Clinical management of epidermal growth factor receptor mutation-positive non-small cell lung cancer patients after progression on previous epidermal growth factor receptor tyrosine kinase inhibitors: the necessity of repeated molecular analysis.

One of the most important advances in the treatment of non-small cell lung cancer (NSCLC) has been the identification of molecular alterations vulnerable to targeted inhibition, such as mutations in the epidermal growth factor receptor () gene. EGFR tyrosine kinase inhibitors (EGFR-TKIs) are targeted agents used to treat mutation-positive advanced NSCLC showing significant improvements in terms of response rate (RR) and progression-free survival (PFS) compared to conventional chemotherapy. However, all patients eventually develop resistance to first-line EGFR-TKIs. The most common mechanism of acquired resistance is the secondary acquisition of a single missense mutation within exon 20 in the EGFR gene, known as the T790M mutation (49-60%). New agents targeting the T790M mutation have undergone clinical development, and among these, osimertinib has shown significant activity in relapsing mutation positive patients harbouring the T790M mutation. Although precision medicine is a reality for NSCLC, obtaining relevant tissue for repeated molecular analysis from these patients remains a challenge. In this article, a group of experts from the Spanish Society of Medical Oncology (SEOM) and the Spanish Lung Cancer Group (GECP) evaluated the role of rebiopsy and the potential application of plasma-testing methodologies in advanced mutation patients progressing after EGFR-TKI.