A functional radioreceptor assay of alpha-V-beta-3 (alpha(v)beta(3)) inhibitor's in plasma: Application as an ex vivo pharmacodynamic model

作者：Chaikin MA; Marugan JJ; De Vries GW; Baciu P; Edelman J; Ni M; Tomczuk BE; Pan WX; Guo ZH; Anaclerio B; Leonard K; Eisennagel SH; Molloy CJ; Manthey CL^*

来源：Journal of Biochemical and Biophysical Methods, 2005, 65(2-3): 107-120.

DOI：10.1016/jjbbin.2005.10.004

• integrin
• echistatin
• pharmacodynamic
• angiogenesis
• plasma
• binding

Development of alpha(v)beta(3)-integrin inhibitors has been hampered by a lack of pharmacodynamic endpoints to identify doses that inhibit alpha(v)beta(3) in vivo. To address this need, we developed an alpha(v)beta(3) radioreceptor assay (RRA) that could be performed in 100% plasma. The RRA was based on I-125-echistatin binding to plate-immobilized alpha(v)beta(3). Small Molecule alpha(v)beta(3) inhibitors efficiently competed echistatin binding to alpha(v)beta(3) when the assay was carried out in buffer. However, when carried out in 100% plasma, the RRA revealed a 45 to > 3000-fold loss in compound potencies. The losses in potency reflected, in part, the high plasma protein binding by the compounds examined. The RRA was adapted as an ex vivo pharmacodynamic model. Echistatin binding was measured in the presence of plasma harvested at timed intervals from rats dosed with select compounds. Using this pharmacodynarnic model, compound and dose selection was optimized for further testing in models of corneal angiogenesis. Moderate anti-angiogenic activity was achieved when rats were dosed sufficient to achieve sustained (> 50%) plasma inhibition through the trough interval. Thus, the RRA provided a simple technique to rank order Compound potency in plasma, and could find general use as an ex vivo pharmacodynamic assay to select compounds and doses for preclinical and clinical proof-of-principle studies.

• 出版日期2005-12-31