Unbalanced Expression of Sicos and Spd‐1 Correlates with Tumor Progression in Gastric Cancer

Background and Objectives T cells are central in antitumor immunity in gastric cancer (GC). The inducible costimulatory molecule (ICOS) is a T cell receptor that primarily transmits positive signals for T cell activation and is associated with poor prognosis in GC. In contrast, the costimulatory molecule programmed death 1 (PD-1) is an inhibitory receptor related to tumor immune escape. This study aimed to analyze soluble sites and sPD-1 levels in GC. Methods This study enrolled 83 GC patients and 20 healthy controls. Results The median survival time was 23.22 months in the GC patients. Low levels of sPD-1 and sICOS in GC patients compared to the control group (p = 0.003; p < 0.0001, respectively). High sPD-1 levels in stage IV patients compared to I/II and III stages groups (p = 0.008 and p = 0.0004, respectively). GC patients with stages I and II had higher levels of sICOS compared to III and IV stages (p = 0.0005 and p = 0.02, respectively). There were no significant differences in sPD-1 and sICOS levels between Lauren subtypes. Conclusion These results suggest a predominance of inhibitory costimulatory signals in advanced stages of GC, facilitating tumor immune escape, as the opposite occurs in early stages, resulting in an effective antitumor T-cell-mediated immune response.