AB047. Acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors by the EGFR T790M mutation in a non-small cell lung cancer patient in Vietnam.

Acquired resistance of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer patients causes re-progression of the disease. This phenomenon prevails after 10-20 months of treatment in most of patients that were primary responses to EGFR TKIs. There was shown to be related to several genetic alterations in which the most frequent (50%) is the secondary mutation T790M in exon 20 of the EGFR gene. This study reports a typical clinical case with TKI acquired resistance: patient with the advanced adenocarcinoma of the lung which had already spread to the bone and the latter lung, harboring a LREA deletion mutation in exon 19 of the EGFR gene. The tumor progressed after 15 month of erlotinib treatment. The re-biopsy tumor revealed a secondary T790M mutation in exon 20, conferring resistance to erlotinib. The study demonstrated a critical role of molecular diagnostics for TKI acquired resistance through rebiopsies at the time of disease progression.