True... EOT does not translate to SVR4... and SVR4 is still too early but starts to be a good indicator. SVR12, however... that you may want to hang your hat on these days. Here is a bit of info on drug pharmacokinetics. Peg has a pretty long half-life (not to mention ribavirin...why do you think the ribavirin label tells you to practice safe you-know-what for a long time AFTER you finish taking the drug?)... anyway you need to get to SVR12 with Peg/Riba just to see if there will be a lot of relapse due to this half-life (I didn't make this up... there is good data in the public domain from companies and the FDA to show this). If you are giving oral therapies with a short half-life, the drug pressure is gone rapidly. HCV also grows very fast (just ask a liver transplant patient) once the drug pressure is removed. I would have strong doubts you will see much relapse if any after SVR12. Probably you will see some patients in the study lost to follow-up between 12 and 24 (that is a long time to expect someone to come back for a blood draw) that may be counted conservatively as a "failure"... but that is really just a failure to obtain a blood draw!
I always find it so funny when people try to say things on these boards to get folks all crazy. I don't even have holding in these companies... I just know the science and it annoys me when people start shouting that the earth is flat and herbs and berries will cure you of all your woes.
Sorry, but the science overwhelmingly supports SVR12. The support was validated during the approval of both PIs actually. 22% relapse would be terrible if the SVR was 50%... but if everyone who doesn't hit SVR relapses.. that is actually pretty good. It just means the virus was nearly eradicated but there was not quite enough drug pressure to do so. If there was say 12% relapse, but 10% failure on-treatment, it would be worse... that would mean the virus is escaping despite constant pressure. 12 weeks is very close here and actually viable for more than just PR intolerant folks. I have no skin in this now... just know the science too well to see these statements that could be misleading to people. I am sure it was not ill-intentioned. It is a complex beast.
You are correct that the 100% SVR was not achieved, but this is not surprising in larger studies. I would be surprised if the 78% drops by more than 1 or 2% (if at all) since the SVR12 timepoint is VERY predictive of SVR24 (lots of data that shows this) and without Peg on-board, it is is likely that anyone who would have relapsed would have done so before the 12 week follow-up visit (Peg has a longer half-life than the orals). I would say the result is only disappointing if you are a perfectionist. It is still a very admirable result and great for the patients. I have no monetary interests. Good luck to everyone!