One of two known mechanisms for action by VX-950 is to foil HCV's ability to block liver's immune response against the virus. It is not surprising to find the apparent synergy between 950 and IFNa. If you need literatures to find more, let me know.
Exactly how does the liver have its immune response blocked? Does the liver have a separate immune system? I'd like to know about this special immune mechanism that is liver specific. Are you talking about a cytokine type anti-viral specific for the liver?
The virus protease inhibitor neutralizes immune cells that attack the virus. The inhibition of the virus PI by VX-950 allows the immune system to attack the virus and infected cells.
The immune system is undoubtedly a huge part of the eradication of the virus in patients and the 4.4 log reduction, now that it can fully participate.
I would add that not only is it a long shot but use of a strategy where immune cells are stimulated enmass (polyclonal stimulation) vs cytokine use to boost stimulated cells is downright dangerous.
Maybe the drug's use has been well demonstrated and the mode of action in animal experimentation, but trans species could bring up many problems. Particularly in humans there would be potential contraindications.