The diagnosis of PCH is made if only the third tube shows hemolysis.³⁵ PCH can persist for 1 to 3 months but is almost always self-limiting. In severe case, steroids may be of benefit.

Drug-Induced Hemolytic Anemia

AIHA caused by a drug reaction is rare, with a lower incidence than drug-related ITP. The rate of severe drug-related AIHA is estimated at 1:1,000,000, but less severe cases may be missed.¹ Most patients will have a positive DAT without signs of hemolysis, but in rare cases patients will have relentless hemolysis resulting in death.

Mechanisms

Multiple mechanisms for drug-induced immune hemolysis have been proposed, including drug-absorption (hapten-induced) and immune complex mechanisms.^1,49 The hapten mechanism is most often associated with the use of high-dose penicillin.⁵⁰ High doses of penicillin or similar drugs such as piperacillin lead to incorporation of the drug into the red cell membrane by binding to proteins. Patients will manifest a positive DAT with IgG antibody but not complement.⁵¹ The patient’s plasma will be reactive only with penicillin-coated red cells and not with normal cells. As mentioned, very few patients will have hemolysis, and if they have hemolysis, it will resolve in a few days after discontinuation of the offending drug.⁵²

Binding of a drug-antibody complex to the red cell membrane may cause hemolysis via the immune com-plex mechanism.⁵³ Again, most often the patient will have just a positive DAT, but rarely patients will have life-threatening hemolysis upon exposure or reexposure to the drug. The onset of hemolysis is rapid, with signs of acute illness and intravascular hemolysis. The paradigm drug is quinine, but many other drugs have been implicated. Testing shows a positive Coombs test with anti-complement but not anti-IgG.⁵⁰ This pattern is due to the effectiveness of the tertiary complex at fixing complement. The patient’s plasma reacts with red cells only when the drug is added.

A form of immune complex hemolysis associated with both disseminated intravascular coagulation (DIC) and brisk hemolysis has been recognized. Patients who receive certain second- and third-generation cephalosporins (especially cefotetan and ceftriaxone.^53,54) have developed this syndrome.^50,55-59 The clinical symptoms start 7 to 10 days after the drug is administered; often the patient has only received the antibiotic for surgical prophylaxis. Immune hemolysis with acute hematocrit drop, hypotension, and DIC ensues. The patients are often believed to have sepsis and are often reexposed to the cephalosporin, resulting in worsening of the clinical status. The outcome is often fatal due to massive hemolysis and thrombosis.^56,60,62

Finally, 8% to 36% of patients taking methyldopa will develop a positive DAT after 6 months of therapy, with less than 1% showing hemolysis.^52,63 The hemolysis in these patients is indistinguishable from warm AIHA, consistent with the notion that methyldopa induces an AIHA. The hemolysis often resolves rapidly after the methyldopa is stopped, but the Coombs test may remain positive for months.⁶³ This type of drug-induced hemolytic anemia has been reported with levodopa, procainamide, and chlorpromazine, but fludarabine is the most common cause currently. This form of AIHA is now being seen with increased use of checkpoint inhibitors.⁶⁴

Diagnosis

In many patients, the first clue to the presence of drug AIHA is the finding of a positive DAT. Rarely, patients will have severe hemolysis, but in many patients the hemolytic process is mild and may be wrongly assumed to be part of the underlying illness. Finding the offending drug can be a challenge, unless a patient has recently started a new drug; in a hospitalized patient on multiple agents, identifying the problem drug is difficult. Patients recently started on “suspect drugs,” especially the most common agents cefotetan, ceftriaxone, and piperacillin, should have these agents stopped (Table 4).^1,49,65 Specialty laboratories such as the Blood Center of Wisconsin or the Los Angeles Red Cross can perform in vitro studies of drug interactions that can confirm the clinical diagnosis of drug-induced AIHA.

Treatment

Therapy for patients with positive DAT without signs of hemolysis is uncertain. If the drug is essential, then the patient can be observed. If the patient has hemolysis, the drug needs to be stopped and the patient observed for signs of end-organ damage. It is doubtful that steroids or other autoimmune-directed therapy is effective. For patients with the DIC-hemolysis syndrome, there are anecdotal reports that TPE may be helpful.¹

Summary

AIHA can range from an abnormal laboratory test (positive DAT and signs of hemolysis) to an acute, life-threatening illness. Treatment is guided by the laboratory work-up and evaluation of the patient’s clinical status. While rituximab is promising for many patients, the lack of robust clinical trials hinders the treatment of patients who fail standard therapies.

The autoimmune hemolytic anemias (AIHA) are rare but important hematologic diseases. They can range in severity from mildly symptomatic illness to a rapidly fatal syndrome. The incidence of AIHA is estimated to be between 0.6 and 3 cases per 100,000 persons.^1,2 AIHA is mediated by antibodies, and in the majority of cases immunoglobulin (Ig) G is the mediating antibody. This type of AIHA is referred to as "warm" AIHA because IgG antibodies bind best at body temperature. "Cold" AIHA is mediated by IgM antibodies, which bind maximally at temperatures below 37°C (Table 1). This article series reviews the most common types of AIHA, with an overview of evaluation and diagnosis presented in this article and management of warm, cold, and drug-induced AIHA reviewed in a separate article.

Pathogenesis

In most cases, the ultimate etiology of AIHA is unknown. In warm AIHA, the target epitopes in most cases are Rh proteins.² What leads the immune system to target these proteins is unidentified, but one theory is that an initial immune response to a foreign antigen starts to cross-react with the Rh proteins and the immune system fails to suppress this autoreactive response, leading to hemolysis. In IgG-mediated (warm) hemolysis, the red cells become coated with IgG molecules, which mark the cells for uptake and destruction by splenic macrophages.³ In "cold" AIHA, IgM molecules fix complement to the surface of red blood cells. Rarely, this can lead to activation of the full complement cascade, resulting in red cell lysis, but more often it is stopped at the C3 stage, leading to C3-coated red cells which are then taken up by hepatic macrophages.⁴

Suspecting the Diagnosis

In many patients, it is the symptoms and signs of anemia that lead to suspicion of hemolysis. Older patients often present earlier in the course of the disease due to lack of tolerance of anemia, especially if there is a sudden drop in the red blood cell count. Dark, cola-colored urine resulting from the presence of free hemoglobin may be noted by some patients. Patients with rapid-onset hemolysis may note lumbar back pain, and those with cold agglutinins often note symptoms related to agglutination of red cells in the peripheral circulation, such as the development of acrocyanosis in cold weather.⁵ In rare cases, patients will have abdominal pain when eating cold food due to ischemia related to agglutination of red cells in the viscera. Some patients with cold agglutinins can have an exacerbation of their hemolysis with cold exposure.

Unlike patients with immune thrombocytopenia, those with AIHA may have mild splenomegaly on exam. The presence of enlarged lymph nodes or massive splenomegaly should raise concern about concomitant lymphoma or chronic lymphocytic leukemia.

Making the Diagnosis

The 2 key steps in diagnosis are (1) demonstrating hemolysis and (2) demonstrating the autoimmune component.

Laboratory Evaluation for Hemolysis

Hemolysis is proven by finding evidence of both red cell breakdown and the compensatory increase in red cell production this stimulates (Table 2). The following sections discuss the laboratory tests that are performed to investigate hemolysis.

Lactate Dehydrogenase

When red cells undergo hemolysis, they release their contents, which are mostly comprised of hemoglobin but also include lactate dehydrogenase (LDH), an enzyme found in high concentration in red cells. Most patients with hemolysis will have an elevated LDH level, making this a sensitive test. However, because many other processes, including liver disease and pneumonia, also raise the serum LDH level, this finding is not specific for hemolysis.

Hemoglobin is salvaged by haptoglobin, and the heme moiety is broken down first to bilirubin and then to urobilinogen, which is excreted in the urine.² Bilirubin produced from the breakdown of heme is not conjugated, but rather is delivered to the liver, where it is conjugated and excreted into the bile. In hemolysis, the concentration of unconjugated bilirubin (indirect bilirubin) is increased, while in liver disease the level of conjugated bilirubin (direct bilirubin) is increased. However, if the patient has concomitant liver disease with an increased direct bilirubin level, the serum bilirubin test is not reliable.

Serum Haptoglobin

Haptoglobin binds free serum hemoglobin and is taken up by the liver. Haptoglobin usually falls to very low levels in hemolysis. A confounder is that haptoglobin is an acute phase reactant and can rise with systemic disease or inflammation. However, patients with advanced liver disease will have low haptoglobin levels due to lack of synthesis, and up to 2% of the population may congenitally lack haptoglobin.¹

Serum Hemoglobin

If the hemolysis is very rapid, the amount of free hemoglobin released will overwhelm the binding capacity of haptoglobin and lead to free hemoglobin in the plasma. This can be crudely quantified by examining the plasma color. Even minute amounts of free hemoglobin will turn the plasma pink. In fulminant hemolysis, the plasma will be cola-colored.

Reticulocyte Count

In most patients with hemolysis, the destruction of red cells is accompanied by an increase in the reticulocyte count. Reticulocytes are red cells that still contain RNA and are a marker of red cells that are approximately 24 hours old or less. Traditionally, reticulocytes were measured manually by staining the blood smear with vital blue and counting the percentage of cells that absorb the stain; this percentage needs to be adjusted for the hematocrit. Usually a percentage above 1.5% is considered indicative of an elevated reticulocyte count. Recently, automated complete blood count machines have taken advantage of the fact that reticulocytes will absorb certain stains; these machines can directly measure the reticulocyte count via flow cytometry, which results in an “absolute” reticulocyte count. The reticulocyte count obtained using this method does not have to be corrected for hematocrit, and levels of approximately 90,000/μL are considered raised. However, the reticulocyte count can also be raised in blood loss or in patients who have other causes of anemia (eg, iron deficiency) under treatment. In addition, as many as 25% of patients with AIHA will never have raised counts for various reasons, such as nutritional deficiency, autoimmune destruction of red cell precursors, or lack of erythropoietin.

Blood Smear

The blood smear provides vital information. The hallmark laboratory parameter of AIHA is spherocytes seen on the blood smear. In AIHA, antibodies and/or complement attach to the red cells, and when the antibodies or complement are taken up by macrophages in the spleen some of the red blood cell mem-brane is removed as well, decreasing the surface area of the cell. As the surface area of the red cell decreases with each pass through the spleen, the cell's shape changes from a biconcave disk to a sphere before the cell is destroyed, reflecting the fact that a sphere has the smallest surface area for a given volume. The vast majority of patients with AIHA will have spherocytes on the blood smear. However, spherocytes are not specific to AIHA, as they can be seen in hereditary spherocytosis, Wilson’s disease, clostridial sepsis, and severe burns.

Patients with cold agglutinins will often have red cell agglutination on the blood smear. In addition, patients with AIHA will often have a raised mean corpuscular volume (MCV) for 2 reasons. In patients with brisk reticulocytosis, the MCV will be raised due to the large size of the reticulocyte. In patients with cold agglutinin disease, the MCV may be falsely raised due to clumping of the red blood cells.

Urinary Hemosiderin

When hemoglobin is excreted by the kidney, the iron is deposited in the tubules. When the tubule cells are sloughed off, they appear in the urine. The urine can be stained for iron, and a positive result is another sign of hemolysis. Hemosiderinuria is a later sign of hemolysis, as it takes 1 week for iron-laden tubule cells to be excreted in sufficient quantities to be detected in the urine.

