Despite the clinical success of osimertinib in EGFR-mutant non-small cell lung cancer, acquired resistance remains a major challenge. In particular, the emergence of the EGFR C797S mutation has fuelled the development of fourth-generation EGFR inhibitors designed to overcome this resistance mechanism.

In our latest publication in Frontiers in Oncology, we performed a side-by-side comparison of osimertinib and three fourth-generation EGFR inhibitors: BLU-945, JBJ-09-063, and silevertinib (BDTX-1535). Using biochemical kinase assays, surface plasmon resonance, a CRISPR-engineered EGFR L858R/T790M/C797S cell model, and a broad panel of cancer cell lines, we investigated how these compounds perform across different EGFR mutation contexts.

Our results reveal that the three fourth-generation EGFR inhibitors exhibit distinct activity profiles across clinically relevant EGFR mutation backgrounds. BLU-945 showed activity across a broad range of activating and resistance-associated EGFR variants, including those containing both T790M and C797S mutations. JBJ-09-063 displayed a distinct profile consistent with its allosteric mechanism of action and demonstrated strong activity in the engineered C797S resistance model. In contrast, silevertinib exhibited exceptional selectivity for EGFR-mutant cell lines over EGFR wild-type cell lines, outperforming osimertinib in this regard.

This study illustrates how combining biochemical assays with cellular profiling can provide a more complete understanding of emerging targeted therapies. While inhibitors may be developed to address the same resistance mechanism, their activities can differ substantially depending on the mutation context and biological model used. By combining kinase profiling, binding studies, and cellular efficacy analyses, researchers can gain deeper insight into compound differentiation and identify the settings in which novel inhibitors are most likely to deliver clinical benefit.