Liquid biopsy in clinical outcomes and detection of T790M mutation in metastatic non-small cell lung cancer after progression to EGFR-TKI.

Background: Liquid biopsy (LB) is used to detect epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) and has been demonstrated to have prognostic and predictive value.

Objective: To associate the rates of EGFR and T790M mutations detected by LB during disease progression after first- or second-generation EGFR-TKIs with clinical characteristics and survival outcomes.

Methods: From January 2018 to December 2021, 295 patients with advanced EGFR mutant (EGFRm) NSCLC treated with first- or second-generation EGFR-TKIs were retrospectively analyzed. LB was collected at the time of progression. The frequency of EGFRT790M mutations, overall survival (OS), and the clinical characteristics associated with LB positivity were determined.

Results: The prevalence of EGFRT790M mutation detected using LB was 44%. In patients with negative vs. positive LB, the median OS was 45.0 months vs. 25.0 months (p= 0.0001), respectively. Patients with a T790M mutation receiving osimertinib had a median OS of 44 months (95% CI [33.05-54.99]). Clinical characteristics associated with positive LB at progression extra-thoracic involvement, > 3 metastatic sites, and bone metastases.

Conclusions: Our findings showed that LB positivity was associated with worse survival outcomes and specific clinical characteristics. This study also confirmed the feasibility and detection rate of T790M mutation in a Latin American population.