Somatic mutations in epidermal growth factor receptor underlying complete responsiveness to gefitinib in a Taiwanese female patient with metastatic adenocarcinoma of lung.

A 61-year-old never-smoker female suffered from adenocarcinoma of the lung with chest wall invasion and peri-adrenal lymph node metastases. After palliative resection of all clinically detectable primary and metastatic adenocarcinoma, she received cisplatin and gemcitabine combination chemotherapy for a total of 3 cycles. New metastatic lesions were found in spleen and para-aortic lymph nodes. Her tumor tissue was subjected to mutation analysis for epidermal growth factor receptor (EGFR) and had been shown to have a T-->G missense mutation in nucleotide 2819 of EGFR full-length cDNA (accession no. NM_005228.3), within exon 21 of the EGFR gene, resulting in amino acid substitutions from leucine to arginine at codon 858 (L858R) as expected. She received oral gefitinib 250 mg/day after mutation analysis. She had a very good tumor response with more than 90% tumor reduction shown by abdominal computed tomographic scan, normalization of previously elevated carcinoembryonic antigen level, and complete resolution of previous uptake signals in spleen and para-aortic lymph nodes shown by positron emission tomographic scan. She has been kept in clinical complete remission for 11+ months after the initiation of gefitinib treatment. Our patient supports the proposition that somatic mutation L858R in exon 21 of the EGFR gene accounts for complete responsiveness to gefitinib in a Taiwanese female patient with metastatic adenocarcinoma of lung.