Abstract P80: Functional Consequences of Structural Variants Arising from Extracellular Domain Mutations in EGFR

Abstract Background: Epidermal growth factor receptor (EGFR) is an oncogene frequently mutated in cancers. Around half of Asian non-small cell lung cancer (NSCLC) tumours harbour activating EGFR mutations, the most prevalent variants being exon19 deletion and L858R point mutation, with enhanced response to tyrosine kinase inhibitors (TKIs). EGFR extracellular domain (ECD) mutations have been detected in NSCLC tumours, particularly among resistant tumours, with limited understanding. Here, we hypothesise that ECD mutations may play a role in driving oncogenesis and resistance mechanisms. Methods: ECD mutations are profiled from a structure-function perspective by combining both computational and functional aspects. A recurring mutation found in advanced NSCLC patients was selected as a proof-of-concept. Structural prediction tools and molecular dynamics (MD) simulations were used to screen and profile the mutation. In vitro cell culture model was established using genomic editing. Functional assays will be performed to understand how the mutation affects cancer hallmarks. Results: Polyphen-2 predicted that mutation affects canonical EGFR function. This could be due to mutant being thermodynamically more stable as predicted by mCSM-stability. Structural analysis revealed possible interactions stabilising active monomers and enhancing dimerization in mutant. MD simulation revealed dynamical differences between mutant and wild-type dimers. Functional profiling suggested that mutant cells gained aberrant growth through enhanced proliferation. Conclusion: ECD mutations may contribute to an under-represented mode of TKI-resistant mechanism driving oncogenesis. Our data suggest that recurring variant among TKI-resistant tumours may drive tumour growth through a non-canonical pathway. It is hoped that with further structural and functional insights into TKI-resistant mechanism, we will be able to guide precision medicine by exploring alternative therapeutics targeting ECD mutations to achieve cancer remission. Citation Format: Hui Qing Yeo, Jun Ting Teo, Aishwary Shivgan, Kannan Srinivasaraghavan, Azhar Bin Ali, Chandra Verma, Li Ren Kong, Boon Cher Goh. Functional Consequences of Structural Variants Arising from Extracellular Domain Mutations in EGFR abstract. In: Proceedings of Frontiers in Cancer Science 2024; 2024 Nov 13-15; Singapore. Philadelphia (PA): AACR; Cancer Res 2025;85 (15Suppl): Abstract nr P80.