User login
VTE prophylaxis is feasible, effective in some high-risk cancer patients
Primary thromboprophylaxis is feasible and worth considering for high-risk ambulatory patients with cancer who are initiating systemic chemotherapy, according to Marc Carrier, MD.
Risk scores can identify patients at high risk for venous thromboembolism (VTE), and treatments that are effective and associated with low bleeding risk are available, Dr. Carrier explained at the biennial summit of the Thrombosis & Hemostasis Societies of North America.
However, caution is advised in patients with certain types of cancer, including some gastrointestinal and genitourinary cancers, because of the possibility of increased major and clinically relevant nonmajor bleeding risk, he said.
VTE and cancer
VTE is relatively rare in the general population, occurring in about 1 or 2 per 1,000 people annually. The risk increases 4.1-fold in patients with cancer, and 6.5-fold in patients with cancer receiving chemotherapy.
“So just putting these numbers together, we’re no longer talking about 1 in 1,000, but 1 in 200, so [this is] something that is very common among cancer patients,” said Dr. Carrier, a professor at the University of Ottawa and chief of the division of hematology at The Ottawa Hospital.
The mortality rate associated with cancer-associated thrombosis is about 9%, comparable to that associated with infection in the cancer outpatient setting, which underscores the importance of educating patients about the signs and symptoms of VTE so they can seek medical treatment quickly if necessary, he added.
It may also be useful to discuss prophylaxis or other ways to prevent venous thromboembolic complications with certain patients, he said, noting that in an observational cohort study of nearly 600 patients at the University of Ottawa, 25% of those initiating chemotherapy were identified as intermediate or high risk using the validated Khorana risk score, and thus would likely benefit from thromboprophylaxis.
Risk assessment
The Khorana risk score assesses VTE risk based on cancer site, blood counts, and body mass index. It is simple to use and has been validated in more than 20,000 people in multiple countries, Dr. Carrier said.
In a well-known validation study, Ay et al. showed a VTE complication rate of 10% in patients with a Khorana risk score of 2 or higher who were followed up to 6 months.
“This is huge,” Dr. Carrier stressed. “This is much higher than what we tolerate for all sorts of different populations for which we would recommend anticoagulation or thromboprophylaxis.”
The question is whether the risk score can be helpful in a real-world clinic setting, he said, adding: “I’d like to think the answer to that is yes.”
In the University of Ottawa cohort study, 11% of high-risk patients experienced a VTE complication, compared with 4% of those with lower risk, suggesting that the validation data for the Khorana risk score is not only accurate, it is “actually applicable in real-world practice, and you can use it in your own center,” he said.
Further, recent studies have demonstrated that treatment based on Khorana risk score assessment reduces VTE complications.
Prophylaxis options
Low-molecular-weight heparin (LMWH) has been shown in several studies to be associated with a significant relative VTE risk reduction in patients with cancer initiating chemotherapy – with only a slight, nonsignificant increase in the risk of major bleeding.
However, the absolute benefit was small, and LMWH is “parenteral, relatively costly, and, based on that, although we showed relatively good risk-benefit ratio, it never really got translated to clinical practice,” Dr. Carrier said.
In fact, a 2015 American Society of Clinical Oncology guidelines update recommended against routine thromboprophylaxis in this setting, but stated that it could be considered in select high-risk patients identified using a validated risk-assessment tool.
The guidelines noted that “individual risk factors such as biomarkers and cancer site don’t reliably identify high-risk patients.”
More recent data provide additional support for risk assessment and treatment based on Khorana risk score of 2 or higher.
The AVERT trial, for which Dr. Carrier was the first author, showed that the direct-acting oral anticoagulant (DOAC) apixaban reduced VTE incidence, compared with placebo, in patients with Khorana score of 2 or higher (4.2% vs. 10.2%; hazard ratio, 0.41 overall, and 1.0 vs. 7.3; HR, 0.14 on treatment), and the CASSINI trial showed that another DOAC, rivaroxaban, reduced VTE incidence, compared with placebo, in those with Khorana score of 2 or higher (5.9 vs. 6.7; HR, 0.6 overall, and 2.6 vs. 6.4; HR, 0.40 on treatment). The differences in the on-treatment populations were statistically significant.
The two trials, which included a variety of tumor types, showed similar rates of major bleeding, with an absolute difference of about 1% between treatment and placebo, which was not statistically significant in the on-treatment analyses (HR, 1.89 in AVERT and HR, 1.96 in CASSINI).
A systematic review of these trials showed an overall significant decrease in VTE complication risk with treatment in high-risk patients, and a nonstatistically significant major bleeding risk increase.
Based on these findings, ASCO guidelines were updated in 2020 to state that “routine thromboprophylaxis should not be offered to all patients with cancer. ... However, high-risk outpatients with cancer may be offered thromboprophylaxis with apixaban, rivaroxaban or LMWH, providing there are no significant risk factors for bleeding or drug-drug interactions, and after having a full discussion with patients ... to make sure they understand the risk-benefit ratio and the rationale for that particular recommendation,” he said.
Real-world implementation
Implementing this approach in the clinic setting requires a practical model, such as the Venous Thromboembolism Prevention in the Ambulatory Cancer Clinic (VTEPACC) program, a prospective quality improvement research initiative developed in collaboration with the Jeffords Institute for Quality at the University of Vermont Medical Center and described in a recent report, Dr. Carrier said.
The “Vermont model” is “really a comprehensive model that includes identifying patients with the electronic medical records, gathering the formal education and insight from other health care providers like pharmacists and nurses in order to really come up with personalized care for your patients,” he explained.
In 918 outpatients with cancer who were included in the program, VTE awareness increased from less than 5% before VTEPACC to nearly 82% during the implementation phase and 94.7% after 2 years, with nearly 94% of high-risk patients receiving VTE prophylaxis at that time.
“So we can certainly do that in our own center.” he said. “It’s a matter of coming up with the model and making sure that the patients are seen at the right time.”
