CD27 is a clinically validated drug target that is a member of the TNF receptor superfamily and plays a critical role in T-cell activation by providing a co-stimulatory signal together with its ligand CD70.  CD27 is highly expressed on naïve T cells and also provides a co-stimulatory signal for NK cell activation.

Anti-CD27 monoclonal antibodies activate and induce the maturation and migration of naïve T cells. CD27 activation also drives the diversification of the T cell repertoire, lowering the activation threshold of T cells against low affinity tumor antigens. Recent data also suggests that an agonist anti-CD27 antibody can activate important innate immune cell populations like natural killer (‘‘NK’’) cells and inflammatory myeloid cells. These cells contribute to an effective anti-tumor response, especially in checkpoint inhibitor (CPI) resistant patients. Recent publications have also demonstrated that anti-CD27 agonist antibodies can drive tumor growth inhibition as a monotherapy and in combination with CPIs.