Blinatumomab therapy for B cell acute lymphoblastic leukemia accompanied by persistent or relapsed low-level MRD prior to hematopoietic stem cell transplantation in Chinese children: a case series

Abstract

Abstract Background Blinatumomab could be successfully used to reduce minimal residual disease (MRD) prior to hematopoietic stem cell transplantation (HSCT) in pediatric B cell precursor acute lymphoblastic leukemia (BCP-ALL), but sound evidence is lacking in China. Case presentation This retrospective study assessed the application of blinatumomab in B-ALL accompanied by persistent or relapsed low-level MRD before HSCT from April 2019 to July 2021. Two cases (Cases 1 and 2) initially achieved remission with MRD < 0.01% upon conventional therapy but had MRD relapse with MRD ≥ 0.01% but < 1% during maintenance treatment. Case 3 had no response to routine treatment, with high MRD (9.88% and 1.23% at days 19 and 46, respectively). Nevertheless, all patients had undetectable MRD. Cases 2 and 3 had undetectable fusion gene following blinatumomab therapy. By bone marrow monitoring (bone marrow morphology, bone marrow MRD and fusion gene) post-HSCT, the patients were persistently negative until May 15, 2022. No patient had serious adverse events before or during blinatumomab treatment. Conclusions Blinatumomab therapy showed a good performance for three pediatric cases with detectable but low MRD before HSCT in China. However, further prospective studies with large sample sizes are still needed for further clarification.