We report on posttransplant relapsed pediatric patients with B-precursor
acute lymphoblastic leukemia with no further standard of care
therapy who were treated with the T-cell engaging CD19/CD3-bispecific single-chain antibody construct
blinatumomab on a compassionate use basis. Blast load was assessed prior to, during and after
blinatumomab cycle using flow cytometry to detect
minimal residual disease, quantitative polymerase chain reaction for rearrangements of the
immunoglobulin or T-cell receptor genes, and bcr/abl mutation detection in one patient with
Philadelphia chromosome-positive
acute lymphoblastic leukemia.
Blinatumomab was administered as a 4-week continuous
intravenous infusion at a dosage of 5 or 15 μg/m(2)/day. Nine patients received a total of 18 cycles. Four patients achieved complete remission after the first cycle of treatment; 2 patients showed a complete remission from the second cycle after previous reduction of blast load by
chemotherapy. Three patients did not respond, of whom one patient proceeded to a second cycle without additional
chemotherapy and again did not respond. Four patients were successfully retransplanted in molecular remission from haploidentical donors. After a median follow up of 398 days, the probability of hematologic event-free survival is 30%. Major toxicities were grade 3
seizures in one patient and grade 3
cytokine release syndrome in 2 patients.
Blinatumomab can induce molecular remission in pediatric patients with posttransplant relapsed B-precursor
acute lymphoblastic leukemia and facilitate subsequent allogeneic
hematopoietic stem cell transplantation from haploidentical donor with subsequent long-term
leukemia-free survival.