HAVCR2 and cancer: In addition to CTLA4, several other negative regulators such as T-cell immunoglobulin, mucin domain-3 protein (TIM-3), lymphocyte-activation gene 3 (LAG-3), T-cell immunoreceptor tyrosine-based inhibition motif domain (TIGIT) and V-domain immunoglobulin-containing suppressor of T-cell activation (VISTA) [9–13], have been identified and are currently being tested in clinical trials to determine their potential as targets for cancer immunotherapy.