The association between multiple myeloma (MM) and venous thromboembolism (VTE) is well known. Indeed, the incidence of VTE is increased in patients with newly diagnosed MM and in patients treated by immunomodulatory drugs in combination with glucocorticoids. Moreover, the clinical outcome of MM is supposed to be correlated to the risk of thrombosis. At the biological level, a number of hemostasis abnormalities participate in increasing VTE incidence. Yet, data on predictive biomarkers linked to VTE are limited.

There is a need to discern predictive biomarkers in order to better identify patients at risk of developing VTE, to decipher the mechanisms by which myeloma treatments interfere and in fine to choose an adequate thromboprophylaxis. In this context, it is important to document the precise expression of coagulation factors and to profile point-of-care tests for coagulation monitoring in newly diagnosed MM patients, before and during treatment. In addition, thromboprophylaxis is systematically included in therapeutic MM strategies, especially direct oral anticoagulants, without knowing whether potential drug interactions are occurring. This study aims at evaluating and validating predictive biomarkers of VTE in MM, and at identifying patients whose thromboprophylaxis is required and may potentially be adjusted because of drug interactions.

Inclusion Criteria:

• Patient affiliated to a social security regimen or beneficiary of the same
• Signed written informed consent form
• Confirmed diagnosis of de novo multiple myeloma, non-previously treated and requiring treatment.

Exclusion Criteria:

• Pregnant women
• Patient under guardianship or deprived of his liberty or any condition that may affect the patient's ability to understand and sign the informed consent
• Refusing participation
• Patient whose follow-up or life expectancy is less than 6 months.