Abstract 4145490: Direct Oral Anticoagulants versus Low Molecular Weight Heparins for Prevention of VTE in Active Malignancy: Insights from a Pooled Analysis of RCTs

Background: Cancer is well known to cause a pro-thrombotic state, however, the pharmacologic therapy for prevention of Venous Thromboembolism (VTE) remains under contention. Direct Oral Anticoagulants (DOACs) and Low Molecular Weight Heparins (LMWHs) remain the mainstay treatment to prevent VTE in active malignancy. The purpose of this pooled analysis is to clarify the safety and efficacy of DOACs and LMWHs in the prevention of VTE and the risk of bleeding. Methods: A systematic search of MEDLINE was conducted using PRISMA guidelines using the search terms “DOAC”, “VTE”, “LMWH” and “Cancer OR Malignancy”. Studies were only included if they were prospective and randomized with a control group. Clinical characteristics of patients and outcomes were aggregated according to the Cochrane Manual. A random effects model using clinical events as dichotomous variables and was utilized to calculate Odds Ratios with 95% confidence intervals. Revman 5.3 was used to aggregate outcomes and statistics. Results: A total of 3880 patients were included in this analysis. Solid organ tumors remained the most enrolled malignancies included in the trials, with gastrointestinal malignancies being the most common. Apixaban, Rivaroxaban, Edoxaban, and Dalteparin were compared in these trials. There was a significant reduction in VTE in favor of the DOACs (OR: 0.64 [0.49, 0.82], P=0.0004). There was no significant difference in major bleeding between DOACs and LMWH (OR: 1.22 [0.80, 1.86], P= 0.36). There was a significant increase in Clinically Relevant Non-Major Bleeding in the DOAC group (OR: 1.68 [1.3, 2.17], P<0.0001). There was no significant difference in All Cause Death (OR: 1.02 [0.88, 1.18], P=0.78). Conclusion: DOACs significantly reduced VTE as compared to LMWHs at the expense of an increase in Clinically relevant Non-Major Bleeding. Shared decision making should be utilized with the patient to balance the risks of VTE versus bleeding. Further trials are needed to confirm the safety and efficacy of anticoagulation with differing types of malignancies to guide VTE treatment.