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

Researchers conducted an open-label, multicenter, randomized phase 3 trial in China to evaluate the safety and efficacy of BuCy compared with TBI-Cy (4.5 Gy × 2) in patients with adult standard-risk B-ALL in CR1 undergoing HLA-matched allo-HSCT (ClinicalTrials.gov Identifier: NCT02670252).

Between January 2016 and February 2020, they randomly assigned (1:1) patients with standard-risk ALL in CR1 (age 14-65 years) to receive BuCy (0.8 mg/kg, 4 times per day on days -7 to -4 and Cy 60 mg/kg, once daily on days -3 to -2) or TBI-Cy (4.5 Gy TBI on days -5 to -4 and Cy 60 mg/kg, once daily on days -3 to -2). The primary endpoint was 2-year overall survival (OS).


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A total of 550 patients were included in the study. Among assessed patients, 273 received BuCy (median age, 26 years; range, 14-59) and 272 received TBI-Cy (median age, 27 years; range, 14-61).

The researchers found that the 2-year OS of BuCy (76.6%; 95% CI, 71.7%-81.8%) was noninferior to that of TBI-Cy (79.4%; 95% CI, 74.7%-84.4%; P =.457; difference, 2.9%; 95% CI, -4.1 to 9.8; P =.022).

They also demonstrated comparable 2-year relapse (20.2% vs 18.4%; P =.616) and nonrelapse mortality (11.0% vs 11.0%; P =.988) rates between the BuCy and TBI-Cy groups and observed no differences in regimen-related toxicity, graft vs host disease, or late effects between the groups.

“In conclusion, our study shows that the BuCy regimen results in noninferior OS, relapse, [disease-free survival], and NRM compared with TBI-Cy (4.5 Gy × 2) in patients with adult standard-risk B-ALL in CR1 undergoing HLA-matched allo-HSCT,” the researchers wrote in their report. “The BuCy regimen might be an alternative conditioning for these populations undergoing allo-HSCT.”

Reference

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