Upregulation of TIM3 and reduced expression of PD-1 on immune cell subsets in advanced prostate cancers

Abstract

Abstract Introduction/Objective Although most prostate cancers behave in an indolent manner, a small proportion is highly aggressive. Both primary and advanced prostate cancer is widely known as a non-inflamed cancer that is characterized by a paucity of immune infiltration. Methods/Case Report To assess the spatial interplay of more than 30 TIM3, CTLA-4, PD-1/-L1 expressing leukocyte subpopulations in 453 prostate cancers, tissue microarrays were stained with 21 antibodies using our BLEACH&STAIN multiplex fluorescence immunohistochemistry approach and analyzed using a deep learning-based image analysis framework. Results (if a Case Study enter NA) The immune cell density of CD8+ cytotoxic T-cells, CD4+ T-helper cells, FOXP3+ regulatory T-cells, M1/ M2 macrophages, as well as CD11c+ dendritic cells increased consistently along with the Gleason grade in primary prostate cancer (p≤ 0.034 each). In recurrent prostate cancers under therapy, the density of FOXP3+regulatory T-cells and M1 macrophages further increased, while the density of CD8+ cytotoxic T-cells, CD4+ T-helper cells, as well as CD11c+ dendritic cells decreased (p≤0.017 each). Although the immune checkpoint expression of TIM3 on T-cell subsets, macrophages and dendritic cells was upregulated in advanced/ recurrent tumors, the expression level of PD-1 was downregulated in all analyzed T-cell subsets. Conclusion Although prostate cancer is a generally considered a low inflamed tumor, the degree of tumor infiltration by various immune cell subtypes increases markedly along with tumor progression and in recurrent tumors under therapy. Taken together, these data suggest that the evaluation of the spatial distribution of immune cell types along with their immune checkpoint expression can provide relevant clinical information in prostate cancer.