Blinatumomab in pediatric acute lymphoblastic leukemia: one center experience

Background. Despite the successes achieved in the treatment of B-cell acute lymphoblastic leukemia (B-ALL), overcoming the toxicity of standard chemotherapy regimens and the treatment of relapsed/refractory (r/r) forms of the disease remains relevant. The most promising option is to use immunotherapy (IT), including a monoclonal antibody blinatumomab (BM). The purpose of the study. To analyze indications of using, as well as efficacy and tolerability of BM in children with V-ALL. Materials and methods. From April 2016 to January 2024 a retrospective assessment of using of BM in children with B-ALL in the chemotherapy department of oncohematological diseases and TCM for children in Almazov National Medical Research Centre was performed. Results. The study included 53 patients, including 28 (53 %) girls and 25 (47 %) boys with median age of 7,7 (2,08–19,8) years. Indications for using of BM were as follows: (1) consolidation of remission (CR) with primary ALL (n = 17, 32 %); (2) persistence of minimal residual disease (MRD) (n = 23, 43 %) after completion of chemotherapy (CT) induction or before the stage of allogeneic haematopoietic stem cell transplantation (alloHSCT); (3) replacement of the standard CR due to the previous toxicity of СT or other contraindications to its implementation (n = 12, 23 %); (4) salvage therapy for r/r ALL (n = 1, 1,9 %). The status of MRD-negative remission after the 1st course of IT was achieved in 89 % of cases. Therapy using BM in a patient with the r/r ALL and total blast infiltration of the bone marrow was effective and facilitated reducing the tumor population to 7,2% by day 15 of therapy, however, there was a fatal outcome due to development and progression of preexisted severe infection. The most common variants of grade III–IV toxicity were leuko-/neutropenia (28 %) and neurotoxicity (3,7 %). BM dose reduction for the purpose of relieving toxicity was required in 19 % of patients, while the median days of therapy with dose reduction was 4. Corticosteroids were used for this purpose in 11 % of cases, antibacterial therapy — in 13 %. At the time of results evalution, there were no relapses of the disease in the study group. The article analyzes the international experience of using BM in patients with B-ALL.Conclusion. Our experience and the presented literature data demonstrate a reasonable expansion of indications for using of BM in children with B-ALL with high efficacy and satisfactory toxicity profile.