Abstract 6395: Atovaquone promotes release of damage-associated molecular patterns from epithelial ovarian cancer cells
Authors: Ponce Mayra A. Betancourt , Boonpattrawong Nicha , Sharma Sejal , Gumperz Jenny , Patankar Manish , Barroilhet Lisa 
Published: April 2023

Abstract
Epithelial ovarian cancer (EOC) is the deadliest gynecologic cancer in the United States. Most patients are diagnosed with EOC at advanced stages and have limited treatment options. Developing new therapies that are effective against localized and disseminated disease is imperative. Unfortunately, clinical trials evaluating immunotherapies in EOC have not been consistently effective. Preclinical data have shown that neoadjuvant chemotherapy can help increase antigen presentation and T cell infiltration, as well as decrease immunosuppressive effectors, suggesting that combining cytotoxic chemotherapy with immunotherapies can be a powerful approach to potentiate antitumor responses in EOC. However, studies looking at the combination of immunotherapies with carboplatin and paclitaxel, which are the mainstay chemotherapies for EOC, have not improved progression-free survival rates. We propose a novel combination approach using the well-tolerated, FDA-approved, oxidative phosphorylation (OXPHOS) inhibitor atovaquone as a sensitizer to cellular immunotherapies for EOC. OXPHOS inhibition leads to oxidative stress, which in turn leads to DNA and protein damage, activation of stress response pathways, and ultimately cell death. During cell injury and death, Damage-Associated Molecular Patterns (DAMPs) can be released into the extracellular environments, activate the innate immune system, and lead to immunogenic cell death. We have previously shown that atovaquone leads to increased reactive oxygen species levels and DNA damage. Thus, we hypothesized that atovaquone treatment would lead to release of DAMPs, including HMGB1 and TFAM, from EOC cells. Following treatment with atovaquone, we collected the supernatant of EOC cell cultures at different timepoints and measured HMGB1 and TFAM concentrations via enzyme-linked immunosorbent assays (ELISAs). We observed that both HMGB1 and TFAM concentrations were elevated at 24 and 48 hours following atovaquone treatment. This suggests that atovaquone can facilitate immune detection and attack by promoting DAMPs release. When DAMPs are released into the extracellular environment, they are recognized by innate immune cells, which become activated to produce pro-inflammatory cytokines and increase antigen presentation to T cells. Given our results showing increased release of DAMPs following exposure to atovaquone, we are developing an in vitro culture system to study immune cell responses to atovaquone-treated EOC cells. We are also monitoring transcriptomic responses of EOC cells treated with atovaquone to identify changes in expression of DAMPs and other immune-activating pathways through RNA sequencing. Our ultimate goal is to test T cell recognition and responses toward atovaquone-treated EOC cells with the intention of utilizing this chemotherapeutic agent as an adjunct to immunotherapeutic efforts for EOC.
Citation Format: Mayra A. Betancourt Ponce, Nicha Boonpattrawong, Sejal Sharma, Jenny Gumperz, Manish Patankar, Lisa Barroilhet. Atovaquone promotes release of damage-associated molecular patterns from epithelial ovarian cancer cells [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 6395.