Phase 2 Study of an Intravenous Busulfan and Melphalan Conditioning Regimen for Autologous Stem Cell Transplantation in Patients with Multiple Myeloma (KMM150).

This prospective study evaluated the efficacy and toxicity of intravenous busulfan and melphalan as a conditioning regimen for autologous stem cell transplantation (ASCT) in patients with multiple myeloma (MM). A total of 99 patients with MM, enrolled between January 2013 and March 2016, received intravenous busulfan (9.6 mg/kg) and melphalan (140 mg/m2) before ASCT. The median time to transplant was 6.2 months, and 90 (90.9%) patients underwent ASCT within 12 months of the diagnosis. The overall response rate after ASCT was 94.0%, including 43.5% with a stringent complete response/complete response, 27.3% with very good partial response, and 23.2% with partial response. The most common severe nonhematologic toxicity (grade 3 to 4) was infection (26.3%) and stomatitis (15.2%). Three (3.2%) patients developed veno-occlusive disease. No treatment-related mortality was observed. After a median follow-up of 26.1 months, the median progression-free survival was 27.2 months (range, 13.0 to 41.4 months) and median overall survival was not reached. In conclusion, a conditioning regimen of intravenous busulfan and melphalan was effective and tolerable. ClinicalTrials.gov. number: NCT01923935.