MELISSE, a large multicentric observational study to determine risk factors of venous thromboembolism in patients with multiple myeloma treated with immunomodulatory drugs.

Immunomodulatory drugs (IMiDs) are associated with an increased risk of venous thromboembolism (VTE) in multiple myeloma (MM) patients. We designed MELISSE, a multicentre prospective observational study, to evaluate VTE incidence and identify risk factors in IMiDs-treated MM. Our objective was to determine the real-life practice of VTE prophylaxis strategy. A total of 524 MM patients were included, and we planned to collect information at baseline, at four and at 12 months, on MM therapy, on VTE risk factors and management. VTE incidence was 7% (n=31), including 2.5% pulmonary embolism (PE) (n=11), similar at four or 12 months. VTE was observed at all risk assessment levels, although the increased risk assessment level correlated to a lower rate of VTE, maybe due to the implemented thromboprophylaxis strategy. VTE occurred in 7% on aspirin vs 3% on low-molecular-weight heparin (LMWH) prophylaxis, and none on vitamin K antagonists (VKA). New risk factors for VTE in IMiDs-treated MM were identified. In conclusion, VTE prophylaxis is compulsory in IMiDs-treated MM, based on individualised VTE risk assessment. Anticoagulation prophylaxis with LMWH should clearly be prioritised in MM patients with high VTE risk, along with VKA. Further prospective studies will identify most relevant VTE risk factors in IMiDs-treated MM to select accurately which MM patients should receive LMWH prophylaxis and for which duration to optimise VTE risk reduction.