Abatacept

Abatacept is a soluble fusion protein, which links the extracellular domain of human cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) to the modified Fc (hinge, CH2, and CH3 domains) portion of human immunoglobulin G1 (IgG1). Structurally, abatacept is a glycosylated fusion protein with a MALDI-MS molecular weight of 92,300 Da and it is a homodimer of two homologous polypeptide chains of 357 amino acids each. It is produced through recombinant DNA technology in mammalian CHO cells. The drug has activity as a selective co-stimulation modulator with inhibitory activity on T lymphocytes. Although approved for the treatment of rheumatoid arthritis, Repligen has entered a slightly different formulation of CTLA4-Ig into clinical trials (RG2077).

Abatacept is indicated in adult patients for the treatment of moderately-to-severely active rheumatoid arthritis and for the treatment of active psoriatic arthritis. In patients two years of age and older, abatacept is also indicated for the treatment of moderately-to-severely active juvenile idiopathic arthritis.

Abatacept is also indicated for the prophylaxis of acute graft-versus-host disease, in combination with methotrexate and a calcineurin inhibitor such as tacrolimus, in patients two years of age and older who are undergoing hematopoietic stem cell transplantation from a matched or 1 allele-mismatched unrelated donor.