With the development of next-generation sequencing (NGS) technology, more and more EGFR-tyrosine kinase inhibitor (TKI) resistance mutation sites have been revealed.  Here, we report a novel EGFR L858R/A859S/Y891D triple mutation in plasma-derived circulating tumor DNA (ctDNA) was identified in a 53-year-old male patient with NSCLC resistant to osimertinib treatment, using an ultra-deep (20,000×) 160-gene panel through the NGS platform. 
NGS
With the development of next-generation sequencing (NGS) technology, more and more EGFR-tyrosine kinase inhibitor (TKI) resistance mutation sites have been revealed.  Here, we report a novel EGFR L858R/A859S/Y891D triple mutation in plasma-derived circulating tumor DNA (ctDNA) was identified in a 53-year-old male patient with NSCLC resistant to osimertinib treatment, using an ultra-deep (20,000×) 160-gene panel through the NGS platform. 
NGS
With the development of next-generation sequencing (NGS) technology, more and more EGFR-tyrosine kinase inhibitor (TKI) resistance mutation sites have been revealed.  Here, we report a novel EGFR L858R/A859S/Y891D triple mutation in plasma-derived circulating tumor DNA (ctDNA) was identified in a 53-year-old male patient with NSCLC resistant to osimertinib treatment, using an ultra-deep (20,000×) 160-gene panel through the NGS platform. 
NGS