EGFR mutation and resistance of non-small-cell lung cancer to gefitinib

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Activating mutations in the epidermal growth factor receptor (EGFR) gene predict response to EGFR inhibitors like gefitinib in non-small-cell lung cancer (NSCLC).
• Despite initial efficacy, acquired resistance to EGFR inhibitors is a significant clinical challenge, leading to disease relapse in most patients.
• The molecular mechanisms underlying acquired resistance to EGFR inhibitors in NSCLC remain incompletely understood.

Observation:

• A patient with advanced NSCLC harboring an EGFR mutation achieved a complete remission with gefitinib therapy.
• After two years of sustained remission, the patient experienced disease relapse.
• Tumor biopsy at relapse revealed a new point mutation in the EGFR gene, specifically a T790M substitution.

Findings:

• The T790M mutation alters the EGFR protein, conferring resistance to gefitinib.
• Structural modeling and biochemical assays confirmed that this secondary mutation impairs gefitinib binding and efficacy.
• This case identifies a specific genetic mechanism for acquired resistance to EGFR-targeted therapy in NSCLC.

Implications:

• The T790M mutation is a key driver of acquired resistance to first-generation EGFR inhibitors in NSCLC.
• Understanding resistance mechanisms can guide the development of next-generation inhibitors targeting resistant mutations.
• This finding has implications for patient monitoring and treatment strategies in EGFR-mutant NSCLC.