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 ≥ 1 year 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 ≥ 5 years 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 38.4 months for the safety population (n = 80) and 43.3 months 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 35.1 months, median TTP was 36.9 months, and median PFS was 36.0 months; 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.
Trial registration: China State Food and Drug Administration (SFDA) registration (CTA reference numbers: 209L10808; 209L10809; 209L10810; and 209L10811) and ClinicalTrials.gov Identifier: NCT02348528. First received January 23, 2015; last updated November 12, 2015; last verified November 2015; study start date September 2012.