The US Food and Drug Administration (FDA) recently granted priority review for sofosbuvir, a daily oral nucleotide analogue inhibitor, for the treatment of hepatitis C viral (HCV) infection. Sofosbuvir is a small molecule compound that blocks HCV’s ability to replicate. It is developed and manufactured by Gilead Sciences Inc., which filed a New Drug Application with the FDA on April 8, 2013. Priority review is given by the FDA to drugs that potentially offer significant advantages over existing treatments.
Gilead is one of several companies investigating alternatives to the existing standard of treatment for HCV--weekly injections of pegylated interferon (peg-IFN) and a daily ribavirin (RBV) oral pill. This regimen is not ideal, as 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. Pharmaceutical companies are experimenting with interferon-free regimens to eliminate some of the challenging side effects.
The application was submitted for approval of sofosbuvir and RBV as an oral therapy for people with genotypes 2 and 3 HCV. It was also submitted for use in treatment-naïve (previously untreated) patients with genotypes 1, 4, 5 and 6 HCV when used in combination with RBV and peg-IFN.
The priority review is based in part on the sofosbuvir trial POSITRON, which included 207 HCV patients. POSITRON showed promising response rates after three months of combination therapy of sofosbuvir/RBV. Positive response rates were 93% in patients with genotype 2 and 61% in those with genotype 3.
“The new sofosbuvir therapy offers a much-needed alternative to standard therapy with interferon, which can cause significant side effects for hepatitis C patients,” said Ira Jacobson, MD, chief of the Division of Gastroenterology and Hepatology and Vincent Astor Distinguished Professor of Medicine at Weill Cornell Medical College in New York. “We have dreamed for years of being able to eliminate interferon from our hepatitis C regimens and this study is one of several that are finally bringing us very close to realizing that goal.”
Another trial, called FUSION, tested the effectiveness of sofosbuvir plus RBV in HCV patients who did not respond to interferon. Patients were evaluated at 12 and 16 weeks of therapy. Investigators, led by David R. Nelson, MD, from the University of Florida at Gainesville, found that the longer the patients took the sofosbuvir combination, the higher their cure rate.
“Given the absence to date of alternative therapies for patients with genotype 2 or 3 who have failed interferon therapy or for whom it is not an option, treatment with the new sofosbuvir regimen offers a vast improvement,” reported Nelson. “But the optimal duration of treatment for genotype 3 patients, in order to maximize their chance of cure, remains undefined. It could be longer than 16 weeks.”
Source: Medical News Today, June 9, 2013