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).
Strelau M, Gal G, et al. • Current oncology (Toronto, Ont.) • 2026
Despite not achieving its pre-defined feasibility goals, likely because of COVID-19 restrictions, this pilot randomized trial of rivaroxaban versus acetylsalicylic acid in multiple myeloma patients on lenalidomide-based therapy concluded that a full-scale trial is feasible.
Key Findings
Results
The pilot RCT recruited 55 patients with multiple myeloma on lenalidomide-based therapy across three Canadian centres and randomized them to low-dose acetylsalicylic acid or rivaroxaban.
Patients were monitored for bleeding and thrombotic events throughout lenalidomide-dexamethasone treatment.
The study was designed to assess whether a full-scale trial comparing rivaroxaban with acetylsalicylic acid thromboprophylaxis would be feasible.
No prior study had directly compared the two thromboprophylaxis approaches.
Results
The study did not achieve its pre-defined feasibility goals.
The authors attribute the enrollment challenges possibly to social restrictions during the COVID-19 pandemic.
Because the pre-defined goals were not met, a post hoc analysis of active recruitment time was used as an alternative definition of recruitment feasibility.
Results
Two venous thromboembolic events and two bleeding events occurred, all in the acetylsalicylic acid arm.
No venous thromboembolic or bleeding events were reported in the rivaroxaban arm.
Total sample was 55 patients, so the event numbers are very small and do not support formal efficacy or safety comparisons.
Conclusions
The authors conclude that a full-scale trial is feasible despite the enrollment challenges.
The conclusion rests on a post hoc analysis of active recruitment time as the feasibility definition.
The authors state that such a trial offers insight into thromboprophylactic management in this population.
What This Means
Patients with multiple myeloma who take lenalidomide-based treatments have a higher risk of blood clots. Low-dose aspirin is commonly used to help prevent them, and the blood thinner rivaroxaban has been tested in small studies, but the two had never been compared directly. This small pilot study asked whether a larger trial comparing them could realistically be run.
The researchers randomly assigned 55 patients at three Canadian centres to aspirin or rivaroxaban and tracked clots and bleeding during treatment. Four events occurred in total: two clots and two bleeding events, all among patients taking aspirin. With so few events, no conclusions can be drawn about which drug is better or safer.
The study did not meet its original targets for recruitment, probably because of COVID-19 restrictions. After re-examining recruitment based on the time the study was actively enrolling, the authors still concluded that a full-scale trial would be feasible. This research suggests that a larger comparison is possible, but the question of which drug is better remains unanswered.
Strelau M, Gal G, McCurdy A, Shivakumar S, Wootten J, Abouzeenni M, et al.. (2026). 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).. Current oncology (Toronto, Ont.). https://doi.org/10.3390/curroncol33100633