Differential Toxicities of Tyrosine Kinase Inhibitors in the Management of Metastatic Lung Cancer

INTRODUCTION: Erlotinib and gefitinib are the most commonly used epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) in the treatment of EGFR mutant nonsmall cell lung cancer (NSCLC). Both erlotinib and gefitinib have shown equal efficacy in terms of response rates and overall survival. Hence, their toxicity profile becomes the most important determining factor in choosing these agents when treating EGFR mutant NSCLC. In this study, we compared the toxicity profile of erlotinib and gefitinib among an Indian subset of lung cancer patients. MATERIALS AND METHODS: In this prospective nonrandomized study, 85 patients of South Indian origin with NSCLC were tested for EGFR mutation status, and EGFR mutant patients were started on either erlotinib or gefitinib. They were periodically monitored for drug toxicities. RESULTS: Out of the 85 patients tested, 34 patients were positive for EGFR mutation. Eleven of them were started on erlotinib and 23 were started on gefitinib. The most common side effect of TKIs was skin rash. Nine out of the 11 patients started on erlotinib and 7 of the 23 patients started on gefitinib had skin rash. Grade 3 and 4 skin rash was significantly more among patients treated with erlotinib which resulted in treatment delays. Other side effects of TKIs such as diarrhea and deranged liver functions were similar among the both subsets of patients. CONCLUSION: Skin toxicity is the major and serious side effect with erlotinib among Indian patients with EGFR mutant lung cancer. This resulted in significant treatment delay, which might adversely affect the overall survival of patients. Gefitinib was better tolerated and had a safer toxicity profile compared to erlotinib in Indian patients.