7516 Background: Erlotinib has demonstrated major activity in EGFR mutation positive NSCLC, but may also benefit those with wild-type tumours. We conducted a single-arm trial of pre-operative erlotinib in early stage NSCLC to assess radiologic and functional response as well as correlation with known and investigational biomarkers. Methods: Patients with clinical stage IA-IIB NSCLC received erlotinib 150 mg daily for 4 weeks followed by surgical resection. Tumor response was assessed using pre- and post-treatment CT and PET imaging. Pharmacodynamic changes were assessed through comparison of pre- and post-treatment tumour samples (including Sequenom MassARRAY analysis) and measurement of circulating markers/ligands for EGFR activation (TGF-α, amphiregulin, epiregulin, EGFR SNP, EGFR ECD). Secondary endpoints included pathological response, toxicity and progression-free survival. Results: Twenty-five patients were enrolled; 22 received erlotinib treatment with a median follow up of 4.4 years (range 2.2 to ...