Epidermal growth factor receptor (EGFR) mutations are leading oncogenic drivers in non-small cell lung cancer (NSCLC). Many third-generation EGFR tyrosine kinase inhibitors (TKIs) have been developed to target EGFR T790M and activating mutations. Osimertinib (AZD9291) was the first approved drug and is now the standard-of-care therapy for untreated EGFR-mutated NSCLC. Our team previously identified ASK120067, for which we have submitted a new drug application (NDA) in China. Although third-generation EGFR TKIs exhibit favorable antitumor effects in NSCLC treatment, acquired resistance with largely unexplored mechanisms still limits their long-term efficacy. In this study, we aimed to investigate the molecular mechanisms underlying resistance to EGFR TKIs and identify new therapeutic strategies for the treatment of NSCLC. Methods: Elevated expression of BCAT1 in EGFR TKI-resistant lung cancer cells was identified using stable isotope labeling by amino acids in cell culture (SILAC)-based proteomics analysis and verified with Western blotting and RT‒qPCR.