Efficacy and safety of apixaban for primary prevention in gastrointestinal cancers: A post-hoc analysis of the AVERT trial

Abstract

Background: Recent trials have demonstrated that thromboprophylaxis using direct oral anticoagulants is effective but associated with a higher rate of major bleeding in intermediate-to-high risk (Khorana score ≥ 2) patients with cancer initiating systemic chemotherapy. Patients with gastrointestinal cancer may be at higher risk of major bleeding complications. We sought to assess the efficacy and safety of using thromboprophylaxis with apixaban in this patient population.

Methods: This is a post-hoc analysis of the AVERT trial, which was a randomized, placebo-controlled, double-blind clinical trial. The primary efficacy outcome was objectively documented venous thromboembolism within 180 days of randomization. The primary safety outcome was a major bleeding episode. Time-to-event analyses were performed in patients with gastrointestinal cancers (upper gastrointestinal, pancreatic/hepatobiliary and colorectal cancers).

Results: A total of 130 patients from the original AVERT trial were included, with 65 patients allocated to each of the apixaban and placebo groups. VTE occurred in 3 (4.6%) patients in the apixaban group and 13 (20%) patients in the placebo group (HR: 0.27; 95% CI: 0.13-0.54; p = 0.0002). Major bleeding occurred in 2 (3.1%) patients in the apixaban group and 1 (1.5%) patient in the placebo group (HR 2.39, 95% CI 0.29-19.78, p = 0.42). None of the major bleeding events occurred in patients with upper gastrointestinal or colorectal cancers.

Conclusion: Primary thromboprophylaxis with apixaban therapy seems to be safe and effective in patients with gastrointestinal cancers. Major bleeding complications are uncommon in our cohort. (Funded by the CIHR and Bristol-Myers Squibb-Pfizer Alliance; NCT02048865).

Keywords: Apixaban; Hemorrhage; Neoplasia; Venous thromboembolism; Venous thrombosis.