While PD-L1 expression by itself is not an indicator of TIL culture success, the ratio of CD8+ T cells to PD-L1+ cells is trending towards a significant separation, suggesting this important negative feedback loop may limit the ability to grow tumor-reactive TIL ex vivo. We subsequently performed unsupervised clustering of the data, which allowed us to further analyze the large amount of information generated with multispectral imaging. This evidence concerns the gene CD8A and neoplasm.