Monoclonal antibodies that target PD-1 or PD-L1 have been known to boost the body’s immune response against cancer cells. Anti-PD-1 antibodies have demonstrated effective treatment of several types of cancer, including melanoma of the skin, non-small cell lung cancer, kidney cancer, head and neck cancers, and Hodgkin’s lymphoma. Junshi Biosciences’ toripalimab is approved in China for the second-line treatment of melanoma, urothelial cancer, and nasopharyngeal carcinoma.
Toripalimab is an anti-PD-1 monoclonal antibody developed for its ability to block PD-1 interactions with its ligands, PD-L1 and PD-L2, and for enhanced receptor endocytosis function. PD-L1 and PD-L2 are tumor checkpoint proteins which recognize the PD-1 receptor on T cells and exhaust their anti-tumor activity. Blocking PD-1 interactions with PD-L1 and PD-L2 is thought to recharge the immune system’s ability to attack and kill tumor cells.
Toripalimab also is thought to encourage efficient internalization (endocytosis) of the PD-1 receptor, enabling a Trojan Horse effect allowing T cells to slip undetected past the tumor PD-L1 and PD-L2 checkpoints.