Metachronous development of L858R and T790M EGFR mutations following ALK inhibitor therapy in stage IV lung adenocarcinoma: a case report

This case represents the first documented occurrence of metachronous L858R and T790M EGFR mutations following ALK inhibitor therapy, highlighting the emergence of distinct driver mutations over time and reflecting temporal and spatial tumor heterogeneity. These findings underscore the importance of monitoring clonal evolution to guide tailored therapeutic strategies in NSCLC. Furthermore, re-biopsy is essential to assess tumor heterogeneity, identify potential drug resistance, and detect new mutations, ensuring that treatment strategies remain optimized for evolving disease conditions.