Abstract 1260: LIPA inhibition enhances the therapeutic efficacy of DNA-damaging agents in ovarian cancer through induction of ER stress and enhancing DNA damage.

Abstract Background: Ovarian cancer (OCa) is the most lethal gynecologic malignancy in the United States, largely due to the lack of effective early detection strategies and the development of chemoresistance following initial treatment. These challenges emphasize the urgent need for improved therapeutic approaches. Recently, our team identified ERX-208, a potent tris-benzamide molecule (IC50-100 nM) with strong activity against OCa cells. ERX-208 targets lysosomal acid lipase A (LIPA), inducing endoplasmic reticulum (ER) stress, disrupting protein synthesis, and promoting apoptosis. The objective of this study is to evaluate the potential of ERX-208 in enhancing the efficacy of FDA-approved chemotherapeutics. Methods: In our study, we performed in vitro screening of 147 FDA-approved chemotherapy drugs in combination with ERX-208 to assess their effects on the viability of OCa model cells. The drug combination dose-response data were analyzed using the SynergyFinder Plus software. To validate the synergistic effects, we conducted several in vitro assays, including tests for cell proliferation, colony formation, cell cycle progression, DNA damage, comet assays, apoptosis, and invasion. Furthermore, preclinical studies were carried out using patient-derived organoids (PDO) and xenograft (PDX) models to evaluate the combination's efficacy in a more clinically relevant setting. Results: Combination therapy screening of 147 FDA-approved chemotherapeutic agents with the LIPA inhibitor ERX-208 identified multiple synergistic drug pairs in OCa models. SynergyFinder analysis revealed strong combination sensitivity and synergy scores for several DNA-damaging agents. ERX-208 monotherapy inhibited OCa cell growth in vitro and in vivo, consistent with its mechanism of inducing LIPA-dependent ER stress. Combination treatments with paclitaxel or cisplatin further amplified these effects, significantly reducing cell viability across OCa cell lines compared to monotherapy. Mechanistic studies demonstrated enhanced gamma-H2AX accumulation, increased DNA damage, robust induction of ER stress markers, and reduced invasion following combination therapy. In PDO and PDX models, ERX-208 combined with DNA-damaging agents produced marked tumor growth suppression beyond monotherapies, confirming the translational relevance of the synergy. Furthermore, ERX-208 effectively reduced the viability of therapy-resistant OCa models in vitro and inhibited xenograft growth in vivo. These findings support ERX-208 as a potent ER stress-inducing agent that enhances the therapeutic efficacy of standard chemotherapies in OCa models. Conclusions: Our findings demonstrate that combining ERX-208 with DNA-damaging agents significantly enhances therapeutic efficacy, highlighting the potential of ERX-208-based combination therapy for treating OCa. Citation Format: Durga Meenakshi Panneerdoss, Tae-Kyung Lee, Khaled Mohamed Nassar, Gaurav Sharma, Scott Terry Elmore, Henry Neal, William Cole Arnold, Edward Kost, Suryavathi Viswanadhapalli, Jung-Mo Ahn, Ganesh V. Raj, Ratna K. Vadlamudi. LIPA inhibition enhances the therapeutic efficacy of DNA-damaging agents in ovarian cancer through induction of ER stress and enhancing DNA damage [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 1260.