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 treatment of unresectable or metastatic melanoma.
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.