Gefitinib As Third-Line Re-Challenge Treatment In Advanced Nsclc Patients With Egfr Activating Mutation Who Benefited From First-Line Gefitinib Treatment Followed By Second-Line Chemotherapy.

9035Background: Several studies show that EGFR-mutant NSCLC patients (pts) gained response to EGFR-TKI treatment again after a TKI free interval. To date, no prospective evaluation of the clinical effects of EGFR-TKI re-challenge in EGFR-mutant NSCLC pts has been performed. Methods: This was a multicenter, open-label, single-arm, phase II study (CTONG1304, NCT01933347). Stage IIIB/IV NSCLC pts with EGFR exon 19del/L858R mutation, who previously benefited from first-line gefitinib treatment followed by second-line chemotherapy, took gefitinib 250mg/d until disease progression or death or intolerable toxicity occurred. Blood samples were dynamically collected for EGFRmutation testing using droplet digital PCR at every visit (from baseline to the end of gefitinib treatment). The primary objective was disease control rate (DCR) at week 8. Secondary objectives were objective response rate (ORR), progression free survival (PFS), and overall survival (OS). Results: From March 2014 to May 2016, 45 eligible pts we...