PB1424 - Primary deep vein thrombosis prophylaxis in high-risk ambulatory multiple myeloma patients: DOACs or vitamin K antagonists are better than aspirin or no prophylaxis

Background: The use of immunomodulatory drugs (IMiD) increases venous thromboembolic (VTE) risk in multiple myeloma (MM). Routine use of ambulatory thromboprophylaxis (TP) with LMWH, aspirin (ASA), or VKA is recommended in this population by international guidelines.

Aims: Descriptive analysis of primary thromboprophylaxis in MM patients treated with or without IMiD compared to patients who did not receive antithrombotics.

Methods: Analytical retrospective cohort study in MM patients and IMiD or chemotherapy from June 2019 to March 2023. Clinical data were collected from electronic medical records. The statistical programs JMP 17 and Statistix 7.0 were used.

Results: 54 MM patients were evaluated. 38 (70%) received thromboprophylaxis and 16 didn’t. High thrombotic risk according to IMPEDE score was present in 47 (87%). Five patients previously anticoagulated for FA/VTE were excluded. The primary prophylaxis schedule was VKA INR 2-3 (n=9), ASA 100mg (n=12) or DOACs (n=12) in prophylactic dose (apixaban 3/rivaroxaban 9). 33/47 high-risk patients received primary prophylaxis, 12 ASA and 21 VKA/DOACs. There were seven (15%) symptomatic VTE in the high-risk group and none in the 7 low risk. VTE occurred in 3/12 ASA (25%) and 4/14 patients without TP (29%). Two clinically relevant hemorrhages with DOACs occurred, both with IMiD. In 40 IMiD patients (92,5% high-risk) 7 received no TP (all high risk), and 33 primary prophylaxis, (30 high-risk). The prophylaxis was VKA INR 2-3 (n=8), DOACs (n=12) and ASA (n=9). VTE incidence was 5/37 (13,5%) (7%/year), being 20% (2/10) in ASA; 43% (3/7) in no TP (OR: 0.10 95% CI [0.01-0.79] NNT 2.78) and 0% in VKA/DOACs.

Conclusion(s): In our experience in high-risk MM patients the use of DOACs/VKA was superior to aspirin or no prophylaxis with a low bleeding risk. If these results are confirmed in prospective studies, DOACs could be considered as a safe and effective option.