A randomized study of melphalan 200 mg/m2 vs 280 mg/m2 as a preparative regimen for patients with multiple myeloma undergoing auto-SCT

Abstract

We aimed to examine whether doses of melphalan higher than 200 mg/m 2 improve response rates when used as conditioning before autologous transplant (ASCT) in multiple myeloma (MM) patients. Patients with MM, n=131, were randomized to 200 mg/m 2 (mel200) vs 280 mg/m 2 (mel280) using amifostine pretreatment. The primary end point was the proportion of patients achieving near complete response (≥nCR). No treatment-related deaths occurred in this study. Responses following ASCT were for mel200 vs mel280, respectively, ≥nCR 22 vs 39%, P=0.03, ≥PR 57 vs 74%, P=0.04. The hazard of mortality was not statistically significantly different between groups (mel200 vs mel280; hazard ratio (HR)=1.15 (95% confidence interval (CI), 0.62-2.13, P=0.66)) nor was the rate of progression/mortality (HR=0.81 (0.52-1.27, P=0.36)). The estimated PFS at 1 and 3 years were 83 and 46%, respectively, for mel200 and 78 and 54%, respectively, for mel280. Amifostine and mel280 were well tolerated, with no grade 4 regimen-related toxicities and only one grade 3 mucositis (none with mel200) and three grade 3 gastrointestinal (GI) toxicities (two in mel200). Hospitalization rates were more frequent in the mel280 group (59 vs 43%, P=0.08). Mel280 resulted in a higher major response rate (CR+nCR) and should be evaluated in larger studies.