Urinary Hemoglobin

One other sign of hemolysis is the presence of hemoglobin in the urine. A quick way to demonstrate hemoglobinuria is to check the urine with a dipstick followed by a microscopic exam. In hemolysis, the dipstick will detect “blood,” while the microscopic exam will be negative for red cells.

Laboratory Evaluation for Autoimmune Component

The autoimmune component is shown by demonstrating the presence of either IgG molecules or complement on the surface of red blood cells.^4,6 This can be done by performing the direct antiglobulin test (DAT) or Coombs test. IgG bound to red cells will not agglutinate them, but if IgM that is directed against IgG or C3 is added, the red cells will agglutinate, proving that there is IgG and/or C3 on the red cell membrane. The finding of a positive DAT in the setting of a hemolytic anemia is diagnostic of AIHA. Beware of individuals with concomitant weak positive DAT and other causes of hemolysis. The strength of the DAT result and the degree of hemolysis must match in order to conclude that the hemolysis is immune-mediated.

There are several pitfalls to the DAT. One is that a positive DAT is found in 1:1000 patients in the normal population and in up to several percent of ill patients, especially those with elevated gamma globulin, such as patients with liver disease or HIV infection.⁶ Administration of intravenous immunoglobulin (IVIG) can also create a positive DAT. Conversely, patients can have AIHA with a negative DAT.^7-9 For some patients, the number of IgG molecules bound to the red cell is below the detection limit of the DAT reagents. Other patients can have IgA or “warm” IgM as the cause of the AIHA.¹⁰ Specialty laboratories can test for these possibilities. The diagnosis of DAT-negative AIHA should be made with caution, and other causes of hemolysis, such as hereditary spherocytosis or paroxysmal hematuria, should be excluded.

Performing transfusions can be very difficult in patients with AIHA.² The presence of the autoantibody can interfere with typing of the blood and almost always interferes with the crossmatch, since this final step consists of mixing the patient’s serum or plasma with donor red cells. In most patients with AIHA, the autoantibodies will react with any donor cells, rendering a negative crossmatch impossible. Without the crossmatch, the concern is that underlying alloantibodies can be missed. Studies indicate that 15% to 32% of patients will have underlying alloantibodies, which can lead to transfusion reactions.² However, there are 2 considerations that may mitigate these concerns.^11,12 First, patients who have never been transfused or pregnant will rarely have alloantibodies. Second, a patient who has been transfused in the remote past may have an anamnestic antibody response but not an immediate hemolytic reaction.

The transfusion service can take several steps to identify alloantibodies. Occasionally, if the autoantibody is weakly reacting when the patient’s serum is tested against a panel of reagent red cells, the alloantibodies can be identified by their stronger reactions as compared with the weakly reactive autoantibody. The most common technique for identifying alloantibodies is the autoadsorption technique.^4,13 This involves incu-bating the patient’s red cells with the patient’s serum to adsorb the autoantibody. After a period of incubation, the cells are pelleted and the serum is collected as the supernatant. The adsorbed serum may be incubated with another sample of the patient’s cells for a second adsorption if the initial agglutination reactions of the patient’s serum with the reagent cells were strong. After 1 to 3 adsorptions, the adsorbed serum is tested with a red cell panel in order to check for “leftover” alloantibodies.

When a patient is first suspected of having AIHA, a generous sample of blood should be given to the transfusion service to allow for adequate testing. Many centers will test the blood not only for blood groups ABO and D but also perform full Rh typing plus check for Kidd, Duffy and Kell status.¹⁴ Increasingly, this is performed by direct genetic sequencing for the appropriate genotypes. This can allow transfusion of phenotypically matched red blood cells to lessen the risk of alloantibody formation.

One difficult issue is timing of transfusion. Clinicians are often hesitant to transfuse patients with AIHA due to fear of reactions, but in patients with severe anemia, especially elderly patients or those with heart disease, transfusion can be lifesaving. Since in some cases it may take hours to screen for alloantibodies, it is often preferable to transfuse patients with severe anemia and observe carefully for reaction.

The autoimmune hemolytic anemias (AIHA) are rare but important hematologic diseases. They can range in severity from mildly symptomatic illness to a rapidly fatal syndrome. The incidence of AIHA is estimated to be between 0.6 and 3 cases per 100,000 persons.^1,2 AIHA is mediated by antibodies, and in the majority of cases immunoglobulin (Ig) G is the mediating antibody. This type of AIHA is referred to as "warm" AIHA because IgG antibodies bind best at body temperature. "Cold" AIHA is mediated by IgM antibodies, which bind maximally at temperatures below 37°C (Table 1). This article series reviews the most common types of AIHA, with an overview of evaluation and diagnosis presented in this article and management of warm, cold, and drug-induced AIHA reviewed in a separate article.

Pathogenesis

In most cases, the ultimate etiology of AIHA is unknown. In warm AIHA, the target epitopes in most cases are Rh proteins.² What leads the immune system to target these proteins is unidentified, but one theory is that an initial immune response to a foreign antigen starts to cross-react with the Rh proteins and the immune system fails to suppress this autoreactive response, leading to hemolysis. In IgG-mediated (warm) hemolysis, the red cells become coated with IgG molecules, which mark the cells for uptake and destruction by splenic macrophages.³ In "cold" AIHA, IgM molecules fix complement to the surface of red blood cells. Rarely, this can lead to activation of the full complement cascade, resulting in red cell lysis, but more often it is stopped at the C3 stage, leading to C3-coated red cells which are then taken up by hepatic macrophages.⁴

Suspecting the Diagnosis

In many patients, it is the symptoms and signs of anemia that lead to suspicion of hemolysis. Older patients often present earlier in the course of the disease due to lack of tolerance of anemia, especially if there is a sudden drop in the red blood cell count. Dark, cola-colored urine resulting from the presence of free hemoglobin may be noted by some patients. Patients with rapid-onset hemolysis may note lumbar back pain, and those with cold agglutinins often note symptoms related to agglutination of red cells in the peripheral circulation, such as the development of acrocyanosis in cold weather.⁵ In rare cases, patients will have abdominal pain when eating cold food due to ischemia related to agglutination of red cells in the viscera. Some patients with cold agglutinins can have an exacerbation of their hemolysis with cold exposure.

Unlike patients with immune thrombocytopenia, those with AIHA may have mild splenomegaly on exam. The presence of enlarged lymph nodes or massive splenomegaly should raise concern about concomitant lymphoma or chronic lymphocytic leukemia.

Making the Diagnosis

The 2 key steps in diagnosis are (1) demonstrating hemolysis and (2) demonstrating the autoimmune component.

Laboratory Evaluation for Hemolysis

Hemolysis is proven by finding evidence of both red cell breakdown and the compensatory increase in red cell production this stimulates (Table 2). The following sections discuss the laboratory tests that are performed to investigate hemolysis.

Lactate Dehydrogenase

When red cells undergo hemolysis, they release their contents, which are mostly comprised of hemoglobin but also include lactate dehydrogenase (LDH), an enzyme found in high concentration in red cells. Most patients with hemolysis will have an elevated LDH level, making this a sensitive test. However, because many other processes, including liver disease and pneumonia, also raise the serum LDH level, this finding is not specific for hemolysis.

Hemoglobin is salvaged by haptoglobin, and the heme moiety is broken down first to bilirubin and then to urobilinogen, which is excreted in the urine.² Bilirubin produced from the breakdown of heme is not conjugated, but rather is delivered to the liver, where it is conjugated and excreted into the bile. In hemolysis, the concentration of unconjugated bilirubin (indirect bilirubin) is increased, while in liver disease the level of conjugated bilirubin (direct bilirubin) is increased. However, if the patient has concomitant liver disease with an increased direct bilirubin level, the serum bilirubin test is not reliable.

Serum Haptoglobin

Haptoglobin binds free serum hemoglobin and is taken up by the liver. Haptoglobin usually falls to very low levels in hemolysis. A confounder is that haptoglobin is an acute phase reactant and can rise with systemic disease or inflammation. However, patients with advanced liver disease will have low haptoglobin levels due to lack of synthesis, and up to 2% of the population may congenitally lack haptoglobin.¹

Serum Hemoglobin

If the hemolysis is very rapid, the amount of free hemoglobin released will overwhelm the binding capacity of haptoglobin and lead to free hemoglobin in the plasma. This can be crudely quantified by examining the plasma color. Even minute amounts of free hemoglobin will turn the plasma pink. In fulminant hemolysis, the plasma will be cola-colored.

Reticulocyte Count

In most patients with hemolysis, the destruction of red cells is accompanied by an increase in the reticulocyte count. Reticulocytes are red cells that still contain RNA and are a marker of red cells that are approximately 24 hours old or less. Traditionally, reticulocytes were measured manually by staining the blood smear with vital blue and counting the percentage of cells that absorb the stain; this percentage needs to be adjusted for the hematocrit. Usually a percentage above 1.5% is considered indicative of an elevated reticulocyte count. Recently, automated complete blood count machines have taken advantage of the fact that reticulocytes will absorb certain stains; these machines can directly measure the reticulocyte count via flow cytometry, which results in an “absolute” reticulocyte count. The reticulocyte count obtained using this method does not have to be corrected for hematocrit, and levels of approximately 90,000/μL are considered raised. However, the reticulocyte count can also be raised in blood loss or in patients who have other causes of anemia (eg, iron deficiency) under treatment. In addition, as many as 25% of patients with AIHA will never have raised counts for various reasons, such as nutritional deficiency, autoimmune destruction of red cell precursors, or lack of erythropoietin.

Blood Smear

The blood smear provides vital information. The hallmark laboratory parameter of AIHA is spherocytes seen on the blood smear. In AIHA, antibodies and/or complement attach to the red cells, and when the antibodies or complement are taken up by macrophages in the spleen some of the red blood cell mem-brane is removed as well, decreasing the surface area of the cell. As the surface area of the red cell decreases with each pass through the spleen, the cell's shape changes from a biconcave disk to a sphere before the cell is destroyed, reflecting the fact that a sphere has the smallest surface area for a given volume. The vast majority of patients with AIHA will have spherocytes on the blood smear. However, spherocytes are not specific to AIHA, as they can be seen in hereditary spherocytosis, Wilson’s disease, clostridial sepsis, and severe burns.

Patients with cold agglutinins will often have red cell agglutination on the blood smear. In addition, patients with AIHA will often have a raised mean corpuscular volume (MCV) for 2 reasons. In patients with brisk reticulocytosis, the MCV will be raised due to the large size of the reticulocyte. In patients with cold agglutinin disease, the MCV may be falsely raised due to clumping of the red blood cells.

Urinary Hemosiderin

When hemoglobin is excreted by the kidney, the iron is deposited in the tubules. When the tubule cells are sloughed off, they appear in the urine. The urine can be stained for iron, and a positive result is another sign of hemolysis. Hemosiderinuria is a later sign of hemolysis, as it takes 1 week for iron-laden tubule cells to be excreted in sufficient quantities to be detected in the urine.

Urinary Hemoglobin

One other sign of hemolysis is the presence of hemoglobin in the urine. A quick way to demonstrate hemoglobinuria is to check the urine with a dipstick followed by a microscopic exam. In hemolysis, the dipstick will detect “blood,” while the microscopic exam will be negative for red cells.

