Predictive factors and prognostic significance of T790M mutation in patients with EGFR-mutant NSCLC

Background: Clinical characteristics of T790M mutation-positive NSCLC have not been characterized well. Objectives: To investigate predictive factors and prognostic significance of T790M mutation positivity in patients with EGFR-mutant NSCLC at the time of rebiopsy after progression on EGFR-TKI. Methods: We retrospectively reviewed 96 EGFR-mutant NSCLC patients who were treated with 1st generation EGFR-TKI and underwent subsequent rebiopsy after confirmation of disease progression between 2014-2017. Results: T790M mutation was detected in 51% of the total 96 tumor samples. T790M prevalence was significantly higher in patients with a smoking history (former/current vs.never; 66.7% vs.43.9%, P=0.039), treatment with erlotinib (erlotinib vs.gefitinib/afatinib; 81.8% vs.47.1%, P=0.03), an absence of new organ metastasis at PD (preexisting organ progression only vs.new organ metastasis; 56.3% vs.26.7%, P=0.035), longer TKI continuation after confirmation of RECIST-PD (≥4 vs. Conclusions: T790M mutation-positive NSCLC exhibits distinctive phenotype with more favorable prognosis.