Given the high frequency of VTE in patients with cancer initiating chemotherapy, the usefulness of risk scores such as the Khorana risk score for identifying those at high risk, and the availability of safe and effective interventions for reducing risk, “we should probably use the data and incorporate them into clinical practice by implementation of programs for primary prevention,” he said.
A word of caution
Caution is warranted, however, when it comes to using DOACs in patients with higher-risk or potentially higher-risk tumor types, he added.
“It’s an important question we are facing as clinicians on a daily basis,” he said, responding to an attendee’s query, as shared by session moderator James Douketis, MD, professor of medicine at McMaster University, Hamilton, Ont., regarding possible bleeding risks in certain genitourinary cancers.
A recent meta-analysis published in Nature, for example, noted that, in the SELECT-D trial, rivaroxaban was associated with significantly higher incidence of clinically relevant nonmajor bleeding, most often in bladder and colorectal cancers, and most often at genitourinary and gastrointestinal sites.
Both Dr. Carrier and fellow panelist Michael Streiff, MD, professor of medicine at Johns Hopkins University and medical director at the Johns Hopkins Hospital Special Coagulation Laboratory, Baltimore, said they approach DOAC use cautiously, but don’t rule it out entirely, in patients with unresected genitourinary tumors that could pose a risk of bleeding.
“It’s worth mentioning and being cautious. In my own personal practice, I’m very careful with unresected urothelial-type tumors or, for example, bladder cancer, for the same reason as [with] unresected luminal GI tumors,” Dr. Carrier said, adding that he’s also mindful that patients with nephropathy were excluded from U.S. DOAC trials because of bleeding risk.
He said he sometimes tries a LMWH challenge first in higher-risk patients, and then might try a DOAC if no bleeding occurs.
“But it certainly is controversial,” he noted.
Dr. Streiff added that he also worries less with genitourinary cancers than with upper GI lesions because “the signals weren’t as big as in GI” cancers, but he noted that “the drugs are going out through the kidneys ... so I’m cautious in those populations.”
“So caution, but not complete exclusion, is the operative management,” Dr. Douketis said, summarizing the panelists’ consensus.
Dr. Carrier reported clinical trial or advisory board participation for Bayer, Pfizer, Servier, Leo Pharma, and/or BMS.
Primary thromboprophylaxis is feasible and worth considering for high-risk ambulatory patients with cancer who are initiating systemic chemotherapy, according to Marc Carrier, MD.
Risk scores can identify patients at high risk for venous thromboembolism (VTE), and treatments that are effective and associated with low bleeding risk are available, Dr. Carrier explained at the biennial summit of the Thrombosis & Hemostasis Societies of North America.
However, caution is advised in patients with certain types of cancer, including some gastrointestinal and genitourinary cancers, because of the possibility of increased major and clinically relevant nonmajor bleeding risk, he said.
VTE and cancer
VTE is relatively rare in the general population, occurring in about 1 or 2 per 1,000 people annually. The risk increases 4.1-fold in patients with cancer, and 6.5-fold in patients with cancer receiving chemotherapy.
“So just putting these numbers together, we’re no longer talking about 1 in 1,000, but 1 in 200, so [this is] something that is very common among cancer patients,” said Dr. Carrier, a professor at the University of Ottawa and chief of the division of hematology at The Ottawa Hospital.
The mortality rate associated with cancer-associated thrombosis is about 9%, comparable to that associated with infection in the cancer outpatient setting, which underscores the importance of educating patients about the signs and symptoms of VTE so they can seek medical treatment quickly if necessary, he added.
It may also be useful to discuss prophylaxis or other ways to prevent venous thromboembolic complications with certain patients, he said, noting that in an observational cohort study of nearly 600 patients at the University of Ottawa, 25% of those initiating chemotherapy were identified as intermediate or high risk using the validated Khorana risk score, and thus would likely benefit from thromboprophylaxis.
Risk assessment
The Khorana risk score assesses VTE risk based on cancer site, blood counts, and body mass index. It is simple to use and has been validated in more than 20,000 people in multiple countries, Dr. Carrier said.
In a well-known validation study, Ay et al. showed a VTE complication rate of 10% in patients with a Khorana risk score of 2 or higher who were followed up to 6 months.
“This is huge,” Dr. Carrier stressed. “This is much higher than what we tolerate for all sorts of different populations for which we would recommend anticoagulation or thromboprophylaxis.”
The question is whether the risk score can be helpful in a real-world clinic setting, he said, adding: “I’d like to think the answer to that is yes.”
In the University of Ottawa cohort study, 11% of high-risk patients experienced a VTE complication, compared with 4% of those with lower risk, suggesting that the validation data for the Khorana risk score is not only accurate, it is “actually applicable in real-world practice, and you can use it in your own center,” he said.
Further, recent studies have demonstrated that treatment based on Khorana risk score assessment reduces VTE complications.
Prophylaxis options
Low-molecular-weight heparin (LMWH) has been shown in several studies to be associated with a significant relative VTE risk reduction in patients with cancer initiating chemotherapy – with only a slight, nonsignificant increase in the risk of major bleeding.
However, the absolute benefit was small, and LMWH is “parenteral, relatively costly, and, based on that, although we showed relatively good risk-benefit ratio, it never really got translated to clinical practice,” Dr. Carrier said.
In fact, a 2015 American Society of Clinical Oncology guidelines update recommended against routine thromboprophylaxis in this setting, but stated that it could be considered in select high-risk patients identified using a validated risk-assessment tool.
The guidelines noted that “individual risk factors such as biomarkers and cancer site don’t reliably identify high-risk patients.”
More recent data provide additional support for risk assessment and treatment based on Khorana risk score of 2 or higher.
