CGEN-15021 is a soluble fusion protein composed of the extracellular domain of a newly discovered B7/CD28 like protein fused to a Fc antibody fragment. This novel B7/CD28 like protein was discovered by Compugen using its Protein Family Members Discovery Platform.

CGEN-15021 acts as a co-inhibitory molecule to suppress T cell activation as demonstrated in cell based experiments. CGEN-15021 demonstrated pronounced therapeutic activity in animal models of multiple sclerosis (MS) and rheumatoid arthritis (RA). In the experimental autoimmune encephalomyelitis (EAE) model of MS, short term administration of CGEN-15021 resulted in dramatic alleviation in clinical manifestation of the disease. This effect lasts after cessation of treatment and is accompanied by inhibition of ‘epitope spreading”, a phenomenon that underlies the relapsing nature of the disease. The longevity of the therapeutic effect of CGEN-15021 treatment, as well as the inhibition of epitope spreading, point to restoration of immune tolerance. In the collagen induced arthritis (CIA) model of rheumatoid arthritis, CGEN-15021 administered to animals with an active disease inhibited further deterioration of disease symptoms. Altogether this data support the therapeutic potential of CGEN-15021 for treatment of autoimmune diseases.