Abstract 6763: A cellular platform for systematic comparison of RAS inhibitors using PRISM multiplexed screening

Abstract The discovery and development of direct inhibitors of KRAS is transforming therapeutic options across diverse cancer types. Here, we use the PRISM collection of nearly 900 cancer cell lines, including more than 150 KRAS-mutant cell lines, to characterize 19 KRAS-targeting inhibitors or degraders, including G12C-, G12D-, and pan-KRAS inhibitors. Agents were tested at 8 doses (threefold dilution) for 5 days across a median of 883 cell lines. For each agent, we assessed its selectivity and correlation with KRAS mutation status and genetic dependency. For each cell line, we categorized its sensitivity to each individual agent and in aggregate by comparing across RAS modulators. For example, all 10 KRAS G12C inhibitors or degraders tested showed significant selectivity for cell lines harboring the G12C mutation, with RMC-6291, adagrasib, divarasib, and sotorasib showing the greatest enrichment. Among G12C-mutant cell lines, all 10 G12C-targeting agents were preferentially active against NCIH358 cells (rank 1-3, median 1.5) while OV56 cells showed much more variability in response (rank 5-623, median 92). Similar trends were observed for pan-KRAS inhibitors (NCIH358: median rank 7; OV56: median rank 655). Further, we characterized a panel of downstream (MEK, ERK) or upstream (SHP2, SOS1, RTK) RAS/MAP kinase pathway modulators in the PRISM assay to understand similarities and differences between direct and indirect RAS pathway suppression. Finally, we also explored orthogonal assay formats, including ultra-low adherent and extended-duration (10-day) screening, to investigate kinetic and environmental factors associated with inhibitor response. Collectively, our work provides a comprehensive profile of the cellular effects of current RAS-targeting therapeutics, and provides a foundation for the characterization of newly-emerging agents. Citation Format: Matthew G. Rees, Mustafa Kocak, Matthew J. Emmett, Colleen T. Harrington, Anthony Fazio, Alvin Kalathungal, Ursula Widocki, Claudine Mapa, Dennie T. Frederick, Jillian N. Eskra, Laura Doherty, Blanche C. Ip, Melissa M. Ronan, William R. Sellers, Jennifer A. Roth. A cellular platform for systematic comparison of RAS inhibitors using PRISM multiplexed screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6763.