A randomised comparison of melphalan with prednisone or dexamethasone as induction therapy and dexamethasone or observation as maintenance therapy in multiple myeloma: NCIC CTG MY.7

The effectiveness of melphalan plus dexamethasone (M-Dex) with melphalan plus prednisone (MP) as induction therapy and dexamethasone with observation as maintenance therapy was compared in 585 older patients with multiple myeloma. Randomization to the M-Dex arm was stopped as a result of an analysis performed which met a predetermined event-related criterion. Of 466 patients randomised to MP or M-Dex, no differences were detected in the respective median progression-free survivals (PFS) [1.8 vs. 1.9 years; Hazard Ratio (HR) = 0.88, 95% CI 0.72-1.07; P = 0.2] or overall survivals (OS) (2.5 vs. 2.7 years; HR = 0.91, 95% CI 0.74-1.11; P = 0.3). Of the initial 585 patients, 292 remained evaluable for maintenance therapy. Patients randomised to maintenance dexamethasone had a superior median PFS (2.8 years vs. 2.1 years; HR = 0.61, 95% CI 0.47-0.79; P = 0.0002). No difference in median OS was detected (4.1 years vs. 3.8 years; HR = 0.88, 95% CI 0.65-1.18; P = 0.4). The maintenance therapy results were robust when analysed by using two additional methodologies. Dexamethasone did not improve clinical outcome when combined with melphalan during induction; maintenance dexamethasone improved PFS, but this did not translate into a detectable survival advantage.