Without delving too deeply into the differences in variants there's one thing I would like to point out. Stratification between variants being done in VRUS' studies is to prove that this metric is no longer needed with PSI-7977 because the drug works equally well for all patients regardless of whether the patient is IL28B, CC, or TT. The metric is highly relevant in studies with Incivek to determine which patients will respond well to treatment as you well know.
I did see in the VRUS trial info the statement "Stratified by IL28B and baseline HCV RNA", but I didnt quite understand how that was applied. I didnt see another reference to just how that was applied in the trial patient selection. I didn't see info comparing the various common predictors, just the statement that it basically didn't matter. I'm questioning this because I've come to realize that in reading trial results sometimes what is NOT said can mean quite a bit. As far as I can tell the trials could have selectively been with the easier to treat patients with low viral loads, European decent and with other high predictors of SVR. I've seen drug companies do much worse that just leave out significant data. I try to work under the theme of "Trust your fellow man, but cut the cards"
The FDA will look very closely at viral load data. I've heard posters on this MB complain how VRUS picks the easy to treat patients but wouldn't that be self-defeating under FDA analysis?
PSI-7977 has shown high levels of efficacy (during mid-stage testing) in all patients regardless of their IL28B status. The late-stage design intends to demonstrate to the FDA that interferon usage and stratification of patients for IL28B status is a thing of the past.