Laboratory Evaluation for Autoimmune Component

The autoimmune component is shown by demonstrating the presence of either IgG molecules or complement on the surface of red blood cells.^4,6 This can be done by performing the direct antiglobulin test (DAT) or Coombs test. IgG bound to red cells will not agglutinate them, but if IgM that is directed against IgG or C3 is added, the red cells will agglutinate, proving that there is IgG and/or C3 on the red cell membrane. The finding of a positive DAT in the setting of a hemolytic anemia is diagnostic of AIHA. Beware of individuals with concomitant weak positive DAT and other causes of hemolysis. The strength of the DAT result and the degree of hemolysis must match in order to conclude that the hemolysis is immune-mediated.

There are several pitfalls to the DAT. One is that a positive DAT is found in 1:1000 patients in the normal population and in up to several percent of ill patients, especially those with elevated gamma globulin, such as patients with liver disease or HIV infection.⁶ Administration of intravenous immunoglobulin (IVIG) can also create a positive DAT. Conversely, patients can have AIHA with a negative DAT.^7-9 For some patients, the number of IgG molecules bound to the red cell is below the detection limit of the DAT reagents. Other patients can have IgA or “warm” IgM as the cause of the AIHA.¹⁰ Specialty laboratories can test for these possibilities. The diagnosis of DAT-negative AIHA should be made with caution, and other causes of hemolysis, such as hereditary spherocytosis or paroxysmal hematuria, should be excluded.

Performing transfusions can be very difficult in patients with AIHA.² The presence of the autoantibody can interfere with typing of the blood and almost always interferes with the crossmatch, since this final step consists of mixing the patient’s serum or plasma with donor red cells. In most patients with AIHA, the autoantibodies will react with any donor cells, rendering a negative crossmatch impossible. Without the crossmatch, the concern is that underlying alloantibodies can be missed. Studies indicate that 15% to 32% of patients will have underlying alloantibodies, which can lead to transfusion reactions.² However, there are 2 considerations that may mitigate these concerns.^11,12 First, patients who have never been transfused or pregnant will rarely have alloantibodies. Second, a patient who has been transfused in the remote past may have an anamnestic antibody response but not an immediate hemolytic reaction.

The transfusion service can take several steps to identify alloantibodies. Occasionally, if the autoantibody is weakly reacting when the patient’s serum is tested against a panel of reagent red cells, the alloantibodies can be identified by their stronger reactions as compared with the weakly reactive autoantibody. The most common technique for identifying alloantibodies is the autoadsorption technique.^4,13 This involves incu-bating the patient’s red cells with the patient’s serum to adsorb the autoantibody. After a period of incubation, the cells are pelleted and the serum is collected as the supernatant. The adsorbed serum may be incubated with another sample of the patient’s cells for a second adsorption if the initial agglutination reactions of the patient’s serum with the reagent cells were strong. After 1 to 3 adsorptions, the adsorbed serum is tested with a red cell panel in order to check for “leftover” alloantibodies.

When a patient is first suspected of having AIHA, a generous sample of blood should be given to the transfusion service to allow for adequate testing. Many centers will test the blood not only for blood groups ABO and D but also perform full Rh typing plus check for Kidd, Duffy and Kell status.¹⁴ Increasingly, this is performed by direct genetic sequencing for the appropriate genotypes. This can allow transfusion of phenotypically matched red blood cells to lessen the risk of alloantibody formation.

One difficult issue is timing of transfusion. Clinicians are often hesitant to transfuse patients with AIHA due to fear of reactions, but in patients with severe anemia, especially elderly patients or those with heart disease, transfusion can be lifesaving. Since in some cases it may take hours to screen for alloantibodies, it is often preferable to transfuse patients with severe anemia and observe carefully for reaction.

The autoimmune hemolytic anemias (AIHA) are rare but important hematologic diseases. They can range in severity from mildly symptomatic illness to a rapidly fatal syndrome. The incidence of AIHA is estimated to be between 0.6 and 3 cases per 100,000 persons.^1,2 AIHA is mediated by antibodies, and in the majority of cases immunoglobulin (Ig) G is the mediating antibody. This type of AIHA is referred to as "warm" AIHA because IgG antibodies bind best at body temperature. "Cold" AIHA is mediated by IgM antibodies, which bind maximally at temperatures below 37°C (Table 1). This article series reviews the most common types of AIHA, with an overview of evaluation and diagnosis presented in this article and management of warm, cold, and drug-induced AIHA reviewed in a separate article.

Pathogenesis

In most cases, the ultimate etiology of AIHA is unknown. In warm AIHA, the target epitopes in most cases are Rh proteins.² What leads the immune system to target these proteins is unidentified, but one theory is that an initial immune response to a foreign antigen starts to cross-react with the Rh proteins and the immune system fails to suppress this autoreactive response, leading to hemolysis. In IgG-mediated (warm) hemolysis, the red cells become coated with IgG molecules, which mark the cells for uptake and destruction by splenic macrophages.³ In "cold" AIHA, IgM molecules fix complement to the surface of red blood cells. Rarely, this can lead to activation of the full complement cascade, resulting in red cell lysis, but more often it is stopped at the C3 stage, leading to C3-coated red cells which are then taken up by hepatic macrophages.⁴

Suspecting the Diagnosis

In many patients, it is the symptoms and signs of anemia that lead to suspicion of hemolysis. Older patients often present earlier in the course of the disease due to lack of tolerance of anemia, especially if there is a sudden drop in the red blood cell count. Dark, cola-colored urine resulting from the presence of free hemoglobin may be noted by some patients. Patients with rapid-onset hemolysis may note lumbar back pain, and those with cold agglutinins often note symptoms related to agglutination of red cells in the peripheral circulation, such as the development of acrocyanosis in cold weather.⁵ In rare cases, patients will have abdominal pain when eating cold food due to ischemia related to agglutination of red cells in the viscera. Some patients with cold agglutinins can have an exacerbation of their hemolysis with cold exposure.

Unlike patients with immune thrombocytopenia, those with AIHA may have mild splenomegaly on exam. The presence of enlarged lymph nodes or massive splenomegaly should raise concern about concomitant lymphoma or chronic lymphocytic leukemia.

Making the Diagnosis

The 2 key steps in diagnosis are (1) demonstrating hemolysis and (2) demonstrating the autoimmune component.

Laboratory Evaluation for Hemolysis

Hemolysis is proven by finding evidence of both red cell breakdown and the compensatory increase in red cell production this stimulates (Table 2). The following sections discuss the laboratory tests that are performed to investigate hemolysis.

Lactate Dehydrogenase

When red cells undergo hemolysis, they release their contents, which are mostly comprised of hemoglobin but also include lactate dehydrogenase (LDH), an enzyme found in high concentration in red cells. Most patients with hemolysis will have an elevated LDH level, making this a sensitive test. However, because many other processes, including liver disease and pneumonia, also raise the serum LDH level, this finding is not specific for hemolysis.

Hemoglobin is salvaged by haptoglobin, and the heme moiety is broken down first to bilirubin and then to urobilinogen, which is excreted in the urine.² Bilirubin produced from the breakdown of heme is not conjugated, but rather is delivered to the liver, where it is conjugated and excreted into the bile. In hemolysis, the concentration of unconjugated bilirubin (indirect bilirubin) is increased, while in liver disease the level of conjugated bilirubin (direct bilirubin) is increased. However, if the patient has concomitant liver disease with an increased direct bilirubin level, the serum bilirubin test is not reliable.

Serum Haptoglobin

Haptoglobin binds free serum hemoglobin and is taken up by the liver. Haptoglobin usually falls to very low levels in hemolysis. A confounder is that haptoglobin is an acute phase reactant and can rise with systemic disease or inflammation. However, patients with advanced liver disease will have low haptoglobin levels due to lack of synthesis, and up to 2% of the population may congenitally lack haptoglobin.¹

Serum Hemoglobin

If the hemolysis is very rapid, the amount of free hemoglobin released will overwhelm the binding capacity of haptoglobin and lead to free hemoglobin in the plasma. This can be crudely quantified by examining the plasma color. Even minute amounts of free hemoglobin will turn the plasma pink. In fulminant hemolysis, the plasma will be cola-colored.

Reticulocyte Count

In most patients with hemolysis, the destruction of red cells is accompanied by an increase in the reticulocyte count. Reticulocytes are red cells that still contain RNA and are a marker of red cells that are approximately 24 hours old or less. Traditionally, reticulocytes were measured manually by staining the blood smear with vital blue and counting the percentage of cells that absorb the stain; this percentage needs to be adjusted for the hematocrit. Usually a percentage above 1.5% is considered indicative of an elevated reticulocyte count. Recently, automated complete blood count machines have taken advantage of the fact that reticulocytes will absorb certain stains; these machines can directly measure the reticulocyte count via flow cytometry, which results in an “absolute” reticulocyte count. The reticulocyte count obtained using this method does not have to be corrected for hematocrit, and levels of approximately 90,000/μL are considered raised. However, the reticulocyte count can also be raised in blood loss or in patients who have other causes of anemia (eg, iron deficiency) under treatment. In addition, as many as 25% of patients with AIHA will never have raised counts for various reasons, such as nutritional deficiency, autoimmune destruction of red cell precursors, or lack of erythropoietin.

Blood Smear

The blood smear provides vital information. The hallmark laboratory parameter of AIHA is spherocytes seen on the blood smear. In AIHA, antibodies and/or complement attach to the red cells, and when the antibodies or complement are taken up by macrophages in the spleen some of the red blood cell mem-brane is removed as well, decreasing the surface area of the cell. As the surface area of the red cell decreases with each pass through the spleen, the cell's shape changes from a biconcave disk to a sphere before the cell is destroyed, reflecting the fact that a sphere has the smallest surface area for a given volume. The vast majority of patients with AIHA will have spherocytes on the blood smear. However, spherocytes are not specific to AIHA, as they can be seen in hereditary spherocytosis, Wilson’s disease, clostridial sepsis, and severe burns.

Patients with cold agglutinins will often have red cell agglutination on the blood smear. In addition, patients with AIHA will often have a raised mean corpuscular volume (MCV) for 2 reasons. In patients with brisk reticulocytosis, the MCV will be raised due to the large size of the reticulocyte. In patients with cold agglutinin disease, the MCV may be falsely raised due to clumping of the red blood cells.

Urinary Hemosiderin

When hemoglobin is excreted by the kidney, the iron is deposited in the tubules. When the tubule cells are sloughed off, they appear in the urine. The urine can be stained for iron, and a positive result is another sign of hemolysis. Hemosiderinuria is a later sign of hemolysis, as it takes 1 week for iron-laden tubule cells to be excreted in sufficient quantities to be detected in the urine.

Urinary Hemoglobin

One other sign of hemolysis is the presence of hemoglobin in the urine. A quick way to demonstrate hemoglobinuria is to check the urine with a dipstick followed by a microscopic exam. In hemolysis, the dipstick will detect “blood,” while the microscopic exam will be negative for red cells.

Laboratory Evaluation for Autoimmune Component

The autoimmune component is shown by demonstrating the presence of either IgG molecules or complement on the surface of red blood cells.^4,6 This can be done by performing the direct antiglobulin test (DAT) or Coombs test. IgG bound to red cells will not agglutinate them, but if IgM that is directed against IgG or C3 is added, the red cells will agglutinate, proving that there is IgG and/or C3 on the red cell membrane. The finding of a positive DAT in the setting of a hemolytic anemia is diagnostic of AIHA. Beware of individuals with concomitant weak positive DAT and other causes of hemolysis. The strength of the DAT result and the degree of hemolysis must match in order to conclude that the hemolysis is immune-mediated.

