PD-1 pathway, comprising immune cell co-receptor Programmed Death 1 (PD-1) and its ligands, PD-L1 (B7-H1) and PD-L2 (B7-DC), mediates local immunosuppression in tumor microenvironment. Drugs designed to block PD-1 or PD-L1 "release brakes" on anti-tumor immunity and have demonstrated clinical activity in several types of advanced cancers, validating this pathway as a target for cancer rapy. Two such drugs have recently been approved to treat melanoma and lung cancers, and regulatory approvals in first- and second-line settings for additional cancer types are anticipated. manageable safety profile of PD-1/PD-L1 blocking drugs identifies m as suitable for outpatient administration and development of combinatorial rapies. Ongoing studies aim to identify biomarkers to guide patient selection, which would furr improve risk:benefit ratio for se drugs.
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