Anti-CD8 Antibody/IL-21 Mutein Fusion Protein AB821

**Semantic type:** Amino Acid, Peptide, or Protein|Pharmacologic Substance

**Definition:** A recombinant fusion protein comprised of an antibody targeting the T-cell surface glycoprotein CD8 linked to an affinity-attenuated and charge-reduced variant of human interleukin-21 (IL-21), with potential immunostimulating and antineoplastic activities. Upon administration of anti-CD8 antibody/IL-21 mutein fusion protein AB821, the anti-CD8 antibody moiety specifically targets and binds to CD8+ T-cells, thereby allowing for the IL-21 mutein moiety to specifically bind to IL-21 receptor (IL-21R) and activate IL-21/IL-21R-mediated signaling in CD8+ T-cells. This enhances cytotoxic T-lymphocyte (CTL)-mediated cytotoxic immune responses against tumor cells. IL-21 plays an important role in the regulation of cellular immune responses. The reduced charge of the IL-21 mutein improves its bioavailability.

**Synonyms:** - AB 821 - AB-821 - AB821 - CD8-targeted IL-21 Mutein Fusion Protein AB821 - Immunocytokine AB821