Erlotinib monotherapy in the treatment of advanced non-small cell lung carcinoma: A single center experience with 187 patients from 2005-2018.

Abstract

e20718 Background: Inhibition of epidermal growth factor receptors (EGFR) bearing somatic mutations in the tyrosine kinase domain is an important molecular target in the treatment of advanced non-small cell lung carcinoma (NSCLC). As such, first generation tyrosine kinase inhibitors such as erlotinib have been adopted as standard of care in the treatment of EGFR mutation positive advanced NSCLC. Herein we describe our experience with erlotinib monotherapy since its approval for clinical use in the United States in late 2004. Methods: A retrospective analysis of 187 patients with a diagnosis of NSCLC who underwent erlotinib monotherapy from 2005-2018 was performed. Clinical variables including patient age, disease stage, EGFR genomic status, adverse events and survival were analyzed. Likelihood Ratio Chi-Square test was applied and statistical significance was set to p < 0.05. Results: Among all patients who received erlotinib monotherapy (n = 187), treatment duration longer than 3 months was associated with EGFR mutant status (p < 0.001), increased rates of repeat lung biopsies (p < 0.002) as well as pulmonary (p = 0.008), gastrointestinal (p = 0.005) and cutaneous adverse events (p = 0.005). Subgroup analysis based on EGFR genomic status (n = 71) revealed that EGFR mutation positive patients remained on erlotinib for at least three months at a higher rate than wildtypes (p < 0.001), but also sustained higher rates of lung re-biopsy (p = 0.0121) and concomitant gastrointestinal (diarrhea) and cutaneous (acneiform, maculopapular rashes) adverse events (grades 1-3) (p = 0.003). EGFR mutant status was associated with increased rates of survival of 12 months or greater since the initiation of erlotinib (p < 0.001). Conclusions: Erlotinib monotherapy duration greater than 3 months and EGFR mutant status are associated with significantly higher rates of repeat lung biopsies and gastrointestinal and cutaneous adverse events. EGFR mutant status is further associated with survival of greater than 1 year.