Venous thromboembolism in multiple myeloma - choice of prophylaxis, role of direct oral anticoagulants and special considerations.

Multiple myeloma is associated with a significant risk of venous thromboembolism (VTE), causing substantial levels of morbidity and mortality. The thrombogenicity of myeloma is multifactorial, with disease- and treatment-related factors playing important roles. Immunomodulatory drugs (IMiDs) and high-dose dexamethasone, in particular, are known to enhance the thrombotic potential of myeloma. For this reason, assessment of the VTE risk has long been advocated prior to treatment initiation in patients with myeloma requiring IMiD-based regimens. However, despite routine use of thromboprophylaxis, these patients can still develop VTE and its sequelae. The optimum choice and dose of thromboprophylactic drug is not entirely clear, and with this, there is growing interest regarding use of the direct oral anticoagulants in this setting. In this review we discuss the pathogenesis of thrombosis in multiple myeloma, its relation to some of the commonly used chemotherapeutic regimens, current risk stratification and the evidence supporting the different anticoagulants used as thromboprophylaxis. We propose an amended risk stratification, and consider management of challenging patients, including those with renal impairment and recurrent thrombosis.