Epidermal growth factor receptor (EGFR) with T790M and activating mutations (EGFR (T790M/Activating))

The Epidermal growth factor receptor (EGFR) is a transmembrane glycoprotein and a member of the receptor tyrosine kinase family that plays a critical role in cell growth, survival, and proliferation through the activation of downstream signaling pathways like MAPK and PI3K/Akt (UniProt P00533) [1]. In many cases of non-small cell lung cancer (NSCLC), activating mutations such as the L858R point mutation or Exon 19 deletions lead to constitutive activation of the receptor, driving oncogenesis (NIH/NCI) [2]. While first-generation tyrosine kinase inhibitors (TKIs) initially target these mutations, patients frequently develop resistance via a secondary gatekeeper mutation known as T790M, which increases the receptor's affinity for ATP (PubMed: 15696186) [3]. Third-generation TKIs, such as osimertinib, were specifically designed to irreversibly bind to the EGFR kinase domain containing both the primary activating mutations and the T790M resistance mutation (PubMed: 24884701) [4]. These drugs are engineered to be highly selective for the mutant forms over the wild-type EGFR, thereby reducing off-target toxicities like severe skin rash and diarrhea (StatPearls) [5]. Monitoring for these specific mutations via tissue biopsy or liquid biopsy (ctDNA) is essential for guiding treatment decisions in advanced NSCLC (PubMed: 27635015) [6]. This target profile represents a major advancement in precision oncology, allowing for prolonged survival in patients with specific genetic drivers.

Other names

ErbB-1HER1Proto-oncogene c-ErbB-1EGFR T790MEGFR L858REGFR Exon 19 deletion

Irreversible (covalent) inhibition of the EGFR tyrosine kinase domain by binding to the Cys797 residue, specifically targeting mutant forms (T790M, L858R, Ex19del) while sparing wild-type EGFR (PubMed: 24884701) [4].