The AVERT trial, for which Dr. Carrier was the first author, showed that the direct-acting oral anticoagulant (DOAC) apixaban reduced VTE incidence, compared with placebo, in patients with Khorana score of 2 or higher (4.2% vs. 10.2%; hazard ratio, 0.41 overall, and 1.0 vs. 7.3; HR, 0.14 on treatment), and the CASSINI trial showed that another DOAC, rivaroxaban, reduced VTE incidence, compared with placebo, in those with Khorana score of 2 or higher (5.9 vs. 6.7; HR, 0.6 overall, and 2.6 vs. 6.4; HR, 0.40 on treatment). The differences in the on-treatment populations were statistically significant.
The two trials, which included a variety of tumor types, showed similar rates of major bleeding, with an absolute difference of about 1% between treatment and placebo, which was not statistically significant in the on-treatment analyses (HR, 1.89 in AVERT and HR, 1.96 in CASSINI).
A systematic review of these trials showed an overall significant decrease in VTE complication risk with treatment in high-risk patients, and a nonstatistically significant major bleeding risk increase.
Based on these findings, ASCO guidelines were updated in 2020 to state that “routine thromboprophylaxis should not be offered to all patients with cancer. ... However, high-risk outpatients with cancer may be offered thromboprophylaxis with apixaban, rivaroxaban or LMWH, providing there are no significant risk factors for bleeding or drug-drug interactions, and after having a full discussion with patients ... to make sure they understand the risk-benefit ratio and the rationale for that particular recommendation,” he said.
Real-world implementation
Implementing this approach in the clinic setting requires a practical model, such as the Venous Thromboembolism Prevention in the Ambulatory Cancer Clinic (VTEPACC) program, a prospective quality improvement research initiative developed in collaboration with the Jeffords Institute for Quality at the University of Vermont Medical Center and described in a recent report, Dr. Carrier said.
The “Vermont model” is “really a comprehensive model that includes identifying patients with the electronic medical records, gathering the formal education and insight from other health care providers like pharmacists and nurses in order to really come up with personalized care for your patients,” he explained.
In 918 outpatients with cancer who were included in the program, VTE awareness increased from less than 5% before VTEPACC to nearly 82% during the implementation phase and 94.7% after 2 years, with nearly 94% of high-risk patients receiving VTE prophylaxis at that time.
“So we can certainly do that in our own center.” he said. “It’s a matter of coming up with the model and making sure that the patients are seen at the right time.”
Given the high frequency of VTE in patients with cancer initiating chemotherapy, the usefulness of risk scores such as the Khorana risk score for identifying those at high risk, and the availability of safe and effective interventions for reducing risk, “we should probably use the data and incorporate them into clinical practice by implementation of programs for primary prevention,” he said.
A word of caution
Caution is warranted, however, when it comes to using DOACs in patients with higher-risk or potentially higher-risk tumor types, he added.
“It’s an important question we are facing as clinicians on a daily basis,” he said, responding to an attendee’s query, as shared by session moderator James Douketis, MD, professor of medicine at McMaster University, Hamilton, Ont., regarding possible bleeding risks in certain genitourinary cancers.
A recent meta-analysis published in Nature, for example, noted that, in the SELECT-D trial, rivaroxaban was associated with significantly higher incidence of clinically relevant nonmajor bleeding, most often in bladder and colorectal cancers, and most often at genitourinary and gastrointestinal sites.
Both Dr. Carrier and fellow panelist Michael Streiff, MD, professor of medicine at Johns Hopkins University and medical director at the Johns Hopkins Hospital Special Coagulation Laboratory, Baltimore, said they approach DOAC use cautiously, but don’t rule it out entirely, in patients with unresected genitourinary tumors that could pose a risk of bleeding.
“It’s worth mentioning and being cautious. In my own personal practice, I’m very careful with unresected urothelial-type tumors or, for example, bladder cancer, for the same reason as [with] unresected luminal GI tumors,” Dr. Carrier said, adding that he’s also mindful that patients with nephropathy were excluded from U.S. DOAC trials because of bleeding risk.
He said he sometimes tries a LMWH challenge first in higher-risk patients, and then might try a DOAC if no bleeding occurs.
“But it certainly is controversial,” he noted.
Dr. Streiff added that he also worries less with genitourinary cancers than with upper GI lesions because “the signals weren’t as big as in GI” cancers, but he noted that “the drugs are going out through the kidneys ... so I’m cautious in those populations.”
“So caution, but not complete exclusion, is the operative management,” Dr. Douketis said, summarizing the panelists’ consensus.
Dr. Carrier reported clinical trial or advisory board participation for Bayer, Pfizer, Servier, Leo Pharma, and/or BMS.
Primary thromboprophylaxis is feasible and worth considering for high-risk ambulatory patients with cancer who are initiating systemic chemotherapy, according to Marc Carrier, MD.
Risk scores can identify patients at high risk for venous thromboembolism (VTE), and treatments that are effective and associated with low bleeding risk are available, Dr. Carrier explained at the biennial summit of the Thrombosis & Hemostasis Societies of North America.
However, caution is advised in patients with certain types of cancer, including some gastrointestinal and genitourinary cancers, because of the possibility of increased major and clinically relevant nonmajor bleeding risk, he said.
VTE and cancer
VTE is relatively rare in the general population, occurring in about 1 or 2 per 1,000 people annually. The risk increases 4.1-fold in patients with cancer, and 6.5-fold in patients with cancer receiving chemotherapy.
“So just putting these numbers together, we’re no longer talking about 1 in 1,000, but 1 in 200, so [this is] something that is very common among cancer patients,” said Dr. Carrier, a professor at the University of Ottawa and chief of the division of hematology at The Ottawa Hospital.
The mortality rate associated with cancer-associated thrombosis is about 9%, comparable to that associated with infection in the cancer outpatient setting, which underscores the importance of educating patients about the signs and symptoms of VTE so they can seek medical treatment quickly if necessary, he added.
It may also be useful to discuss prophylaxis or other ways to prevent venous thromboembolic complications with certain patients, he said, noting that in an observational cohort study of nearly 600 patients at the University of Ottawa, 25% of those initiating chemotherapy were identified as intermediate or high risk using the validated Khorana risk score, and thus would likely benefit from thromboprophylaxis.
