Pharmacokinetics and Pharmacodynamics of an Antisense phosphorothioate oligonucleotide Targeting Fas mRNA in Mice

摘要

ISIS 22023 is a modified phosphorothioate antisense oligonu-cleotide targeting murine Fas mRNA. Treatment of mice with ISIS 22023 reduced Fas expression in liver in a concentration-dependent and sequence-specific manner, which completely protected mice from fulminant death induced by agonistic Fas antibody. In this study, we characterized the relationships in mice between total dose administered, dose to the target or-gan, and ultimately, the intracellular concentration within target cell types to the pharmacologic activity of ISIS 22023. After subcutaneous injection, ISIS 22023 distributed to the liver rap-idly and remained in the liver with the t112 ranging from 11 to 19 days, depending on dose. There were apparent differences in patterns of uptake and elimination in different types of liver cells. Oligonucleotide appeared within hepatocytes rapidly, whereas the peak concentrations in Kupffer cells were delayeduntil 2 days after dose administration. Hepatocytes cleared oligonucleotide the most rapidly, whereas Kupffer cells ap-peared to retain oligonucleotide longer. The reduction of Fas mRNA levels (pharmacodynamic response) paralleled the in-crease of oligonucleotide concentration in mouse liver with maximum mRNA reduction of 90% at 2 days after a single 50 mg/kg subcutaneous administration. Moreover, the pharmaco-dynamics of ISIS 22023 correlated better with the pharmaco-kinetics in hepatocytes, supporting the concept that the pres-ence of oligonucleotide in target cells results in reductions in mRNA and, ultimately, pharmacologic activity. These results provide a comprehensive understanding of the kinetics of an antisense drug at the site of action and demonstrate that the reductions in mRNA induced by this antisense oligonucleotide correlate with its concentrations in cell targets.