Safety and efficacy of apixaban thromboprophylaxis in cancer patients with metastatic disease: A post-hoc analysis of the AVERT trial

Background: The risk of venous thromboembolism (VTE) is increased in patients with active cancer and the risk is highest in those with metastatic disease. The risks and benefits of thromboprophylaxis among cancer patients with metastatic disease initiating chemotherapy treatment are unknown. To address this important knowledge gap, we evaluated the efficacy and safety of apixaban thromboprophylaxis in patients with and without metastatic disease. Methods: Post-hoc analysis of the AVERT trial, which was a randomized, placebo-controlled, double-blind trial comparing apixaban therapy to placebo for VTE prophylaxis among cancer patients who were intermediate-to-high risk for VTE and who were initiating chemotherapy. The hazards ratios (HRs) for VTE and major bleeding episodes in patients with and without metastatic disease were calculated using a Cox regression model controlling for age, gender, and center. Results: A total of 574 patients underwent randomization and 365 patients could be stratified according to the presence (n = 138) or absence (n = 227) of metastatic disease. In patients with metastatic disease, those receiving apixaban had a significantly lower risk of VTE (HR 0.55; 95% CI 0.32 to 0.97) without a significant increase in major bleeding complications (HR 1.36 95% CI 0.27 to 6.93) compared to those on placebo. In patients without metastatic disease, the use of apixaban was also associated with a significantly lower risk of VTE (HR 0.34 95% CI 0.19 to 0.60) without a significant increase in major bleeding complications (HR 1.14 95% CI 0.08 to 15.91). Conclusions: In patients with and without metastatic disease, apixaban thromboprophylaxis was associated with a significantly lower rate of VTE compared to placebo. © 2020 Elsevier Ltd