Risk assessment
The Khorana risk score assesses VTE risk based on cancer site, blood counts, and body mass index. It is simple to use and has been validated in more than 20,000 people in multiple countries, Dr. Carrier said.
In a well-known validation study, Ay et al. showed a VTE complication rate of 10% in patients with a Khorana risk score of 2 or higher who were followed up to 6 months.
“This is huge,” Dr. Carrier stressed. “This is much higher than what we tolerate for all sorts of different populations for which we would recommend anticoagulation or thromboprophylaxis.”
The question is whether the risk score can be helpful in a real-world clinic setting, he said, adding: “I’d like to think the answer to that is yes.”
In the University of Ottawa cohort study, 11% of high-risk patients experienced a VTE complication, compared with 4% of those with lower risk, suggesting that the validation data for the Khorana risk score is not only accurate, it is “actually applicable in real-world practice, and you can use it in your own center,” he said.
Further, recent studies have demonstrated that treatment based on Khorana risk score assessment reduces VTE complications.
Prophylaxis options
Low-molecular-weight heparin (LMWH) has been shown in several studies to be associated with a significant relative VTE risk reduction in patients with cancer initiating chemotherapy – with only a slight, nonsignificant increase in the risk of major bleeding.
However, the absolute benefit was small, and LMWH is “parenteral, relatively costly, and, based on that, although we showed relatively good risk-benefit ratio, it never really got translated to clinical practice,” Dr. Carrier said.
In fact, a 2015 American Society of Clinical Oncology guidelines update recommended against routine thromboprophylaxis in this setting, but stated that it could be considered in select high-risk patients identified using a validated risk-assessment tool.
The guidelines noted that “individual risk factors such as biomarkers and cancer site don’t reliably identify high-risk patients.”
More recent data provide additional support for risk assessment and treatment based on Khorana risk score of 2 or higher.
The AVERT trial, for which Dr. Carrier was the first author, showed that the direct-acting oral anticoagulant (DOAC) apixaban reduced VTE incidence, compared with placebo, in patients with Khorana score of 2 or higher (4.2% vs. 10.2%; hazard ratio, 0.41 overall, and 1.0 vs. 7.3; HR, 0.14 on treatment), and the CASSINI trial showed that another DOAC, rivaroxaban, reduced VTE incidence, compared with placebo, in those with Khorana score of 2 or higher (5.9 vs. 6.7; HR, 0.6 overall, and 2.6 vs. 6.4; HR, 0.40 on treatment). The differences in the on-treatment populations were statistically significant.
The two trials, which included a variety of tumor types, showed similar rates of major bleeding, with an absolute difference of about 1% between treatment and placebo, which was not statistically significant in the on-treatment analyses (HR, 1.89 in AVERT and HR, 1.96 in CASSINI).
A systematic review of these trials showed an overall significant decrease in VTE complication risk with treatment in high-risk patients, and a nonstatistically significant major bleeding risk increase.
Based on these findings, ASCO guidelines were updated in 2020 to state that “routine thromboprophylaxis should not be offered to all patients with cancer. ... However, high-risk outpatients with cancer may be offered thromboprophylaxis with apixaban, rivaroxaban or LMWH, providing there are no significant risk factors for bleeding or drug-drug interactions, and after having a full discussion with patients ... to make sure they understand the risk-benefit ratio and the rationale for that particular recommendation,” he said.
Real-world implementation
Implementing this approach in the clinic setting requires a practical model, such as the Venous Thromboembolism Prevention in the Ambulatory Cancer Clinic (VTEPACC) program, a prospective quality improvement research initiative developed in collaboration with the Jeffords Institute for Quality at the University of Vermont Medical Center and described in a recent report, Dr. Carrier said.
The “Vermont model” is “really a comprehensive model that includes identifying patients with the electronic medical records, gathering the formal education and insight from other health care providers like pharmacists and nurses in order to really come up with personalized care for your patients,” he explained.
In 918 outpatients with cancer who were included in the program, VTE awareness increased from less than 5% before VTEPACC to nearly 82% during the implementation phase and 94.7% after 2 years, with nearly 94% of high-risk patients receiving VTE prophylaxis at that time.
“So we can certainly do that in our own center.” he said. “It’s a matter of coming up with the model and making sure that the patients are seen at the right time.”
Given the high frequency of VTE in patients with cancer initiating chemotherapy, the usefulness of risk scores such as the Khorana risk score for identifying those at high risk, and the availability of safe and effective interventions for reducing risk, “we should probably use the data and incorporate them into clinical practice by implementation of programs for primary prevention,” he said.
A word of caution
Caution is warranted, however, when it comes to using DOACs in patients with higher-risk or potentially higher-risk tumor types, he added.
“It’s an important question we are facing as clinicians on a daily basis,” he said, responding to an attendee’s query, as shared by session moderator James Douketis, MD, professor of medicine at McMaster University, Hamilton, Ont., regarding possible bleeding risks in certain genitourinary cancers.
A recent meta-analysis published in Nature, for example, noted that, in the SELECT-D trial, rivaroxaban was associated with significantly higher incidence of clinically relevant nonmajor bleeding, most often in bladder and colorectal cancers, and most often at genitourinary and gastrointestinal sites.
Both Dr. Carrier and fellow panelist Michael Streiff, MD, professor of medicine at Johns Hopkins University and medical director at the Johns Hopkins Hospital Special Coagulation Laboratory, Baltimore, said they approach DOAC use cautiously, but don’t rule it out entirely, in patients with unresected genitourinary tumors that could pose a risk of bleeding.
“It’s worth mentioning and being cautious. In my own personal practice, I’m very careful with unresected urothelial-type tumors or, for example, bladder cancer, for the same reason as [with] unresected luminal GI tumors,” Dr. Carrier said, adding that he’s also mindful that patients with nephropathy were excluded from U.S. DOAC trials because of bleeding risk.
