NBI-74330 is a small molecule antagonist for CXCR3, NBI-74330 demonstrates potent inhibition of [(125)I]CXCL10 and [(125)I]CXCL11 specific binding (K (i) of 1.5 and 3.2 nM, respectively.
Chemokines (CXCR3) and their ligands (CXCL9, CXCL10, and CXCL11) exert exquisite control over T-cell trafficking and are critical for activation, differentiation and effector T cell function[3].NBI-74330 is a potent antagonist for CXCR3, and exhibits potent inhibition of (125I)CXCL10 and (125I)CXCL11 specific binding with Ki of 1.5 and 3.2 nM, respectively. BI-74330 demonstrates potent inhibition of [125I]CXCL11 specific binding to membranes prepared from transfected CHO cells expressing CXCR3 (CXCR3-CHO) (Ki=3.6 nM). NBI-74330 is 12- and 3.5-fold more potent than CXCL9 (Ki=45.2 nM) and CXCL10 (Ki=12.5 nM), respectively, at inhibiting [125I]CXCL11 binding to CXCR3-CHO cell membranes. NBI-74330 inhibits calcium mobilization in response to CXCL11 and CXCL10 with an IC50 value of 7 nM for both ligands used at their EC80 concentrations (1 nM for CXCL11 and 30 nM for CXCL10). NBI-74330 specifically inhibits CXCR3-mediated calcium mobilization. NBI-74330 also dose-dependently inhibits CXCL11-induced [35S]GTPγS binding in membranes of cells endogenously expressing CXCR3 (H9 cells, IC50 value 5.5 nM). BI-74330 inhibits CXCL11-induced chemotaxis in these cells with an IC50 of 3.9 nM[4]. Administration of NBI-74330 to mice resulted in the formation of an N-oxide metabolite, also an antagonist of CXCR3. Both antagonists were detectable up to 7 h post oral dose and 24 h post subcutaneous dose. Measurement of CXCR3 internalization demonstrated significant antagonism of this response ex vivo, 24 h following subcutaneous administration of NBI-74330[5].Antagonizing CXCR3 with NBI-74330 resulted in a significant reduction in CD4+ T cell and macrophage migration to the peritoneal cavity, which was as shown in ex vivo migration studies totally CXCR3 dependent. Atherosclerotic lesion formation in the aortic valve leaflet area and the entire aorta was significantly inhibited in NBI-74330 treated mice. Lymph nodes draining from the aortic arch were significantly smaller in treated mice and were enriched in regulatory T cells and contained fewer activated T cells, whereas the markers for regulatory T cells within the lesion were enhanced after NBI-74330 treatment[6].
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