Erlotinib for Pretreated Squamous Cell Carcinoma of the Lung in Japanese Patients

Objective: Erlotinib has demonstrated survival benefit in patients with not only adenocarcinoma but also squamous cell carcinoma. Epidermal growth factor receptor-tyrosine kinase inhibitors are more effective in Asian populations, including the Japanese than in western populations. However, a higher incidence of interstitial lung disease has been reported as a fatal adverse event in the Japanese population. There is little data on erlotinib for Japanese patients with pretreated squamous cell carcinoma. Methods: Between January 2004 and October 2010, we retrospectively evaluated the efficacy and toxicity of erlotinib administered as the first epidermal growth factor receptor-tyrosine kinase inhibitors for 41 Japanese patients with pretreated squamous cell carcinoma. Patients with pre-existing interstitial lung disease were carefully excluded by several examinations including high-resolution computed tomography. Results: The response rate and disease control rate were 9.7% [95% confidence interval: 2.7-23.1%) and 43.9% (95% confidence interval: 28.5-60.2%], respectively. Median time to treatment failure and overall survival were 2.2 months (95% confidence interval: 1.0-2.8 months) and 11.0 months (95% confidence interval: 5.7-15.7 months), respectively. Interstitial lung disease (Grade 5) was observed in one (2.4%) patient. Patients with Grade 0-1 skin rashes vs. patients with Grades 2-3 exhibited disease control rates of 28 vs. 83% (P = 0.0017), and median time to treatment failure of 1.2 months vs. 3.4 months (P = 0.0099). Conclusions: Erlotinib has moderate efficacy for pretreated squamous cell carcinoma in Japanese patients. A higher grade of skin rash was associated with clinical benefit. Careful exclusion of pre-existing interstitial lung disease can minimize the occurrence of interstitial lung disease.