Abstract 3210: Monoclonal antibodies targeting PD-1, LAG-3, and TIM-3 do not cause reproductive or endocrine toxicity in a syngeneic model of triple negative breast cancer

Background: Few targeted treatments exist for triple negative breast cancer (TNBC), an aggressive form of breast cancer that is diagnosed more frequently in reproductive-age women. As a result, most patients receive frontline chemotherapies and often experience infertility and endocrine disruption. Immunotherapies are a promising option for less toxic therapeutic approaches, but little is known about their effects on reproductive and endocrine function. Methods: E0771 cells were injected into the bilateral mammary pads of 8-week-old female C57Bl/6J mice. After tumor development (14 days post-implantation), E0771 mice received 200 ug doses of immunotherapy (anti-PD-1, anti-LAG-3, or anti-TIM-3 antibodies) or IgG isotype control every four days, with treatments ceasing after the third dose. 8 days after the final dose, estrus cycling was monitored via vaginal cytology. 11-15 days after the final dose, mice were euthanized during proestrus stage, and serum and ovaries were collected. Serum levels of anti-Mullerian hormone (AMH), luteinizing hormone (LH), and follicle stimulating hormone (FSH) were quantified via ELISA. Ovaries were fixed in formalin and embedded in paraffin, then sectioned serially. Follicle staging and abundance was quantified via hematoxylin and eosin staining. Follicle health and apoptosis was evaluated via TUNEL staining. Results: There were no significant differences between any of the treatment and control groups in the percentage of time spent in each stage of the estrus cycle, indicating that treatment with the selected immunotherapies does not cause perturbations in reproductive cyclicity. Serum hormone analysis revealed no significant differences in AMH, LH, or FSH levels between treatment and control groups, indicating that these immunotherapies do not cause endocrine toxicity. There were no significant differences in follicle abundance between any of the treatment and control groups, suggesting that the immunotherapies are not toxic to the ovarian reserve or developing follicles. TUNEL staining revealed no significant differences in granulosa cell or oocyte apoptosis between treatment groups. Conclusion: Treatment with anti-PD-1, anti-LAG-3, or anti-TIM-3 monoclonal antibodies does not cause reproductive or endocrine toxicity in a tumor-bearing mouse model. These results demonstrate that immunotherapy may be a promising component of fertility-sparing therapeutic regimens for patients who wish to maintain ovarian and endocrine function after cancer treatment. Citation Format: Payton De La Cruz, Jennifer Ribeiro, Kathryn Grive. Monoclonal antibodies targeting PD-1, LAG-3, and TIM-3 do not cause reproductive or endocrine toxicity in a syngeneic model of triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3210.