Purpose: Adenocarcinomas of the esophagus (AEG) and stomach (AS) are among the most common cancers worldwide. Novel markers for risk stratification and guiding treatment are strongly needed. Activin is a multi-functional cytokine with context specific pro- and anti-tumorigenic effects. We aimed to investigate the prognostic role of activin tumor protein expression in AEG/ASs.
Methods: Tissue from a retrospective cohort of 277 patients with AEG/AS treated primarily by surgery at the Charite - Universitatsmedizin Berlin was collected and analyzed by immunohistochemistry using a specific antibody to the activin homodimer inhibin beta A. Additionally, we evaluated T-cell infiltration and PD1 expression as well as expression of PD-L1 by immunohistochemistry as possible confounding factors. Clinico-pathologic data were collected and correlated with activin protein expression.
Results: Out of 277 tumor samples, 72 (26.0%) exhibited high activin subunit inhibin beta A protein expression. Higher expression was correlated with lower Union for International Cancer Control (UICC) stage and longer overall survival. Interestingly, activin subunit expression correlated with CD4(+) T-cell infiltration, and the correlation with higher overall survival was exclusively seen in tumors with high CD4(+) T-cell infiltration, pointing towards a role of activin in the tumor immune response in AEG/ASs.
Conclusion: In our cohort of AEG/AS, higher activin subunit levels were correlated with longer overall survival, an effect exclusively seen in tumors with high CD4(+) cell infiltration. Further mechanistic research is warranted discerning the exact effect of this context specific cytokine.