Abstract 1023P
Background
The identification of reliable biomarkers of immune checkpoint inhibitors (ICI) efficacy is a high priority. Host-related parameters including gut microbiota (Routy B Science 2018, Derosa L Nature Med 2022) and resting energy expenditure (Boudou-Rouquette P Ebiomedecine 2021) have recently emerged. We hypothesized that 18F-FDG colonic uptake might be a surrogate marker for gut microbiome composition, influence energy expenditure and help to identify responders to ICI.
Methods
Consecutive patients with advanced NSCLC treated with single agent ICI between January 2017 and December 2020 and baseline 18F-FDG colonic uptake were retrospectively analyzed. Colonic uptake on 18F-FDG PET/CT was visually assessed and quantified by two nuclear medicine physicians for each patient by manually drawing region of interest on four colonic segments. Patients were then stratified in low vs high colonic uptake groups according to maximum standardized uptake value (SUV max). Resting energy expenditure (REE) was measured using ambulatory indirect calorimetry. PDL1 expression was also collected.
Results
Eighty-one patients were included, among which 43 were treated with pembrolizumab and 38 with nivolumab. 18F-FDG colonic uptake was predominant in the caecum in 33 (41%) patients. As expected,18F-FDG PET colonic uptake was highly variable: the SUVmax in the caecum ranged from 1.23 to 16.93. In pembrolizumab-treated patients, 10/43 (23%) had high bowel uptake in at least one colonic segment. Increased REE i.e. >110% of the theoretical value provided by Harris&Benedict formula was observed in about half of patients.
Conclusions
Pre-therapeutic REE and 18F-FDG colonic uptake on PET/CT discriminate several patients profiles susceptible to respond differently to ICI. The predictive value of these parameters on 6-months progression free survival and overall survival will be presented at the Meeting.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.