Obexelimab (XmAb5871) is a humanized anti-CD19 antibody. Obexelimab works by inhibiting B cell receptor (BCR) mediated calcium influx and promoting the phosphorylation of Fc γ receptor IIb (FcγRIIb), which reduces B cell activation and function, leading to B cell apoptosis. Obexelimab can be used in research for rheumatoid arthritis and systemic lupus erythematosus.
Obexelimab can induce the expression levels of apoptosis pathway related genes and promote B cell apoptosis[1].Obexelimab (10 μg/mL, 3 min) inhibits B cell activation and function by suppressing BCR mediated calcium flux and promoting Fc γ RIIb phosphorylation[2].
Obexelimab (10 mg/kg; twice a week; i.p.) can inhibit the autoimmune response of immune deficient mice implanted with peripheral blood mononuclear cells (PBMCs) from rheumatoid arthritis (RA) patients[2].
References:
[1]. Boyles JS, et al. A nondepleting anti-CD19 antibody impairs B cell function and inhibits autoimmune diseases. JCI Insight. 2023 Jul 10;8(13):e166137.
[2]. Chu SY, et al. Suppression of rheumatoid arthritis B cells by XmAb5871, an anti-CD19 antibody that coengages B cell antigen receptor complex and Fcγ receptor IIb inhibitory receptor. Arthritis Rheumatol. 2014 May;66(5):1153-64.
[3]. Horton HM, et al. Antibody-mediated coengagement of FcγRIIb and B cell receptor complex suppresses humoral immunity in systemic lupus erythematosus. J Immunol. 2011 Apr 1;186(7):4223-33.