Abstract 1220: Deep mutational scanning of EGFR reveals potential domain-specific TKI sensitivities in lung cancer and glioblastoma

Abstract The epidermal growth factor receptor, EGFR, is frequently activated in lung cancer and glioblastoma by genomic alterations including missense mutations. The different mutation spectra in these diseases are reflected in divergent responses to EGFR inhibition: significant patient benefit in lung cancer, but limited in glioblastoma. Here, we report a comprehensive mutational analysis of EGFR function. We performed saturation mutagenesis of EGFR and assessed function of ~22, 500 variants in a human EGFR-dependent lung cancer cell line. This approach revealed enrichment of erlotinib-insensitive variants of known and unknown significance in the dimerization, transmembrane, and kinase domains. Multiple EGFR extracellular domain variants, lacking approved targeted therapies, were sensitive to dacomitinib. Strikingly, at least two glioblastoma patients with G598V dimerization domain mutations showed responses to dacomitinib treatment together with subsequent off-target resistance in one case. In summary, this comprehensive screen reveals novel functional EGFR variants and suggests broader clinical investigation of EGFR inhibition for cancers harboring extracellular domain mutations. Citation Format: Tikvah Hayes, Elisa Aquilanti, Erica Kim, Nicole Persky, Lisa Brenan, Amy Goodale, Ted Sharpe, Doug Alan, Robert Shue, Lior Golomb, Brianna Silverman, Yvonne Li, Lindsay Westlake, Federica Piccioni, Andrew Cherniack, Xiaoping Yang Yang, David Root, J. Kevin Hicks, Andrew Chi, Jorg Dietrich, Daniel Cahill, Cory Johannessen, Tracy Batchelor, Matthew Meyerson. Deep mutational scanning of EGFR reveals potential domain-specific TKI sensitivities in lung cancer and glioblastoma 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 (6Suppl): Abstract nr 1220.