Assessing Full Benefit of Rivaroxaban Prophylaxis in High-Risk Ambulatory Patients with Cancer: Thromboembolic Events in the Randomized CASSINI Trial

Cancer patients and ischemic stroke

Patients with cancer have an increased risk of ischemic stroke compared to the general population. Additionally, these patients have a worse prognosis compared to stroke patients without cancer. Activation of coagulation appears to play a key role in the pathophysiology of ischemic stroke in patients with cancer. However, the underlying mechanisms remain unknown. Moreover, we do not have a way to identify cancer patients with a high risk of stroke and cannot develop prevention strategies. Therefore, there is an urgent need for neurologists and oncologists to develop screening and prevention strategies for stroke in patients with cancer. In this review, we summarize the characteristics of cancer patients at a high risk of stroke, the predictors for the development of stroke and survival in cancer patients, and possible treatments.

Anticoagulation for the Prevention of Arterial Thrombosis in Ambulatory Cancer Patients: Systematic Review and Meta-Analysis

Background

The risk of arterial thrombotic events (ATEs) is high among patients on systemic anticancer therapies. Despite the efficacy of anticoagulants in the prevention of cancer-associated venous thromboembolism, it is unknown whether anticoagulation is effective to prevent ATEs.

Objectives

This study sought to examine the efficacy and safety of anticoagulants in ATE prevention among ambulatory cancer patients.

Methods

We performed a systematic review using Medline, Embase, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) from inception to May 21, 2022, and included studies comparing oral or parenteral anticoagulation with no anticoagulation among ambulatory patients receiving systemic anticancer therapy with no other indication for anticoagulation. The primary outcome was ATE (myocardial infarction, ischemic stroke, intra-abdominal arterial embolism, or peripheral artery occlusion). The secondary outcomes were major and nonmajor bleeding and all-cause mortality.

Results

Fourteen randomized trials involving low-molecular-weight heparins, direct oral anticoagulants, and warfarin were included. ATEs were captured as coefficacy endpoints or adverse events. Anticoagulant use was not associated with a reduction in ATEs compared with placebo or standard treatment (RR: 0.73, 95% CI: 0.50-1.04; P = 0.08; I2 = 0%). RRs of major and minor bleeding were 1.56 (95% CI: 1.12-2.17) and 2.25 (95% CI: 1.45-3.48) with anticoagulant use. In 13 trials that reported all-cause mortality, risk of death was not reduced with anticoagulants (RR: 0.99; 95% CI: 0.95-1.02; P = 0.38; I2 = 0%).

Conclusions

Anticoagulants did not reduce ATE risk among ambulatory patients on systemic anticancer therapy and were associated with increased bleeding. Based on the current data, anticoagulants have a limited role in ATE prevention in this population as a whole.

Direct-Acting Oral Anticoagulant Therapy in Cancer Patients-A Review

Venous thromboembolism (VTE) is an important aspect in cancer patients. There are various pharmacological methods used for thrombotic event treatment. DOACs (direct-acting oral anticoagulants) are gaining popularity among both physicians and researchers and are slowly starting to replace VKAs (vitamin K antagonists), thus becoming a substitute or alternative option for LMWHs (low-molecular-weight heparins). In this article, we present DOACs' main therapeutic advantages and disadvantages in patients with cancer. The only major concern with using DOACs is the higher risk of bleeding; however, there are discrepancies in this matter. There are still some types of cancer for which DOACs are not recommended. Specific cancer types may influence the efficacy of DOAC therapy. Additionally, race and ethnicity may affect therapy in cancer patients with DOACs. A sizeable number of clinical trials are focused on comparing DOACs with other anticoagulants. The current guidelines of different scientific associations are not unanimous in their DOAC assessments. There is still a need for more evidence of DOACs' potential advantages over other methods of anticoagulation in cancer patients to facilitate their position in this recommendation. This literature review presents the current state of knowledge about the use of DOACs in patients with neoplastic growth.

Approach to Contemporary Risk Assessment, Prevention and Management of Thrombotic Complications in Multiple Myeloma

Multiple myeloma (MM) is associated with an increased risk of thrombotic complications, which remains substantial despite the implementation of thromboprophylaxis. The procoagulant state that characterizes the disease is multifactorial, and a greater understanding of the underlying pathophysiology is required to inform appropriate thrombosis prevention. Currently, there is a shift towards using direct oral anticoagulants (DOACs) in this setting; head-to-head comparisons in the context of controlled clinical trials between class agents are still missing. MM-specific VTE risk assessment scores have been developed to optimize management and minimize the associated mortality/morbidity. Their clinical utility remains to be evaluated. The value of adding biomarkers to clinical scores to optimize their performance and increase their discriminatory power is also under assessment.