There are several pitfalls to the DAT. One is that a positive DAT is found in 1:1000 patients in the normal population and in up to several percent of ill patients, especially those with elevated gamma globulin, such as patients with liver disease or HIV infection.⁶ Administration of intravenous immunoglobulin (IVIG) can also create a positive DAT. Conversely, patients can have AIHA with a negative DAT.^7-9 For some patients, the number of IgG molecules bound to the red cell is below the detection limit of the DAT reagents. Other patients can have IgA or “warm” IgM as the cause of the AIHA.¹⁰ Specialty laboratories can test for these possibilities. The diagnosis of DAT-negative AIHA should be made with caution, and other causes of hemolysis, such as hereditary spherocytosis or paroxysmal hematuria, should be excluded.

Performing transfusions can be very difficult in patients with AIHA.² The presence of the autoantibody can interfere with typing of the blood and almost always interferes with the crossmatch, since this final step consists of mixing the patient’s serum or plasma with donor red cells. In most patients with AIHA, the autoantibodies will react with any donor cells, rendering a negative crossmatch impossible. Without the crossmatch, the concern is that underlying alloantibodies can be missed. Studies indicate that 15% to 32% of patients will have underlying alloantibodies, which can lead to transfusion reactions.² However, there are 2 considerations that may mitigate these concerns.^11,12 First, patients who have never been transfused or pregnant will rarely have alloantibodies. Second, a patient who has been transfused in the remote past may have an anamnestic antibody response but not an immediate hemolytic reaction.

The transfusion service can take several steps to identify alloantibodies. Occasionally, if the autoantibody is weakly reacting when the patient’s serum is tested against a panel of reagent red cells, the alloantibodies can be identified by their stronger reactions as compared with the weakly reactive autoantibody. The most common technique for identifying alloantibodies is the autoadsorption technique.^4,13 This involves incu-bating the patient’s red cells with the patient’s serum to adsorb the autoantibody. After a period of incubation, the cells are pelleted and the serum is collected as the supernatant. The adsorbed serum may be incubated with another sample of the patient’s cells for a second adsorption if the initial agglutination reactions of the patient’s serum with the reagent cells were strong. After 1 to 3 adsorptions, the adsorbed serum is tested with a red cell panel in order to check for “leftover” alloantibodies.

When a patient is first suspected of having AIHA, a generous sample of blood should be given to the transfusion service to allow for adequate testing. Many centers will test the blood not only for blood groups ABO and D but also perform full Rh typing plus check for Kidd, Duffy and Kell status.¹⁴ Increasingly, this is performed by direct genetic sequencing for the appropriate genotypes. This can allow transfusion of phenotypically matched red blood cells to lessen the risk of alloantibody formation.

One difficult issue is timing of transfusion. Clinicians are often hesitant to transfuse patients with AIHA due to fear of reactions, but in patients with severe anemia, especially elderly patients or those with heart disease, transfusion can be lifesaving. Since in some cases it may take hours to screen for alloantibodies, it is often preferable to transfuse patients with severe anemia and observe carefully for reaction.

Patients with sickle cell disease are 2.5 times more likely to be readmitted within 30 days of a hospital stay than those without SCD, according to the Agency for Healthcare Research and Quality.

The 30-day all-cause readmission rate for index stays with a principal diagnosis of SCD was 33.5% in 2016, compared with 12.5% for non-SCD hospital stays. Patients with a secondary diagnosis of SCD had readmission rates of 32.9% with a pain crisis and 21.0% without one, and the overall readmission rate for an index stay with any SCD diagnosis was 31.1%, Kathryn R. Fingar, PhD, MPH, of IBM Watson Health, Sacramento, Calif., and associates wrote in an AHRQ statistical brief.

When age is factored in, the readmission gap between a principal SCD diagnosis and non-SCD becomes even greater – and smaller. The difference was greatest for patients aged 18-34 years – 39.4% with a principal diagnosis of SCD versus 7.8% without any SCD – and then narrowed as patients got older. For those aged 65 years and older, the rates were 22.6% with a principal diagnosis of SCD and 15.9% without, the investigators reported.

The approximately 100,000 Americans with SCD accounted for 134,000 admissions in 2016, and more than three-quarters of those stays involved a pain crisis. A principal diagnosis of SCD was recorded for almost 96,000 of those visits, and nearly all (96%) of those stays involved a pain crisis. For those with a secondary diagnosis of SCD, the most common reasons for hospitalization were diseases of the respiratory system (14.3% of those stays) and infectious and parasitic diseases (13.2%).

Patients with SCD were more likely than non-SCD patients to be admitted from the ED (79.6% vs. 51.3%), and they were more likely to discharged against medical advice (4.1% vs. 1.2%). Among those who left the hospital against medical advice, patients with SCD were much more likely to be readmitted than those without SCD (46.6% vs. 26.5%), based on data from the AHRQ’s Nationwide Readmissions Database.

Improved treatment of complications has “reduced mortality rates so that nearly 95% of individuals born with SCD in the United States reach 18 years of age [but] limited knowledge of SCD treatment guidelines among healthcare professionals continues to pose a barrier to effective patient-provider relationships, and this barrier contributes to lower quality of life,” Dr. Fingar and associates wrote.

[email protected]

Patients with sickle cell disease are 2.5 times more likely to be readmitted within 30 days of a hospital stay than those without SCD, according to the Agency for Healthcare Research and Quality.

The 30-day all-cause readmission rate for index stays with a principal diagnosis of SCD was 33.5% in 2016, compared with 12.5% for non-SCD hospital stays. Patients with a secondary diagnosis of SCD had readmission rates of 32.9% with a pain crisis and 21.0% without one, and the overall readmission rate for an index stay with any SCD diagnosis was 31.1%, Kathryn R. Fingar, PhD, MPH, of IBM Watson Health, Sacramento, Calif., and associates wrote in an AHRQ statistical brief.

When age is factored in, the readmission gap between a principal SCD diagnosis and non-SCD becomes even greater – and smaller. The difference was greatest for patients aged 18-34 years – 39.4% with a principal diagnosis of SCD versus 7.8% without any SCD – and then narrowed as patients got older. For those aged 65 years and older, the rates were 22.6% with a principal diagnosis of SCD and 15.9% without, the investigators reported.

The approximately 100,000 Americans with SCD accounted for 134,000 admissions in 2016, and more than three-quarters of those stays involved a pain crisis. A principal diagnosis of SCD was recorded for almost 96,000 of those visits, and nearly all (96%) of those stays involved a pain crisis. For those with a secondary diagnosis of SCD, the most common reasons for hospitalization were diseases of the respiratory system (14.3% of those stays) and infectious and parasitic diseases (13.2%).

Patients with SCD were more likely than non-SCD patients to be admitted from the ED (79.6% vs. 51.3%), and they were more likely to discharged against medical advice (4.1% vs. 1.2%). Among those who left the hospital against medical advice, patients with SCD were much more likely to be readmitted than those without SCD (46.6% vs. 26.5%), based on data from the AHRQ’s Nationwide Readmissions Database.

Improved treatment of complications has “reduced mortality rates so that nearly 95% of individuals born with SCD in the United States reach 18 years of age [but] limited knowledge of SCD treatment guidelines among healthcare professionals continues to pose a barrier to effective patient-provider relationships, and this barrier contributes to lower quality of life,” Dr. Fingar and associates wrote.

[email protected]

Patients with sickle cell disease are 2.5 times more likely to be readmitted within 30 days of a hospital stay than those without SCD, according to the Agency for Healthcare Research and Quality.

The 30-day all-cause readmission rate for index stays with a principal diagnosis of SCD was 33.5% in 2016, compared with 12.5% for non-SCD hospital stays. Patients with a secondary diagnosis of SCD had readmission rates of 32.9% with a pain crisis and 21.0% without one, and the overall readmission rate for an index stay with any SCD diagnosis was 31.1%, Kathryn R. Fingar, PhD, MPH, of IBM Watson Health, Sacramento, Calif., and associates wrote in an AHRQ statistical brief.

When age is factored in, the readmission gap between a principal SCD diagnosis and non-SCD becomes even greater – and smaller. The difference was greatest for patients aged 18-34 years – 39.4% with a principal diagnosis of SCD versus 7.8% without any SCD – and then narrowed as patients got older. For those aged 65 years and older, the rates were 22.6% with a principal diagnosis of SCD and 15.9% without, the investigators reported.

The approximately 100,000 Americans with SCD accounted for 134,000 admissions in 2016, and more than three-quarters of those stays involved a pain crisis. A principal diagnosis of SCD was recorded for almost 96,000 of those visits, and nearly all (96%) of those stays involved a pain crisis. For those with a secondary diagnosis of SCD, the most common reasons for hospitalization were diseases of the respiratory system (14.3% of those stays) and infectious and parasitic diseases (13.2%).

Patients with SCD were more likely than non-SCD patients to be admitted from the ED (79.6% vs. 51.3%), and they were more likely to discharged against medical advice (4.1% vs. 1.2%). Among those who left the hospital against medical advice, patients with SCD were much more likely to be readmitted than those without SCD (46.6% vs. 26.5%), based on data from the AHRQ’s Nationwide Readmissions Database.

Improved treatment of complications has “reduced mortality rates so that nearly 95% of individuals born with SCD in the United States reach 18 years of age [but] limited knowledge of SCD treatment guidelines among healthcare professionals continues to pose a barrier to effective patient-provider relationships, and this barrier contributes to lower quality of life,” Dr. Fingar and associates wrote.

[email protected]

Older patients with immune thrombotic thrombocytopenic purpura (iTTP) more often have an atypical neurological presentation, which could result in a delayed diagnosis, according to authors of a recent retrospective analysis.

“Practitioners should be aware of this in order to shorten the time to treatment, which could improve the prognosis in older iTTP patients,” Paul Coppo, MD, PhD, of Hôpital Saint-Antoine, Paris, and coauthors wrote in Blood.

The older patients also had increased 1-month and 1-year mortality compared with younger patients, and had more than a threefold risk of long-term mortality compared with elderly patients without iTTP, according to the study report.

The analysis included 411 patients with iTTP entered into a national registry in France between 2000 and 2016. Seventy-one patients were 60 years of age or older.

Time from hospital admission to diagnosis was 3 days for those older patients, versus just 1 day for patients under 60 years of age (P = .0001), Dr. Coppo and colleagues reported.

Clinical records were available for 67 of the older iTTP patients, of whom 17 had no evidence of delayed diagnosis. The remainder had a “possible diagnostic delay,” according to the report; among those, the iTTP diagnosis was preceded by neurological manifestations in 26 cases, and transient ischemic stroke that usually led to focal deficiency or aphasia in 14 cases. Other features preceding the diagnosis included malaise, behavioral abnormalities, seizure, and dizziness.

Many of these findings are “not specific to a disease, and they are less alarming than in young patients,” the researchers wrote. “In this context, the presence of a thrombocytopenia with anemia should alert physicians to this possible rare diagnosis.”

Older patients also presented with less pronounced cytopenias compared with younger patients, which could have contributed to a late diagnosis, they added.

Older age is a known risk factor for mortality related to iTTP. In the present study, rates of 1-month mortality were 37% for patients aged 60 years and older, and 9% for those younger than age 60 (P less than .0001). The 1-year mortality rates were 49% and 11% for older and younger patients, respectively (P less than .0001).

Compared with older individuals without iTTP from a different study, older iTTP patients had a lower long-term survival rate. iTTP remained an independent risk factor for death even after adjustment for age, sex, and some comorbidities (hazard ratio, 3.44; 95% confidence interval, 2.02-5.87).

