A Prospective, Randomized Study of Single Versus Double Autologous Stem Cell Transplantation for Multiple Myeloma

Following demonstration that single autologous transplantation for the treatment of younger patients with newly diagnosed multiple myeloma prolonged overall survival in comparison with conventional chemotherapy, double autologous transplantation was tested, initially in refractory myeloma and subsequently to include also patients with newly diagnosed disease. To explore the role of double autologous stem-cell transplantation as part of up-front therapy for multiple myeloma, in 1996 we launched a prospective, randomized trial comparing a single course of stem-cell-supported melphalan with the same regimen followed, after three to six months, by a second autologous transplantation in support of melphalan and busulfan. The study was designed to detect a 15 percent increase in complete or near complete response rate with double transplants compared to a single transplantation. With a 2-sided significance level α = 0.05 and a power 1-β = 0.80, 162 patients were required in each treatment arm of the study to detect a statistically significant increase in complete or near complete response rate from 30% in the single-transplant arm to 45% in the double-transplant arm. Primary study endpoint was the complete or near complete response rate. Secondary study endpoints were relapse-free survival, event-free survival and overall survival. The recruitment target was 324 patients.