Advances in Research on Cancer Immunotherapy Targeting T Cell Co-signalling

It has been widely accepted that T cell-mediated antitumor immunity requires at least two signals from T cell receptor and costimulatory molecules. The co-signal provided by co-inhibitory or co-stimulatory molecules determines the final outcome of the immune response mediated by T cell receptor signalling. Recently, great clinical successes have been achieved in drugs targeting co-inhibitory signaling such as CTLA-4 and PD-1, which makes immunotherapy become the most notable research area and receive the 2013's Breakthrough of Year award made by the journal Science. Cancer immunotherapy is expected to become a mainstay treatment for cancer in addition to surgery, radiation, chemotherapy, and targeted therapy. In this review, the most important co-inhibitory(CTLA4, PD-1/PD-L1) and co-stimulatory drug targets(CD137), their mechanisms of regulating cellular immune responses, as well as the recent development and applications of the targeted agents in cancer therapy were discussed.