Predictive Factors and Outcomes after Allogeneic Stem Cell Transplantation for Adults with Acute Lymphoblastic Leukemia in Brazil

Abstract

Allogeneic stem cell transplantation (HSCT) remains a potentially curative approach for acute lymphoblastic leukemia (ALL), especially for high-risk patients and those with relapsed/refractory disease, although its efficacy is offset by a not-negligible toxicity. Adult patients with ALL fare worse in developing countries, with little data about the HSCT in this setting. In this study, we aimed to describe outcomes and examine risk factors for overall survival (OS), leukemia-free survival (LFS), cumulative incidence of relapse (CIR), nonrelapse mortality (NRM), and graft-versus-host disease (GVHD) after HSCT for ALL in Brazilian centers. This retrospective registry study included patients with ALL or ambiguous lineage leukemia age >16 years who underwent a first HSCT at 5 Brazilian centers between January 2007 and December 2017. A total of 275 patients were included, with a median age of 31 years (range, 16 to 65 years). Thirty-five percent were Philadelphia chromosome-positive. A matched sibling donor was used in 53%, a matched unrelated donor (MUD) in 19%, a mismatched unrelated donor in 9%, a haploidentical donor in 19%, and umbilical cord blood in 5%. The engraftment failure rate was 1.5%. The 5-year cumulative incidence of acute grade II-IV was 54.2%, and that of chronic GVHD was 26.2%. Five-year CIR and NRM were 28.1% and 34.1%, respectively. Central nervous system involvement at diagnosis (hazard ratio [HR], 2.2) and disease status (HR, 1.8 for second or later complete response and 7.9 for refractory) were associated with increased relapse incidence, whereas the use of peripheral blood graft (HR, .51) and a haploidentical donor (HR, .4) significantly decreased relapse incidence. Five-year OS and LFS were 40.7% (95% confidence interval [CI], 35.1-47.1) and 37.8% (95% CI, 32.3-44.1), respectively. Patient age, donor age, and disease status were independently associated with OS and LFS. Pre-HSCT positivity of minimal residual disease (>.01%) was associated with worse LFS (HR, 1.47) in available cases. This is the largest series of adults with ALL undergoing HSCT from Brazil reported to date. Although OS and LFS were similar to data reported in the literature, NRM was higher. Patient age and donor age outweighed donor type or graft source in our analysis. Interestingly, haploidentical HSCT was associated with lower CIR, whereas the use of MUDs was associated with higher NRM and GVHD rates. These results impact donor selection strategy in Brazil with the aim of offering timely HSCT for high-risk ALL patients in our setting.