Predicting early treatment response of advanced stage non-small cell lung cell to erlotinib by molecular imaging with 11c-PD153035 PET/CT.

Abstract

e13555 Background: To determine whether 11C-PD153035 PET/CT imaging was early predictive of the outcome of patients with advanced stage NSCLC who were treated with gefitinib or erlotinib. Methods: Nineteenpatients with pathologically proved advanced stage NSCLC were enrolled. A baseline 11C-PD153035 PET/CT was performed within 1 week before the initiation of treatment, and follow-up 11C-PD153035 PET/CT was performed at 4 weeks after start of treatment with assessment of maximum standardized uptake values (SUVmax) for correlation with response. Treatment response was also expressed as CT results on the basis of traditional response evaluation criteria in solid tumors (RECIST). Patients were followed for survival until death. Results: All patients were registered for this study between July 2007 and January 2009. All of them underwent baseline 11C-PD153035 PETCT scan and five patients did not complete the follow-up PET/CT. Receiver operating characteristic (ROC) curve analysis was performed to separated responders from those with PD. The area under the curve was 0.89 ± 0.07, with a sensitivity of 70.9% and a specificity of 85.7%. The baseline SUVmax was 2.8 that served as the optimal threshold for early treatment response. Tumor responders (PR+SD) had a higher baseline SUVmax than non-responders (PD) (p=0.004). However, there was no significant difference between baseline and follow-up SUVmax among 14 patients and 11C-PD153035 uptake changes between non-responder and responder groups (p=0.49, p=0.08, respectively). 12 patients had died and overall 6-month survival was 78.9%. Using the cutoff values, the baseline 11C- PD153035 uptake was significant predictors of patients' survival (p=0.016). Likewise, SUVmax at 4 weeks was weakly significant for overall survival (p=0.049). Conclusions: Our data indicated that 11C-PD153035 PET/CT before therapy may play a vital role for identification of patients that could be suitable for EGFR targeted therapies. Thus, it offers opportunities to individualize and optimize target therapy for NSCLC patients. No significant financial relationships to disclose.