MEDI-570 is a humanized IgG1 monoclonal antibody produced in CHO cells, targeting the inducible T-cell costimulator (ICOS/CD278). Functioning as a potent agonist, it binds with high affinity to the ICOS receptor, mimicking and amplifying the costimulatory signal of its natural ligand, ICOS-L. This agonistic activity promotes the activation, proliferation, survival, and cytokine production of T cells, including effector T cells and T follicular helper (Tfh) cells. It is developed as a cancer immunotherapeutic agent designed to combat tumors by enhancing T-cell function.