A multicenter clinical study to determine the feasible initial dose of lenalidomide for maintenance therapy in patients with multiple myeloma following autologous peripheral blood stem-cell transplantation.

Maintenance therapy with lenalidomide (LEN) for patients with multiple myeloma (MM) following autologous peripheral blood stem cell transplantation (auto-PBSCT) may be a promising option for preventing relapse or disease progression. However, the recommended dose of LEN has yet to be firmly established. We herein report the results of a multicenter clinical study for determining the feasible initial dose (FID) of LEN. In this trial, a total of 11 patients who achieved a very good partial response or complete response following auto-PBSCT were enrolled from five transplant centers in Japan. Three dose levels of LEN (level 0, 5 mg; level 1, 10 mg; and level 2,:15 mg) were tested in this study. FID was defined as the maximum estimated dose at which 70% of the patients could receive maintenance therapy for 12 weeks without any serious adverse events or disease progression. Using a continual reassessment method, 6 patients were assigned to level 0 and the remaining 5 patients were assigned to level 1. All 6 patients (100%) at level 0, but only 2 patients (40%) at level 1, completed 12 weeks of administration with their assigned dose of LEN. The results of our study demonstrated that, although 5 mg of LEN was acceptable in terms of safety, 7.5 mg of LEN may also be an acceptable FID.