Lenalidomide and low‐dose dexamethasone in Japanese patients with newly diagnosed multiple myeloma: A phase II study

In the FIRST trial (MM‐020), lenalidomide plus low‐dose dexamethasone (Rd) reduced the risk of disease progression or death compared with combination melphalan–prednisone–thalidomide. As the FIRST trial did not include any Japanese patients, the efficacy and safety of continuous treatment with Rd was evaluated in 26 Japanese patients with newly diagnosed multiple myeloma (NDMM) in a single‐arm, multicenter, open‐label phase II trial (MM‐025). Patients received lenalidomide on days 1–21 of each 28‐day cycle, with a starting dose of 25 mg/day (dose adjusted for renal impairment), and 40 mg/day dexamethasone (dose adjusted for age) on days 1, 8, 15 and 22 of each 28‐day cycle until disease progression or discontinuation for any reason. In the efficacy evaluable population, overall response rate was 87.5%, including 29.2% of patients who achieved a complete response/very good partial response. Median durations of response, progression‐free survival and overall survival have not been reached. The most common grade 3–4 adverse events were neutropenia (23%) and anemia (19%). The efficacy and safety of Rd were consistent with data from larger studies, including the FIRST trial, thereby supporting the use of Rd continuous in Japanese patients with NDMM who are ineligible for stem cell transplantation.