Prior partial responders ( N = 152 ) were randomized to 24 weeks of twice-daily danoprevir/r 100/100mg , mericitabine 1000 mg and ribavirin 1000/1200 mg ( IFN-free ) ; danoprevir/r plus PegIFN alfa-2a / ribavirin ( triple ) ; or danoprevir/r , mericitabine and PegIFN alfa-2a / ribavirin ( Quad ) .