Continuation of Tyrosine Kinase Inhibitor is Associated with Survival Benefit in NSCLC Patients with Exon 19 Deletion after Solitary Progression

Introduction: The benefit and selection criteria of continuing tyrosine kinase inhibitor (TKI) after secondary resistance in non-small cell lung cancers (NSCLCs) with epidermal growth factor receptor (EGFR) mutation remain largely unknown. This study was designed to investigate the role and predictive factors of TKI continuation in patients with solitary progression. Methods: We retrospectively analyzed NSCLCs treated with first generation of TKI from June 2009 to October 2014 in our cancer center. Number of progressive lesions upon first progression was recorded per RECIST v1.1. Results: Sixty-one of 144 (42.4%) patients progressed with one lesion. Postprogression TKI use information was available in 58 patients. No brain metastases and stable disease compared to immediate prior scans were associated continued TKI. In the whole cohort, TKI as the first line treatment was found to be associated with longer postprogression survival, but TKI continuation was not. In patients with exon 19 deletion, TKI continuation compared to discontinuation was significantly associated with longer postprogression survival (32.0 months, 95% CI: 20.8 - 43.3 vs. 15.6 months, 95% CI: 7.3 - 23.8, p=0.013). This difference was not observed in L858R mutation. Exon 19 deletion patients had longer time to TKI cessation after progression (13.7 months, 95% CI: 4.5-22.9 vs. 5.6 months in L858R, 95% CI: 0.0-11.9, p = 0.047). Conclusions: TKI continuation may prolong survival of NSCLCs with exon 19 deletion rather than L858R. Further studies are required to validate this finding.