Apixaban versus warfarin for primary thromboprophylaxis in patients with multiple myeloma undergoing immunomodulatory treatment.

7548 Background: Immunomodulatory drugs (IMiDs) have been demonstrated to improve clinical outcomes in patients with multiple myeloma (MM), but are associated with an elevated risk of thromboembolism. Existing guidelines recommend low-dose direct oral anticoagulants as an alternative to warfarin for primary thromboprophylaxis in MM. However, the data comparing these two therapies are limited. We aim to compare the efficacy and safety of apixaban versus warfarin in patients with MM undergoing IMiD treatment. Methods: We conducted a retrospective propensity score-matched cohort study using the TriNetX Analytics Network database, which contains de-identified data from over 120 participating healthcare institutions. We included adult patients with MM who underwent IMiD treatment. Patients treated with apixaban were matched in a 1:1 ratio to those treated with warfarin using clinical variables a priori. The primary safety outcomes included all-cause mortality, intracranial hemorrhage, and gastrointestinal bleeding, while the primary efficacy outcomes included thromboembolic events including pulmonary embolism, deep venous thrombosis, and ischemic stroke within a 3-year period following IMiDs initiation. Results: We identified 448 patients on apixaban who were matched to patients on warfarin. In a Cox proportional hazard analysis, apixaban was associated with a 30% lower risk of all-cause mortality compared to warfarin (Hazard ratio (HR), 0.70 95% CI: 0.56-0.88).There was a tendency toward a reduced risk of gastrointestinal bleeding in patients treated with apixaban compared to warfarin (HR, 0.58 95% CI: 0.31-1.08, log-rank p = 0.083). The risk of intracranial hemorrhage was similar between the two groups.The risks of thromboembolic events including pulmonary embolism, deep venous thrombosis, and ischemic stroke were comparable between the apixaban and warfarin cohorts. Conclusions: Apixaban was associated with a lower risk of all-cause mortality and a comparable risk of bleeding and thromboembolism compared with warfarin among MM patients undergoing immunomodulatory treatment. Table: see text