THE-349

THE-349 is a fourth-generation, brain-penetrant, mutant-selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor being developed by Theseus Pharmaceuticals for the treatment of EGFR-mutant non-small cell lung cancer (NSCLC), particularly in the setting of acquired resistance to earlier-generation EGFR TKIs such as osimertinib. It is a potent and highly selective small molecule designed to inhibit all major classes of EGFR activating and resistance mutations, including single, double, and triple mutants (e.g., exon 19 deletions and L858R with or without T790M and C797S), while sparing wild-type EGFR to improve tolerability. Preclinical data demonstrate robust and durable tumor regression in osimertinib-resistant patient-derived xenografts and NSCLC models and significant central nervous system (CNS) activity due to good brain penetration, positioning THE-349 as a potential best-in-class EGFR inhibitor for monotherapy or combination regimens in resistant EGFR-mutant NSCLC.[2][8][10][14][15]