Abstract 3093: SLC25A28 is a synthetic lethal target in nucleotide excision repair-deficient cancer

Abstract Background: Nucleotide excision repair-deficient (NER-D) cancers comprise approximately 10% of bladder urinary tract and uterine cancers. Platinum-based chemotherapy is the current standard of care for NER-D cancers; however, its nephrotoxicity limits applicability in patients with compromised renal function. No druggable targets have been identified for NER-D tumors. Genome-wide CRISPR screening offers a powerful strategy to identify synthetic lethal interactions. We performed a genome-wide screen to identify potential synthetic lethal targets in NER-deficient cells. Methods: An RT112/84 ERCC4 knockout (ERCC4-/-) cell line was generated. ERCC4 status was examined by Sanger sequencing and Western blotting, and nucleotide excision repair activity was assessed using the Host Cell Reactivation Assay (HCRA). A genome-wide CRISPR screen was performed in RT112/84 wild-type (WT) and ERCC4-/- cells to identify candidate synthetic lethal targets. Colony formation assays validated candidate interactions, and SLC25A28 was further tested for synthetic lethality with ERCC2, ERCC3, and ERCC5. RNA sequencing was conducted to investigate the mechanism underlying SLC25A28-ERCC4 synthetic lethality. Results: Sanger sequencing and Western blot confirmed ERCC4 knockout in RT112/84 cells. HCRA demonstrated markedly reduced NER activity in ERCC4-/- cells. Genome-wide CRISPR screening identified SLC25A28 as a top synthetic lethal candidate with ERCC4. Colony assays validated the synthetic lethality between SLC25A28 and ERCC2, ERCC3, ERCC4 and ERCC5. Conclusions: Our findings identify SLC25A28 as a novel synthetic lethal target in NER-deficient cancers, suggesting that inhibition of SLC25A28 may represent a potential therapeutic strategy for tumors harboring NER pathway mutations. This study was supported by STTR 1 R41 CA275627-01, the Niehaus Center for Inherited Cancer Genomics, and the Breast Cancer Research Foundation. Citation Format: Nan Yang, Vijai Joseph, Lisa Hoeg, Xuechun Bai, Sizhi Gao, Ouathek Ouerfelli, David B. Solit, Jian Carrot-Zhang, Gopa Iyer, Daniel Durocher, Kent W. Mouw, Kenneth Offit, Steven M. Lipkin. SLC25A28 is a synthetic lethal target in nucleotide excision repair-deficient cancer 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 3093.