O-262 Concomitant administration of temsirolimus and anti-Müllerian hormone is effective in protecting fertility from chemotherapy-induced damage

Abstract Study question Our goal was to determine whether the administration of temsirolimus and recombinant AMH, concomitant with chemotherapy, is effective in protecting fertility from chemotherapy-induced damage. Summary answer The administration of temsirolimus and recombinant AMH concomitant with chemotherapy proved effective in protecting the fertility, as assessed five weeks after treatment. What is known already Alkylating agents cause apoptosis of growing follicles which produce anti-Müllerian hormone (AMH), a key factor controlling primordial follicle dormancy. Their loss lowers AMH levels, leading to indirect overactivation and extensive recruitment of primordial follicles. Additionally, alkylating agents directly overactivate primordial follicles through the PI3K–mTOR pathway, ultimately depleting the ovarian reserve. Given chemotherapy’s role in activating primordial follicles, recent studies have shown that blocking both indirect and direct activation pathways by administering AMH and an mTOR inhibitor effectively protects the ovary from chemotherapy-induced damage. However, no data is available on residual fertility and longer-term effectiveness. Study design, size, duration Thirty-eight female NMRI mice were randomly assigned to one of three treatment groups: (i) control group; (ii) chemotherapy group; and (iii) gonadoprotection group. Five weeks after treatment, all mice underwent ovarian stimulation and were mated with males to evaluate residual fertility. After mating, the animals were euthanized for embryo collection and ovarian recovery. The ovarian reserve was assessed by follicle count, while follicle damage was evaluated through analyses of apoptosis, activation and proliferation. Participants/materials, setting, methods The control group (n = 10) received a 100µL intraperitoneal injection of PBS. The chemotherapy group (n = 13) received a single 100µL intraperitoneal injection of chemotherapy (120mg/kg cyclophosphamide + 12 mg/kg busulfan). The gonadoprotection group (n = 15) received five injections of 5 mg/kg temsirolimus over one week prior to chemotherapy, followed by a chemotherapy injection, then five injections of 5µg rAMH over the 24 hours following chemotherapy. All mice were stimulated five weeks later with Menopur 3.75IU. Main results and the role of chance In terms of residual fertility, the control group showed the highest mean number of retrieved embryos (41.40 ± 14.74), closely followed by the gonadoprotection group (36.27 ± 17.22), with comparable fertility outcomes (p = 0.4449). In contrast, the chemotherapy group exhibited a significant reduction (20.63 ± 12.12) compared to both the control group (p = 0.0046) and the gonadoprotection group (p = 0.0349). Regarding ovarian reserve, the control group showed the highest total follicle count (897.4 ± 392.8), with no significant difference compared to the gonadoprotection group (714.4 ± 283.9). In contrast, the chemotherapy group demonstrated a significant decline in total follicle count per ovary (320.7 ± 145.5) compared to both the control group (p < 0.0001) and the gonadoprotection group (p = 0.0008). Follicle damage was assessed by immunohistochemistry analyses of caspase-3 for apoptosis, phospho-Akt for activation and Ki67 for proliferation. Follicle proliferation rates were significantly higher in the chemotherapy group (59.38% ± 14.67%) than in the control group (20.72% ± 10.52%) (p < 0.0001). Gonadoprotective treatment led to a decrease in follicle proliferation (42.23% ± 18.37%) compared to the chemotherapy group (p = 0.0083), but the proliferation rate remained significantly higher than in the control group (p = 0.0020). No significant difference was observed between groups for follicle apoptosis and activation. Limitations, reasons for caution Temsirolimus and AMH show gonadoprotective potential in murine models but their effects on human ovarian tissue remain unclear. Studies on AMH in xenografts report conflicting results: some indicating inhibition of follicle activation and others suggesting promotion of follicle growth. Further research is needed to clarify their applicability in human models. Wider implications of the findings Our findings suggest that temsirolimus and AMH show promise as gonadoprotective agents, potentially preserving fertility and the ovarian reserve against chemotherapy. This could provide new fertility preservation options for patients who cannot benefit from current available techniques, such as oocyte and embryo cryopreservation or ovarian tissue cryopreservation and transplantation. Trial registration number No