Evaluation of tumor-infiltrating gammadelta T cells across solid tumor indications

The tumor microenvironment is a complex heterogeneous cellular mixture containing not only tumor cells, but also immune cells, fibroblasts, and endothelial cells. Based on numerous factors, including cellular subtype and activation, these cell types can have both tumor-promoting and tumor-eradicating activities. We have previously analyzed both intra-tumoral alphabeta T cells and B cells using a combination of flow cytometry and single cell transcriptomics across solid tumor indications such as bladder, colorectal, endometrial, lung, ovarian, prostate, and renal cancer using human dissociated tumor cells (DTCs). alphabeta T cells represented the largest tumor-infiltrating lymphocyte (TIL) subset, and the majority of alphabeta T cells were in an exhausted state based on high surface expression of inhibitory receptors such as PD1 and TIGIT. Across all indications, B cells were the next most prevalent TIL subset, although indication-specific differences were observed. Overall, like alphabeta T cells, intra-tumoral B cells had an exhausted phenotype, and a high proportion of these B cells were plasmablasts.gammadelta T cells represent an attractive candidate for immunomodulation as they recognize their cognate antigens in an HLA-independent manner and have intrinsic cytotoxic potential. Previous studies utilized large scale bulk transcriptomics inferred a substantial percentage of gammadelta T cells across several solid tumor indications. Further studies in melanoma and colorectal cancer analyzed the activation status and Vdelta1/2 usage of intra-tumoral gammadelta T cells; however, a fully comprehensive evaluation and comparison of gammadelta T cell activation status, Vgamma/Vdelta usage, and putative gammadelta T cell ligand expression across numerous indications remains unstudied. We have now utilized DTCs across twelve solid tumor indications to analyze the relative percentages of gammadelta T cells, including their Vgamma chain and Vdelta chain usage. The naïve versus memory phenotype of the gammadelta T cells and the surface expression of exhaustion and natural cytotoxicity receptors were also evaluated. Finally, the expression of gammadelta T cell ligands, such as stress receptors and butyrophilins, on the tumor cells was assessed. Collectively, these studies provide crucial insight into the indication-specific gammadelta T cell composition to inform future gammadelta T cell-mediated immunotherapies.