805PParameters of local cellular immunity in metastatic gastric cancer

• Published in: Annals of oncology Vol. 30; no. Supplement_5
• Main Authors: Sagakyants, A B, Kit, O I, Samoylenko, N S, Novikova, I A, Zlatnik, E Y, Frantsiyants, E M, Bondarenko, E S, Vladimirova, L Y
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01.10.2019
• ISSN: 0923-7534; 1569-8041
• DOI: 10.1093/annonc/mdz247.131

Abstract Background A special role in the tumour progression is played by heterogeneous components of the microenvironment of tumours, premetastatic tumour niches, influencing which seems likely to change the disease course. Our purpose was to analyze some characteristics of the local cellular immunity in metastatic GC. Methods 33 GC patients aged 30-80 years were divided into 2 groups: group 1 – M0, non-metastatic GC, n = 17, mean age 61.7±8.9 years (G2 – 11, G3 – 6 patients); group 2 – M1, GC with peritoneal and omentum metastases, n = 16, mean age 58.7±11.5 years (G2 – 7, G3 – 5, G4 - 3 patients). Tumours (T), peritumoral tissues (PT), omentum (O) and peritoneum (P) tissues were studied. Lymphocytes were determined by flow cytometry using FACSCantoII (BD) and T-, B-, NK antibody panels; quantitative content of DN (CD3+CD4-CD8-), DP (CD3+CD4+CD8+) T lymphocytes and regulatory (T-regs) T cells (CD4+CD25+CD127dim) was studied. Results Patients with M1 GC demonstrated increased CD3+ lymphocytic infiltration of T, PT, O and P tissues. IRI in M1 O was significantly higher than in M0 (1.95±0.3 vs 0.7±0.2), being similar in other tissues. Levels of DN lymphocytes were lower in O of M1, compared to M0 (7.7±2.5 vs 15.7±5.6, p ≤ 0.05). Contents of NK cells, NKT lymphocytes significantly decreased in O of M1 patients, compared to M0 (3.3≤1.1 vs 14.0≤2.3 and 1.7±0.5 vs 3.8±0.8, respectively). Higher levels of NKT lymphocytes were registered in M1 PT, compared to M0 (3.3±1.1 vs 1.3±0.4), as well as lower levels of NK cells in T (2.3±0.9 vs 5.33±0.2). Percentage of Treg lymphocytes in P and O were significantly lower in M1 than in M0 (respectively, 6.9±1.5 vs 12.6±4.9 and 5.9±1.3 vs 12.6±4.9). Higher amount of B lymphocytes was registered in all tissues of M1 patients, compared to M0, maximal in O (13.1±3.3 vs 3.4±1.5), T (23.5±5.1 vs 17.2±2.3) and P (8.2±3.4 vs 3.5±1.2), while in PT it was lower (15.7±4.2 vs 43.7±4.5). Conclusions GC metastasis to the omentum and peritoneum is characterized by a change in their immunological features – a decrease in the tissue level of NK and NKT lymphocytes, a loss in the prevalence of CD3+CD8+ due to an increase in the number of CD3+CD4+ cells, and an increase in the level of CD19 + (B2) lymphocytes. This probably contributes to the appearance of metastatic lesions in these organs in gastric cancer. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.