Safety of lenalidomide, dexamethasone, and cyclophosphamide in elderly Japanese patients with relapsed and refractory multiple myeloma: results of phase 1 study

The RCd regimen (lenalidomide [LEN]-cyclophosphamide [CY]-dexamethasone [DEX]) was effective and welltolerated in relapsed and refractory multiple myeloma (RRMM) European patients aged between 59 and 65 years. However, most Japanese myeloma patients are over 70 years old. Thus, we analyzed the safety of RCd therapy in a phase 1 study of elderly Japanese RRMM patients aged >70 years (median age 76 years). CY was administered to three cohorts of three patients each at 200, 300, and 400 mg on days 1, 8, and 15 of a 28-day cycle with DEX (40 mg on days 1, 8, 15, and 22) and LEN (15 mg on days 1–21) for a maximum 8 cycles. One patient receiving 200 mg CY developed thrombocytopenia (Gr.4) and pneumonia (Gr.3). Two patients each developed neutropenia (Gr.4) at 300 mg and skin rash (Gr.3) at 200 mg. No severe adverse events were observed. Maximum tolerated dose of CY was determined to be 400 mg. After 2 cycles, the overall response rate was 88.9%. After a median follow-up of 36.4 months, median duration of response, progression-free survival, and overall survival were 8.3, 10.6, and 36.4 months, respectively. (UMIN Clinical Trials Registry number, UMIN000009391).