Haploidentical versus Matched-Sibling Transplant in Adults with Philadelphia-Negative High-Risk Acute Lymphoblastic Leukemia: A Biologically Phase III Randomized Study

Abstract Purpose: Although matched-sibling donor (MSD) hematopoietic stem-cell transplantation (HSCT) has an established role in the management of adults with acute lymphoblastic leukemia (ALL) in first complete remission (CR1), the effect of haploidentical donor (HID) HSCT as post-remission treatment for this portion of patients is not defined. Experimental Design: Transplantation outcomes from HIDs or MSDs were compared in a disease-specific, biologically phase III randomized, multicenter study. Between July 2010 and December 2013, 210 patients with Philadelphia-negative high-risk ALL in CR1 were assigned to undergo unmanipulated HIDs (121 patients) or MSDs HSCT (89 patients) according to donor availability on an intent-to-treat (ITT) basis. Results: Overall, 24 of the 210 patients had lost transplant eligibility. Therefore, 186 of 210 (88%) patients were finally transplanted from MSD (n = 83) or HID (n = 103). Based on the ITT principle, the 3-year disease-free survival (DFS) did not differ between HID and MSD groups [61%, 95% confidence interval (CI), 52%–70%; vs. 60%, CI, 49%–71%; P = 0.91] from CR, neither did DFS differ between the two groups (68%, CI, 58%–78%; vs. 64%, CI, 52%–76%; P = 0.56) from time of the graft, with cumulative incidence of nonrelapse mortality of 13% (CI, 7%–19%) and 11% (CI, 4%–18%; P = 0.84) and relapse rates of 18% (CI, 10%–26%) and 24% (CI, 14%–34%; P = 0.30), respectively. Conclusions: Haploidentical HSCT achieves outcomes similar to those of MSD-HSCT for Philadelphia-negative high-risk ALL patients in CR1. Such transplantation could be a valid alternative as post-remission treatment for high-risk ALL patients in CR1 lacking an identical donor. Clin Cancer Res; 22(14); 3467–76. ©2016 AACR.