Gonadal function in male pediatric patients after allogeneic hematopoietic stem cell transplantation: a comparison of the effects of treosulfan- and total body irradiation-based conditioning

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment for many orphan diseases that can significantly improve prognosis and survival in patients. Conditioning prior to HSCT includes alkylating agents and/or total body irradiation (TBI) that are both known to be highly gonadotoxic. This is why it is so important to choose drugs and treatment options with minimal side effects. The aim of our study was to evaluate the reproductive function of male HSCT recipients who had received treosulfan- and TBI-based conditioning. The study was approved by the Independent Ethics Committee and the Scientific Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology of Ministry of Healthcare of the Russian Federation. We included 112 boys. The concentrations of follicle-stimulating and luteinizing hormones, testosterone levels, testicular size (measured using ultrasound) and pubertal development (as per the Tanner scale) were assessed over time. The obtained data showed that the effect of treosulfan on gonadal function in the males was less significant than that of TBI, with the cumulative probability of developing hypogonadism at 4 years after HSCT equaling 0% and 24% respectively. However, the toxicity of other alkylating agents included in a treosulfan-based conditioning regimen eliminates the difference in the cumulative probability of hypogonadism between the two approaches. Further annual monitoring is needed to fully understand the reproductive potential of the patients.