Exceptional response to afatinib in a patient with persistent G719A EGFR-mutant NSCLC

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Non-small cell lung cancer (NSCLC) is a leading cause of cancer death.
• Epidermal growth factor receptor (EGFR) mutations are common drivers in NSCLC.
• Tyrosine kinase inhibitors (TKIs) targeting EGFR have revolutionized NSCLC treatment.

Observation:

• A patient with metastatic NSCLC presented with co-occurring EGFR G719A and T790M mutations.
• The T790M mutation emerged during treatment with early-generation EGFR TKIs.
• Initial Guardant 360 testing identified G719A as the dominant clone.

Findings:

• Osimertinib treatment resulted in only radiographic stabilization, followed by clinical and radiographic progression.
• Upon progression, the T790M mutation was undetectable, while G719A remained the dominant clone.
• Subsequent treatment with afatinib led to both clinical and radiological response.

Implications:

• This is the first reported case of co-occurring EGFR G719A and T790M mutations.
• The study highlights clonal evolution of EGFR mutations during anti-EGFR therapies.
• Understanding mutation dynamics is crucial for optimizing treatment strategies in NSCLC.