New Drugs for Hepatitis C

Today's excellent medical news, via Nature:

A new generation of drugs with the potential to cure hepatitis C is set to flood the market. . . .

The virus infects liver cells and can cause cirrhosis and liver cancer. It affects about 3% of the world's population — and new treatments are urgently needed.

Currently, patients spend about a year taking a combination of interferon-α, a protein that boosts the immune system, and ribavirin, an antiviral drug that does not specifically target HCV. Roughly half of all patients with hepatitis C are cured by this course, but it can also cause serious side effects, such as depression, anaemia, and flu-like illness.

Enter Vertex's drug telaprevir and Merck's boceprevir. Both block HCV's protease enzyme so that it cannot carry out one of its key tasks. All of HCV's proteins are initially produced as one long polyprotein, which needs to be cleaved into its component proteins by the protease. Blocking the protease prevents the virus from producing functional proteins.

The companies will submit their medicines to the US Food and Drug Administration by the end of this year, with an eye towards approval in mid-2011.

Data released this month fulfil the pharmaceutical industry's high expectations for the effectiveness of these drugs. Boceprevir, combined with interferon-α and ribavirin, cured the infections of about two-thirds of the patients who followed a 48-week course, Merck announced on 4 August. Some patients were able to finish the course even sooner, at 28 or 36 weeks.

Telaprevir, also combined with the standard drugs, cured 72% of patients after just 24 weeks of treatment, Vertex said on 10 August. Patients who responded quickly to the drug, within 4 to 12 weeks, were the most likely to be cured by it. Another phase III trial of telaprevir, the results for which Vertex released in May, had already demonstrated the benefits of the 24-week course, but the latest study confirmed that it was just as effective as a 48-week regimen for most patients.

Hepatitis C is a major problem in China, and many of the children available for adoption as "special needs" children are infected.