ABCL-104 Direct Oral Anticoagulants for the Treatment of Venous Thromboembolism in Patients With Hematological Malignancies

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Data is needed on direct oral anticoagulants (DOACs) for the treatment of venous thromboembolism (VTE) in hematological malignancies (HM). Retrospective studies to date have lacked a control group and included patients with atrial fibrillation and/or VTE, but not VTE alone. Assess the incidence of VTE recurrence and bleeding in HM patients treated with low molecular weight heparin (LMWH) or DOACs for acute VTE. Retrospective cohort study. The study included subjects with active HM and newly diagnosed VTE treated as inpatients or outpatients in the hemato-oncology department at Rabin or Meir Medical Centers (1/2015-7/2021). Patients were indexed on the first day of anticoagulation for VTE and followed for 12 months. Type of anticoagulation at study index, classified as LMWH or DOAC. Composite of recurrent VTE, clot progression, major bleeding, or clinically relevant non-major bleeding (CRNMB). Cumulative incidence (95% confidence interval [CI]) was calculated for each anticoagulation group (LMWH, DOAC) and hazard ratios (HRs) were calculated using the Cox proportional-hazards model with death as a competing risk. A total of 143 HM patients treated with LMWH (96) or DOACs (47) for acute VTE were included. HM was lymphoma in 83 (58%). DOAC-treated patients were older and had more pulmonary embolisms and less splanchnic vein thrombosis. The 12-month cumulative incidence of the primary outcome was 24.2% (95% CI 15.9%-33.5%; n=22) in the LMWH group and 18.5% (8.5%-31.5%; n=8) in the DOAC group (HR 1.51 [0.695-3.297]). Two recurrent VTEs occurred (both in the DOAC group while off-treatment). Nine (9.4%) LMWH-treated patients and 1 (2.1%) DOAC-treated patient (HR 4.85 [0.64-36.56]) had major bleeding. There were 13 (13.5%) CRNMB cases in the LMWH group and 5 (10.6%) in the DOAC group (HR 1.44 [0.52-3.98]). This study generates the hypothesis that DOACs may be a safe and effective alternative to LMWH for VTE in patients with lymphoma or plasma cell dyscrasia. Larger prospective studies are needed to confirm these findings.