PD1PDL1inhibitors

PD-1 and PD-L1 inhibitors are a class of monoclonal antibodies used in cancer immunotherapy. They block the interaction between the PD-1 receptor on T cells and its ligands PD-L1 (and, for PD-1 inhibitors, PD-L2) to release a brake on the immune response. By restoring T-cell activity, these drugs aim to promote immune-mediated tumor destruction. They can be used as single agents or in combination with chemotherapy, targeted therapies, or other immunotherapies.

The main agents are divided into PD-1 inhibitors, such as nivolumab and pembrolizumab, and PD-L1 inhibitors, such as atezolizumab, durvalumab, and avelumab. These drugs are approved for a range of malignancies, including melanoma, non-small cell lung cancer, renal cell carcinoma, urothelial carcinoma, head and neck cancer, gastric/GEJ cancer, hepatocellular carcinoma, and others. Indications and approvals continue to evolve as new data emerge.

Administration is by intravenous infusion, with dosing schedules varying by agent and treatment setting. Treatment requires monitoring for response and for immune-related adverse events, which can affect skin, colon, liver, endocrine organs, lungs, and other systems. Management may involve corticosteroids or other immunosuppressants for moderate to severe irAEs.

Biomarkers such as PD-L1 expression, tumor mutational burden, microsatellite instability, and mismatch repair status are used to guide some treatment choices, though responses can occur across a range of biomarker profiles. Limitations include nonresponse in some patients and potential autoimmune toxicity, but PD-1/PD-L1 inhibitors remain central to modern cancer immunotherapy.