JS403

JS403 is a bifunctional fusion protein developed by TopAlliance Biosciences (Junshi Biosciences) for the treatment of various solid tumors. It is designed to simultaneously target the Programmed Death-Ligand 1 (PD-L1) checkpoint and deliver Interleukin-2 (IL-2) activity to the tumor microenvironment. By blocking PD-L1, JS403 relieves immune suppression, while the IL-2 component stimulates the proliferation and activation of effector T cells and natural killer (NK) cells. This dual mechanism aims to enhance anti-tumor immune responses while potentially reducing the systemic toxicity typically associated with high-dose IL-2 therapy through targeted delivery.