Transplant Outcomes for Children with T Cell Acute Lymphoblastic Leukemia in Second Remission: A Report from the Center for International Blood and Marrow Transplant Research

•Survival for children with relapsed T-ALL is poor when treated with chemotherapy alone, and outcomes after allogeneic HCT are not well described.•We report the largest pediatric HCT cohort to date of patients with relapsed T-ALL in CR2.•Patients with relapsed T-ALL in CR2 and a BM relapse, with or without concurrent extramedullary relapse, were most likely to relapse post-HCT as compared with patients with isolated extramedullary disease.•Three-year OS and DFS for patients with relapsed T-ALL who received an HCT in CR2 were 48% and 46%, respectively.•These results are encouraging and appear to be durable, particularly when compared with chemotherapy alone for relapse T-ALL where survival is <20%, providing further evidence to support the role of transplant in these patients.

Survival for children with relapsed T cell acute lymphoblastic leukemia (T-ALL) is poor when treated with chemotherapy alone, and outcomes after allogeneic hematopoietic cell transplantation (HCT) is not well described. Two hundred twenty-nine children with T-ALL in second complete remission (CR2) received an HCT after myeloablative conditioning between 2000 and 2011 and were reported to the Center for International Blood and Marrow Transplant Research. Median age was 10 years (range, 2 to 18). Donor source was umbilical cord blood (26%), matched sibling bone marrow (38%), or unrelated bone marrow/peripheral blood (36%). Acute (grades II to IV) and chronic graft-versus-host disease occurred in, respectively, 35% (95% confidence interval [CI], 27% to 45%) and 26% (95% CI, 20% to 33%) of patients. Transplant-related mortality at day 100 and 3-year relapse rates were 13% (95% CI, 9% to 18%) and 30% (95% CI, 24% to 37%), respectively. Three-year overall survival and disease-free survival rates were 48% (95% CI, 41% to 55%) and 46% (95% CI, 39% to 52%), respectively. In multivariate analysis, patients with bone marrow relapse, with or without concurrent extramedullary relapse before HCT, were most likely to relapse (hazard ratio, 3.94; P = .005) as compared with isolated extramedullary disease. In conclusion, HCT for pediatric T-ALL in CR2 demonstrates reasonable and durable outcomes, and consideration for HCT is warranted.