Predictors of response in EGFR-mutant metastatic non-small cell lung cancer patients treated with tyrosine kinase inhibitors

Abstract

Background: The goal of the study was to evaluate the efficacy of tyrosine kinase inhibitors in patients with epidermal growth factor receptor (EGFR)-mutant metastatic non-small cell cancer and to determine the factors that predict objective response.

Materials and methods: In the study, data from metastatic non-small cell lung cancer patients with EGFR mutations treated with tyrosine kinase inhibitors were retrospectively reviewed. Factors predicting objective response were evaluated with logistic regression analysis.

Results: The study evaluated the data of 105 patients. The most common EGFR mutations detected in patients were exon 19 (56.2%) and exon 21 (23.8%). The median progression-free survival (PFS) associated with EGFR tyrosine kinase inhibitors was 20.1 (95% confidence interval [CI], 13.4-26.7) months. The median overall survival (OS) in the post-metastasis period was found to be 30.8 (95% CI, 20.2-41.4) months. Five- and seven-year OS was determined as 28.7% and 22.9%, respectively. Factors predicting the objective response were analyzed. Presence of drug-related toxicity (P = 0.02), histopathologic type (P = 0.01), metastasis burden (P = 0.03), and EGFR mutation type (P = 0.04) were found to be statistically significant in multivariate analysis.

Conclusions: In our study, we found that EGFR tyrosine kinase inhibitors are effective and safe. Better response to EGFR inhibitors was observed in the presence of drug-induced toxicity, adenocarcinoma histology, low metastasis burden, and exon 19 mutation.