Direct Oral Anticoagulants (DOACs) Vs. Low Molecular Weight Heparins (LMWH) for Venous Thromboembolism (VTE) in Patients with Primary Brain Tumors or Secondary Brain Metastases

Background: Management of venous thromboembolism (VTE) in patients with central nervous system (CNS) malignancies is challenging as there is an increased risk of recurrent VTE and intracranial hemorrhage (ICH). Low molecular weight heparins (LMWH) have historically been the standard of care for treatment of cancer-associated thrombosis (CAT). Current guidelines recommend direct oral anticoagulants (DOACs) for CAT treatment, but patients with CNS malignancies have limited representation in the supporting clinical trials. This multicenter, retrospective cohort study evaluated the safety and efficacy of DOACs compared to LMWH for CAT in patients with primary brain tumors or secondary brain metastases.

Patients/Methods: In this multicenter, retrospective cohort study, adult patients with a diagnosis of primary brain tumor or secondary brain metastases who received either a DOAC or LMWH for CAT were evaluated. The primary outcome was the incidence of any bleeding event within a 6-month period following the initiation of anticoagulation. Secondary outcomes included incidence of recurrent VTE events, major bleeding, clinically relevant non-major bleeding (CRNMB), and minor bleeding, within a 6-month period following the initiation of anticoagulation. Patients were excluded if their indication for anticoagulation was stroke, non-cancer-associated VTE, or VTE prophylaxis, were on LMWH for one week or less while bridging to warfarin, or received a diagnosis of VTE at an outside hospital. All bleeding events were defined by the International Society on Thrombosis and Haemostasis (ISTH) criteria. Primary and secondary outcomes were analyzed using Fisher's exact test for categorical variables and Wilcoxon rank-sum tests for non-parametric continuous variables.

Results: Between January 1, 2012 to October 9, 2019, one-hundred eleven patients met inclusion criteria. Of the patients who met inclusion criteria, 26 (23.4%) patients had primary brain tumors and 85 (76.6%) patients had secondary brain metastases. Bleeding events occurred in 7 of 55 patients (12.7%) in the DOAC group compared to 13 of 56 (23.2%) patients in the LMWH group (RR 0.55, 95% CI 0.24-1.27). Recurrent VTE events occurred in 3 of 55 (5.5%) patients in the DOAC group compared to 3 of 56 (5.4%) patients in the LMWH group (RR 1.02, 95% CI 0.21-4.83). Major bleeding occurred in 3 of 55 (5.5%) patients in the DOAC group, compared to 4 of 56 (7.1%) patients in the LMWH group (RR 0.76, 95% CI 0.18-3.26). There were no differences in the rates of CRNMB and rates of minor bleeding between groups.

Conclusion: In this multicenter retrospective cohort study, therapeutic anticoagulation with DOACs showed no significant difference in bleeding events or recurrent VTE events when compared to LMWH, in patients with primary brain tumors or secondary brain metastases. We conclude that DOACs may be potentially safe and efficacious for VTE treatment in patients with primary brain tumors or secondary brain metastases. As prescribing practices are expected to continue to shift towards DOACs, this study provides preliminary evidence of the safety of DOACs in this high-bleeding risk patient population.