Dynamics of 18-FDG Uptake in Stage III/IV Non Small Cell Lung Cancer During First Line Pembrolizumab Treatment

Immunotherapy with anti-PD1 antibody, such as Pembrolizumab, is widely used in the treatment of stage III/IV non small cell lung cancer. In order to refine treatments and patients' prognosis, early assessment of tumour response is needed. The aim of this study is to describe the early tumour metabolic changes in non smal cell lung cancer during first line treatment with pembrolizumab, and to evaluate whether or not they differ according to treatment response. Eligible patients with stage III/IV, PDL1\>50% NSCLC will receive pembrolizumab treatment as per standard of care. Tumour metabolism will be assessed by 18-FDG PETscan before each of the 3 first pembrolizumab infusions. Treatment response will be determined by RECIST, irRC and mCHOI criteria at 3 months. Prognostic and predictive value of baseline and dynamic metabolic parameters will be assessed.