Hepatitis C, an infection of the liver, is caused by the deadly hepatitis C virus. This contagious liver disease can be either acute or chronic. Currently there is no vaccine to prevent hepatitis C. But there are approved anti-viral medications to treat hepatitis C.
The current standard treatment is a combination of pegylated interferon-alpha-2a or pegylated interferon-alpha-2b (brand names: Pegasys or PEG-Intron) given as a shot and antiviral drug ribavirin ( brand names: Copegus, Rebetol, Ribasphere, Vilona and Virazole) given in pill form, for a period of 24 or 48 weeks, depending on the hepatitis C virus genotype.
Peg-Intron/Rebetrol manufactured by Schering-Plough Corp, which is wholly-owned by Merck & Co. Inc. (MRK) , and Pegasys/Copegus of Swiss pharmaceutical giant Roche Holding AG are the leading hepatitis C therapies in the U.S. In 2010, Peg-Intron generated global sales of $737 million while Pegasys booked sales of 1.6 billion Swiss francs.
According to the Centers for Disease Control and Prevention, an estimated 3.2 million persons in the United States have chronic Hepatitis C virus infection. Hepatitis C is a silent killer as it produces no symptoms for decades. Three out of four people with hepatitis C currently remain
undiagnosed and unaware of their infection.
The number of new HCV cases in the U.S. has significantly declined over the years, thanks to safer needle practices and improved blood-donor screening. But that said, a substantial disease burden is present among the baby boomers as those already infected with HCV begin to experience disease progression. Baby boomers are said to account for two out of every three cases of chronic HCV infection in the United States.
A patient's response to hepatitis C treatment is assessed by measuring the amount of hepatitis C virus in a person's blood (also called HCV RNA or viral load) at specific times before, during and after treatment. If the HCV RNA is not detected six months even after treatment ends, then that patient is said to have achieved an SVR ( sustained virological response) or viral cure.
The current available combination therapy (pegylated interferon plus ribavirin) for hepatitis C, which works by increasing body's immune response against the virus, is lengthy and is effective in only less than half of those who are treated. The available treatment for hepatitis C is also associated with some serious side effects, including flulike symptoms and anemia. The search for new hepatitis C drugs with higher success rates sans the awful side effects has spurred a revolution in the HCV treatment.
Two new investigational drugs - Merck's Boceprevir with a proposed brand name of Victrelis and Vertex Pharmaceuticals Inc.'s (VRTX) Telaprevir with a brand name of Incivek, that could fortify the current two-drug treatment and bring about a paradigm shift in HCV therapy offer a new hope for this silent epidemic.
Both the drugs, administered orally, work by blocking protease, an enzyme needed by the hepatitis C virus to replicate itself. Having cleared the Advisory Committee review - the penultimate hurdle on the road to the U.S. pharmacy shelves, Victrelis and Telaprevir now await the FDA's final decision.
In clinical studies, it has been found that the addition of Victrelis to the current two-drug cocktail (PEGINTRON and ribavirin) in a 48-week regimen achieved an SVR or viral cure rate of 66 percent compared to 21 percent for control.
On April 27, 2011, the Antiviral Drugs Advisory Committee of the FDA voted unanimously recommending approval of Merck's Victrelis for the treatment of patients with chronic hepatitis C virus genotype 1 infection in combination with current standard therapy. The final decision of the regulatory agency on Victrelis is expected by mid-May.
The cure rate achieved by adding Telaprevir to the current standard therapy was as high as 79 percent in one of the studies compared to 46 percent for control.
On April 28, 2011, Telaprevir was recommended for approval by the Antiviral Drugs Advisory Committee of the FDA for people with genotype 1 chronic hepatitis C in combination with pegylated-interferon and ribavirin. The regulatory agency is expected to make a decision on the approval of Telaprevir by May 23, 2011.
Cowen & Co analyst Phil Nadeau sees potential for Telaprevir to generate peak annual U.S. sales of around $3 billion and another $1 billion oversees. If approved, the potential sales of Victrelis could be $604 million in 2013, according to some analysts.
Victrelis and Telaprevir are also under review by the European Medicines Agency.
The drawbacks associated with the two investigational drugs are the complex dosing schedule in which the duration of the treatment depends upon the response of the patients to the drugs and the unpleasant side effects. Rash and anemia occurred more frequently among those treated with Telaprevir-based combination therapy compared with those who received pegylated-interferon and ribavirin alone. Victrelis is associated with adverse hematologic effects, primarily anemia.
Having got "thumbs up" from the FDA panel, the two next generation drugs - Victrelis and Telaprevir, now have just one more hurdle to cross in their journey from laboratory to medicine cabinet. Will the drugs pass the regulatory muster? Stay tuned...
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