Real-life venous thromboembolism risk scores in multiple myeloma receiving daratumumab, lenalidomide, and dexamethasone

Background: Treatment with daratumumab and lenalidomide has improved survival in patients with multiple myeloma (MM), however the risk of venous thromboembolism (VTE) is high. Data on the accuracy of VTE risk scores in MM receiving daratumumab are limited. Objectives: To assess (i) the prognostic accuracy of available VTE risk scores (IMPEDE-VTE, SAVED, PRISM, and EHR-CAT scores) in non-transplant-eligible MM (NTE-MM) and relapsed/refractory MM (RRMM) consecutively treated with daratumumab, lenalidomide and dexamethasone (Dara-Rd); and (ii) the feasibility and safety of guideline-recommended thromboprophylaxis with low molecular weight heparin for 6 months followed by aspirin (LMWH-ASA). Design: Single-center, retrospective, cohort study. Methods: All consecutive MM patients treated with Dara-Rd and concomitant LMWH-ASA thromboprophylaxis between July, 2018 and September, 2023 were evaluated through chart review. Kaplan-Meier method and Concordance-Index (C-index) were used to estimate risk scores’ prognostic accuracy. Results: 95 patients (median age 74 years) were included (n= 47 NTE-MM, and n= 48 RRMM). At 12 months from Dara-Rd initiation, 10 (10.4%) patients developed VTE; 4 (4.2%) had bleeding complications, and 2 (2.1%) patients died. Six VTE events (6.2%) occurred within first 6 months from Dara-Rd initiation while on LMWH prophylaxis, whereas 2 VTE (2%) developed in two patients receiving aspirin. The accuracy of IMPEDE-VTE, SAVED, PRISM and EHR-CAT scores was generally poor, with C-Index values ranging from 0.43 (95% confidence intervals [95%CI] 0.30 to 0.56) to 0.53 (95%CI: 0.38 to 0.68). LMWH-ASA prophylaxis was completed by 89.5% of the cohort. Conclusions: In this real-life cohort of MM patients treated with Dara-Rd and guideline-recommended antithrombotic prophylaxis, currently available VTE risk scores demonstrated moderate to poor prognostic accuracy. LMWH-ASA prophylaxis was feasible but associated with residual VTE risk.