The Khorana score and venous and arterial thrombosis in patients with cancer treated with immune checkpoint inhibitors: A Danish cohort study

BACKGROUND

Thrombosis is common among patients with cancer. Primary thromboprophylaxis guided by the Khorana score is endorsed by guidelines but recommendations rely mainly on data from patients treated with chemotherapy.

OBJECTIVES

To explore if the Khorana score could risk stratify patients with cancer treated with immune checkpoint inhibitors according to risk of venous and arterial thrombosis.

PATIENTS/METHODS

The study population and Khorana score were defined using administrative Danish health registries. The primary outcome was 6-month risk of venous thromboembolism after initiation of checkpoint inhibitor treatment. Secondary outcomes were arterial thrombosis and any thromboembolic event. Death was considered a competing risk event.

RESULTS

Among 3946 patients with cancer initiating checkpoint inhibitor treatment without other indications for anticoagulation, the overall 6-month incidence of venous thromboembolism was 2.6% (95% confidence interval [CI]: 2.1-3.1). Risks were 2.1% (95% CI: 1.5-3.0), 2.6% (95% CI: 2.0-3.4), and 3.7% (95% CI: 2.1-5.9) in low (score 0), intermediate (score 1-2), and high risk (score ≥3) Khorana categories, respectively. Among patients eligible for primary thromboprophylaxis according to guidelines (Khorana score ≥2), risk of venous thromboembolism was 4.1% (95% CI: 3.1-5.4). Higher Khorana risk category was also associated with higher 6-month risk of both arterial thrombosis and any thromboembolic events.

CONCLUSIONS

The Khorana score was able to risk stratify patients with cancer treated with immune checkpoint inhibitors according to 6-month risk of thromboembolic events. Risks of venous thromboembolism were lower than in randomized thromboprophylaxis trials, thus questioning the absolute benefit of routine primary thromboprophylaxis in an unselected population of patients treated with immune checkpoint inhibitors.

Cancer-associated venous thromboembolism

Cancer-associated thrombosis (including venous thromboembolism (VTE) and arterial events) is highly consequential for patients with cancer and is associated with worsened survival. Despite substantial improvements in cancer treatment, the risk of VTE has increased in recent years; VTE rates additionally depend on the type of cancer (with pancreas, stomach and primary brain tumours having the highest risk) as well as on individual patient's and cancer treatment factors. Multiple cancer-specific mechanisms of VTE have been identified and can be classified as mechanisms in which the tumour expresses proteins that alter host systems, such as levels of platelets and leukocytes, and in which the tumour expresses procoagulant proteins released into the circulation that directly activate the coagulation cascade or platelets, such as tissue factor and podoplanin, respectively. As signs and symptoms of VTE may be non-specific, diagnosis requires clinical assessment, evaluation of pre-test probability, and objective diagnostic testing with ultrasonography or CT. Risk assessment tools have been validated to identify patients at risk of VTE. Primary prevention of VTE (thromboprophylaxis) has long been recommended in the inpatient and post-surgical settings, and is now an option in the outpatient setting for individuals with high-risk cancer. Anticoagulant therapy is the cornerstone of therapy, with low molecular weight heparin or newer options such as direct oral anticoagulants. Personalized treatment incorporating risk of bleeding and patient preferences is essential, especially as a diagnosis of VTE is often considered by patients even more distressing than their cancer diagnosis, and can severely affect the quality of life. Future research should focus on current knowledge gaps including optimizing risk assessment tools, biomarker discovery, next-generation anticoagulant development and implementation science.

Risk of Thrombo-Embolic Events in Ovarian Cancer: Does Bevacizumab Tilt the Scale? A Systematic Review and Meta-Analysis

Simple Summary

Thromboembolic events (TEs) are the second cause of death in cancer patients. Two forms of thromboembolic events may arise: arterial, such as ischemic stroke or myocardial infarction; and venous, such as deep vein thrombosis or pulmonary embolism. Bevacizumab is a monoclonal antibody directed against vascular endothelial-derived growth factor, and is widely used in advanced ovarian cancer. However, whether bevacizumab increases the risk of thromboembolic events in ovarian cancer is matter of debate since studies have shown conflicting results. In our systematic review and meta-analysis, we included 14 trials with bevacizumab in ovarian cancer. We found that the risk of arterial thromboembolic events more than doubled with a risk ratio of 2.45. Also the risk of venous thromboembolism increased 30% with bevacizumab treatment. Bevacizumab, therefore, can be considered an additional risk factor for selecting patients for primary prophylaxis with anticoagulants.

