Busulfan Plus Fludarabine Compared With Busulfan Plus Cyclophosphamide for AML Undergoing HLA-Haploidentical Hematopoietic Cell Transplantation: A Multicenter Randomized Phase III Trial
Yiwen Ling, Li Xuan, Na Xu, Fen Huang, Zhiping Fan, Ziwen Guo, Xiaojun Xu, Hui Liu, Ren Lin, Sijian Yu, Haiyan Zhang, Hua Jin, Meiqing Wu, Can Liu, Xinquan Liang, Ruiming Ou, Yuping Zhang, Xiaodan Liu, Hong Qu, Xiao Zhai, Jing Sun, Ying Zhao, Qifa Liu
Abstract
PURPOSE The busulfan plus fludarabine (BuFlu) conditioning regimen has lower transplant-related mortality (TRM) than busulfan plus cyclophosphamide (BuCy) in HLA-matched transplantation. We aimed to compare outcomes of the BuFlu regimen with those of the BuCy regimen in HLA-haploidentical hematopoietic cell transplantation (haplo-HCT). METHODS We performed an open-label, randomized phase III trial at 12 hospitals in China. Eligible patients with AML (18-65 years) were randomly assigned 1:1 to receive BuFlu (busulfan 0.8 mg/kg four times per day on days –6 to –3; fludarabine 30 mg/m 2 once daily on days –7 to –3) or BuCy (same dose of busulfan; cyclophosphamide 60 mg/kg once daily on days –3 and –2). The primary end point was 1-year TRM in the intention-to-treat population and safety in the per-protocol population. This trial is registered with ClinicalTrials.gov (identifier: NCT02487069 ) and is complete. RESULTS From November 20, 2015, to September 30, 2019, 386 patients were randomly assigned to receive the BuFlu (n = 194) or BuCy (n = 192) regimen. The median follow-up was 55.0 (IQR, 46.5-69.0) months after random assignment. The 1-year TRM was 7.2% (95% CI, 4.1 to 11.4) and 14.1% (95% CI, 9.6 to 19.4; hazard ratio [HR], 0.51; 95% CI, 0.27 to 0.97; P = .041), the 5-year relapse was 17.9% (95% CI, 9.6 to 28.3) and 14.2% (95% CI, 9.1 to 20.5; HR, 1.12; 95% CI, 0.65 to 1.95; P = .670), and the 5-year overall survival was 72.5% (95% CI, 62.2 to 80.4) and 68.2% (95% CI, 58.9 to 75.9; HR, 0.84; 95% CI, 0.56 to 1.26; P = .465) in two groups, respectively. Grade 3 regimen-related toxicity (RRT) was reported for 0 of 191 patients following the BuFlu regimen and 9 (4.7%) of 190 patients following the BuCy regimen ( P = .002). At least one type of grade 3-5 adverse event was reported for 130 (68.1%) of the 191 patients and 147 (77.4%) of the 190 patients in two groups, respectively ( P = .041). CONCLUSION The BuFlu regimen has a lower TRM and RRT and similar relapse for patients with AML undergoing haplo-HCT compared with the BuCy regimen.