Although current cancer immunotherapies have the capacity to target major immune checkpoints such as PD-1, PD-L1, or CTLA-4 to galvanize the anti-cancer T cell response [134,135,136], numerous other immune regulatory checkpoints are also upregulated on the surface of EMT cancers, including CD73 [137], CD155 [138], PD-L2 [139], and HVEM [140], which are not addressed by current ICI therapies. This evidence concerns the gene CTLA4 and cancer.