4-1bbl-ox40l fusion protein

The 4-1bbl-ox40l fusion protein is a recombinant fusion protein designed to enhance anti-tumor immune responses. It combines the extracellular domains of two costimulatory ligands, 4-1BB ligand (4-1BBL, also known as CD137L) and OX40 ligand (OX40L), both members of the tumor necrosis factor (TNF) superfamily. These ligands bind to their respective receptors—4-1BB and OX40—on T cells, providing potent co-stimulatory signals that promote T cell activation, proliferation, survival, and effector function. The dual engagement by this single-chain fusion format aims to synergistically boost anti-tumor immunity by enhancing CAR-T cell activity or other immunotherapeutic strategies[3][1][4]. Preclinical studies suggest that co-expression or administration of this fusion protein can improve the efficacy of B7-H3-targeted CAR-T cells against solid tumors[3][1]. The mechanism relies on preserved ligand–receptor binding capacity in the single-chain format[4].