The chimeric mFVIIa-FMR molecule can bind mEPCR in vivo. (A) C57BL/6 mice (n = 5 per group per time point) were infused via the tail vein with 500 µg/kg of mFVIIa or mFVIIa-FMR, and blood was collected at various time points thereafter. Plasma protein concentration was measured by antigen and activity assays and shown as recovery (percentage of the initial amount of injectant, mean ± SD). Recovery of mFVIIa-FMR is reduced compared with mFVIIa. Asterisk indicates P < .05 vs mFVIIa-FMR. (B) Cohorts of C57BL/6 mice were initially infused via the tail vein with 50 µg of either mEPCR blocking antibody (RCR-252) or isotype control IgG. The type of antibody administered in each cohort is indicated by the + or − symbol. One hour later, 500 µg/kg of mFVIIa, mFVIIa-FMR, or buffer was infused, and antigen levels at 5 minutes after injection were determined. *P < .05 for each indicated comparison. Data are expressed as mean ± SD.