He said he sometimes tries a LMWH challenge first in higher-risk patients, and then might try a DOAC if no bleeding occurs.
“But it certainly is controversial,” he noted.
Dr. Streiff added that he also worries less with genitourinary cancers than with upper GI lesions because “the signals weren’t as big as in GI” cancers, but he noted that “the drugs are going out through the kidneys ... so I’m cautious in those populations.”
“So caution, but not complete exclusion, is the operative management,” Dr. Douketis said, summarizing the panelists’ consensus.
Dr. Carrier reported clinical trial or advisory board participation for Bayer, Pfizer, Servier, Leo Pharma, and/or BMS.
FROM THE THSNA BIENNIAL SUMMIT
Factor XI inhibitor–based anticoagulation strategies gain ground
according to Jeffrey I. Weitz, MD.
These strategies could pick up where direct-acting oral anticoagulants leave off, he suggested during a presentation at the biennial summit of the Thrombosis & Hemostasis Societies of North America.
“We all know that the direct oral anticoagulants – the DOACs – are an advance over vitamin K antagonists,” said Dr. Weitz, professor of medicine and biochemistry at McMaster University, Hamilton, Ontario.
Not only are DOACs at least as effective as vitamin K antagonists such as warfarin for stroke prevention in atrial fibrillation or for treatment of venous thromboembolism (VTE), but they also reduce intracranial bleeding and major bleeding risk in those settings, respectively, and they are more convenient to administer because they can be delivered using fixed doses without the need for coagulation monitoring, he added.
Still, new targets are needed, he said, explaining that, although DOACs moved closer to the goal of attenuating thrombosis without increasing the risk of bleeding, annual rates of major bleeding remain at 2%-3% in the atrial fibrillation population, and rates of major and clinically relevant nonmajor bleeding are about 10%.
“The fear of bleeding leads to underuse of anticoagulants for eligible patients with atrial fibrillation and inappropriate use of low-dose [non–vitamin K antagonist oral anticoagulant] regimens, which can leave patients unprotected from thrombotic complications,” he said.
Factor XI
That’s where Factor XI (FXI) may come in, Dr. Weitz said.
Current anticoagulants target enzymes, including FXa or thrombin, in the common pathway of coagulation, but the intrinsic pathway at the level of FXI and FXII has attracted attention in recent years.
The intrinsic pathway is activated when blood comes into contact with medical devices like stents, mechanical heart valves, or central venous catheters, but evidence also suggests that it plays a role in clot stabilization and growth, he explained, noting additional evidence of attenuation of thrombosis in mice deficient in FXI or FXII and in animals with FXI or FXII inhibitors.
“There is no bleeding with congenital FXII deficiency, and patients with FXI deficiency rarely have spontaneous bleeding, although they can bleed with surgery or trauma,” he noted. “Therefore, the promise of contact pathway inhibition is that we can attenuate thrombosis with little or no disruption of hemostasis.”
The initiators of the intrinsic pathway are naturally occurring polyphosphates that can activate FXI and FXII, promote platelet activation, and lead to thrombosis. A number of agents are being investigated to target these enzymes – particularly FXI, for which the strongest epidemiological and other evidence of its link with thrombosis exists. He noted that FXI deficiency appears protective against deep-vein thrombosis (DVT) and ischemic stroke, whereas high levels are linked with an increased risk of venous and arterial thrombosis.
Investigative strategies include the use of antisense oligonucleotides to reduce hepatic synthesis of FXI, aptamers to bind FXI and block its activity, antibodies to bind FXI and block its activation or activity, and small molecules to bind reversibly to the active site of FXI and block its activity “much like the DOACs block the activity of FXa or thrombin.”
“We have to remember that the DOACs have taken over from vitamin K antagonists, like warfarin, for many indications, and as they go generic their uptake will increase even further,” Dr. Weitz said. “When we compare the FXI inhibitors with existing anticoagulants, we don’t necessarily want to go up against the DOACs – we’re looking for indications where [DOACs] have yet to be tested or may be unsafe.”
Potential indications include the following:
Prevention of major adverse cardiovascular events in patients with end-stage renal disease with or without atrial fibrillation.
Provision of a safer platform for antiplatelet therapy in patients with acute coronary syndrome.
Secondary stroke prevention.
Prevention or treatment of cancer-associated VTE.
Prevention of thrombosis associated with central venous catheters, left ventricular assist devices, or mechanical heart valves.
Agents in development
Of the FXI inhibitors in development, ISIS-FXIRx, an antisense oligonucleotide against FXI, is furthest along. In a study published in Blood, ISIS-FXIRx produced a dose-dependent and sustained reduction in FXI levels in healthy volunteers, and in a later randomized study published in The New England Journal of Medicine, it significantly reduced the incidence of DVT in patients undergoing voluntary total knee arthroplasty (30.4% with enoxaparin vs. 4.2% with ISIS-FXIRx at a dose of 300 mg). Bleeding rates were 8.3% and 2.6%, respectively.
The findings showed the potential for reducing thrombosis without increasing bleeding by targeting FXI, Dr. Weitz said, adding that ISIS-FXIRx was also evaluated in a small study of patients with end-stage renal disease undergoing hemodialysis and was shown to produce a dose-dependent reduction in FXI levels and to reduce the incidence of category 3 and 4 clotting in the air trap and dialyzer, compared with placebo, when given in addition to heparin.
This suggests that FXI knockdown can attenuate device-associated clotting to a greater extent than heparin alone, Dr. Weitz said.
The FXIa-directed inhibitory antibody osocimab has also been evaluated in both healthy volunteers and in patients undergoing total knee arthroplasty. In a 2019 study of healthy volunteers, a single IV injection showed a dose-dependent pharmacokinetic profile and produced FXI inhibition for about 1 month, and in the FOXTROT trial published in January in JAMA by Dr. Weitz and colleagues, osocimab was shown to reduce the incidence of symptomatic VTE, asymptomatic DVT, and VTE-related death up to day 10-13 after total knee arthroplasty.
