Prospective Study of Repeated Biopsy Feasibility and Acquired Resistance at Disease Progression in Patients With AdvancedEGFRMutant Lung Cancer Treated With Erlotinib in a Phase 2 Trial

Tumor genotyping is standard-of-care for patients with advanced non-small-cell lung cancer (NSCLC), 1 but treatment decisions for patients with progressive disease increasingly depend on identifying the specific mechanism of acquired resistance. 2,3 To our knowledge, a comprehensive assessment of consent to undergo a repeated biopsy and logistical outcomes in patients receiving targeted therapy has not been prospectively evaluated in a single study; thus we performed a phase 2 prospective analysis of repeated biopsy in patients with advanced, tyrosine kinase inhibitor (TKI)-nave, EGFR-mutant NSCLC treated with erlotinib until progression.