Immunonutrition supplementation for resectable gastric cancer during standard perioperative chemotherapy (CT) FLOT: A pivotal study, I–SUPPLY.

57 Background: Gastric carcinomas (GC) can be divided into immunogenic and immune-resistant based on the infiltration of the tumour microenvironment (TME) from different immune cells (ICs) such as Natural Killer (NK), activated CD8+, CD3+ and CD4+ memory T cells. High ImmunoScore (IS) (positive cells/mm2 for each marker (CD8+, CD3+, Foxp3+) in the Core Tumour and Invasive Margins) is strongly related to better prognosis of GC patients in terms of Disease-Free Survival and Overall Survival. ICs activation and consequent immunogenic TME requires high nutrient absorption and synthesis accumulation of protein, lipid and nucleotides. However, tumour cells (TCs) promote their own proliferation by stealing the available micronutrients to ICs therefore leading to an immunosuppressive TME phenotype. Methods: This is a translational, prospective, non-randomized study. Primary endpoint is to assess if enteral immune nutrition (EIN) supplementation during the acme of the activity of cytotoxic of perioperative FLOT (docetaxel, oxaliplatin and 5-fluorouracil) in stage II-III GC can revert the TME in favour of ICs over TCs, witnessed by an increase of IS in surgical specimen over biopsy controls. A steady amount of EIN with Arginine, Omega-3-fatty acids, Glutamine and ribonucleic acid, will be added to patient’s diet from day 3 to 8 of each FLOT cycle, twice a day. We plan to use Image analysis software for automatic tumor detection and quantification of CD3+ and CD8+ stained cells whose densities will be converted into IS with pre-defined cutoffs. IS utilizes standardized percentile values (0 to 100%). We identify IS as Low, Intermediate (Int) and High with a mean percentile of 0-25%, >25-70%, >70-100% respectively. Two-group classifications are planned, corresponding to IS Low and Int-High. To better define the kind of tumor infiltrating cells (TILs) and assess the amount of immune suppressive cells, more IHC scoring will be evaluated: helper T-cells CD4+, CD8 T memory (CD 103+), T regulatory (both CD4+ and Foxp3+/CD105+), Macrophages M1 (CD 68+) and M2 (CD 163+). Results: Based on historical controls the rate of Int-High IS (>25-70%, >70% respectively) is about 64%, we expect to find a 20% increase of Int-High IS GC over biopsy control (internal validation cohort). To detect an increase in the percentage of high IS among patients treated with EIN (estimated around 85%) compared to biopsy controls (estimated around 64%) assuming a probability α and β of 0.2, the required sample size will be of 21 patients with resectable GC receiving EIN supplementation plus standard CT. To define the sample size a single proportion test was used. Conclusions: Our hypothesis is that EIN given during perioperative CT might prevent the establishment of an unfavourable TME for ICs in both auxotrophic and non-auxotrophic malignancies, thus leading to an increase of GC immunogenic pattern.