Candidate mechanisms of acquired resistance to first-line osimertinib in EGFR-mutated advanced non-small cell lung cancer

In the phase III FLAURA study (NCT02296125), the third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) osimertinib provided superior progression-free survival versus comparator EGFR-TKIs in patients with NSCLC. Here, by next-generation sequencing of circulating tumor DNA, the authors assess candidate mechanisms of acquired resistance to first-line osimertinib in patients from the FLAURA trial. Osimertinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), potently and selectively inhibits EGFR-TKI-sensitizing and EGFR T790M resistance mutations. In the Phase III FLAURA study (NCT02296125), first-line osimertinib improved outcomes vs comparator EGFR-TKIs in EGFRm advanced non-small cell lung cancer. This analysis identifies acquired resistance mechanisms to first-line osimertinib. Next-generation sequencing assesses circulating-tumor DNA from paired plasma samples (baseline and disease progression/treatment discontinuation) in patients with baseline EGFRm. No EGFR T790M-mediated acquired resistance are observed; most frequent resistance mechanisms are MET amplification (n = 17; 16%) and EGFR C797S mutations (n = 7; 6%). Future research investigating non-genetic acquired resistance mechanisms is warranted.

Automated summary

By sequencing circulating tumor DNA in patients from the FLAURA trial, this study identifies MET amplification and EGFR C797S mutation as the most frequent acquired resistance mechanisms to first-line osimertinib.