Long-term use of lenalidomide and low-dose dexamethasone in Chinese patients with relapsed/refractory multiple myeloma: MM-024 Extended Access Program

Abstract

Background: The efficacy and safety of lenalidomide plus low-dose dexamethasone (Rd) in Chinese patients with relapsed/refractory multiple myeloma (RRMM) was demonstrated in a phase 2, multicenter trial (MM-021). MM-024 was an Extended Access Program (EAP) that allowed responding patients in the MM-021 trial to continue to receive Rd, and to provide additional safety and efficacy data with longer follow-up. Methods: Chinese patients with RRMM who completed ≥1year of Rd therapy in MM-021 and who remained progression-free under Rd entered the Treatment Phase of the MM-024 EAP, continuing Rd at the same dose and schedule. Patients in MM-021 who discontinued Rd treatment or progressed were allowed to enroll in the Safety Follow-Up Phase of the MM-024 EAP. Safety data, including the incidence of second primary malignancies (SPMs), were collected for ≥5years from the time the last on-study patient enrolled in the MM-021 trial (primary end point). Efficacy outcomes (time to progression [TTP], progression-free survival [PFS], and overall survival [OS]) were secondary end points. Results: Median follow-up was 38.4months for the safety population (n = 80) and 43.3months for the treatment cohort (n = 41). In the safety population, Grade 3-4 adverse events (AEs) occurred in 60.0% of patients; the most common grade 3-4 AEs were neutropenia (20.0%), decreased neutrophil count (13.8%), and anemia (11.3%). There was no evidence of cumulative toxicity, and no patients discontinued Rd due to AEs; 2 patients had SPMs. In the treatment cohort, median duration of response was 35.1months, median TTP was 36.9months, and median PFS was 36.0months; median OS was not reached due to the low number of deaths (n = 5). Conclusion: Long-term treatment with Rd has a predictable and manageable safety profile and provides sustained efficacy in Chinese patients with RRMM.