Real-world patterns of aspirin and anticoagulant prophylaxis at IMiD-associated VTE onset in multiple myeloma: A phase-specific analysis.

Abstract

e19534 Background: Immunomodulatory drugs (IMiDs) increase venous thromboembolism (VTE) risk in multiple myeloma (MM). Guidelines endorse risk-adapted prophylaxis with aspirin (ASA) or anticoagulation (AC), but real-world data on IMiD-associated VTE and prophylaxis use across treatment phases are limited. Methods: We conducted a retrospective single-center cohort study of adults with MM treated with IMiD-based regimens who developed image-confirmed VTE between 2020-2025. Clinical and treatment data, including ECOG, IMWG/R-ISS stage, IMPEDE-VTE score, line of therapy, VTE prophylaxis at the time of VTE (ASA, AC, or none), and time from diagnosis and IMiD initiation to VTE, were collected and summarized descriptively. Results: Of the 110 patients screened, 61 met the inclusion criteria and were included in the final analysis. Median age was 72 years, median BMI 30.6 kg/m², and 85% of patients had ECOG 0–1. IMWG/R-ISS stage was I/II/III in 27%/56%/17%. Median IMPEDE-VTE score at VTE was 4; 10% were high-risk (IMPEDE ≥8). At the time of VTE, 39 patients (64%) were on ASA, 7 (11%) on AC, and 15 (25%) were not on prophylaxis. Patients without prophylaxis had the highest IMPEDE scores (median 7 vs 4 with ASA/AC). Median time from MM diagnosis to VTE was 18 months, with events distributed throughout the disease course. Median time from IMiD initiation to VTE was 8 months; ~50% of events occurred within 12 months, and ~25% occurring >24 months. At the time of VTE, 26 (43%) were on induction and 27 (44%) on maintenance therapy, indicating clustering of VTE in these phases. Median time from IMiD initiation to VTE varied by prophylaxis, occurring earliest with AC (3.5 months), later with ASA (13.0 months), and at 4.0 months without prophylaxis. Two-thirds of patients on AC developed VTE within 6 months of IMiD start, whereas patients on ASA showed both early events and a late cluster beyond 24 months. Patients without prophylaxis had high IMPEDE scores, and VTE occurrence did not appear to be associated with timing of disease. VTE recurrence occurred in 5 patients (8%). Conclusions: In this real-world, VTE-enriched cohort of MM patients treated with IMiD therapy, thrombotic events clustered during induction and maintenance, with higher occurrence among those receiving ASA or no prophylaxis. While incidence and comparative effectiveness cannot be determined from this VTE-only dataset, the frequent VTE events observed in patients with elevated IMPEDE-VTE scores who were not anticoagulated highlight opportunities to improve risk stratification and prophylaxis selection. These findings support a phase-conscious approach to VTE prevention, emphasizing early anticoagulant prophylaxis in selected patients and cautious de-escalation as treatment- and disease-related risks diminish.