A busulfan plus cyclophosphamide (BuCy) conditioning regimen appears noninferior to total body irradiation plus cyclophosphamide (TBI-Cy) in adults with standard-risk B-cell acute lymphoblastic leukemia (B-ALL) in first complete remission (CR1) undergoing HLA-matched allogeneic hematopoietic stem cell transplant (allo-HSCT), according to a report published in the Journal of Clinical Oncology.

Rates of overall survival (OS), relapse, and non-relapse mortality were similar with the 2 regimens, as were adverse events, researchers reported.

The researchers compared the regimens in a randomized, phase 3 trial (ClinicalTrials.gov Identifier: NCT02670252) of patients with adult standard-risk B-ALL in CR1 undergoing allo-HSCT. A total of 273 patients received BuCy (median age, 26 years; range, 14-59) and 272 received TBI-Cy (median age, 27 years; range, 14-61).

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BuCy consisted of busulfan at 0.8 mg/kg, 4 times per day, on days -7 to -4 and cyclophosphamide at 60 mg/kg, once daily, on days -3 to -2. TBI-Cy consisted of TBI at 4.5 Gy on days -5 to -4 and cyclophosphamide at 60 mg/kg, once daily, on days -3 to -2.

The primary endpoint was 2-year OS. The 2-year OS rate with BuCy was noninferior to that of TBI-Cy — 76.6% and 79.4%, respectively (P =.457).

The 2-year relapse rate was similar between the BuCy and TBI-Cy groups as well (20.2% and 18.4%, respectively; P =.616), and the rate of nonrelapse mortality at 2 years was exactly the same in both arms (11.0%; P =.988).

In addition, there were no significant differences in regimen-related toxicity, graft-vs-host disease, or late effects between the groups.

Based on these results, the researchers concluded that BuCy might be an alternative conditioning regimen for this patient population.


Zhang H, Fan Z, Huang F, et al. Busulfan plus cyclophosphamide versus total body irradiation plus cyclophosphamide for adults acute B lymphoblastic leukemia: An open-label, multicenter, phase III trial. J Clin Oncol. Published online September 9, 2022. doi:10.1200/JCO.22.00767

This article originally appeared on Hematology Advisor