Superior survival of unmanipulated haploidentical haematopoietic stem cell transplantation compared with intensive chemotherapy as post-remission treatment for children with very high-risk philadelphia chromosome negative B-cell acute lymphoblastic leukaemia in first complete remission.

We explored the prognostic factors for children with very high-risk (VHR) Philadelphia chromosome (Ph) negative B-cell acute lymphoblastic leukaemia (B-ALL) and compared the therapeutic effects of intensive chemotherapy and unmanipulated haploidentical haematopoietic stem cell transplantation (haplo-HSCT) as post-remission treatment in these patients undergoing first complete remission (CR1). A total of 104 paediatric patients with VHR B-ALL in CR1 were retrospectively enrolled in this study, including 42 receiving unmanipulated haplo-HSCT (Group A) and 62 receiving ongoing chemotherapy (Group B). Estimated 3-year overall survival (OS), disease-free survival (DFS) and cumulative incidence of relapse (CIR) at 36·2 months median follow-up were 69·5 ± 4·7%, 63·5 ± 4·8% and 32·4 ± 4·7%, respectively. Maintenance of persistent positive or conversion from negative to positive of measurable residual disease (MRD) and chemotherapy were independent risk factors associated with inferior long-term survival and higher CIR. OS, DFS, and CIR differed significantly between the groups in patients with persistent positive or negative-to-positive MRD. Haplo-HSCT may be an option for children with VHR Ph-negative B-ALL in CR1, especially for patients with persistent positive or negative-to-positive MRD, and could achieve better survival than intensive chemotherapy as post-remission treatment.