ASP2409

ASP2409 is a next-generation cytotoxic T-lymphocyte associated protein 4-immunoglobulin (CTLA4-Ig) fusion protein engineered for enhanced immunosuppressive activity. It exhibits significantly higher binding affinity and selectivity for the CD86 ligand compared to earlier CTLA4-Ig agents such as abatacept and belatacept, with up to 220-fold increased affinity for CD86 while retaining similar binding to CD80. This selective costimulation blockade inhibits T-cell activation by preventing the interaction of CD28 on T cells with its ligands (CD80/CD86) on antigen-presenting cells, thereby suppressing immune responses involved in organ transplant rejection and autoimmune diseases like rheumatoid arthritis. Developed as an intravenous agent, ASP2409 demonstrated dose-dependent pharmacokinetics and receptor occupancy in clinical studies but was discontinued after phase 1 trials due to strategic reasons rather than safety concerns[1][2][3][6][7][9].