CTLA4 and cancer: The differentiation and activation levels of CD8 + T cells in this ICT refractory cancer type revealed a regulatory phenotype (HLA-DR + CD38 + CTLA-4- CD8 + T cells) rather than a cytolytic one [61], suggesting that the immune-privileged aspect of some organs, such as the eye and liver, can suppress T-cell activation and exhaustion, which make them unresponsive to ICT.