A successful second allogeneic hematopoietic stem cell transplantation from an alternative donor in a patient with loss of HLA heterozygosity relapse of juvenile myelomonocytic leukemia: case series analysis

The development of inhibitory antibodies against FVIII is the most serious complication associated with the use of FVIII concentrates in hemophilia A patients. There is a need for more research on measures that could reduce the risk of inhibitor formation in previously untreated patients (PUPs) with severe hemophilia A. The purpose of this study was to determine the effectiveness of the prevention of clotting inhibitor development in PUPs (or minimally treated patients) with severe hemophilia A by administering plasma-derived factor VIII concentrate (pdFVIII) at a dose of 25 IU/kg once a week for a year. The study was approved by the Independent Ethics Committee and the Scientific Council of the Belarusian Research Center for Pediatric Oncology, Hematology and Immunology (the Republic of Belarus). Between 2010 and 2022, 56 boys were newly diagnosed with severe hemophilia A. Twenty-one of them received pdFVIII as on-demand treatment to stop bleeding (Group 1). Thirty-five boys received pdFVIII at a dose of 25 IU/kg body weight once a week during the first 50 weeks of treatment for the prevention of inhibitor development (Group 2). The administration of pdFVIII at a dose of 25 IU/kg once a week in the PUPs (or minimally treated patients) contributed to a decrease in the cumulative incidence of inhibitors to 15.9 ± 7.7% (4 out of the 35 patients who had been treated prophylactically) compared with 43.7 ± 11.8% (8 out of the 21 patients who had received hemostatic therapy to stop bleeding) (log-rank test, p = 0.041). Thus, the administration of pdFVIII concentrate at a dose of 25 IU/kg once a week for the first 50 weeks of treatment lead to a decrease (p = 0.009) in the cumulative incidence of inhibitors against the administered coagulation factor VIII to 15.9 ± 7.7%.