SAFETY AND EFFECTIVENESS ASSESSMENT OF THE HEMATOPOIETIC STEM CELL MOBILIZATION AND COLLECTION METHOD IN CHILDREN FROM DIFFERENT AGE GROUPS WITH MALIGNANT NEOPLASMS. A SINGLE-CENTER EXPERIENCE

High dose chemotherapy (HDCT) with autologous hematopoietic stem cell transplantation (auto-HSCT) is used currently as a consolidating stage in cancer treatment protocols for children from different age groups with various malignant neoplasms. Auto-HSCT can improve both progression-free survival and overall survival of such patients. At the same time the optimization of the collection of autologous hematopoietic stem cells (HSCs) seems to be an important factor in the successful implementation of auto-HSCT. The purpose of this research was to evaluate the safety and effectiveness of the HSCs mobilization and collection method in children from different age groups with various malignancies. Materials and methods used: a single-center retrospective cohort study of 258 pediatric patients (median body weight 20.0 [13.8; 42.0] (7.0-95.0) kg and median height 116 [97; 155] (55.0-189) cm) with various cancers aged 1 to 18 y/o (median 78.0 [36; 144] (3-215) months old) who received treatment in Jan. 2020-Jan. 2023 at the Research Institute of Pediatric Oncology and Hematology named after Academician L.A. Durnov with the N.N. Blokhin Russian Cancer Research Center (Moscow, Russia). Patients were divided into 3 age groups: younger than 1 y/o, 1 to 10 y/o and 11 to 18 y/o. Results: 242 (93.8%) of HSC apheresis procedures were successful on the first attempt, 16 patients underwent repeated apheresis (a total of 274 procedures were performed). The median number of CD34+ cells obtained was 110.95 [45.6; 276.4] (0.70-2338.2) cells/µl, median apheresis duration was 253.5 [189; 338] (82-575) min. No serious complications were observed during the HSCs mobilization and collection in any patient. None of the patients developed hemodynamic disturbances. The main criteria for effectiveness was the CD34+/kg level, the median of which was 5.1 [2.4; 12.7] (0.01-95.6)•106. One of the safety criteria for the patients from all the three age groups was the absence of hemodynamic disorders and citrate reactions in the form of numbness, cyanosis of the skin and respiratory disorders. Another important safety criteria were the absence of a significant decrease in both platelet and hemoglobin levels. The median platelet levels prior to the procedure was 125.5 [68; 210] (14.0-815)•109/l and 129 [73; 210] (17.0-823)•109/l at the end of the procedure (p<0.001). Hemoglobin levels before and after the procedure were 100 [94; 110] (75-242) g/l and 99 [93; 109] (70-142) g/l, respectively (p<0.001). Considering it safe to reduce hemoglobin (g/l) and/or platelets (•109/l) by no more than 10 units in each measurement, in 87.6±4.1% (83.0-91.1) of observed cases the procedure was safe without statistically significant differences in all age groups. The effectiveness of the HSCs mobilization and collection method proposed by the Authors in children of the older age group (11 to 18 y/o) was the lowest and was statistically significantly different from the effectiveness in the group of children aged 1 to 10 y/o (p<0.001) with cancer and amounted to 84.5±4.4% (79.6-88.4). Conclusion: with the multidisciplinary team of practitioners, HSC apheresis in children is a safe and effective technique used as part of the complex cancer treatment in patients from poor prognosis groups. The apheresis algorithm that the Authors have proposed allows high-quality collection of CD34+ positive cells in amounts sufficient for further auto-HSCT.