New checkpoints in cancer immunotherapy

Summary Immune responses must be fine‐tuned to allow effective clearance of invading pathogens, while maintain tolerance to self‐antigens. T cells are the major effector cells for fighting and killing tumor cells. Immune checkpoints play a pivotal role in T cell activation, and determine the functional outcome of T cell receptor ( TCR ) signaling. The blockade of immune checkpoints CTLA ‐4 and PD ‐1 has already been one of the most successful cancer immunotherapies. In this review, we will focus on three novel inhibitory B7 family checkpoint molecules, B7‐H3, B7S1 and VISTA . The aim of this article is to summarize their expressions in tumors as well as their roles in controlling and suppressing T cell immune responses and anti‐tumor immunity. These pathways may be explored in future cancer immunotherapy.