Etrolizumab (rhuMAb Beta7) is a humanized intestinal-selective anti-β7 integrin monoclonal antibody that selectively blocks the transport and retention of lymphocytes in the intestinal tract for the study of inflammatory bowel disease (IBD).

peripheral blood lymphocytes (human, PBLs):31.7 pM (Kd), peripheral blood lymphocytes (rabbit, PBLs):57 pM (Kd), peripheral blood lymphocytes (cynomolgus monkeys, PBLs):25.7 pM (Kd), E-calmodulin:3.96 nM, α4β7 (human):18 nM (Kd), α4β7-293 (human):116 pM (Kd), MAdCAM-1:0.075 nM, αEβ7-293 (human):1800 pM (Kd), α4β7-38C13 (mouse):181 pM (Kd), VCAM-1:0.089 nM

Etrolizumab binds the β7 subunit of α4β7 and αEβ7 integrins with high affinity. Its binding dissociation constants (Kd) with human α4β7, human αEβ7-293, mouse α4β7-38C13, human α4β7-293, rabbit peripheral blood lymphocytes (PBLs), human PBLs, and cynomolgus monkeys PBLs were 18 nM, 1800 pM, 181 pM, 116 pM, 57 pM, 31.7 pM, and 25.7 pM, respectively. The Kd
In RPMI 8866 cells and αEβ7-293 cells, Etrolizumab blocked the binding of α4β7 to its ligands MAdCAM-1 and VCAM-1, with half inhibitory concentrations (IC50) of 0.075 nM and 0.089 nM, respectively; meanwhile, it also blocked the interaction of αEβ7 with its ligand E-calmodulin, with IC50 values of 3.96 nM. [1]

Intravenous injection of 5 mg/kg Etrolizumab, administered as a single dose, reduced β7 integrin expression on T lymphocytes of normal female BALB/c mice. In addition, a single intraperitoneal injection of 200 μg (100 μL) of Etrolizumab inhibited lymphocyte homing in a CD45RB high T-cell reorganization model of colitis in SCID mice. [2]