Melphalan/Prednisone/Lenalidomide (MPR) Versus High-Dose Melphalan and Autologous Transplantation (MEL200) in Newly Diagnosed Multiple Myeloma (MM) Patients <65 Years: Results of a Randomized Phase III Study

High-dose chemotherapy with haemopoietic stem-cell improves outcome in multiple myeloma (MM). The introduction of novel agents questions the role of autologous stem-cell transplantation (ASCT) in MM patients.In this prospective randomized study, we compared conventional melphalan-prednisone-lenalidomide (MPR) with tandem high-dose melphalan (MEL200) in newly diagnosed MM patients younger than 65 years.All patients (N=402) received four 28-day cycles of lenalidomide (25 mg, d1-21) and low-dose dexamethasone (40 mg, d1, 8, 15, 22) (Rd) as induction. As consolidation, patients were randomized to MPR (N=202) consisting of six 28-day cycles of melphalan (0.18 mg/kg d1-4), prednisone (2 mg/kg d1-4) and lenalidomide (10 mg d1-21); or tandem melphalan 200 mg/m2 MEL200 (N=200) with stem-cell support. All patients enrolled were stratified according to International Staging System (stages 1 and 2 vs. stage 3) and age (<60 vs. ≥60 years). Progression-free survival (PFS) was the primary end point. Data were analyzed in intention-to-treat.Response rates were similar: at least very good partial response (≥VGPR) rate was 60% with MPR vs. 58% with MEL200 (p=.24); the complete response (CR) rate was 20% with MPR vs. 25% with MEL200 (p=.49). After a median follow-up of 26 months, the 2-year PFS was 54% in MPR and 73% in MEL200 (HR=0.51, p<.001). The 2-year overall survival (OS) was similar in the two groups: 87% with MPR and 90% with MEL200 (HR 0.68, p=.19). In a subgroup analysis, MEL200 significantly prolonged PFS in both standard-risk patients without t(4;14) or t(14;16) or del17p abnormalities (2-year PFS was 46% in the MPR group vs. 78% in the MEL200 group, HR=0.57, p=.007) and high-risk patients with t(4;14) or t(14;16) or del17p abnormalities (2-year PFS was 27% for MPR vs. 71% for MEL200, HR=0.32, p=.004). In patients who achieved CR, the 2-year PFS was 66% for MPR vs. 87% for MEL200 (HR 0.26; p<.001); in those who achieved a partial response (PR), the 2-year PFS was 56% for MPR vs. 77% for MEL200 (HR 0.45; p<.001). In the MPR and MEL200 groups, G3-4 neutropenia was 55% vs. 89% (p<.001); G3-4 infections were 0% vs. 17% (p<.001); G3-4 gastrointestinal toxicity was 0% vs. 21% (p<.001); the incidence of second tumors was 0.5% in MPR patients and 1.5% in MEL200 patients (p=.12). Deep vein thrombosis rate was 2.44% with MPR vs. 1.13% with MEL200 (p=.43).PFS was significantly prolonged in the MEL200 group compared to MPR. This benefit was maintained in the subgroup of patients with standard- or high-risk cytogenetic features. Toxicities were significantly higher in the MEL200 group. This is the first report showing a PFS advantage for ASCT in comparison with conventional therapies including novel agents. These data will be updated at the meeting.Palumbo: celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Cavallo:Celgene: Honoraria; Janssen-Cilag: Honoraria. Cavo:celgene: Honoraria. Ria:celgene: Consultancy. Caravita Di Toritto:Celgene: Honoraria, Research Funding. Di Raimondo:celgene: Honoraria. Boccadoro:celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.