Endogenous ligand for ICOS
] that is expressed on the surface of antigen presenting cells. Inhibiting the ICOS/ICOSL axis is predicted to provide anti-inflammatory activity applicable for the treatment of autoimmune diseases.
The ICOSL protein contains an immunoglobulin (Ig)-like domain that resembles the antibody variable domain, that has been coined the 'V-set domain'. The genes for all human V-set domain containing proteins are listed in HGNC gene group 590
The anti-ICOSL monoclonal antibody MEDI5872 (AMG557) is being evaluated in Phase 2 clinical trial in patients with primary Sjögren's syndrome (NCT02334306
). Phase 1 trials of the same biologic in systemic lupus erythematosus (SLE) and psoriasis were terminated.