Predictive and prognostic value of early response assessment using 18FDG-PET in advanced non-small cell lung cancer patients treated with erlotinib

Background: [18F]fluorodeoxyglucose (FDG)-PET is being evaluated as a tool for the early detection of response to various targeted agents in solid tumors. The aim of this study was to evaluate the predictive value of PET response after 2 days of erlotinib in unselected pretrated patients with stage IV NSCLC. Patients and methods: FDG-PET/CT scans were conducted at baseline and after 2 days of erlotinib, with a CT evaluation performed at baseline and after 45-60 days of therapy. PET responses were evaluated by quantitative changes on SUVmax tumor/non-tumor ratio and classified according to EORTC criteria. PET responses were compared with RECIST responses and related to progression-free (PFS) and overall (OS) survival. Erlotinib effects on glucose uptake were also studied in a panel of NSCLC cell lines. Results: Fifty-three patients were enrolled. At 2 days of erlotinib, 20 (38 %) patients showed partial metabolic response (PMR), 25 (47 %) had stable metabolic disease (SMD) and 8 (15 %) had progressive metabolic disease (PMD). All patients with PMD had confirmed RECIST progression at 45-60 days. Patients with early PMR and SMD had significantly longer PFS (p <0.001 and p = 0.001, respectively) and OS (p = 0.001 for both) than PMD patients. Conclusions: FDG-PET assessment after 2 days of erlotinib could be useful to identify early resistent patients and to predict survival in unselected NSCLC pretreated population.