TIGIT and CD226: tipping the balance between costimulatory and coinhibitory molecules to augment the cancer immunotherapy toolkit.

Combination therapies are becoming a focal point in cancer immunotherapy. In this issue of Cancer Cell, Johnston and colleagues identify the TIGIT/CD226 pathway, which provides significant interest for combination with PD-1 pathway blockade to improve anticancer CD8(+) T cell responses, because it acts by a novel mechanism to regulate CD8(+) T cell functions within the tumor microenvironment.