Abstract

Thromboembolic events are the second cause of death in cancer patients. In ovarian cancer, 3–10% of patients present with venous thromboembolism (VTE), but the incidence may rise to 36% along the disease course. Bevacizumab is a monoclonal antibody directed against vascular endothelial-derived growth factor, and in in vitro studies it showed a predisposition to hemostasis perturbation, including thrombosis. However, in vivo and clinical studies have shown conflicting results for its use as a treatment for ovarian cancer, so we conducted a systematic review and meta-analysis on the risk of arterial thromboembolism (ATE) and VTE in ovarian cancer patients treated with bevacizumab. The review comprised 14 trials with 6221 patients: ATE incidence was reported in 5 (4811 patients) where the absolute risk was 2.4% with bevacizumab vs. 1.1% without (RR 2.45; 95% CI 1.27–4.27, p = 0.008). VTE incidence was reported in 9 trials (5121 patients) where the absolute risk was 5.4% with bevacizumab vs. 3.7% without (RR 1.32; 95% CI 1.02–1.79, p = 0.04). Our analysis showed that the risk of arterial and venous thromboembolism increased in patients treated with bevacizumab. Thrombolic events (TEs) are probably underreported, and studies should discriminate between ATE and VTE. Bevacizumab can be considered as an additional risk factor when selecting patients for primary prophylaxis with anticoagulants.

Pulmonary embolism at autopsy in cancer patients

BACKGROUND

Pulmonary embolism (PE) is a potentially fatal disease, but data on the incidence of fatal PE in cancer patients are scant.

OBJECTIVE

We sought to estimate the proportion of cancer patients with PE at autopsy.

METHODS

For this retrospective cohort study, all autopsy reports of cancer patients were retrieved from PALGA: Dutch Pathology Registry and used for data extraction. The primary outcome was PE at time of autopsy, defined as any clot obstructing a pulmonary artery. The secondary outcome was venous thromboembolism, defined as the composite of thrombotic PE, deep vein thrombosis, splanchnic vein thrombosis, or internal jugular vein thrombosis.

RESULTS

A total of 9571 cancer patients were included. In 1191 (12.4%; 95% confidence interval [CI], 11.8-13.1) patients, one or more PE events were observed at autopsy, of whom 1074 (90.2%) had a thrombotic embolism, 168 (14.1%) a tumor embolism, 9 (0.8%) a septic embolism, 7 (0.6%) a fat tissue embolism, and 3 (0.3%) a bone marrow embolism. Among patients with PE for whom the cause of death was specified in the autopsy report, death was considered PE-related in 642 patients (66.7%), which was 6.7% of the total study population. Venous thromboembolism was observed in 1223 (12.8%; 95% CI, 12.1-13.5) patients.

CONCLUSION

The proportion of PE in cancer patients at autopsy is substantial. Although the study population is not representative for the total cancer population, it suggests that PE is an important disease complication in cancer patients.

Primary prophylaxis for venous thromboembolism in ambulatory cancer patients receiving chemotherapy

BACKGROUND

Venous thromboembolism (VTE) often complicates the clinical course of cancer. The risk is further increased by chemotherapy, but the trade-off between safety and efficacy of primary thromboprophylaxis in cancer patients treated with chemotherapy is uncertain. This is the third update of a review first published in February 2012.

OBJECTIVES

To assess the efficacy and safety of primary thromboprophylaxis for VTE in ambulatory cancer patients receiving chemotherapy compared with placebo or no thromboprophylaxis, or an active control intervention.

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Cochrane Vascular, CENTRAL, MEDLINE, Embase and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 3 August 2020. We also searched the reference lists of identified studies and contacted content experts and trialists for relevant references.

SELECTION CRITERIA

Randomised controlled trials comparing any oral or parenteral anticoagulant or mechanical intervention to no thromboprophylaxis or placebo, or comparing two different anticoagulants.

DATA COLLECTION AND ANALYSIS

We extracted data on risk of bias, participant characteristics, interventions, and outcomes including symptomatic VTE and major bleeding as the primary effectiveness and safety outcomes, respectively. We applied GRADE to assess the certainty of evidence.

