Reduction of FXI in the liver and in blood following ISIS 416858 treatment. Cynomologus monkeys were administered ISIS 416858 (0, 4, 8, 12, 40 mg/kg/wk, SC) for up to 13 weeks. Additional animals in the 0, 12, and 40 mg/kg/wk groups were allowed a 13-week treatment-free period. Liver tissue or blood were harvested for assessment of (A) FXI mRNA levels or (B) FXI activity, respectively, at several time points following treatment initiation. Data represents mean ± SD. *Statistical difference from the control group (P < .05).