Acquired Resistance to First-Line Afatinib and the Challenges of Prearranged Progression Biopsies

Area of Science:

• Oncology
• Molecular Biology
• Clinical Trials

Background:

• Acquired resistance to epidermal growth factor receptor (EGFR) inhibitors like afatinib is a significant clinical challenge in non-small cell lung cancer (NSCLC).
• The specific mechanisms driving resistance to afatinib, particularly the T790M mutation, require further elucidation.

Purpose of the Study:

• To prospectively determine the prevalence of the T790M mutation in patients who developed acquired resistance to afatinib.
• To assess the feasibility of repeat biopsies for molecular analysis at the time of progression.

Main Methods:

• A prospective clinical trial enrolled 24 patients with EGFR mutations, naive to tyrosine kinase inhibitors, treated with afatinib (40 mg daily).
• Patients consented to repeat biopsies upon disease progression for molecular analysis.
• Tumor samples were analyzed for the presence of the T790M mutation.

Main Results:

• The study enrolled 24 patients, achieving an objective response rate of 58% and median progression-free survival of 11.4 months.
• Of 23 patients who progressed, 14 underwent repeat biopsy, with 11 samples suitable for molecular analysis.
• The T790M mutation was detected in four of these 11 patients (36%).

Conclusions:

• The T790M mutation is a likely common mechanism of acquired resistance to first-line afatinib treatment.
• Repeat biopsies are critical for understanding resistance but face clinical and technical limitations.
• Development of noninvasive tumor-genotyping strategies is crucial for overcoming biopsy challenges.