Back HIV Treatment Experimental HIV Drugs Simeprevir for Hepatitis C Approved in Japan, Cobicistat Gets Nod in Europe

Simeprevir for Hepatitis C Approved in Japan, Cobicistat Gets Nod in Europe


The HCV protease inhibitor simeprevir (formerly TMC435) has been granted approval in Japan for the treatment of people with genotype 1 chronic hepatitis C, Medivir announced this week. In related news, Gilead Sciences said their new pharmacoenhancer cobicistat -- brand name Tybost -- has been approved as a stand-alone drug in the European Union for use as a booster for certain HIV protease inhibitors.


Simeprevir, being developed jointly by Medivir and Janssen, is the first of the next-generation HCV direct-acting antivirals (DAAs) to be approved. It is currently under review in the U.S. and Europe, along with Gilead's sofosbuvir (formerly GS-7977).

Recent studies have shown that simeprevir is highly effective both as an add-on to pegylated interferon + ribavirin and in all-oral, interferon-free regimens including simeprevir + sofosbuvir. Compared with the first-generation DAAs boceprevir (Victrelis) and telaprevir (Incivek or Incivo), simeprevir is well-tolerated and has minimal side effects.

The Japanese approval is for once-daily simeprevir taken with pegylated interferon/ribavirin for 12 weeks, followed by pegylated interferon/ribavirin alone for an additional 12 or 36 weeks.

"The approval in Japan is a very important step in providing patients with new treatment options," Medivir CEO Maris Hartmanis stated in a company press release."Japan is commercially a very exciting market with a huge unmet medical need among hepatitis C patients."

It is estimated that approximately 1.5 to 2 million people in Japan have chronic hepatitis C, with 70% having HCV genotype 1.

In the CONCERTO trials simeprevir + pegylated interferon/ribavirin produced a 12-week post treatment sustained virological response (SVR) rate of 89% for previously untreated genotype 1 patients, rising to 96% for prior interferon relapsers, according to the release.


Gilead announced this week that the European Commission has granted marketing approval for cobicistat, to be marketed under the brand name Tybost.

Cobicistat is a pharmacoenhancer, or "booster," that raises levels of other drugs metabolized by the CYP3A4 enzyme in the liver. It is a component of the Stribild (elvitegravir/cobicistat/tenofovir/emtricitabine) single-tablet regimen -- approved in the U.S. Food and Drug Administration (FDA) in August 2012 and in the EU this past May -- as a booster for the integrase inhibitor elvitegravir. The FDA, however, declined to approve cobicistat and elvitegravir as stand-alones due to "deficiencies in documentation and validation of certain quality testing procedures and methods," according to a May 2013 Gilead press release.

The European approval will allow cobicistat to be used to boost other drugs. Clinical trials have shown that cobicistat is as effective as ritonavir (Norvir) as a booster for the HIV protease inhibitors atazanavir (Reyataz) and darunavir (Prezista). Unlike ritonavir, however, it does not have anti-HIV activity of it's own. Studies to date have shown that cobicistat is generally safe and well-tolerated, though it alter raise kidney biomarkers.

"Gilead is pleased to offer HIV patients who rely on protease inhibitors a new boosting option to help facilitate once-daily dosing -- an important factor in supporting treatment adherence," Gilead Chief Scientific Officer Norbert Bischofberger said in a company press release.

At this time, "Tybost must not be used as a pharmacokinetic enhancer of any other HIV-1 protease inhibitor or any other antiretroviral medicinal product that requires boosting since dosing recommendations for such co-administration have not been established and may result in insufficient plasma level of the antiretroviral medicinal product(s) leading to loss of therapeutic effect and development of resistance," Gilead cautioned.



Medivir AB. Simeprevir Has Been Approved in Japan for the Treatment of Genotype 1 Chronic Hepatitis C Infection. Press release. September 27, 2013.

Gilead Sciences. European Commission Approves Gilead Sciences’ Tybost, a New Boosting Agent for HIV Therapy. Press release. September 25, 2013.