The study was partly funded by a grant from the French Ministry of Health. Dr. Coppo reported that he is a clinical advisory board member for Alexion, Ablynx (now part of Sanofi), Shire, and Octapharma. Two other co-authors reported participating in advisory boards for Ablynx.

SOURCE: Prevel R et al. Blood. 2019 Sep 17. doi: 10.1182/blood.2019000748.

Older patients with immune thrombotic thrombocytopenic purpura (iTTP) more often have an atypical neurological presentation, which could result in a delayed diagnosis, according to authors of a recent retrospective analysis.

“Practitioners should be aware of this in order to shorten the time to treatment, which could improve the prognosis in older iTTP patients,” Paul Coppo, MD, PhD, of Hôpital Saint-Antoine, Paris, and coauthors wrote in Blood.

The older patients also had increased 1-month and 1-year mortality compared with younger patients, and had more than a threefold risk of long-term mortality compared with elderly patients without iTTP, according to the study report.

The analysis included 411 patients with iTTP entered into a national registry in France between 2000 and 2016. Seventy-one patients were 60 years of age or older.

Time from hospital admission to diagnosis was 3 days for those older patients, versus just 1 day for patients under 60 years of age (P = .0001), Dr. Coppo and colleagues reported.

Clinical records were available for 67 of the older iTTP patients, of whom 17 had no evidence of delayed diagnosis. The remainder had a “possible diagnostic delay,” according to the report; among those, the iTTP diagnosis was preceded by neurological manifestations in 26 cases, and transient ischemic stroke that usually led to focal deficiency or aphasia in 14 cases. Other features preceding the diagnosis included malaise, behavioral abnormalities, seizure, and dizziness.

Many of these findings are “not specific to a disease, and they are less alarming than in young patients,” the researchers wrote. “In this context, the presence of a thrombocytopenia with anemia should alert physicians to this possible rare diagnosis.”

Older patients also presented with less pronounced cytopenias compared with younger patients, which could have contributed to a late diagnosis, they added.

Older age is a known risk factor for mortality related to iTTP. In the present study, rates of 1-month mortality were 37% for patients aged 60 years and older, and 9% for those younger than age 60 (P less than .0001). The 1-year mortality rates were 49% and 11% for older and younger patients, respectively (P less than .0001).

Compared with older individuals without iTTP from a different study, older iTTP patients had a lower long-term survival rate. iTTP remained an independent risk factor for death even after adjustment for age, sex, and some comorbidities (hazard ratio, 3.44; 95% confidence interval, 2.02-5.87).

The study was partly funded by a grant from the French Ministry of Health. Dr. Coppo reported that he is a clinical advisory board member for Alexion, Ablynx (now part of Sanofi), Shire, and Octapharma. Two other co-authors reported participating in advisory boards for Ablynx.

SOURCE: Prevel R et al. Blood. 2019 Sep 17. doi: 10.1182/blood.2019000748.

Older patients with immune thrombotic thrombocytopenic purpura (iTTP) more often have an atypical neurological presentation, which could result in a delayed diagnosis, according to authors of a recent retrospective analysis.

“Practitioners should be aware of this in order to shorten the time to treatment, which could improve the prognosis in older iTTP patients,” Paul Coppo, MD, PhD, of Hôpital Saint-Antoine, Paris, and coauthors wrote in Blood.

The older patients also had increased 1-month and 1-year mortality compared with younger patients, and had more than a threefold risk of long-term mortality compared with elderly patients without iTTP, according to the study report.

The analysis included 411 patients with iTTP entered into a national registry in France between 2000 and 2016. Seventy-one patients were 60 years of age or older.

Time from hospital admission to diagnosis was 3 days for those older patients, versus just 1 day for patients under 60 years of age (P = .0001), Dr. Coppo and colleagues reported.

Clinical records were available for 67 of the older iTTP patients, of whom 17 had no evidence of delayed diagnosis. The remainder had a “possible diagnostic delay,” according to the report; among those, the iTTP diagnosis was preceded by neurological manifestations in 26 cases, and transient ischemic stroke that usually led to focal deficiency or aphasia in 14 cases. Other features preceding the diagnosis included malaise, behavioral abnormalities, seizure, and dizziness.

Many of these findings are “not specific to a disease, and they are less alarming than in young patients,” the researchers wrote. “In this context, the presence of a thrombocytopenia with anemia should alert physicians to this possible rare diagnosis.”

Older patients also presented with less pronounced cytopenias compared with younger patients, which could have contributed to a late diagnosis, they added.

Older age is a known risk factor for mortality related to iTTP. In the present study, rates of 1-month mortality were 37% for patients aged 60 years and older, and 9% for those younger than age 60 (P less than .0001). The 1-year mortality rates were 49% and 11% for older and younger patients, respectively (P less than .0001).

Compared with older individuals without iTTP from a different study, older iTTP patients had a lower long-term survival rate. iTTP remained an independent risk factor for death even after adjustment for age, sex, and some comorbidities (hazard ratio, 3.44; 95% confidence interval, 2.02-5.87).

The study was partly funded by a grant from the French Ministry of Health. Dr. Coppo reported that he is a clinical advisory board member for Alexion, Ablynx (now part of Sanofi), Shire, and Octapharma. Two other co-authors reported participating in advisory boards for Ablynx.

SOURCE: Prevel R et al. Blood. 2019 Sep 17. doi: 10.1182/blood.2019000748.

The Food and Drug Administration has approved afamelanotide (Scenesse) to “increase pain-free light exposure” in adults with a history of phototoxic reactions from erythropoietic protoporphyria, a rare condition that causes extremely painful reactions when skin is exposed to light, according to an FDA announcement.

Olivier Le Moal/Getty Images

This is the first treatment approved to help patients with this condition increase their exposure to light, according to the release.

Afamelanotide, administered in a subcutaneous implant, is a melanocortin-1 receptor (MC1-R) agonist, which “increases the production of eumelanin in the skin independent of exposure to sunlight or artificial light sources,” the release says.

Approval is based on a pair of parallel-group clinical trials that compared the number of hours spent in sunlight in the treatment and placebo groups. The first trial enrolled 93 patients; 48 received afamelanotide. The treated patients spent a median of 61 hours in total over 180 days in direct sunlight between 10 a.m. and 6 p.m. on days with no pain, compared with 41 hours for patients taking placebo.

The second trial assessed the total number of hours over 270 days spent outdoors between 10 a.m. and 3 p.m. on days with no pain for which “most of the day” was spent in direct sunlight. In this study, 38 patients treated with afamelanotide spent a median total of 6 hours, compared with 0.75 hours among the remaining 36 who were taking a placebo.

The most common side effects include implant site reaction, nausea, and oropharyngeal pain. The implant should be administered only by trained professionals. Because afamelanotide may cause skin darkening, it’s recommended that patients should undergo twice-yearly skin examinations. Patients are also encouraged to maintain sun protection measures to help prevent phototoxic reactions.

“Today’s approval is one example of the FDA’s ongoing commitment to encourage industry innovation of therapies to treat rare diseases, and work with drug developers to make promising new therapies available to patients as safely and efficiently as possible,” said Julie Beitz, MD, director of FDA’s Center for Drug Evaluation and Research Office of Drug Evaluation III in the FDA release.

[email protected]

The Food and Drug Administration has approved afamelanotide (Scenesse) to “increase pain-free light exposure” in adults with a history of phototoxic reactions from erythropoietic protoporphyria, a rare condition that causes extremely painful reactions when skin is exposed to light, according to an FDA announcement.

Olivier Le Moal/Getty Images

This is the first treatment approved to help patients with this condition increase their exposure to light, according to the release.

Afamelanotide, administered in a subcutaneous implant, is a melanocortin-1 receptor (MC1-R) agonist, which “increases the production of eumelanin in the skin independent of exposure to sunlight or artificial light sources,” the release says.

Approval is based on a pair of parallel-group clinical trials that compared the number of hours spent in sunlight in the treatment and placebo groups. The first trial enrolled 93 patients; 48 received afamelanotide. The treated patients spent a median of 61 hours in total over 180 days in direct sunlight between 10 a.m. and 6 p.m. on days with no pain, compared with 41 hours for patients taking placebo.

The second trial assessed the total number of hours over 270 days spent outdoors between 10 a.m. and 3 p.m. on days with no pain for which “most of the day” was spent in direct sunlight. In this study, 38 patients treated with afamelanotide spent a median total of 6 hours, compared with 0.75 hours among the remaining 36 who were taking a placebo.

The most common side effects include implant site reaction, nausea, and oropharyngeal pain. The implant should be administered only by trained professionals. Because afamelanotide may cause skin darkening, it’s recommended that patients should undergo twice-yearly skin examinations. Patients are also encouraged to maintain sun protection measures to help prevent phototoxic reactions.

“Today’s approval is one example of the FDA’s ongoing commitment to encourage industry innovation of therapies to treat rare diseases, and work with drug developers to make promising new therapies available to patients as safely and efficiently as possible,” said Julie Beitz, MD, director of FDA’s Center for Drug Evaluation and Research Office of Drug Evaluation III in the FDA release.

[email protected]

The Food and Drug Administration has approved afamelanotide (Scenesse) to “increase pain-free light exposure” in adults with a history of phototoxic reactions from erythropoietic protoporphyria, a rare condition that causes extremely painful reactions when skin is exposed to light, according to an FDA announcement.

Olivier Le Moal/Getty Images

This is the first treatment approved to help patients with this condition increase their exposure to light, according to the release.

Afamelanotide, administered in a subcutaneous implant, is a melanocortin-1 receptor (MC1-R) agonist, which “increases the production of eumelanin in the skin independent of exposure to sunlight or artificial light sources,” the release says.

Approval is based on a pair of parallel-group clinical trials that compared the number of hours spent in sunlight in the treatment and placebo groups. The first trial enrolled 93 patients; 48 received afamelanotide. The treated patients spent a median of 61 hours in total over 180 days in direct sunlight between 10 a.m. and 6 p.m. on days with no pain, compared with 41 hours for patients taking placebo.

The second trial assessed the total number of hours over 270 days spent outdoors between 10 a.m. and 3 p.m. on days with no pain for which “most of the day” was spent in direct sunlight. In this study, 38 patients treated with afamelanotide spent a median total of 6 hours, compared with 0.75 hours among the remaining 36 who were taking a placebo.

The most common side effects include implant site reaction, nausea, and oropharyngeal pain. The implant should be administered only by trained professionals. Because afamelanotide may cause skin darkening, it’s recommended that patients should undergo twice-yearly skin examinations. Patients are also encouraged to maintain sun protection measures to help prevent phototoxic reactions.

“Today’s approval is one example of the FDA’s ongoing commitment to encourage industry innovation of therapies to treat rare diseases, and work with drug developers to make promising new therapies available to patients as safely and efficiently as possible,” said Julie Beitz, MD, director of FDA’s Center for Drug Evaluation and Research Office of Drug Evaluation III in the FDA release.

[email protected]

Three researchers have won the 2019 Nobel Prize in Physiology or Medicine “for their discoveries of how cells sense and adapt to oxygen availability.”

William G. Kaelin Jr., MD; Sir Peter J. Ratcliffe, MB ChB, MD; and Gregg L. Semenza, MD, PhD, described the molecular machinery that regulates gene activity in response to oxygen levels.


