A phase 1 study of bendamustine and melphalan conditioning for autologous stem cell transplantation in multiple myeloma
Antineoplastic Combined Chemotherapy Protocols
Hematopoietic Stem Cell Transplantation
Nitrogen Mustard Compounds
Bendamustine has efficacy in multiple myeloma with a toxicity profile limited to myelosuppression. We hypothesized that adding bendamustine to autologous stem cell transplant conditioning in myeloma would enhance response without significant additional toxicity. We conducted a phase 1 trial adding escalating doses of bendamustine to the current standard conditioning of melphalan 200 mg/m(2). Twenty-five subjects were enrolled into 6 cohorts. A maximum tolerated dose was not encountered and the highest dose level cohort of bendamustine 225 mg/m(2) + melphalan 200 mg/m(2) was expanded to further evaluate safety. Overall, there was no transplant related mortality and only one grade 4 dose-limiting toxicity was observed. Median number of days to neutrophil and platelet engraftment were 11 (range, 9 to 14) and 13 (range, 10 to 21), respectively. Disease responses at day +100 posttransplantation were progression in 5 (21%), partial response in 1 (4%), very good partial response in 7 (33%), complete response in 1 (4%), and stringent complete response in 9 (38%). Six patients (24%) with pre-existing high-risk disease died from progressive myeloma during study follow-up, all at or beyond 100 days after autologous stem cell transplant. Bendamustine up to a dose of 225 mg/m(2) added to autologous stem cell transplantation conditioning with high-dose melphalan in patients with multiple myeloma did not exacerbate expected toxicities.