Sixteen of these patients did not undergo rebiopsy because of concurrent illness that made the procedure infeasible (n = 6), inaccessible tumor sites (n = 5), treatment discontinuation due to adverse events (n = 2), the decision of the physician (based on the presence of an uncommon EGFR mutation) (n = 2), or continuation of afatinib treatment beyond progressive disease (PD) (n = 1). Here, EGFR is linked to neoplasm.