Their work “established the basis for our understanding of how oxygen levels affect cellular metabolism and physiological function” and “paved the way for promising new strategies to fight anemia, cancer, and many other diseases,” according to a statement by The Nobel Assembly at Karolinska Institutet.

Dr. Semenza, of Johns Hopkins Medicine in Baltimore, studied how the erythropoietin (EPO) gene is regulated by oxygen levels. Via experiments in mice, he identified DNA segments next to the EPO gene that mediate the response to hypoxia.

Dr. Ratcliffe, of the University of Oxford (England) and the Francis Crick Institute in London, also studied oxygen-dependent regulation of the EPO gene. Both his and Dr. Semenza’s groups found the oxygen-sensing mechanism was present in nearly all tissues.

Dr. Kaelin, of the Dana-Farber Cancer Institute and Harvard Medical School, both in Boston, was researching von Hippel-Lindau’s (VHL) syndrome, an inherited disorder in which mutations can lead to tumors in multiple organs. He found the VHL gene encodes a protein that prevents cancer onset, and cancer cells without a functional VHL gene express high levels of hypoxia-regulated genes.

Research by other groups showed that VHL is part of a complex that labels proteins with ubiquitin, tagging them for degradation. Dr. Ratcliffe and his group found that VHL is required for the degradation of HIF-1a at normal oxygen levels.

Dr. Kaelin’s and Dr. Ratcliffe’s groups also showed that, under normal oxygen conditions, hydroxyl groups are added at two locations in HIF-1a. This modification – prolyl hydroxylation – allows VHL to bind to HIF-1a. So the researchers found that normal oxygen levels control HIF-1a degradation with the help of prolyl hydroxylases.

Additional research by Dr. Ratcliffe’s group and others revealed the specific prolyl hydroxylases involved in HIF-1a degradation. The researchers also found that HIF-1a’s gene-activating function was regulated by oxygen-dependent hydroxylation.

This work has improved the understanding of how different oxygen levels regulate physiological processes. In particular, oxygen sensing is essential for erythropoiesis, so these findings have implications for the treatment of anemia.

“There are several drugs that are now in clinical trials that serve to increase HIF activity and, as a result, will increase the production of erythropoietin and stimulate red blood cell production,” Dr. Semenza said in an interview after the announcement of his Nobel win. “These are all small molecules that can be given by mouth, and that may be a great convenience for patients who, at the present time, may require injections of recombinant human erythropoietin.”

[email protected]

Three researchers have won the 2019 Nobel Prize in Physiology or Medicine “for their discoveries of how cells sense and adapt to oxygen availability.”

William G. Kaelin Jr., MD; Sir Peter J. Ratcliffe, MB ChB, MD; and Gregg L. Semenza, MD, PhD, described the molecular machinery that regulates gene activity in response to oxygen levels.


Their work “established the basis for our understanding of how oxygen levels affect cellular metabolism and physiological function” and “paved the way for promising new strategies to fight anemia, cancer, and many other diseases,” according to a statement by The Nobel Assembly at Karolinska Institutet.

Dr. Semenza, of Johns Hopkins Medicine in Baltimore, studied how the erythropoietin (EPO) gene is regulated by oxygen levels. Via experiments in mice, he identified DNA segments next to the EPO gene that mediate the response to hypoxia.

Dr. Ratcliffe, of the University of Oxford (England) and the Francis Crick Institute in London, also studied oxygen-dependent regulation of the EPO gene. Both his and Dr. Semenza’s groups found the oxygen-sensing mechanism was present in nearly all tissues.

Dr. Kaelin, of the Dana-Farber Cancer Institute and Harvard Medical School, both in Boston, was researching von Hippel-Lindau’s (VHL) syndrome, an inherited disorder in which mutations can lead to tumors in multiple organs. He found the VHL gene encodes a protein that prevents cancer onset, and cancer cells without a functional VHL gene express high levels of hypoxia-regulated genes.

Research by other groups showed that VHL is part of a complex that labels proteins with ubiquitin, tagging them for degradation. Dr. Ratcliffe and his group found that VHL is required for the degradation of HIF-1a at normal oxygen levels.

Dr. Kaelin’s and Dr. Ratcliffe’s groups also showed that, under normal oxygen conditions, hydroxyl groups are added at two locations in HIF-1a. This modification – prolyl hydroxylation – allows VHL to bind to HIF-1a. So the researchers found that normal oxygen levels control HIF-1a degradation with the help of prolyl hydroxylases.

Additional research by Dr. Ratcliffe’s group and others revealed the specific prolyl hydroxylases involved in HIF-1a degradation. The researchers also found that HIF-1a’s gene-activating function was regulated by oxygen-dependent hydroxylation.

This work has improved the understanding of how different oxygen levels regulate physiological processes. In particular, oxygen sensing is essential for erythropoiesis, so these findings have implications for the treatment of anemia.

“There are several drugs that are now in clinical trials that serve to increase HIF activity and, as a result, will increase the production of erythropoietin and stimulate red blood cell production,” Dr. Semenza said in an interview after the announcement of his Nobel win. “These are all small molecules that can be given by mouth, and that may be a great convenience for patients who, at the present time, may require injections of recombinant human erythropoietin.”

[email protected]

Three researchers have won the 2019 Nobel Prize in Physiology or Medicine “for their discoveries of how cells sense and adapt to oxygen availability.”

William G. Kaelin Jr., MD; Sir Peter J. Ratcliffe, MB ChB, MD; and Gregg L. Semenza, MD, PhD, described the molecular machinery that regulates gene activity in response to oxygen levels.


Their work “established the basis for our understanding of how oxygen levels affect cellular metabolism and physiological function” and “paved the way for promising new strategies to fight anemia, cancer, and many other diseases,” according to a statement by The Nobel Assembly at Karolinska Institutet.

Dr. Semenza, of Johns Hopkins Medicine in Baltimore, studied how the erythropoietin (EPO) gene is regulated by oxygen levels. Via experiments in mice, he identified DNA segments next to the EPO gene that mediate the response to hypoxia.

Dr. Ratcliffe, of the University of Oxford (England) and the Francis Crick Institute in London, also studied oxygen-dependent regulation of the EPO gene. Both his and Dr. Semenza’s groups found the oxygen-sensing mechanism was present in nearly all tissues.

Dr. Kaelin, of the Dana-Farber Cancer Institute and Harvard Medical School, both in Boston, was researching von Hippel-Lindau’s (VHL) syndrome, an inherited disorder in which mutations can lead to tumors in multiple organs. He found the VHL gene encodes a protein that prevents cancer onset, and cancer cells without a functional VHL gene express high levels of hypoxia-regulated genes.

Research by other groups showed that VHL is part of a complex that labels proteins with ubiquitin, tagging them for degradation. Dr. Ratcliffe and his group found that VHL is required for the degradation of HIF-1a at normal oxygen levels.

Dr. Kaelin’s and Dr. Ratcliffe’s groups also showed that, under normal oxygen conditions, hydroxyl groups are added at two locations in HIF-1a. This modification – prolyl hydroxylation – allows VHL to bind to HIF-1a. So the researchers found that normal oxygen levels control HIF-1a degradation with the help of prolyl hydroxylases.

Additional research by Dr. Ratcliffe’s group and others revealed the specific prolyl hydroxylases involved in HIF-1a degradation. The researchers also found that HIF-1a’s gene-activating function was regulated by oxygen-dependent hydroxylation.

This work has improved the understanding of how different oxygen levels regulate physiological processes. In particular, oxygen sensing is essential for erythropoiesis, so these findings have implications for the treatment of anemia.

“There are several drugs that are now in clinical trials that serve to increase HIF activity and, as a result, will increase the production of erythropoietin and stimulate red blood cell production,” Dr. Semenza said in an interview after the announcement of his Nobel win. “These are all small molecules that can be given by mouth, and that may be a great convenience for patients who, at the present time, may require injections of recombinant human erythropoietin.”

[email protected]

Several initiatives are in the works to improve the management of patients with sickle cell disease in the ED, experts said at a recent webinar held by the National Heart, Lung, and Blood Institute.

JazzIRT/Getty Images

In 2014, the NHLBI released evidence-based guidelines for the management of patients with sickle cell disease. The expert panel provided recommendations on the treatment of acute complications of sickle cell disease, many of which are common reasons for ED visits.

Optimizing the treatment of acute complications, namely vasoocclusive crisis, is essential to ensure improved long-term outcomes, explained Paula Tanabe, PhD, of Duke University, Durham, N.C.

Pain management

While the majority of pain-related ED visits in sickle cell are the result of vasoocclusive crisis, other causes, such as acute chest syndrome, abdominal catastrophes, and splenic sequestration, are also important.

The hallmark of pain management in this population is rapid and aggressive treatment with intravenous opioids. The use of individualized doses is also important, but if not available, an sickle cell disease–specific pain protocol can be used, she explained.

Recent evidence has confirmed the benefit of using an individualized (patient-specific) dosing protocol. Dr. Tanabe reported the results of a randomized pilot study that compared two pain protocols for patients undergoing a vasoocclusive episode in the ED.

“The reason we pursued this project is to generate additional evidence beyond the expert panel,” she said.

The primary outcome of the study was the difference in pain scores from arrival to discharge between patients receiving an individualized or weight-based dosing protocol. Secondary outcomes included safety, pain experience, and side effects, among others.

The researchers found that patients who received an individualized protocol had significantly lower pain scores, compared with a standard weight-based protocol (between-protocol pain score difference, 15.6 plus or minus 5.0; P = .002).

Additionally, patients in the individualized dosing arm were admitted less often than those in the weight-based arm (P = .03), Dr. Tanabe reported.

The findings from the previous study formed the basis for an ongoing study that is further examining the impact of patient-specific dosing in patients who present with a vasoocclusive episode. The COMPARE VOE study is currently enrolling patients and is being funded by NHLBI.

The NHLBI also provides funding to eight Sickle Cell Disease Implementation Consortium sites throughout the United States. The objective of this grant funding is to help implement NHLBI recommendations in the emergency setting.

Quality improvement

“One area [that] we want to improve is how quickly we administer [analgesic therapy] to patients when they are experiencing a vasoocclusive episode,” said Caroline Freiermuth, MD, of the University of Cincinnati.

Some common barriers to delivering rapid analgesia in this setting include difficulties in obtaining intravenous access, high patient volumes, lack of education, and provider biases, she explained.

With respect to high patient volumes, one strategy that may help overcome this barrier is to triage patients as Emergency Severity Index level 2, allowing for accelerated room placement.

Sickle cell patients undergoing vasoocclusive crisis meet the criteria for level 2 based on morbidity, degree of pain, and the level of resources often required.

Another important strategy is improving education related to sickle cell disease, particularly the high morbidity and mortality seen in these patients, Dr. Freiermuth said.

“The median lifespan for patients with HbSS disease is in the 40s, basically half of the lifespan of a typical American,” she said.

At present, acute chest syndrome is the principal cause of death in patients with sickle cell disease, and most frequently occurs during a vasoocclusive episode. As a result, screening for this complication is essential to reduce mortality in the emergency setting.

Dr. Freiermuth explained that one of the best ways to prevent acute chest syndrome is to encourage the use of incentive spirometry in patients undergoing a vasoocclusive episode.

In order to increase the likelihood of obtaining intravenous access, the use of ultrasound may help guide placement. Educating nurses on the proper use of ultrasound-guided placement of intravenous catheters is one practical approach, she said.

