Abstract 792: Immunoprotective effects of metformin against delayed doxorubicin-induced immune perturbation in C57BL/6 mice

Abstract Introduction: Chronic immunological perturbations that leave cancer survivors with a long list of sequelae, such as an increased risk of death due to infection, remain a major complication of traditional chemotherapy. This risk is particularly pronounced in childhood cancer survivors treated with doxorubicin (DOX), a well-known culprit of immunosuppressive activities that may linger for years following the cessation of chemotherapy. Metformin is a first-line drug against Type-2 Diabetes Mellitus and has recently entered the pharma-oncology limelight due to its senomorphic and immunoprotective properties. In this study, we determined the potential immunoprotective effects of metformin against delayed DOX-induced immune perturbation in a mouse model of childhood cancer survivors. Methods: Five-week-old C57BL/6N mice were randomly assigned to four groups: Control, Metformin, DOX, and Metformin/DOX. DOX-treated mice received intraperitoneal injections with either DOX (4 mg/kg/week) or saline for three weeks. Metformin-treated mice were administered metformin (250 mg/kg/day) via drinking water. Metformin treatment began three days before the first DOX injection and was continued throughout and five weeks post DOX injections. Five weeks following the last dose of DOX, all mice were humanely euthanized in accordance with institutional guidelines. Blood and bone marrow samples were collected during the necroscopy and analyzed with a Flow Cytometer and a Hematological Analyzer to provide insight into individual immune cell populations. Results: Metformin alleviated delayed DOX-induced perturbations in several immune subpopulations. In the innate immune system, metformin decreased neutrophil and monocyte frequency in the blood and bone marrow. However, metformin also ameliorated DOX-induced depletion of the CCR2+ activated and CD86+ invasive monocyte frequencies. In the adaptive immune system, metformin increased the frequency of lymphocytes, particularly B cells, in the blood. This trend is supported by the increased population of Ki67+ proliferating B cells in the bone marrow across all stages of maturation. Conclusion: DOX-induced lingering effects on immune cell populations were partially mitigated by metformin. Metformin improved the functionality of the attenuated monocyte population in the bone marrow and increased the frequency of B lymphocytes in the blood, which can be traced to the expanded population of proliferating B cells in the bone marrow. These results suggest metformin has dual effects on the immune system and may serve as a therapeutic option to mitigate chronic immune perturbations in childhood cancer survivors. Citation Format: Ian J. Ahlberg, Mary R. Daniel, Benu George, Marianne K.O. Grant, Korbyn J.V. Dahlquist, Christina D. Camell, Beshay N. Zordoky. Immunoprotective effects of metformin against delayed doxorubicin-induced immune perturbation in C57BL/6 mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 792.