Emerging Family of Protein-protein Interaction Inhibitors Targeting PD-1 Checkpoint Pathway

Background: T cell activation via the blockade of PD-1 pathway has been recognized as an emerging drug target for cancer immunotherapy which provides a rationale for clinical trials in cancer patients. The recent breakthrough approvals of T cell checkpoint inhibitors targeting PD-1 pathway boost the era of immuno-oncology drugs. Methods: The progress of PD-1 checkpoint inhibitor as a single agent in the field of immuno-oncology is reviewed. Antibodies targting PD-1 and PD-L1 with regulatroy approvals are discussed with the current coverage of indications. Other candidates in clinical investigations are also summarized. Results: Monoclonal antibodies that block protein-protein interactions between PD-1 and its ligand have shown the promise for the treatment of a variety of cancer types. The fast growing family of PD-1 checkpoint inhibitors been observed both in regulatroy approvals and clinical investigations. Conclusion: The potential use of PD-1 checkpoint inhibitor alone or in combination with other agents is substantial, and will further reveal the important role of PD-1 pathway in immunomodulation and disease control.