Abstract 1619: The HIV protease inhibitor nelfinavir increases the sensitivity of epithelial ovarian cancer cells to cisplatin

Abstract Chemotherapy resistance is a major challenge in epithelial ovarian cancer (EOC) treatment. Standard treatment involves cytoreductive surgery in combination with platinum (Pt)-based chemotherapy. While initial treatment is often successful, over 80% of patients develop recurrent Pt-resistant disease. Therefore, therapeutics which increase sensitivity to platinating agents such as CDDP are essential to kill EOC cells. One candidate drug that may increase the sensitivity of CDDP to resistant EOC cells is the HIV protease inhibitor nelfinavir (NFV), which has previously shown anti-cancer activity against EOC in vitro. The goal of this study was to determine if the combination of NFV and CDDP is effective against EOC cells. Four EOC cell lines, with varying degrees of CDDP resistance, were exposed to increasing concentrations of CDDP in the presence or absence of NFV. In all cell lines, the addition of NFV significantly enhanced the cytotoxicity and decreased the IC50 of CDDP. Furthermore, the combination of NFV and CDDP was determined to be synergistic using the Loewe model of drug interaction. Interestingly, EOC cells treated with NFV and CDDP displayed characteristics of lytic cell death, such as an increased proportion of annexin-V and 7-AAD co-staining, and the release of LDH into the culture supernatant. Additionally, morphological assessment with brightfield and fluorescent microscopy revealed significant cellular swelling and cytoplasmic vacuolization, signs of inflammatory cell death. Immunoblotting revealed cleavage of the pyroptotic effector proteins gasdermin D and gasdermin E, suggesting a shift from apoptosis to pyroptosis with NFV and CDDP combination. Further evidence for pyroptosis include cleavage of the inflammatory caspase-1, as well as release of the inflammatory cytokine IL-1β into the supernatant as determined through ELISA. Interestingly, the combination of CDDP and NFV resulted in decreased expression of mature lamin A, leading to severe nuclear deformation and increased DNA damage. Furthermore, the loss of lamin A was associated with the leakage of nuclear DNA into the cytosol, as analyzed through droplet digital PCR (ddPCR) after cellular fractionation. Cytosolic dsDNA is an activation signal for the AIM2 inflammasome; to confirm its involvement, EOC cells were incubated with CDDP and NFV in the presence or absence of the AIM2 inhibitor suramin. Addition of suramin to the CDDP and NFV treated EOC cells rescued cell viability, and simultaneously decreased IL-1β. Overall, these results demonstrate a transition from apoptotic to pyroptotic cell death when EOC are treated with CDDP and NFV. Resistance to apoptosis is a major mechanism by which EOC cells become Pt-resistant. Therefore, NFV and CDDP together, may be a feasible therapeutic option for these patients through the induction of pyroptosis. Citation Format: Benjamin Forgie, Sarah T. Ferrier, Farah H. Abdalbari, Edith Zorychta, Alicia A. Goyeneche, Julia V. Burnier, Carlos M. Telleria. The HIV protease inhibitor nelfinavir increases the sensitivity of epithelial ovarian cancer cells to cisplatin [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 1619.