New & experimental HIV treatments

Hepatitis C protease inhibitor does well in early clinical trial

Michael Carter
Estimated reading time 2 minutes
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A hepatitis C virus protease inhibitor has done well in early clinical trials. The oral drug, VX-950, which is being developed by Vertex Pharmaceuticals, achieved significant reductions in hepatitis C viral load when used in combination with pegylated interferon alfa-2a (Pegasys).

Current treatment for hepatitis C virus involves weekly injections with pegylated interferon and daily doses of ribavirin. This treatment is not universally effective and has unpleasant, often intolerable side-effects. Coinfection with hepatitis C is common amongst HIV-positive individuals and the current standard of treatment is less effective in coinfected individuals than in patients who are only infected with hepatitis C.

In the phase Ib study, the combination of VX-950 and Pegasys produced a significant reduction in hepatitis C viral load in the first two days of treatment, and by day 14, 50% of patients provided with the investigational therapy had an undetectable hepatitis C viral load (below 10 copies IU/ml).

Glossary

investigational

In medicine, a drug that is approved by the regulatory authorities (Food and Drug Administration, European Medicines Agency) for testing in clinical trials, but not yet approved for commercial marketing and sale. Also called experimental drug, investigational agent, and investigational new drug (IND).

pegylated interferon

Pegylated interferon, also known as peginterferon, is a chemically modified form of the standard interferon, sometimes used to treat hepatitis B and C. The difference between interferon and peginterferon is the PEG, which stands for a molecule called polyethylene glycol. The PEG does nothing to fight the virus. But by attaching it to the interferon (which does fight the virus), the interferon will stay in the blood much longer. 

placebo

A pill or liquid which looks and tastes exactly like a real drug, but contains no active substance.

monotherapy

Taking a drug on its own, rather than in combination with other drugs.

blinding

When a clinical trial is blinded, the participants are unaware as to whether they are receiving the experimental drug or a placebo (or another drug). Double blinding refers to the participant, their doctor and researchers running the trial not knowing which treatment is received by each group until all data have been recorded. Blinding is done to reduce bias in clinical trials.

The 14-day randomised, blinded, placebo-controlled trial involved 20 individuals with hepatitis C virus genotype 1. This is the commonest and hardest to treat of the hepatitis C genotypes. Patients were randomised to receive VX-950 at a dose of 750mg every eight hours in combination with Pegasys, the same dose of VX-950 alone, or Pegasys alone. On entry to the study, patients had a median hepatitis C viral load of over four million copies IU/ml.

Analysis of preliminary results showed that individuals taking the investigational protease inhibitor with Pegasys had a median fall of 5.5 log10 in their viral load, compared to a median fall of 4 log10 in patients taking VX-950 alone and 1 log10 in individuals randomised to take Pegasys monotherapy.

No serious side-effects were reported and patients taking VX-950 reported only mild adverse events.

Vertex have announced plans for larger phase II clinical trials which will investigate the safety and effectiveness of VX-950 in combination with both Pegasys and ribavirin. The trial will start in the next few months and involve 200 patients.

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New & experimental HIV treatments
Hepatitis & HIV
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