The treatment of patients with metastatic non-small cell lung cancer (NSCLC) whose tumors have epidermal growth factor receptor (EGFR) exon 19 deletions or exon 21 (L858R) substitution mutations as detected by an FDA-approved test receiving first-line, maintenance, or second or greater line treatment after progression following at least one prior chemotherapy regimen.

Consequently, the patient was diagnosed with anaplastic thyroid carcinoma (ATC) with signet-ring cell carcinoma...(EGFR) gene mutation status of both transbronchial biopsy and cervical biopsy specimens and detected L858R in exon 21 by the peptide....this report describes the first case of a patient with ATC harboring L858R in exon 21 who exhibited a marked clinical response to erlotinib.