Osocimab at doses ranging from 0.3-1.8 mg/kg given postoperatively or preoperatively were noninferior to enoxaparin (rates of 15.7%-23.7% vs. 26.3%), and osocimab at a preoperative dose of 1.8 mg/kg was superior to both enoxaparin and apixaban (11.5% vs. 26.3% and 14.5%, respectively), he said.
Bleeding rates ranged from 0%-5% with osocimab, compared with 6% with enoxaparin and 2% with apixaban
Ongoing studies
Currently ongoing studies of FXI-directed anticoagulation strategies include a study comparing ISIS-FXIRx with placebo in 200 patients with end-stage renal disease, a study comparing osocimab with placebo in 600 patients with end-stage renal disease, and a study comparing abelacimab – an antibody that binds to FXI and prevents its activation by either FXIIa or thrombin, with enoxaparin in 700 patients undergoing total knee arthroplasty, Dr. Weitz said.
Additionally, there is “considerable activity” with small molecule inhibitors of FXIa, including a phase 2, placebo-controlled, dose-ranging study looking at the novel JNG-7003/BMS-986177 agent for secondary stroke/transient ischemic attack prevention in 2,500 patients and a phase 2 study comparing it with enoxaparin for postoperative thromboprophylaxis in 1,200 patients undergoing total knee arthroplasty.
Parallel phase 2 studies are also underway to compare the novel BAY-2433334 small molecule inhibitor with placebo for stroke/transient ischemic attack prevention, with apixaban for atrial fibrillation, and for prevention of major adverse cardiovascular events in patients with acute MI.
These ongoing trials will help determine the risk-benefit profile of FXI inhibitors he said.
Session comoderator Anne Rose, PharmD, pharmacy coordinator at the University of Wisconsin, Madison, noted that these types of agents have been discussed “for quite some time” and asked whether they will be available for use in clinical practice in the near future.
Dr. Weitz predicted it will be at least a few years. The studies are just now moving to phase 2b and will still need to be evaluated in phase 3 trials and for appropriate new indications, he said.
Dr. Weitz reported research support from Canadian Institutes of Health research, Heart and Stroke Foundation, and Canadian Fund for Innovation, and he is a consultant and/or scientific advisory board member for Anthos, Bayer, Boehringer-Ingelheim, Bristol-Myers Squibb, Daiichi-Sankyo, Ionis Pharmaceuticals, Janssen, Merck, Novartis, Pfizer, Portola, Servier , and Thetherex.
according to Jeffrey I. Weitz, MD.
These strategies could pick up where direct-acting oral anticoagulants leave off, he suggested during a presentation at the biennial summit of the Thrombosis & Hemostasis Societies of North America.
“We all know that the direct oral anticoagulants – the DOACs – are an advance over vitamin K antagonists,” said Dr. Weitz, professor of medicine and biochemistry at McMaster University, Hamilton, Ontario.
Not only are DOACs at least as effective as vitamin K antagonists such as warfarin for stroke prevention in atrial fibrillation or for treatment of venous thromboembolism (VTE), but they also reduce intracranial bleeding and major bleeding risk in those settings, respectively, and they are more convenient to administer because they can be delivered using fixed doses without the need for coagulation monitoring, he added.
Still, new targets are needed, he said, explaining that, although DOACs moved closer to the goal of attenuating thrombosis without increasing the risk of bleeding, annual rates of major bleeding remain at 2%-3% in the atrial fibrillation population, and rates of major and clinically relevant nonmajor bleeding are about 10%.
“The fear of bleeding leads to underuse of anticoagulants for eligible patients with atrial fibrillation and inappropriate use of low-dose [non–vitamin K antagonist oral anticoagulant] regimens, which can leave patients unprotected from thrombotic complications,” he said.
Factor XI
That’s where Factor XI (FXI) may come in, Dr. Weitz said.
Current anticoagulants target enzymes, including FXa or thrombin, in the common pathway of coagulation, but the intrinsic pathway at the level of FXI and FXII has attracted attention in recent years.
The intrinsic pathway is activated when blood comes into contact with medical devices like stents, mechanical heart valves, or central venous catheters, but evidence also suggests that it plays a role in clot stabilization and growth, he explained, noting additional evidence of attenuation of thrombosis in mice deficient in FXI or FXII and in animals with FXI or FXII inhibitors.
“There is no bleeding with congenital FXII deficiency, and patients with FXI deficiency rarely have spontaneous bleeding, although they can bleed with surgery or trauma,” he noted. “Therefore, the promise of contact pathway inhibition is that we can attenuate thrombosis with little or no disruption of hemostasis.”
The initiators of the intrinsic pathway are naturally occurring polyphosphates that can activate FXI and FXII, promote platelet activation, and lead to thrombosis. A number of agents are being investigated to target these enzymes – particularly FXI, for which the strongest epidemiological and other evidence of its link with thrombosis exists. He noted that FXI deficiency appears protective against deep-vein thrombosis (DVT) and ischemic stroke, whereas high levels are linked with an increased risk of venous and arterial thrombosis.
Investigative strategies include the use of antisense oligonucleotides to reduce hepatic synthesis of FXI, aptamers to bind FXI and block its activity, antibodies to bind FXI and block its activation or activity, and small molecules to bind reversibly to the active site of FXI and block its activity “much like the DOACs block the activity of FXa or thrombin.”
“We have to remember that the DOACs have taken over from vitamin K antagonists, like warfarin, for many indications, and as they go generic their uptake will increase even further,” Dr. Weitz said. “When we compare the FXI inhibitors with existing anticoagulants, we don’t necessarily want to go up against the DOACs – we’re looking for indications where [DOACs] have yet to be tested or may be unsafe.”
Potential indications include the following:
Prevention of major adverse cardiovascular events in patients with end-stage renal disease with or without atrial fibrillation.
Provision of a safer platform for antiplatelet therapy in patients with acute coronary syndrome.
Secondary stroke prevention.
Prevention or treatment of cancer-associated VTE.