Alternatively, opioid analgesia can be administered subcutaneously. Benefits of subcutaneous delivery include comparable pharmacokinetics, less pain, and a reduced likelihood of sterile abscesses that are often seen with intramuscular administration.

Dr. Freiermuth outlined the quality-improvement initiative being tested at her institution, which involves the administration of parenteral opioid therapy during triage for sickle cell patients undergoing a suspected vasoocclusive crisis. The initiative was developed with input from both the emergency and hematology departments at the site.

Early results have shown no significant changes using this approach, but the data is still preliminary. Initial feedback has revealed that time to room placement has been the greatest barrier, she reported.

Dr. Tanabe reported grant/research support from the National Institutes of Health and the Agency for Healthcare Research and Quality. Dr. Freiermuth reported research support from Pfizer.

Several initiatives are in the works to improve the management of patients with sickle cell disease in the ED, experts said at a recent webinar held by the National Heart, Lung, and Blood Institute.

JazzIRT/Getty Images

In 2014, the NHLBI released evidence-based guidelines for the management of patients with sickle cell disease. The expert panel provided recommendations on the treatment of acute complications of sickle cell disease, many of which are common reasons for ED visits.

Optimizing the treatment of acute complications, namely vasoocclusive crisis, is essential to ensure improved long-term outcomes, explained Paula Tanabe, PhD, of Duke University, Durham, N.C.

Pain management

While the majority of pain-related ED visits in sickle cell are the result of vasoocclusive crisis, other causes, such as acute chest syndrome, abdominal catastrophes, and splenic sequestration, are also important.

The hallmark of pain management in this population is rapid and aggressive treatment with intravenous opioids. The use of individualized doses is also important, but if not available, an sickle cell disease–specific pain protocol can be used, she explained.

Recent evidence has confirmed the benefit of using an individualized (patient-specific) dosing protocol. Dr. Tanabe reported the results of a randomized pilot study that compared two pain protocols for patients undergoing a vasoocclusive episode in the ED.

“The reason we pursued this project is to generate additional evidence beyond the expert panel,” she said.

The primary outcome of the study was the difference in pain scores from arrival to discharge between patients receiving an individualized or weight-based dosing protocol. Secondary outcomes included safety, pain experience, and side effects, among others.

The researchers found that patients who received an individualized protocol had significantly lower pain scores, compared with a standard weight-based protocol (between-protocol pain score difference, 15.6 plus or minus 5.0; P = .002).

Additionally, patients in the individualized dosing arm were admitted less often than those in the weight-based arm (P = .03), Dr. Tanabe reported.

The findings from the previous study formed the basis for an ongoing study that is further examining the impact of patient-specific dosing in patients who present with a vasoocclusive episode. The COMPARE VOE study is currently enrolling patients and is being funded by NHLBI.

The NHLBI also provides funding to eight Sickle Cell Disease Implementation Consortium sites throughout the United States. The objective of this grant funding is to help implement NHLBI recommendations in the emergency setting.

Quality improvement

“One area [that] we want to improve is how quickly we administer [analgesic therapy] to patients when they are experiencing a vasoocclusive episode,” said Caroline Freiermuth, MD, of the University of Cincinnati.

Some common barriers to delivering rapid analgesia in this setting include difficulties in obtaining intravenous access, high patient volumes, lack of education, and provider biases, she explained.

With respect to high patient volumes, one strategy that may help overcome this barrier is to triage patients as Emergency Severity Index level 2, allowing for accelerated room placement.

Sickle cell patients undergoing vasoocclusive crisis meet the criteria for level 2 based on morbidity, degree of pain, and the level of resources often required.

Another important strategy is improving education related to sickle cell disease, particularly the high morbidity and mortality seen in these patients, Dr. Freiermuth said.

“The median lifespan for patients with HbSS disease is in the 40s, basically half of the lifespan of a typical American,” she said.

At present, acute chest syndrome is the principal cause of death in patients with sickle cell disease, and most frequently occurs during a vasoocclusive episode. As a result, screening for this complication is essential to reduce mortality in the emergency setting.

Dr. Freiermuth explained that one of the best ways to prevent acute chest syndrome is to encourage the use of incentive spirometry in patients undergoing a vasoocclusive episode.

In order to increase the likelihood of obtaining intravenous access, the use of ultrasound may help guide placement. Educating nurses on the proper use of ultrasound-guided placement of intravenous catheters is one practical approach, she said.

Alternatively, opioid analgesia can be administered subcutaneously. Benefits of subcutaneous delivery include comparable pharmacokinetics, less pain, and a reduced likelihood of sterile abscesses that are often seen with intramuscular administration.

Dr. Freiermuth outlined the quality-improvement initiative being tested at her institution, which involves the administration of parenteral opioid therapy during triage for sickle cell patients undergoing a suspected vasoocclusive crisis. The initiative was developed with input from both the emergency and hematology departments at the site.

Early results have shown no significant changes using this approach, but the data is still preliminary. Initial feedback has revealed that time to room placement has been the greatest barrier, she reported.

Dr. Tanabe reported grant/research support from the National Institutes of Health and the Agency for Healthcare Research and Quality. Dr. Freiermuth reported research support from Pfizer.

Several initiatives are in the works to improve the management of patients with sickle cell disease in the ED, experts said at a recent webinar held by the National Heart, Lung, and Blood Institute.

JazzIRT/Getty Images

In 2014, the NHLBI released evidence-based guidelines for the management of patients with sickle cell disease. The expert panel provided recommendations on the treatment of acute complications of sickle cell disease, many of which are common reasons for ED visits.

Optimizing the treatment of acute complications, namely vasoocclusive crisis, is essential to ensure improved long-term outcomes, explained Paula Tanabe, PhD, of Duke University, Durham, N.C.

Pain management

While the majority of pain-related ED visits in sickle cell are the result of vasoocclusive crisis, other causes, such as acute chest syndrome, abdominal catastrophes, and splenic sequestration, are also important.

The hallmark of pain management in this population is rapid and aggressive treatment with intravenous opioids. The use of individualized doses is also important, but if not available, an sickle cell disease–specific pain protocol can be used, she explained.

Recent evidence has confirmed the benefit of using an individualized (patient-specific) dosing protocol. Dr. Tanabe reported the results of a randomized pilot study that compared two pain protocols for patients undergoing a vasoocclusive episode in the ED.

“The reason we pursued this project is to generate additional evidence beyond the expert panel,” she said.

The primary outcome of the study was the difference in pain scores from arrival to discharge between patients receiving an individualized or weight-based dosing protocol. Secondary outcomes included safety, pain experience, and side effects, among others.

The researchers found that patients who received an individualized protocol had significantly lower pain scores, compared with a standard weight-based protocol (between-protocol pain score difference, 15.6 plus or minus 5.0; P = .002).

Additionally, patients in the individualized dosing arm were admitted less often than those in the weight-based arm (P = .03), Dr. Tanabe reported.

The findings from the previous study formed the basis for an ongoing study that is further examining the impact of patient-specific dosing in patients who present with a vasoocclusive episode. The COMPARE VOE study is currently enrolling patients and is being funded by NHLBI.

The NHLBI also provides funding to eight Sickle Cell Disease Implementation Consortium sites throughout the United States. The objective of this grant funding is to help implement NHLBI recommendations in the emergency setting.

Quality improvement

“One area [that] we want to improve is how quickly we administer [analgesic therapy] to patients when they are experiencing a vasoocclusive episode,” said Caroline Freiermuth, MD, of the University of Cincinnati.

Some common barriers to delivering rapid analgesia in this setting include difficulties in obtaining intravenous access, high patient volumes, lack of education, and provider biases, she explained.

With respect to high patient volumes, one strategy that may help overcome this barrier is to triage patients as Emergency Severity Index level 2, allowing for accelerated room placement.

Sickle cell patients undergoing vasoocclusive crisis meet the criteria for level 2 based on morbidity, degree of pain, and the level of resources often required.

Another important strategy is improving education related to sickle cell disease, particularly the high morbidity and mortality seen in these patients, Dr. Freiermuth said.

“The median lifespan for patients with HbSS disease is in the 40s, basically half of the lifespan of a typical American,” she said.

At present, acute chest syndrome is the principal cause of death in patients with sickle cell disease, and most frequently occurs during a vasoocclusive episode. As a result, screening for this complication is essential to reduce mortality in the emergency setting.

Dr. Freiermuth explained that one of the best ways to prevent acute chest syndrome is to encourage the use of incentive spirometry in patients undergoing a vasoocclusive episode.

In order to increase the likelihood of obtaining intravenous access, the use of ultrasound may help guide placement. Educating nurses on the proper use of ultrasound-guided placement of intravenous catheters is one practical approach, she said.

Alternatively, opioid analgesia can be administered subcutaneously. Benefits of subcutaneous delivery include comparable pharmacokinetics, less pain, and a reduced likelihood of sterile abscesses that are often seen with intramuscular administration.

Dr. Freiermuth outlined the quality-improvement initiative being tested at her institution, which involves the administration of parenteral opioid therapy during triage for sickle cell patients undergoing a suspected vasoocclusive crisis. The initiative was developed with input from both the emergency and hematology departments at the site.

Early results have shown no significant changes using this approach, but the data is still preliminary. Initial feedback has revealed that time to room placement has been the greatest barrier, she reported.

Dr. Tanabe reported grant/research support from the National Institutes of Health and the Agency for Healthcare Research and Quality. Dr. Freiermuth reported research support from Pfizer.

Researchers are leading several studies designed to improve hematopoietic stem cell transplantation (HSCT) for patients with sickle cell disease (SCD), experts at the National Heart, Lung, and Blood Institute reported during a recent webinar.

bubaone/DigitalVision Vectors

“HSCT offers a potential cure [for SCD], which may improve quantity and quality of life [for patients],” said Courtney D. Fitzhugh, MD, a Lasker Clinical Research Scholar in the Laboratory of Early Sickle Mortality Prevention at NHLBI.

Currently, HLA-matched sibling and matched unrelated donor sources provide the best outcomes for sickle cell patients undergoing allogeneic HSCT, she explained. Alternative stem cell sources include umbilical cord blood and haploidentical donors.

Over the past 2 years, the majority of novel transplant techniques have been primarily aimed at improving conditioning regimens and lowering rates of graft-versus-host disease (GVHD).
 

Recent evidence

A recent international survey found high survival rates in patients with SCD who underwent HLA-matched sibling HSCT during 1986-2013. At 5-years, overall- and event-free survival rates were 92.9% and 91.4%, respectively, with even higher rates (95% and 93%) seen in children aged younger than 16 years.

With respect to safety, the cumulative incidence rates of acute and chronic GVHD were 14.8% and 14.3%, Dr. Fitzhugh reported.

Much of the success seen with HLA-matched sibling donors is attributable to recent data demonstrating that complete transformation of patient’s bone marrow is unnecessary to illicit a curative effect.

With donor myeloid chimerism levels of at least 20%, the sickle disease phenotype can be reversed, and there’s a reduced risk of GVHD, she said.

In mouse models, researchers have found that inclusion of sirolimus in HLA-matched pretransplant conditioning regimens leads to higher levels of donor cell engraftment. As a result, some conditioning regimens now administer sirolimus (target 10-15 ng/dL) one-day prior to transplantation.

In 55 patients transplanted using this technique, overall- and event-free survival rates of 93% and 87% have been reported, with no transplant-related mortality or evidence of GVHD. Other institutions have also begun to adopt this technique, and have reported similar findings, Dr. Fitzhugh reported.

