GW-3333

A series of N-hydroxyformamide tumor necrosis factor-alpha converting enzyme (TACE)/matrix metalloprotease (MMP) inhibitors were evaluated for their potential to induce human cytochrome P450 3A (CYP3A). Two in vitro assays were used: 1) a cell-based reporter gene assay for activation of the pregnane X receptor (PXR), and 2) a primary "sandwich" culture of human hepatocytes. Approximately 50 TACE/MMP inhibitors were evaluated in the human PXR assay. A range of PXR activation was observed, 0 to 150% of the activation of the known human CYP3A inducer rifampicin. Three TACE/MMP inhibitors were evaluated in rat and human hepatocytes. Significantly higher PXR activation/CYP3A induction was observed in PXR/hepatocyte models, respectively, for (2R,3S) 3-(formyl-hydroxyamino)-2-(2-methyl-1-propyl)-4-methylpentanoic acid [(1S,2S)-2-methyl-1-(2-pyridylcarbamoyl)-1-butyl]amide (GW3333) compared with (2R,3S)-6,6,6-trifluoro-3-[formyl(hydroxy)amino]-2-isobutyl-N-[(1S,2R)-2-methoxy-1-[(1,3-thiazol-2-ylamino)carbonyl]propyl]hexanamide (GW6495) and (2R)-N-[(1S)-2,2-dimethyl-1-[(methylamino)carbonyl]-propyl]-2-[(1S)-1-[formyl(hydroxy)amino]ethyl]-5-phenylpentanamide (GI4023). The CYP3A induction level achieved with GW3333 at a concentration of approximately 10 microM in human hepatocytes was comparable to that achieved with rifampicin at a concentration of 10 microM. The extent of rodent CYP3A induction caused by GW3333 was confirmed in vivo after daily oral administration for 14 days to rats. In conclusion, GW3333 is a potential inducer of CYP3A expression in vivo in humans, but other N-hydroxyformamides are less likely to induce CYP3A.

Clinical trials showing the benefits of reducing the effects of TNF- alpha in rheumatoid arthritis have highlighted the key role of the cytokine TNF- alpha in this inflammatory condition. A new approach to reducing the effects of TNF- alpha is to decrease its synthesis by inhibiting TNF- alpha converting enzyme with GW3333. In rat models of arthritis, GW3333 has some beneficial effects. Further longer-term studies of GW3333 in animal models are required to determine whether its benefit is maintained. TACE inhibition may represent a new approach to treating inflammation.