Prospective exosome-focused translational research for afatinib (EXTRA) study of patients with nonsmall cell lung cancer harboring EGFR mutation: an observational clinical study

Background: The exosome-focused translational research for afatinib (EXTRA) study is the first trial to identify novel predictive biomarkers for longer treatment efficacy of afatinib in patients with epidermal growth factor receptor (EGFR) mutation-positive nonsmall cell lung cancer (NSCLC) via a comprehensive association study using genomic, proteomic, epigenomic, and metabolomic analyses. Objectives: We report details of the clinical portion prior to omics analyses. Design: A prospective, single-arm, observational study was conducted using afatinib 40 mg/day as an initial dose in untreated patients with EGFR mutation-positive NSCLC. Dose reduction to 20 mg every other day was allowed. Methods: Progression-free survival (PFS), overall survival (OS), and adverse events (AEs) were evaluated. Results: A total of 103 patients (median age 70 years, range 42–88 years) were enrolled from 21 institutions in Japan between February 2017 and March 2018. After a median follow-up of 35.0 months, 21% remained on afatinib treatment, whereas 9% had discontinued treatment because of AEs. The median PFS was 18.4 months, with a 3-year PFS rate of 23.3%. The median afatinib treatment duration in patients with final doses of 40 (n = 27), 30 (n = 23), and 20 mg/day (n = 35), and 20 mg every other day (n = 18) were 13.4, 15.4, 18.8, and 18.3 months, respectively. The median OS was not reached, with a 3-year OS rate of 58.5%. The median OS in patients who did (n = 25) and did not (n = 78) receive osimertinib during the entire course of treatment were 42.4 months and not reached, respectively (p = 0.654). Conclusions: As the largest prospective study in Japan, this study confirmed favorable OS following first-line afatinib in patients with EGFR mutation-positive NSCLC in a real-world setting. Further analysis of the EXTRA study is expected to identify novel predictive biomarkers for afatinib. Trial registration: UMIN-CTR identifier (UMIN000024935, https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_his_list.cgi?recptno=R000028688