MAIN RESULTS

We identified six additional randomised controlled trials (3326 participants) for this update, bringing the included study total to 32 (15,678 participants), all evaluating pharmacological interventions and performed mainly in people with locally advanced or metastatic cancer. The certainty of the evidence ranged from high to very low across the different outcomes and comparisons. The main limiting factors were imprecision and risk of bias. Thromboprophylaxis with direct oral anticoagulants (direct factor Xa inhibitors apixaban and rivaroxaban) may decrease the incidence of symptomatic VTE (risk ratio (RR) 0.43, 95% confidence interval (CI) 0.18 to 1.06; 3 studies, 1526 participants; low-certainty evidence); and probably increases the risk of major bleeding compared with placebo (RR 1.74, 95% CI 0.82 to 3.68; 3 studies, 1494 participants; moderate-certainty evidence). When compared with no thromboprophylaxis, low-molecular-weight heparin (LMWH) reduced the incidence of symptomatic VTE (RR 0.62, 95% CI 0.46 to 0.83; 11 studies, 3931 participants; high-certainty evidence); and probably increased the risk of major bleeding events (RR 1.63, 95% CI 1.12 to 2.35; 15 studies, 7282 participants; moderate-certainty evidence). In participants with multiple myeloma, LMWH resulted in lower symptomatic VTE compared with the vitamin K antagonist warfarin (RR 0.33, 95% CI 0.14 to 0.83; 1 study, 439 participants; high-certainty evidence), while LMWH probably lowers symptomatic VTE more than aspirin (RR 0.51, 95% CI 0.22 to 1.17; 2 studies, 781 participants; moderate-certainty evidence). Major bleeding was observed in none of the participants with multiple myeloma treated with LMWH or warfarin and in less than 1% of those treated with aspirin. Only one study evaluated unfractionated heparin against no thromboprophylaxis, but did not report on VTE or major bleeding. When compared with placebo or no thromboprophylaxis, warfarin may importantly reduce symptomatic VTE (RR 0.15, 95% CI 0.02 to 1.20; 1 study, 311 participants; low-certainty evidence) and may result in a large increase in major bleeding (RR 3.82, 95% CI 0.97 to 15.04; 4 studies, 994 participants; low-certainty evidence). One study evaluated antithrombin versus no antithrombin in children. This study did not report on symptomatic VTE but did report any VTE (symptomatic and incidental VTE). The effect of antithrombin on any VTE and major bleeding is uncertain (any VTE: RR 0.84, 95% CI 0.41 to 1.73; major bleeding: RR 0.78, 95% CI 0.03 to 18.57; 1 study, 85 participants; very low-certainty evidence).

AUTHORS' CONCLUSIONS

In ambulatory cancer patients, primary thromboprophylaxis with direct factor Xa inhibitors may reduce the incidence of symptomatic VTE (low-certainty evidence) and probably increases the risk of major bleeding (moderate-certainty evidence) when compared with placebo. LMWH decreases the incidence of symptomatic VTE (high-certainty evidence), but increases the risk of major bleeding (moderate-certainty evidence) when compared with placebo or no thromboprophylaxis. Evidence for the use of thromboprophylaxis with anticoagulants other than direct factor Xa inhibitors and LMWH is limited. More studies are warranted to evaluate the efficacy and safety of primary prophylaxis in specific types of chemotherapeutic agents and types of cancer, such as gastrointestinal or genitourinary cancer.

Prediction and Prevention of Cancer-Associated Thromboembolism

Venous and arterial thromboembolism are prevalent, highly burdensome, and associated with risk of worse outcomes for patients with cancer. Risk for venous thromboembolism (VTE) varies widely across specific cancer subpopulations. The ability to predict risk of cancer-associated VTE is critical because an optimal thromboprophylaxis strategy is best achieved by targeting high-risk patients with cancer and avoiding prophylaxis in patients with cancer at low risk for VTE. A validated risk tool for solid tumors has been available for a decade. Newer tools have focused on specific populations, such as patients with multiple myeloma. Emerging studies continue to optimize risk prediction approaches in patients with cancer. Recent randomized trials have specifically addressed risk-adapted thromboprophylaxis using direct oral anticoagulants, and revised guidelines have included these new data to formulate recommendations for outpatient thromboprophylaxis. Implementation science approaches to enhance use of outpatient prophylaxis in the context of these guideline changes are under way. However, major knowledge gaps remain, including a lack of data for inpatient thromboprophylaxis in the cancer setting and a lack of formal tools for identifying risk of bleeding. This review describes optimal approaches to risk prediction and patient selection for primary pharmacologic thromboprophylaxis of cancer-associated VTE, addresses barriers to implementing these practices, and highlights strategies to overcome them. IMPLICATIONS FOR PRACTICE: Risk for venous thromboembolism (VTE) varies widely among patients with cancer. Individual risk can be determined using validated approaches. Inpatient and postsurgical thromboprophylaxis is more widely accepted. However, most patients with cancer develop VTE in the outpatient setting. Recent randomized trials have demonstrated benefit to risk-adapted outpatient thromboprophylaxis. High-risk patients may therefore be considered for outpatient thromboprophylaxis as recommended by recently updated guidelines. System-wide implementation approaches are necessary to improve compliance with prophylaxis.