Effect of rebiopsy methods and clinical features on T790M mutation after first-line EGFR-TKI treatment failure

This study investigated the association between clinical data and T790M mutation in rebiopsy after EGFR tyrosine kinase inhibitors (EGFR-TKIs) failure, and explored the prognosis of T790M-positive patients. Patients with non-small-cell lung cancer undergoing rebiopsy after first-generation TKI failure were reviewed. Patients with brain metastases, negative TP53, initial 19del and longer initial PFS had higher positive rate of T790M. The median progression-free survival (PFS) of T790M-positive patients with cytology and tissue rebiopsy were longer than patients with liquid rebiopsy. The median PFS of T790M-positive patients rebiopsied by ordinary bronchoscope and endobronchial ultrasound-guided transbronchial lung biopsy with a guided sheath (EBUS-GS-TBLB) were longer than that of the patients rebiopsied by EBUS transbronchial needle aspiration (TBNA). A specific genetic mutation, T790M, is the main cause of drug resistance in patients with lung cancer receiving a type of drug called EGFR tyrosine kinase inhibitors (EGFR-TKIs), such as gefitinib and erlotinib. We explored the factors that influence the prognosis of T790M-positive patients and how this mutation causes resistance. We found a number of biomarkers that are linked to higher expression of T790M, including brain metastases and longer initial treatment period of EGFR-TKI. The median length of time before tumors started progressing in T790M-positive patients who underwent cytology and tissue rebiopsy was longer than patients who received a blood biopsy. The length of time before progression in patients undergoing different rebiopsy methods (such as ordinary bronchoscope and endobronchial ultrasound bronchoscope) was different.