Management agrees and is on record to that effect.
It’s a pretty long longshot, but ENTA could conceivably reduce its tax rate by buying a foreign company and doing a tax inversion. (The new US Treasury rules on tax inversions rules wouldn’t be much of an impediment for a company like ENTA.)
If ENTA in-licenses compounds, the most likely areas are virology and liver diseases (but not HCV, as noted above). Buying a whole company working in these areas is also a possibility.