New drug class heralds emerging era of hepatitis C treatment

Two drugs currently awaiting regulatory approval could radically change the face of hepatitis C treatment.

Telaprevir and boceprevir target the NS3 protease of hepatitis C virus, which is essential for viral replication.
Telaprevir and boceprevir target the NS3 protease of hepatitis C virus, which is essential for viral replication.

Telaprevir and boceprevir are protease inhibitors – the first agents to directly target the hepatitis C virus (HCV). Added to the current standard of care, pegylated interferon (PEG-IFN) plus ribavirin (RBV), these drugs have the potential to boost cure rates and cut treatment time.

Hepatitis C can lead to cirrhosis and hepatocellular carcinoma, and is a major cause of liver transplantation.

Telaprevir and boceprevir have been granted accelerated assessment status by the EMA, meaning that they could be available to prescribe this year. They are both given as tablets or capsules.

Telaprevir, co-developed by Vertex and Tibotec, has been evaluated in three Phase 3 studies in patients with the most common form of the virus, HCV genotype 1:

  • ADVANCE showed that adding 8 or 12 weeks of telaprevir to PEG-IFN + RBV produced significantly higher rates of sustained virologic response in treatment-naïve patients than 48 weeks of PEG-IFN + RBV alone: 69% and 75%, respectively, versus 44% (p<0.0001 for both comparisons). 
  • REALIZE investigators reported similar findings in patients who had previously failed standard treatment. 
  • ILLUMINATE indicated that reducing the duration of PEG-IFN + RBV treatment from 48 to 24 weeks in treatment-naïve individuals who achieved a rapid viral response to 12 weeks of telaprevir-based treatment did not significantly affect response rates.

Boceprevir, from MSD, was tested in two pivotal trials. In both, adding 44 weeks of boceprevir to 48 weeks of PEG-IFN + RBV significantly increased sustained virologic response rates:

  • In the treatment-naïve setting (SPRINT-2), response rates for boceprevir compared with PEG-IFN + RBV alone were 68% versus 40% in non-black patients (p<0.0001) and 53% versus 23% in black patients (who typically show a poorer response to HCV treatment; p=0.004).
  • In patients who had previously relapsed or failed to respond to treatment (RESPOND-2), overall response rates were 67% with boceprevir versus 21% with PEG-IFN + RBV  alone (p<0.0001).

In both studies, rapid responders who discontinued all therapy at 28 weeks (treatment-naive) or 36 weeks (treatment-failed) had similar sustained response rates to those who were assigned to the fixed 44-week treatment period.

The two drugs are associated with similar adverse events, including fatigue, nausea, headache and anaemia.

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