Changes in FDG- and FLT-PET imaging in patients with non-small cell lung cancer (NSCLC) following treatment with erlotinib (E).

7567 Background: Assessing the efficacy of molecularly targeted agents, especially in the absence of tumor shrinkage, remains a challenge. The primary objective of this prospective international trial was to evaluate whether on-treatment 18F-deoxyglucose (FDG) and 18F-deoxythymidine (FLT) PET responses predict improved progression-free (PFS) and overall survival (OS) following treatment of 2nd/3rd line NSCLC with E, an epidermal growth factor receptor (EGFR) inhibitor. Methods: Study assessments included FDG- and FLT-PET/CT imaging at baseline (BL), d14 and d56, and diagnostic CT at BL and d56. Detailed uniform protocols were applied for image acquisition and analysis. PET and CT response were determined by central review. Up to 5 target lesions that met RECIST 1.0 and were FDG avid (SUVmax > 2.5) were identified in each pt at BL. Based on EORTC PET response guidelines, partial metabolic response (PMR) was defined as mean decrease >15% in SUVmax across all target lesions. PFS was investigator determined. ...