Sustained virologic response rates with telaprevir by response after 4 weeks of lead-in therapy in patients with prior treatment failure

Background & Aims: For hepatitis C virus (HCV)-infected patients who have not responded to previous PegIFN/ribavirin treatment, it is unclear whether subsequent direct-acting antiviral therapy outcomes are better predicted by prior treatment response or by on-treatment response to a PegIFN/ribavirin lead-in. Methods: In REALIZE, treatment-experienced patients randomized to the lead-in telaprevir arm received 4 weeks of PegIFN-α-2a (180 μg/week) and ribavirin (1000-1200 mg/day), then 12 weeks of telaprevir (750 mg every 8 h) plus PegIFN-α-2a/ribavirin, followed by 32 weeks of PegIFN-α-2a/ ribavirin. This subanalysis only included patients in the lead-in telaprevir arm with available week 4 on-treatment response data (n = 240). Results: After 4 weeks of PegIFN/ribavirin, 90% of relapsers, 60% of partial responders, and 41% of null responders in the lead-in telaprevir arm had ≥1 log₁₀ HCV RNA reduction. Sustained virologic response (SVR) rates for telaprevir-treated patients with ≥1 versus <1 log₁₀ HCV RNA reduction after the PegIFN/ribavirin lead-in were 94% versus 62% in relapsers, 59% versus 56% in partial responders and 54% versus 15% in null responders. Conclusions: In prior relapsers and partial responders there is no apparent benefit of assessing response after a PegIFN/ribavirin lead-in with the aim of guiding telaprevir-based treatment. For patients known to be prior null responders, on-treatment response after a 4-week PegIFN/ribavirin lead-in may provide clinically useful prognostic information. However, withholding telaprevir-containing therapy in uncategorised treatment-experienced patient populations (i.e., that could include prior relapsers or partial responders), using response after a PegIFN/ribavirin lead-in could potentially exclude some patients with a high chance of SVR.