Prevention of thrombosis associated with central venous catheters, left ventricular assist devices, or mechanical heart valves.
Agents in development
Of the FXI inhibitors in development, ISIS-FXIRx, an antisense oligonucleotide against FXI, is furthest along. In a study published in Blood, ISIS-FXIRx produced a dose-dependent and sustained reduction in FXI levels in healthy volunteers, and in a later randomized study published in The New England Journal of Medicine, it significantly reduced the incidence of DVT in patients undergoing voluntary total knee arthroplasty (30.4% with enoxaparin vs. 4.2% with ISIS-FXIRx at a dose of 300 mg). Bleeding rates were 8.3% and 2.6%, respectively.
The findings showed the potential for reducing thrombosis without increasing bleeding by targeting FXI, Dr. Weitz said, adding that ISIS-FXIRx was also evaluated in a small study of patients with end-stage renal disease undergoing hemodialysis and was shown to produce a dose-dependent reduction in FXI levels and to reduce the incidence of category 3 and 4 clotting in the air trap and dialyzer, compared with placebo, when given in addition to heparin.
This suggests that FXI knockdown can attenuate device-associated clotting to a greater extent than heparin alone, Dr. Weitz said.
The FXIa-directed inhibitory antibody osocimab has also been evaluated in both healthy volunteers and in patients undergoing total knee arthroplasty. In a 2019 study of healthy volunteers, a single IV injection showed a dose-dependent pharmacokinetic profile and produced FXI inhibition for about 1 month, and in the FOXTROT trial published in January in JAMA by Dr. Weitz and colleagues, osocimab was shown to reduce the incidence of symptomatic VTE, asymptomatic DVT, and VTE-related death up to day 10-13 after total knee arthroplasty.
Osocimab at doses ranging from 0.3-1.8 mg/kg given postoperatively or preoperatively were noninferior to enoxaparin (rates of 15.7%-23.7% vs. 26.3%), and osocimab at a preoperative dose of 1.8 mg/kg was superior to both enoxaparin and apixaban (11.5% vs. 26.3% and 14.5%, respectively), he said.
Bleeding rates ranged from 0%-5% with osocimab, compared with 6% with enoxaparin and 2% with apixaban
Ongoing studies
Currently ongoing studies of FXI-directed anticoagulation strategies include a study comparing ISIS-FXIRx with placebo in 200 patients with end-stage renal disease, a study comparing osocimab with placebo in 600 patients with end-stage renal disease, and a study comparing abelacimab – an antibody that binds to FXI and prevents its activation by either FXIIa or thrombin, with enoxaparin in 700 patients undergoing total knee arthroplasty, Dr. Weitz said.
Additionally, there is “considerable activity” with small molecule inhibitors of FXIa, including a phase 2, placebo-controlled, dose-ranging study looking at the novel JNG-7003/BMS-986177 agent for secondary stroke/transient ischemic attack prevention in 2,500 patients and a phase 2 study comparing it with enoxaparin for postoperative thromboprophylaxis in 1,200 patients undergoing total knee arthroplasty.
Parallel phase 2 studies are also underway to compare the novel BAY-2433334 small molecule inhibitor with placebo for stroke/transient ischemic attack prevention, with apixaban for atrial fibrillation, and for prevention of major adverse cardiovascular events in patients with acute MI.
These ongoing trials will help determine the risk-benefit profile of FXI inhibitors he said.
Session comoderator Anne Rose, PharmD, pharmacy coordinator at the University of Wisconsin, Madison, noted that these types of agents have been discussed “for quite some time” and asked whether they will be available for use in clinical practice in the near future.
Dr. Weitz predicted it will be at least a few years. The studies are just now moving to phase 2b and will still need to be evaluated in phase 3 trials and for appropriate new indications, he said.
Dr. Weitz reported research support from Canadian Institutes of Health research, Heart and Stroke Foundation, and Canadian Fund for Innovation, and he is a consultant and/or scientific advisory board member for Anthos, Bayer, Boehringer-Ingelheim, Bristol-Myers Squibb, Daiichi-Sankyo, Ionis Pharmaceuticals, Janssen, Merck, Novartis, Pfizer, Portola, Servier , and Thetherex.
according to Jeffrey I. Weitz, MD.
These strategies could pick up where direct-acting oral anticoagulants leave off, he suggested during a presentation at the biennial summit of the Thrombosis & Hemostasis Societies of North America.
“We all know that the direct oral anticoagulants – the DOACs – are an advance over vitamin K antagonists,” said Dr. Weitz, professor of medicine and biochemistry at McMaster University, Hamilton, Ontario.
Not only are DOACs at least as effective as vitamin K antagonists such as warfarin for stroke prevention in atrial fibrillation or for treatment of venous thromboembolism (VTE), but they also reduce intracranial bleeding and major bleeding risk in those settings, respectively, and they are more convenient to administer because they can be delivered using fixed doses without the need for coagulation monitoring, he added.
Still, new targets are needed, he said, explaining that, although DOACs moved closer to the goal of attenuating thrombosis without increasing the risk of bleeding, annual rates of major bleeding remain at 2%-3% in the atrial fibrillation population, and rates of major and clinically relevant nonmajor bleeding are about 10%.
“The fear of bleeding leads to underuse of anticoagulants for eligible patients with atrial fibrillation and inappropriate use of low-dose [non–vitamin K antagonist oral anticoagulant] regimens, which can leave patients unprotected from thrombotic complications,” he said.
Factor XI
That’s where Factor XI (FXI) may come in, Dr. Weitz said.
Current anticoagulants target enzymes, including FXa or thrombin, in the common pathway of coagulation, but the intrinsic pathway at the level of FXI and FXII has attracted attention in recent years.
The intrinsic pathway is activated when blood comes into contact with medical devices like stents, mechanical heart valves, or central venous catheters, but evidence also suggests that it plays a role in clot stabilization and growth, he explained, noting additional evidence of attenuation of thrombosis in mice deficient in FXI or FXII and in animals with FXI or FXII inhibitors.
