Current status and problems of T790M detection, a molecular biomarker of acquired resistance to EGFR tyrosine kinase inhibitors, with liquid biopsy and re-biopsy

Abstract

Background/Aim: The purpose of this study was to consider appropriate application of liquid and re-biopsy through analysis of current status in practice. Patients and Methods: We performed a retrospective analysis of 22 patients with epidermal growth factor receptor (EGFR) mutation-positive non-small cell lung cancer who exhibited 1st/2nd generation EGFR-tyrosine kinase inhibitors resistance. The cobas® method was used to detect T790M with re-biopsy and the mutation-biased PCR and quenched probe method was used with liquid biopsy. Results: T790M detection rate was 52% with re-biopsy and 58% with liquid biopsy. The concordance between tissue and plasma was 58%. One patient who was T790M-positive with liquid biopsy showed heterogeneity among metastatic lesions in terms of osimertinib efficacy, as revealed by T790M detection with re-biopsy. Conclusion: Liquid biopsy reflects the whole body, whereas re-biopsy is useful for spatial diagnosis. Considering these characteristics, a combination of liquid and re-biopsy contribute to enhanced treatment.