A mechanistic, functional, and clinical perspective on targeting CD70 in cancer

The oncoimmunology research has witnessed notable advancements in recent years. Reshaping the tumor microenvironment (TME) approach is an effective method to improve antitumor immune response. The T cell-mediated antitumor response is crucial for favorable therapeutic outcomes in several cancers. The United States Food and Drug Administration (FDA) has approved immune checkpoint inhibitors (ICIs) for targeting the immune checkpoint proteins (ICPs) expressed in various hematological and solid malignancies. The ICPs are T cell co-inhibitory molecules that block T cell activation and, thus, antitumor response. Currently, most of the FDA-approved ICIs are antagonistic antibodies of programmed death-ligand 1 (PD-L1), programmed cell death protein 1 (PD-1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). In contrast to ICPs, the T cell costimulatory molecules are required for T cell activation, expansion, and effector function. However, the abrupt expression of these costimulatory molecules in tumors presents a concern for T cell-mediated antitumor response. One of the T cell costimulatory molecules, the cluster of differentiation 70 (CD70), has emerged as a druggable target in various hematological and solid malignancies due to its role in T cell effector function and immune evasion. The present review describes the expression of CD70, factors affecting the CD70 expression, the physiological and clinical relevance of CD70, and the current approaches to target CD70 in hematological and solid malignancies.