Simeprevir
In November, the US Food and Drug Administration (FDA) approved simeprevir, a new oral drug, to treat the hepatitis C virus (HCV). Olysio™, manufactured by Johnson & Johnson, is a protease inhibitor that halts the progression of HCV, preventing it from reproducing. The drug is used in combination with weekly injections of pegylated interferon (peg-IFN) and a daily ribavirin (RBV) oral pill.
In May 2011, the FDA approved the first protease inhibitors, Merck's boceprevir (brand name Victrelis™) and Vertex Pharmaceutical's telaprevir (brand name Incivek™). At the time, these two drugs represented the first new HCV therapies in 10 years.
In clinical trials, Olysio was evaluated in combination with peg-IFN and RBV. The therapy is intended for adults with compensated liver disease (diseased liver that is still functioning), including cirrhosis, who have not received treatment for their infection (treatment naïve) or for whom previous treatment has not been effective (treatment experienced).
The 2,026 patients enrolled in the five clinical trials were treated for 24 weeks. The results showed that 80% of the treatment-naïve patients who were given Olysio plus peg-IFN/RBV demonstrated sustained viral response (SVR), meaning they no longer had detectable virus in their blood. Of the treatment-experienced patients on the same regimen, 79% achieved SVR. In contrast, only 37% of the remaining group, those on peg-IFN/RBVonly, displayed SVR.
The most severe side effects from the combination of Olysio and peg-IFN/RBV were itching, nausea and a severe photosensitivity rash. Olysio will have a warning on its label about the danger of sun exposure while on the drug.
Several pharmaceutical companies are pursuing alternatives to the existing standard of treatment for HCV, the combination peg-IFN/RBV, because nearly 50% of patients do not respond to it. In addition, those who do respond often experience debilitating side effects that can last the duration of the treatment—either 24 or 48 weeks. Interferon-free regimens should eliminate some of the most severe side effects.
"Olysio is the third FDA-approved protease inhibitor to treat chronic hepatitis C virus infection, and provides health professionals and patients with a new, effective treatment for this serious disease," said Edward Cox, director of the Office of Antimicrobial Products in the FDA's Center for Drug Evaluation and Research.
Sofosbuvir
The FDA is scheduled to decide by December 8, 2013, whether to approve sofosbuvir, an investigational HCV therapy manufactured by Gilead Sciences, Inc. Sofosbuvir is a daily oral nucleotide analogue inhibitor composed of a small molecule compound that blocks HCV's ability to replicate.
If approved, sofosbuvir, taken in combination with RBV, would be the first all-oral treatment for two forms of HCV, genotypes 2 and 3, representing as many as 25% of HCV patients. HCV has six genotypes. In the US, patients with genotype 1 account for about 70% of those with HCV.
In the spring of 2013, the FDA granted priority review for sofosbuvir. Priority review is to drugs that potentially offer significant advantages over existing treatments. The drug is expected to be approved by the FDA next month.
Sources: Bloomberg News, November 23, 2013; FDA news release, November 22, 2013
