TNFRSF4 (tumor necrosis factor receptor superfamily member 4), also known as OX40 or CD134. is a co-stimulatory receptor primarily expressed on activated CD4+ and CD8+ T cells. It belongs to the TNF receptor family and interacts with its ligand OX40L (CD252), a TNF superfamily protein, to amplify T-cell activation, survival, and effector functions. This signaling axis plays a critical role in sustaining immune responses, particularly in chronic inflammation, autoimmune disorders, and antitumor immunity.
Antibodies targeting TNFRSF4 are widely used in research to modulate T-cell activity. Antagonistic antibodies block OX40-OX40L interactions, suppressing excessive T-cell activation, making them potential therapeutics for autoimmune diseases (e.g., rheumatoid arthritis, multiple sclerosis) and graft-versal-host disease. Conversely, agonistic antibodies enhance OX40 signaling to boost T-cell proliferation and cytokine production, which is being explored in cancer immunotherapy to overcome immune checkpoint resistance.
Structurally, TNFRSF4 antibodies typically recognize extracellular domains of the receptor, influencing downstream pathways like NF-κB and PI3K-Akt. Their therapeutic potential is underscored by clinical trials evaluating both antagonistic and agonistic formats. However, context-dependent effects require careful optimization to balance pro-inflammatory and immunosuppressive outcomes. Research continues to refine antibody specificity, isotype selection, and combination strategies with other immunomodulators.