Exon 19 L747P mutation presented as a primary resistance to EGFR-TKI: a case report.

Active mutations of the EGFR gene have been proved to predict the activity of EGFR-TKI. The most common mutations are the exon 19 deletion and exon 21 point mutation, both of which are sensitive to EGFR-TKI. However, rare EGFR mutations or complex mutations still exist, and data of which are scarce and controversial. Their response to EGFR-TKI remains uncertain. We presented a patient diagnosed with stage IV lung adenocarcinoma who was found to have the EGFR mutation in exon 19 (L747P) before any treatment. The disease progressed 2 months after the chemotherapy containing cisplatin and pemetrexed, and erlotinib was administered, but there was no response found. This EGFR-TKI naïve patient failed to achieve the desired effect with the therapy of EGFR-TKI. L747P may be associated with primary resistance to EGFR-TKI in this case.