Abstract 7133: Phenomics-enabled discovery and optimization of small-molecule RBM39 degraders as an alternative to CDK12 targeting in high-grade serous ovarian cancer (HGSOC)

Abstract

Abstract Phenomics-enabled drug discovery is a powerful approach to identify novel targets and relationships previously unappreciated in biology. We built a phenomics platform leveraging high content microscopy and generated unique phenoprints for >7,000 genes using CRISPR/Cas9 technology and a diverse chemical library of >1 million compounds. This phenomics dataset contains an unprecedented quantity of gene-gene, gene-compound, and compound-compound relationships. We applied our phenomics platform and an inference based target-agnostic drug discovery approach to discover novel genes and small molecules that mimic CDK12 inhibition, an important transcriptional regulator of DNA damage response, while avoiding inhibition of the paralog CDK13. We discovered a novel and unappreciated association between CDK12 and RBM39 as well as small molecule degraders of RBM39. We established structure activity relationships (SAR) solely leveraging our phenomics platform, to generate REC-1170204, an RBM39 degrader. Unlike inhibitors of CDK12, we show that REC-1170204 does not directly inhibit CDK12, CDK13 or other kinases. However, REC-1170204 demonstrates candidate quality properties with improved potency, selectivity, and drug-like characteristics. Finally we show that REC-1170204 shows efficacy in High Grade Serous Ovarian cancer (HGSOC) pre-clinical models and synergizes with PARP inhibition in a PARP-resistant patient-derived xenograft (PDX) model. Together, our data suggests that targeting RBM39 may provide an attractive and safer approach to targeting CDK12 in the clinic. Citation Format: Chase Neumann, Harish Shankaran, Kiran Nadella, Kelly Biette, Shane Rowley, Ethan Gardner, Shadi Swaidani, Vamshi Manda, Lu Chen, Daria Beshnova, Ashraf Saeed, Christopher Bailey, Janet Paulsen, Paul Rearden, Carl Brooks, Ashish Bhandari, Chris Gibson, Laura Schaevitz, Imran Haque, Hayley Donnella, Michael Cuccarese, Marie Evangelista. Phenomics-enabled discovery and optimization of small-molecule RBM39 degraders as an alternative to CDK12 targeting in high-grade serous ovarian cancer (HGSOC) [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 7133.