CTLA4 and melanoma: In the presence of s.c. B16 melanoma tumors, combined PD-1 plus CTLA-4 blockade resulted in drastic upregulation of T cell entry receptors vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) on blood vessels within intracranial tumors, which might have contributed to the enhanced T cell infiltration (Taggart et al., 2018).