Abstract 7149: Discovery of a novel USP1 inhibitor: Targeted therapy for BRCA-mutated and PARPi-resistant cancers

Abstract Harnessing synthetic lethality offers an innovative approach to targeted cancer treatment. USP1, a specific deubiquitinating enzyme, has gained attention as a potential synthetic lethality target for BRCA-mutated cancers. At AIGEN Sciences, Inc., we've integrated the advanced capabilities of our human-in-the-loop (HITL) AI drug discovery platform, AIGEN ChemTailor. This cutting-edge platform thrives on continuous learning enhanced by expert feedback, refining our approach to drug discovery. Using AIGEN ChemTailor, we synthesized a specific USP1 inhibitor. Its inhibitory capabilities were validated through the Ubiquitin-rhodamine 110 assay. Notably, our inhibitor presented remarkable anti-proliferative effects on BRCA1 mutant cells (MDA-MB-436) while showing no activity against BRCA wild-type cells (HCC1954), highlighting its specificity. The efficacy of our inhibitor was enhanced when combined with PARP inhibitors, such as olaparib or AZD5305, especially in UWB1.289 cells. Impressively, the USP1 inhibitor also effectively targeted PARPi-resistant cell lines, including A2780-ola, UWB1.289-nir, HCC38-ola, MDA-MB-468-ola, U251MG-ola, and OVCAR8-ola. Clonogenic assays with MDA-MB-436 and MCF-10A emphasized our inhibitor's selectivity towards BRCA mutant phenotypes. Subsequent studies demonstrated the compound's mechanism: inducing replication stress by impairing of DNA synthesis and activating DNA damage pathways via ATR signaling. Preclinical mouse studies highlighted favorable pharmacokinetics and involved the assessment of anti-tumor effects in animal models. In summation, our USP1 inhibitor, developed using AIGEN ChemTailor and advanced molecular modeling techniques, stands out as a potent therapeutic against BRCA-mutated cancers and PARP inhibitor-resistant strains. Citation Format: Jihye Kim, Sunkyu Kim, Sejeong Park, Sanghoon Lee, Kiwoong Yoo, Ho-Jeong Lee, Jaewoo Kang, Kwang-Ok Lee. Discovery of a novel USP1 inhibitor: Targeted therapy for BRCA-mutated and PARPi-resistant cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7149.