A Novel Reduced-Toxicity Myeloablative Conditioning Regimen Using Full-Dose Busulfan, Fludarabine, and Melphalan for Single Cord Blood Transplantation Provides Durable Engraftment and Remission in Nonremission Myeloid Malignancies

•A novel myeloablative regimen in cord blood transplantation was investigated for patients with active diseases•The regimen provided reliable engraftment and durable remission with acceptable nonrelapse mortality•Overall survival and progression-free survival were both estimated as 54.9% at 2 years after transplantation

A pilot study of a novel, reduced-toxicity, myeloablative conditioning regimen using intravenous busulfan 12.8 mg/kg, fludarabine 180 mg/m2, and melphalan 80 mg/m2 for single cord blood transplantation (CBT) was conducted at our institution. Fifty-one patients with myeloid malignancies not in remission were included in this study. Their median age was 59 years (range, 19 to 70 years), with a median hematopoietic cell transplantation-specific comorbidity index score of 3. With a median observation period of 39.6 months (range, 24.3 to 90.8 months) among the survivors, overall survival and progression-free survival at 2 years were both 54.9%. Forty-six of 51 achieved neutrophil engraftment at a median of 19.5 days (range, 13 to 38 days) after transplantation, with a cumulative incidence of 90.2%. No patient developed graft rejection in this study. All patients who achieved engraftment showed hematological complete remission with complete donor chimerism. Eleven patients relapsed at a median of 4.9 months (range, .5 to 26.7 months). Cumulative incidences of nonrelapse mortality (NRM) at 100 days and 2 years were 11.8% and 25.5%, respectively. In conclusion, the present results show that the novel conditioning regimen for single CBT provided durable engraftment and remission with acceptable NRM leading to excellent survival, even for a relatively older population with myeloid malignancies not in remission.