A Multicenter, Single-Arm, Open-Label Study To Evaluate the Efficacy and Safety of Single-Agent Lenalidomide in Patients with Relapsed and Refractory Multiple Myeloma; Prelininary Results.

INTRODUCTION: Lenalidomide (REVLIMID®; CC-5013) is a novel, orally active immunomodulatory drug under investigation for the treatment of multiple myeloma (MM). Phase 1 dose-escalation studies in patients (pts) with relapsed and refractory MM determined that the maximum tolerated dose (MTD) of lenalidomide was 25 mg/day, based upon myelosuppression encountered beyond 28 days, which was manageable with growth factor support and dose reduction. In a multicenter phase 2 study to determine optimal dose and schedule, 102 pts with relapsed or refractory MM were randomized to receive lenalidomide at either 15 mg bid (n=34) or 30 mg qd (n=68), for 21 days every 4 wks. Both treatment arms showed significant activity with manageable toxicity. An increased incidence of cytopenia was noted in the 15-mg bid group and thus the 30 mg qd schedule was taken forward. METHODS: The objective of this multicenter, phase 2, open-label study (CC-5013-MM-014) was to further evaluate the effectiveness and safety of single-agent lenalidomide administered at a dose of 30 mg qd for 21 days every 28 days (28-day cycle) in pts with relapsed and refractory MM. Eligible patients included those who had received prior thalidomide, bortezomib, or SCT. RESULTS: 222 pts were enrolled into the study. All patients had received at least 2 prior anti-myeloma treatments, including bortezomib (41%), thalidomide (80%), and SCT (44%). Table 1 shows Best Response data, excluding patients in whom responses were not evaluable (n=10). Partial response or better occurred in 25% of patients and SD or better in 71%. Time to Progression was a median of 22.4 wks (range 1.8– 66 wks). The median survival has not been reached (the lower bound of the 95% CI exceeds 15 months). The most common treatment-related AEs (those reported in ≥10% of patients overall) included upper respiratory tract infection, neutropenia and thrombocytopenia. AEs that most frequently led to dose reduction or interruption by percentage of cases were neutropenia (40%), thrombocytopenia (23%), fatigue (5%), and anemia (5%). CONCLUSION: Oral lenalidomide in relapsed and refractory MM patients achieved PR+CR in 25%, stable disease or better in 71%, a median TTP of approximately 6 months and a median survival that has not been reached. Toxicity has been manageable with a very low incidence of DVT and minimal treatment-emergent neuropathy. Table 1. Best Response Best Response* n (%) *Excluding patients not evaluable (n=10); CR=complete response and PR=partial response (EBMT criteria) ≥PR (CR + PR) 53 (25) Stable disease 152 (71)