Vertex Shareholders Stay Vexed

Twelve weeks after stopping treatment, patients are being analyzed to see whether the hepatitis C virus in their system remains at undetectable levels. In hepatitis C circles, this is what's known as a "sustained virologic response," or SVR. Since SVR, in this case, is being measured 12 weeks after treatment ends, the data that Vertex will share at the EASL meeting will be SVR12 (from Arm D of the Prove 1 trial, to be exact.)

"This will be the first time in a clinical trial that any [hepatitis C] infected patient will have systematically been stopped at 12 weeks to see whether or not they can achieve SVR or not," explained Vertex's Chief Medical Officer John Alam at an investor conference last week.

What makes these data so intriguing is that they represent Vertex's home-run strategy with regard to telaprevir, because 12 weeks on a drug would be the shortest treatment ever conceived for hepatitis C patients. Currently, hep C patients, like those enrolled in Prove 1, need to be treated for 48 weeks with interferon and ribavirin before they can be cured.

Naturally, an aggressive stab at a 12-week treatment schedule is a risky strategy for Vertex, so the other arms of the study are exploring different treatment regimens: all dose telaprevir for 12 weeks like in Arm D, but they also extend interferon-ribavirin treatment for longer periods.