Apixaban reduces VTE risk across multiple chemotherapy regimens in ambulatory cancer patientsApixaban reduces blood clot risk for patients starting chemotherapy

BACKGROUND: Venous thromboembolism (VTE) is a leading cause of morbidity and mortality in cancer patients. The AVERT trial showed apixaban thromboprophylaxis reduced VTE in intermediate-to-high-risk patients initiating chemotherapy. However, the efficacy and safety of apixaban according to baseline chemotherapy class remain incompletely characterized. METHODS: We conducted a post hoc analysis stratified by chemotherapy class of the randomized, double-blind, placebo-controlled AVERT trial comparing apixaban (2.5 mg twice daily) with placebo in ambulatory cancer patients initiating chemotherapy. The primary efficacy outcome was VTE, and the primary safety outcome was clinically relevant bleeding (major or clinically relevant non major bleeding (CRNMB)) per ISTH criteria. A subgroup analysis compared platinum-based with non-platinum chemotherapy. Cox proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CI), adjusted for age, sex, and study site. Treatment-by-platinum interaction terms were used to assess effect modification by platinum exposure. RESULTS: A total of 563 patients were included and categorized by one or more chemotherapy classes at randomization. Compared with placebo, apixaban appeared to reduce VTE in patients on platinum (HR 0.30, 95% CI 0.16-0.57), taxane (HR 0.42, 95% CI 0.23-0.75), taxane-platinum (HR 0.28, 95% CI 0.12-0.68), topoisomerase inhibitor (HR 0.32, 95% CI 0.19-0.53), and antimetabolite regimens (HR 0.25, 95% CI 0.12-0.54), without increased bleeding. Among placebo-treated patients, platinum-based chemotherapy was associated with a higher risk of VTE compared with non-platinum regimens (HR 2.25, 95% CI 1.48-3.42), whereas no statistically significant difference was observed among apixaban-treated patients. Treatment-by-platinum interaction testing did not demonstrate significant effect modification by platinum exposure. CONCLUSION: In this exploratory, hypothesis-generating analysis, apixaban thromboprophylaxis was associated with reduced VTE across several chemotherapy regimens with generally acceptable safety outcomes. Patients receiving platinum-based chemotherapy may derive greater absolute benefit from thromboprophylaxis in the setting of higher underlying thrombotic risk.