soluble PD-1

Soluble PD-1 (sPD-1) refers to the circulating, non-membrane-bound isoforms of the programmed cell death protein 1 (PD-1) receptor. It is generated naturally through alternative splicing or proteolytic shedding of the membrane-bound receptor by matrix metalloproteinases such as MMP-9. While primarily utilized as a liquid biopsy biomarker to predict disease progression and treatment response in oncology (e.g., NSCLC, melanoma) and autoimmune diseases (e.g., rheumatoid arthritis, type 1 diabetes), recombinant and engineered forms of sPD-1 are being investigated as therapeutic agents. In cancer immunotherapy, sPD-1 acts as a decoy receptor that sequesters PD-L1 and PD-L2, preventing them from engaging membrane-bound PD-1 on T-cells and thereby reversing tumor-induced immunosuppression. In autoimmune contexts like systemic sclerosis, recombinant PD-1 fusion proteins (such as PD-1:Fc) are explored for their ability to modulate the PD-1/PD-L axis to attenuate inflammatory cytokine production and fibrosis. Experimental delivery methods, including engineered bacteria (e.g., VNP20009) expressing sPD-1, are also under development for localized tumor therapy.

Other names

soluble programmed death-1soluble programmed cell death protein 1recombinant soluble PD-1