Molecular targeted therapy of lung cancer: EGFR mutations and response to EGFR inhibitors

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Somatic mutations in the epidermal growth factor receptor (EGFR) kinase domain occur in ~10% of non-small-cell lung cancer (NSCLC).
• These mutations are more frequent in adenocarcinomas of never-smokers, women, and individuals of Asian ethnicity.
• EGFR mutations create "oncogene addiction," leading to sensitivity to reversible tyrosine kinase inhibitors (TKIs) like gefitinib and erlotinib.

Purpose of the Study:

• To review the molecular and clinical insights gained from targeting EGFR in NSCLC.
• To discuss the challenges posed by acquired drug resistance to EGFR-targeted therapies.
• To highlight the potential of irreversible EGFR inhibitors in overcoming resistance.

Main Methods:

• Review of preclinical and clinical studies on EGFR mutations in NSCLC.
• Analysis of mechanisms of acquired resistance to EGFR TKIs.
• Evaluation of the efficacy of irreversible EGFR inhibitors in vitro and in clinical trials.

Main Results:

• Reversible EGFR TKIs induce dramatic responses in "oncogene addicted" NSCLC but are often limited by acquired resistance.
• Resistance mechanisms include mutations in the EGFR kinase domain, such as T790M.
• Irreversible EGFR inhibitors demonstrate in vitro activity against resistant cells and are being investigated in genotype-directed trials.

Conclusions:

• Targeting EGFR in NSCLC provides a paradigm for targeted therapy in solid tumors.
• Overcoming acquired resistance is crucial for improving patient survival.
• Irreversible EGFR inhibitors represent a promising therapeutic strategy for NSCLC patients with acquired resistance.