Challenges of Conducting a Feasibility Pilot Randomized Controlled Trial During COVID-19 Restrictions: Rivaroxaban Versus Acetyl Salicylic Acid in Patients with Multiple Myeloma on Lenalidomide-Based Therapy (RithMM)

Venous thromboembolism is a serious medical complication with an increased risk in patients with multiple myeloma undergoing combination treatment regimens. Acetylsalicylic acid is routinely used as a method of thromboprophylaxis in multiple myeloma patients treated with lenalidomide, and rivaroxaban has been assessed in small-scale studies in multiple myeloma patients treated with immunomodulatory drugs; yet, no study has compared the two methods. In this pilot, we asked if a full-scale trial would be feasible to assess the benefits of rivaroxaban over acetylsalicylic acid as a thromboprophylactic approach. This pilot recruited patients with multiple myeloma on lenalidomide-based therapy and randomized them to either low-dose acetylsalicylic acid or rivaroxaban, then monitored bleeding and thrombotic events throughout lenalidomide–dexamethasone treatment. A total of 55 patients were recruited across three Canadian centres, with two venous thromboembolic events and two bleeding events, all in the acetylsalicylic acid arm. We conducted a post hoc analysis of active recruitment time as a definition of recruitment feasibility, as we did not achieve our pre-defined feasibility goals. Despite the challenges in enrollment, possibly due to social restrictions during the COVID-19 pandemic, we maintain that a full-scale trial is feasible and offers insight into thromboprophylactic management in this population.