Among adolescent and pediatric patients with relapsed/refractory B cell precursor acute lymphoblastic leukemia (BCP-ALL), T cell replete HLA haploidentical hematopoietic stem cell transplantation (TCR-haplo-HSCT) with low-dose anti-thymocyte globulin (ATG) may improve outcomes, according to research published in Frontiers in Pediatrics.

Patients with BCP-ALL who relapse after HSCT or complete remission, or who do not respond to induction therapy, have a dismal prognosis. While recently introduced treatments, including blinatumomab, inotuzumab, and chimeric antigen receptor (CAR) T-cell therapy, may improve outcomes in this population, some patients maintain residual minimal residual disease (MRD).

Given the low number of treatment options among patients with relapsed/refractory BCP-ALL, effective novel therapies are badly needed. For this study, researchers evaluated the safety and efficacy of TCR-haplo-HSCT with ATG among a group of younger patients with relapsed/refractory BCP-ALL.

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Overall, 19 patients were included in this study. The median patient age at the time of transplantation was 10 years (range, 1.7-16.9), 63% of patients were male sex, 18 patients had relapsed disease, and 1 patient was refractory to primary induction. All TCR-haplo-HSCT procedures were conducted using peripheral blood stem cells.

A total of 18 patients in the cohort reached primary engraftment, and the acute graft-vs-host disease (GVHD) rate was 100%. Grade II acute GVHD occurred in 9 patients, grade III occurred in 8 patients, and grade IV was noted in 1 patient. A total of 10 cases of chronic GVHD were noted in 15 patients evaluable for the event.

Transplant-related death occurred in 3 patients. The 3-year leukemia-free survival rate was 42.1%; the 3-year overall survival (OS) rate was 57.4%. Patients younger than 10 years old (3-year OS rate, 100%) had greatly improved OS compared with patients older than 10 years (3-year OS rate, 20%; P =.002).

“In conclusion, we suggest that our TCR-haplo-HSCT method has the potential to save the lives of [relapsed/refractory]-BCP-ALL patients with a very poor prognosis and no other treatment options,” the authors wrote in their report. “However, this study was conducted on a small number of patients at a single institution, and the results should be interpreted with caution.”


Sano H, Mochizuki K, Kobayashi S, et al. Effectiveness of T-cell replete haploidentical hematopoietic stem cell transplantation for refractory/relapsed B cell acute lymphoblastic leukemia in children and adolescents. Front Pediatr. 2021;9:743294. doi:10.3389/fped.2021.743294