ZB004

ZB004 is a recombinant fusion protein designed as a CTLA-4-Ig (cytotoxic T-lymphocyte-associated antigen 4 immunoglobulin) with enhanced binding affinity and extended half-life. It contains two extracellular domain substitutions in the CTLA-4 region to increase binding to CD80 and CD86, key ligands involved in T-cell activation. The Fc domain of ZB004 is engineered with M428L and N434S amino acid substitutions (Xtend™ Fc domain) to prolong its half-life. ZB004 acts as an immunomodulator by inhibiting the interaction between CD80/CD86 on antigen-presenting cells and CD28 on T cells, thereby suppressing immune responses. It is being developed for autoimmune diseases, with clinical studies showing target engagement through dose-dependent receptor occupancy of CD86 and inhibition of IL-2 production[1][2].