Primary refractory and relapsed refractory acute myeloid leukemia remains an unresolved problem in pediatric oncology. Children with AML who fail to achieve complete remission on high-dose cytarabine and antracyclines have no chance for survival without allogeneic hematopoietic stem cell transplantation. We evaluated the outcome of αβ-T-cell-depleted haploidentical transplantation in a cohort of children with chemorefractory acute myeloid leukemia. Thirty-six patients with either primary refractory (n = 14) or relapsed refractory (n = 22) acute myeloid leukemia in active disease status received a transplantation from haploidentical donors. The preparative regimen included cytoreduction with fludarabine and cytarabine and subsequent treatment with treosulfan and either melphalan or thiophosphamide. Serotherapy consisted of antithymocyte globuline in 14 pts and targeted immunomodulation with tocilizumab +/- abatacept in 22 pts. Grafts were PBSCs engineered by TCR-αβ/CD19 depletion. Posttransplant preemptive therapy included modified donor lymphocyte infusions with or without hypomethylating agents. Complete remission was achieved in 30 (83%) рts. The cumulative incidence of acute GVHD grade II–IV was 25%, and the cumulative incidence of chronic GVHD was 18%. Transplant-related mortality was 6%, and relapse incidence was 48%. Event-free survival was 46%, and overall survival was 41% at 2 years. Good early recovery of NK cells was associated with significantly improved survival and decreased relapse incidence. Our data suggest that αβ-T-cell-depleted haploidentical HSCT provides a reasonable chance of cure in a cohort of children with chemorefractory acute myeloid leukemia and creates a solid basis for further improvement. The study was approved by the Independent Ethics Committee of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology, and Immunology.

The article presents retrospective data analysis of a cohort of patients with PKD (n = 41 patients, aged 4 months – 26,5 years, median of age – 5 years 1 month) who were examined at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology for unspecifid hereditary hemolytic anemia during the period 2013–2020. The study was approved by the Independent Ethics Committee of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. In all patients, the diagnosis was confimed by Next Generation sequencing (NGS). The homozygous mutations in the PKLR gene were found in 10 patients (24.39%), compound heterozygous mutations in 31 patients (75.61%), 77.78% of them were missense mutations. Gender distribution (male:female) was 1:1.73. At least once transfusion of erythrocyte suspension was required to 40 (97.56%) patients. The minimum age at the time of the debut of transfusion dependence was the fist day of life, the maximum was 4 years. Exchange blood transfusion was performed in 13 children, severe normocytic hyperregenerative anemia with transfusion of red blood cells in the fist days of life was noted in 12 children, at the 1st month of life – in 9 children, at the 2nd month of life – in 8 children, at the 3rd month – in 6 children, at the 5th month – in 2 children, at the 1st year – in 1 child, and 2 children underwent single transfusions on the background of infectious episodes at 3 and 4 years respectively. Splenectomy due to high transfusion dependence was performed in 10 patients: transfusion independence was achieved in 5 patients, in 5 – an increase in the interval between blood transfusions. Median of surgical intervention (9 patients): 7 years 4 months, minimum age – 1 year 4 months, maximum – 14 years 4 months. In total, 36 genotypes were described in 41 patients, among them were: c.1529G>A in 3 patients, c.1137_1139del / c.1456C>T – in 2 patients, c.1079G>A/c.1529G>A in 2 patients, c.1130T>C/c.1456C>T in 2 patients, other genotypes occurred once. Two mutations were the most frequent: c.1456C>T (16.67%) and c.1529G>A (16.67%). 19 (46,34%) of patients had previously not described mutations.