Real-world Outcomes in Patients with Relapsed and Refractory Multiple Myeloma with Prior Proteasome Inhibitor and Lenalidomide Exposure: A Single-Center Study in Sweden.

The use of proteasome inhibitors (PI) and immunomodulatory drugs (IMiD) such as lenalidomide (Len) in early lines of therapy in multiple myeloma (MM) has resulted in a high proportion of patients with relapsed or refractory multiple myeloma (RRMM) being Len-refractory. Len refractoriness is associated with inferior outcomes, constituting an unmet need in clinical practice. This retrospective single-center study aimed to provide real-world characteristics and outcomes in RRMM previously exposed to PI and Len during 1-3 prior lines of therapy (LOT), stratified by Len refractoriness. RRMM patients between Jan 2017 and May 2023 were included. We studied clinical characteristics, treatments and survival outcomes. A total of 218 patients were included (n=85 Len refractory). The median progression-free survival was 13.6 months in Len-refractory versus 14.9 months in Len non-refractory patients. The median overall survival was 20.3 months in Len refractory, and not reached in Len non-refractory patients. The overall response rates to the subsequent LOT were 58.8% and 61.7% in Len refractory and non-refractory cohorts, respectively. IMiD-based and anti-CD38 monoclonal antibody-containing regimens were the most frequent subsequent LOT, 44% and 41%, respectively. This study shows suboptimal outcomes in Len refractory RRMM patients, highlighting the need to develop effective treatment options.