In Vitro: In a dose-responsive fashion, PF-1355 inhibits MPO activity in phorbol ester-stimulated human neutrophils as measured by taurine chlorination (EC50=1.47 μM) as well as lipopolysaccharide-treated human blood measuring residual MPO activity (EC50=2.03 μM).
In Vivo: Oral administration of PF-1355 reduces plasma MPO activity, vascular edema, neutrophil recruitment, and elevates circulating cytokines. In a model of anti-glomerular basement membrane disease, formerly known as Goodpasture disease, albuminuria and chronic renal dysfunction are completely suppressed by PF-1355 treatment.