“There is no bleeding with congenital FXII deficiency, and patients with FXI deficiency rarely have spontaneous bleeding, although they can bleed with surgery or trauma,” he noted. “Therefore, the promise of contact pathway inhibition is that we can attenuate thrombosis with little or no disruption of hemostasis.”
The initiators of the intrinsic pathway are naturally occurring polyphosphates that can activate FXI and FXII, promote platelet activation, and lead to thrombosis. A number of agents are being investigated to target these enzymes – particularly FXI, for which the strongest epidemiological and other evidence of its link with thrombosis exists. He noted that FXI deficiency appears protective against deep-vein thrombosis (DVT) and ischemic stroke, whereas high levels are linked with an increased risk of venous and arterial thrombosis.
Investigative strategies include the use of antisense oligonucleotides to reduce hepatic synthesis of FXI, aptamers to bind FXI and block its activity, antibodies to bind FXI and block its activation or activity, and small molecules to bind reversibly to the active site of FXI and block its activity “much like the DOACs block the activity of FXa or thrombin.”
“We have to remember that the DOACs have taken over from vitamin K antagonists, like warfarin, for many indications, and as they go generic their uptake will increase even further,” Dr. Weitz said. “When we compare the FXI inhibitors with existing anticoagulants, we don’t necessarily want to go up against the DOACs – we’re looking for indications where [DOACs] have yet to be tested or may be unsafe.”
Potential indications include the following:
Prevention of major adverse cardiovascular events in patients with end-stage renal disease with or without atrial fibrillation.
Provision of a safer platform for antiplatelet therapy in patients with acute coronary syndrome.
Secondary stroke prevention.
Prevention or treatment of cancer-associated VTE.
Prevention of thrombosis associated with central venous catheters, left ventricular assist devices, or mechanical heart valves.
Agents in development
Of the FXI inhibitors in development, ISIS-FXIRx, an antisense oligonucleotide against FXI, is furthest along. In a study published in Blood, ISIS-FXIRx produced a dose-dependent and sustained reduction in FXI levels in healthy volunteers, and in a later randomized study published in The New England Journal of Medicine, it significantly reduced the incidence of DVT in patients undergoing voluntary total knee arthroplasty (30.4% with enoxaparin vs. 4.2% with ISIS-FXIRx at a dose of 300 mg). Bleeding rates were 8.3% and 2.6%, respectively.
The findings showed the potential for reducing thrombosis without increasing bleeding by targeting FXI, Dr. Weitz said, adding that ISIS-FXIRx was also evaluated in a small study of patients with end-stage renal disease undergoing hemodialysis and was shown to produce a dose-dependent reduction in FXI levels and to reduce the incidence of category 3 and 4 clotting in the air trap and dialyzer, compared with placebo, when given in addition to heparin.
This suggests that FXI knockdown can attenuate device-associated clotting to a greater extent than heparin alone, Dr. Weitz said.
The FXIa-directed inhibitory antibody osocimab has also been evaluated in both healthy volunteers and in patients undergoing total knee arthroplasty. In a 2019 study of healthy volunteers, a single IV injection showed a dose-dependent pharmacokinetic profile and produced FXI inhibition for about 1 month, and in the FOXTROT trial published in January in JAMA by Dr. Weitz and colleagues, osocimab was shown to reduce the incidence of symptomatic VTE, asymptomatic DVT, and VTE-related death up to day 10-13 after total knee arthroplasty.
Osocimab at doses ranging from 0.3-1.8 mg/kg given postoperatively or preoperatively were noninferior to enoxaparin (rates of 15.7%-23.7% vs. 26.3%), and osocimab at a preoperative dose of 1.8 mg/kg was superior to both enoxaparin and apixaban (11.5% vs. 26.3% and 14.5%, respectively), he said.
Bleeding rates ranged from 0%-5% with osocimab, compared with 6% with enoxaparin and 2% with apixaban
Ongoing studies
Currently ongoing studies of FXI-directed anticoagulation strategies include a study comparing ISIS-FXIRx with placebo in 200 patients with end-stage renal disease, a study comparing osocimab with placebo in 600 patients with end-stage renal disease, and a study comparing abelacimab – an antibody that binds to FXI and prevents its activation by either FXIIa or thrombin, with enoxaparin in 700 patients undergoing total knee arthroplasty, Dr. Weitz said.
Additionally, there is “considerable activity” with small molecule inhibitors of FXIa, including a phase 2, placebo-controlled, dose-ranging study looking at the novel JNG-7003/BMS-986177 agent for secondary stroke/transient ischemic attack prevention in 2,500 patients and a phase 2 study comparing it with enoxaparin for postoperative thromboprophylaxis in 1,200 patients undergoing total knee arthroplasty.
Parallel phase 2 studies are also underway to compare the novel BAY-2433334 small molecule inhibitor with placebo for stroke/transient ischemic attack prevention, with apixaban for atrial fibrillation, and for prevention of major adverse cardiovascular events in patients with acute MI.
These ongoing trials will help determine the risk-benefit profile of FXI inhibitors he said.
Session comoderator Anne Rose, PharmD, pharmacy coordinator at the University of Wisconsin, Madison, noted that these types of agents have been discussed “for quite some time” and asked whether they will be available for use in clinical practice in the near future.
Dr. Weitz predicted it will be at least a few years. The studies are just now moving to phase 2b and will still need to be evaluated in phase 3 trials and for appropriate new indications, he said.
Dr. Weitz reported research support from Canadian Institutes of Health research, Heart and Stroke Foundation, and Canadian Fund for Innovation, and he is a consultant and/or scientific advisory board member for Anthos, Bayer, Boehringer-Ingelheim, Bristol-Myers Squibb, Daiichi-Sankyo, Ionis Pharmaceuticals, Janssen, Merck, Novartis, Pfizer, Portola, Servier , and Thetherex.
FROM THE THSNA BIENNIAL SUMMIT