Therapies that target the hepatitis C virus (HCV) are predicted to generate a multi-billion-dollar market in the next few years. And drug firms are rushing to stock their pipelines with potential treatments. On 7 January, Bristol-Myers Squibb of New York said that it would spend US$2.5 billion to acquire Inhibitex of Alpharetta, Georgia, with the main focus being Inhibitex’s INX-189 a potential hepatitis C treatment that is now in phase II clinical trials.
INX-189 is a nucleoside polymerase inhibitor, meaning that it prevents HCV from copying its genome. In November of last year, Gilead Sciences in Foster City, California, splashed out $11 billion on biotech firm Pharmasset, of Princeton, New Jersey. Pharmasset has three treatments for hepatitis C in clinical trials — including some nucleoside polymerase inhibitors.
All told, there are perhaps 60 compounds in preclinical and clinical development against HCV, using a variety of methods to disrupt the virus’s biology. Two drugs approved by the US Food and Drug Administration last year — boceprevir, made by Merck of Rahway, New Jersey, and telaprevir, made by Vertex Pharmaceuticals in Cambridge, Massachusetts — target an HCV protein called the NS3 protease, which is crucial for proper processing of the virus’s proteins.
Both Gilead and Bristol-Myers Squibb also have runners in the NS3 race, and additionally are developing treatments that disrupt an HCV protein called NS5A, essential for the assembly of infectious viral particles and the amplification of viral RNA. Other drugs block the virus’s entry into human cells.
Not all of these drugs can be winners. But the virus, which infects liver cells and can cause cirrhosis and liver cancer, affects around 3% of the world’s population. So there’s plenty of scope for new targeted treatments, which might be more effective and cause fewer side effects than the course of generic antivirals and immune-boosting interferon proteins now used. For more on HCV treatments, see Nature‘s article ‘New drug targets raise hopes for hepatitis C cure‘ and the more detailed (but not free) pipeline update in Nature Reviews Drug Discovery from last February.