Pediatric patients with acute lymphoblastic leukemia treated with blinatumomab in a real-world setting: Results from the NEUF study

Background: Prior to regulatory approval of blinatumomab in pediatric patients with relapsed/refractory Philadelphia chromosome-negative B-cell precursor acute lymphoblastic leukemia (R/R Ph− BCP-ALL), blinatumomab was made available via an expanded access program (EAP). Procedure: This retrospective observational study included patients receiving blinatumomab in the EAP between January 1, 2014 and June 30, 2017 who were followed until death, entry into a clinical trial, end of follow-up, or end of the study period (December 31, 2017), whichever occurred first. Results: Among 113 children enrolled, 72 were diagnosed with R/R Ph− BCP-ALL and 41 were minimal residual disease positive (MRD+, either Ph− or Ph+). In the R/R group, 38 (53%) patients achieved hematological response within two cycles. Of these, 19 (50%) proceeded to hematopoietic stem cell transplantation (HSCT) without bridging myelosuppressive therapy. Of 36 patients in the R/R group evaluable for MRD, 30 (83%) had an MRD response. In the R/R group, median relapse-free survival was 5.4 months and median overall survival (OS) was 8.2 months. Of 36 patients in the MRD+ group who were evaluable for MRD after two cycles, 27 (75%) had an MRD response. Overall, 24 (59%) of the MRD+ patients proceeded to HSCT without other bridging therapy. Median disease-free survival was 13.6 months; median OS was not reached. Conclusions: In this real-world pediatric cohort, blinatumomab was effective within two cycles. Over half of patients with R/R Ph− BCP-ALL achieved hematological response and most achieved MRD response in the MRD+ group, confirming the efficacy of blinatumomab in pediatric trials.