http://tinyurl.com/3y4hyp Roche got an 8% SVR rate using Pegasys in non-responders to prior Peg-Intron. This was raised to 16% when second-line therapy was continued out to 72 weeks.
SGP got a 23% SVR rate using Peg-Intron in a mixed pool of non-responders/relapsers to prior Pegasys/Intron-A.
The Roche trial above is the more applicable trial with respect to what VRTX/JNJ are trying to do.