CTLA4 and cancer: Following the success of CTLA4 and PD1/PDL1 therapies, there has unsurprisingly been interest in targeting other immune checkpoints including BTLA, VISTA, TIM‐3, and CD47 as well as co‐stimulatory molecules such as CD137, OX40, and GITR84 with the hope that targeting other immune checkpoints may result in lower rates of toxicity or greater efficacy in a given cancer.