Background Paediatric patients with relapsed B-precursor acute lymphoblastic leukaemia (ALL) after haematopoietic stem cell transplantation (HSCT) have a poor prognosis and need to achieve another haematologic remission or very low or negative minimal residual disease (MRD) before proceeding to a subsequent HSCT. Blinatumomab is the first of a new class of bispecific single-chain antibody construct (BiTE) and is indicated for the treatment of adults with Philadelphia chromosome negative relapsed or refractory B-precursor ALL. In paediatrics, blinatumomab is currently under investigation.

Purpose To describe the efficacy and safety of treatment with blinatumomab in a post-transplant relapsed paediatric case with B-precursor ALL compassionate use.

Material and methods Retrospective case report of the use of blinatumomab in a 12-years-old child diagnosed with post-transplant relapsed B-precursor ALL. The data were obtained from the digital clinical history. MRD response was defined as MRD level <10^-4 at the end of treatment (MRD quantification by flow cytometry).

Results Initially, the patient was treated according to the ALL SEHOP/PETHEMA-2013 paediatric protocol. After the induction regimen, the patient did not achieve MRD-negative (MRD=14%) and complete remission (CR). Similarly, MRD-negative was not reached after intensive consolidation (MRD=4.9%). Since MRD was >0.1%, the patient was treated with clofarabine +cytarabine and conditioning with thiotepa, busulfan and cyclophosphamide. After this treatment, the patient underwent haploidentical (HSCT), achieving MRD-negative and CR. Eight months’ later, this patient underwent an isolated bone marrow relapse (MRD=19% and 25% blasts in the bone marrow). The patient was treated with two cycles of blinatumomab, which was administered by continuous intravenous infusion for 28 days followed by a 14 day treatment-free interval per cycle (doses: 5 mcg/m² during the first 8 days and 15 mcg/m2 for the rest of the treatment). This child achieved MRD-negative and CR. Safety: side-effects related to chemotherapy were febrile neutropaenia and mucositis, and after HSCT developed cutaneous graft-versus-host disease. No neurological and infectious symptomatology was developed with blinatumomab, just a cold for 7 days.

Conclusion In this case of a paediatric patient with high-risk ALL who relapsed after HSCT, the use of blinatumomab was shown to be safe and effective, achieving MRD. Nevertheless, more studies are required to demonstrate its efficacy and safety profile.

No conflict of interest