“When you [administer high-dose] chemotherapy, you don’t expect that patients are able to have children, but we are excited to report that 8 of our patients have had 13 healthy babies post transplant,” Dr. Fitzhugh said.

As a whole, several recent studies have emphasized the importance of the conditioning regimen in successful transplantation for patients with SCD.

With HLA-matched sibling donors, myeloablative regimens that include antithymocyte globulin have demonstrated greater efficacy, she said.

In patients receiving a transplant from a matched unrelated donor, early use of alemtuzumab is linked to higher rates of GVHD, while ongoing studies are exploring whether abatacept reduces the risk of GVHD, she further explained.

With respect to haploidentical and unrelated umbilical cord donors, T-cell depletion and higher-intensity conditioning have been shown to reduce graft rejection rates, she said.

Dr. Fitzhugh acknowledged that long-term efficacy and safety of these novel conditioning regimens is largely unknown. Thus, ongoing follow-up is essential to monitor for potential late effects.
 

NHLBI-funded trials

Nancy L. DiFronzo, PhD, program director at NHLBI, explained that the agency has funded specific clinical studies evaluating allogeneic HSCT in patients with severe SCD.

“[Surprisingly], this treatment modality is [actually] quite rare, with [only] approximately 9,000 allogeneic transplants occurring in the United States each year,” she said.

One of the primary barriers to HSCT for SCD is a lack of compatible donors. Currently, fewer than 20% of sickle cell patients have a matched unrelated donor or HLA-matched sibling donor, she reported.

Another common barrier are the risks associated with the procedure, including treatment-related toxicities and death. Active participation in a clinical trial is one strategy that can mitigate these risks, she said.

The Blood and Marrow Transplant Clinical Trials Network (BMT CTN) is a group of transplant centers that are recognized experts in HSCT. Dr. DiFronzo explained that the consortium is cosponsored by the National Cancer Institute and NHLBI, with the goal of improving outcomes for both pediatric and adult patients with SCD undergoing HSCT.

At present, the BMT CTN has directly funded three multicenter clinical studies for SCD, including the SCURT study, which has now been completed, as well as the STRIDE2 and Haploidentical HCT trials, both of which are currently enrolling patients.

“The goal of these new approaches [being studied in these 3 trials] is cure, where individuals can live longer with a better quality of life,” Dr. DiFronzo said. “We’ve [specifically] adjusted regimens with [this goal] in mind.”

Dr. Fitzhugh and Dr. DiFronzo did not provide information on financial disclosures.

Researchers are leading several studies designed to improve hematopoietic stem cell transplantation (HSCT) for patients with sickle cell disease (SCD), experts at the National Heart, Lung, and Blood Institute reported during a recent webinar.

bubaone/DigitalVision Vectors

“HSCT offers a potential cure [for SCD], which may improve quantity and quality of life [for patients],” said Courtney D. Fitzhugh, MD, a Lasker Clinical Research Scholar in the Laboratory of Early Sickle Mortality Prevention at NHLBI.

Currently, HLA-matched sibling and matched unrelated donor sources provide the best outcomes for sickle cell patients undergoing allogeneic HSCT, she explained. Alternative stem cell sources include umbilical cord blood and haploidentical donors.

Over the past 2 years, the majority of novel transplant techniques have been primarily aimed at improving conditioning regimens and lowering rates of graft-versus-host disease (GVHD).
 

Recent evidence

A recent international survey found high survival rates in patients with SCD who underwent HLA-matched sibling HSCT during 1986-2013. At 5-years, overall- and event-free survival rates were 92.9% and 91.4%, respectively, with even higher rates (95% and 93%) seen in children aged younger than 16 years.

With respect to safety, the cumulative incidence rates of acute and chronic GVHD were 14.8% and 14.3%, Dr. Fitzhugh reported.

Much of the success seen with HLA-matched sibling donors is attributable to recent data demonstrating that complete transformation of patient’s bone marrow is unnecessary to illicit a curative effect.

With donor myeloid chimerism levels of at least 20%, the sickle disease phenotype can be reversed, and there’s a reduced risk of GVHD, she said.

In mouse models, researchers have found that inclusion of sirolimus in HLA-matched pretransplant conditioning regimens leads to higher levels of donor cell engraftment. As a result, some conditioning regimens now administer sirolimus (target 10-15 ng/dL) one-day prior to transplantation.

In 55 patients transplanted using this technique, overall- and event-free survival rates of 93% and 87% have been reported, with no transplant-related mortality or evidence of GVHD. Other institutions have also begun to adopt this technique, and have reported similar findings, Dr. Fitzhugh reported.

“When you [administer high-dose] chemotherapy, you don’t expect that patients are able to have children, but we are excited to report that 8 of our patients have had 13 healthy babies post transplant,” Dr. Fitzhugh said.

As a whole, several recent studies have emphasized the importance of the conditioning regimen in successful transplantation for patients with SCD.

With HLA-matched sibling donors, myeloablative regimens that include antithymocyte globulin have demonstrated greater efficacy, she said.

In patients receiving a transplant from a matched unrelated donor, early use of alemtuzumab is linked to higher rates of GVHD, while ongoing studies are exploring whether abatacept reduces the risk of GVHD, she further explained.

With respect to haploidentical and unrelated umbilical cord donors, T-cell depletion and higher-intensity conditioning have been shown to reduce graft rejection rates, she said.

Dr. Fitzhugh acknowledged that long-term efficacy and safety of these novel conditioning regimens is largely unknown. Thus, ongoing follow-up is essential to monitor for potential late effects.
 

NHLBI-funded trials

Nancy L. DiFronzo, PhD, program director at NHLBI, explained that the agency has funded specific clinical studies evaluating allogeneic HSCT in patients with severe SCD.

“[Surprisingly], this treatment modality is [actually] quite rare, with [only] approximately 9,000 allogeneic transplants occurring in the United States each year,” she said.

One of the primary barriers to HSCT for SCD is a lack of compatible donors. Currently, fewer than 20% of sickle cell patients have a matched unrelated donor or HLA-matched sibling donor, she reported.

Another common barrier are the risks associated with the procedure, including treatment-related toxicities and death. Active participation in a clinical trial is one strategy that can mitigate these risks, she said.

The Blood and Marrow Transplant Clinical Trials Network (BMT CTN) is a group of transplant centers that are recognized experts in HSCT. Dr. DiFronzo explained that the consortium is cosponsored by the National Cancer Institute and NHLBI, with the goal of improving outcomes for both pediatric and adult patients with SCD undergoing HSCT.

At present, the BMT CTN has directly funded three multicenter clinical studies for SCD, including the SCURT study, which has now been completed, as well as the STRIDE2 and Haploidentical HCT trials, both of which are currently enrolling patients.

“The goal of these new approaches [being studied in these 3 trials] is cure, where individuals can live longer with a better quality of life,” Dr. DiFronzo said. “We’ve [specifically] adjusted regimens with [this goal] in mind.”

Dr. Fitzhugh and Dr. DiFronzo did not provide information on financial disclosures.

Researchers are leading several studies designed to improve hematopoietic stem cell transplantation (HSCT) for patients with sickle cell disease (SCD), experts at the National Heart, Lung, and Blood Institute reported during a recent webinar.

bubaone/DigitalVision Vectors

“HSCT offers a potential cure [for SCD], which may improve quantity and quality of life [for patients],” said Courtney D. Fitzhugh, MD, a Lasker Clinical Research Scholar in the Laboratory of Early Sickle Mortality Prevention at NHLBI.

Currently, HLA-matched sibling and matched unrelated donor sources provide the best outcomes for sickle cell patients undergoing allogeneic HSCT, she explained. Alternative stem cell sources include umbilical cord blood and haploidentical donors.

Over the past 2 years, the majority of novel transplant techniques have been primarily aimed at improving conditioning regimens and lowering rates of graft-versus-host disease (GVHD).
 

Recent evidence

A recent international survey found high survival rates in patients with SCD who underwent HLA-matched sibling HSCT during 1986-2013. At 5-years, overall- and event-free survival rates were 92.9% and 91.4%, respectively, with even higher rates (95% and 93%) seen in children aged younger than 16 years.

With respect to safety, the cumulative incidence rates of acute and chronic GVHD were 14.8% and 14.3%, Dr. Fitzhugh reported.

Much of the success seen with HLA-matched sibling donors is attributable to recent data demonstrating that complete transformation of patient’s bone marrow is unnecessary to illicit a curative effect.

With donor myeloid chimerism levels of at least 20%, the sickle disease phenotype can be reversed, and there’s a reduced risk of GVHD, she said.

In mouse models, researchers have found that inclusion of sirolimus in HLA-matched pretransplant conditioning regimens leads to higher levels of donor cell engraftment. As a result, some conditioning regimens now administer sirolimus (target 10-15 ng/dL) one-day prior to transplantation.

In 55 patients transplanted using this technique, overall- and event-free survival rates of 93% and 87% have been reported, with no transplant-related mortality or evidence of GVHD. Other institutions have also begun to adopt this technique, and have reported similar findings, Dr. Fitzhugh reported.

“When you [administer high-dose] chemotherapy, you don’t expect that patients are able to have children, but we are excited to report that 8 of our patients have had 13 healthy babies post transplant,” Dr. Fitzhugh said.

As a whole, several recent studies have emphasized the importance of the conditioning regimen in successful transplantation for patients with SCD.

With HLA-matched sibling donors, myeloablative regimens that include antithymocyte globulin have demonstrated greater efficacy, she said.

In patients receiving a transplant from a matched unrelated donor, early use of alemtuzumab is linked to higher rates of GVHD, while ongoing studies are exploring whether abatacept reduces the risk of GVHD, she further explained.

With respect to haploidentical and unrelated umbilical cord donors, T-cell depletion and higher-intensity conditioning have been shown to reduce graft rejection rates, she said.

Dr. Fitzhugh acknowledged that long-term efficacy and safety of these novel conditioning regimens is largely unknown. Thus, ongoing follow-up is essential to monitor for potential late effects.
 

NHLBI-funded trials

Nancy L. DiFronzo, PhD, program director at NHLBI, explained that the agency has funded specific clinical studies evaluating allogeneic HSCT in patients with severe SCD.

“[Surprisingly], this treatment modality is [actually] quite rare, with [only] approximately 9,000 allogeneic transplants occurring in the United States each year,” she said.

One of the primary barriers to HSCT for SCD is a lack of compatible donors. Currently, fewer than 20% of sickle cell patients have a matched unrelated donor or HLA-matched sibling donor, she reported.

Another common barrier are the risks associated with the procedure, including treatment-related toxicities and death. Active participation in a clinical trial is one strategy that can mitigate these risks, she said.

The Blood and Marrow Transplant Clinical Trials Network (BMT CTN) is a group of transplant centers that are recognized experts in HSCT. Dr. DiFronzo explained that the consortium is cosponsored by the National Cancer Institute and NHLBI, with the goal of improving outcomes for both pediatric and adult patients with SCD undergoing HSCT.

At present, the BMT CTN has directly funded three multicenter clinical studies for SCD, including the SCURT study, which has now been completed, as well as the STRIDE2 and Haploidentical HCT trials, both of which are currently enrolling patients.

“The goal of these new approaches [being studied in these 3 trials] is cure, where individuals can live longer with a better quality of life,” Dr. DiFronzo said. “We’ve [specifically] adjusted regimens with [this goal] in mind.”

Dr. Fitzhugh and Dr. DiFronzo did not provide information on financial disclosures.