(Reuters) - Gilead Sciences Inc said its experimental hepatitis C drug sofosbuvir, in a late-stage clinical study, was clearly superior to historical cure rates at both 12 and 16 weeks of treatment in patients who were not helped by prior therapy.
The cure rate for those with genotype 2 and 3 of the serious liver disease was significantly higher for patients who received 16 weeks of treatment: 73 percent versus 50 percent for those treated for 12 weeks, according to study results released on Tuesday.
Both rates were far higher than the comparable 25 percent historic cure rate - or sustained virologic response (SVR) - for these types of patients.
"Fusion is the fourth Phase III trial of sofosbuvir that has met its primary endpoint with no significant adverse events," Sanford Bernstein analyst Geoffrey Porges said in a research note.
"We believe these results represent the final piece of de-risking for the asset, and approval is as close to certainty as it can be," he added.
In the latest trial, genotype 2 patients fared better than those with genotype 3, which is more difficult to treat. Rates of SVR, which is considered tantamount to a cure, were also lower in patients suffering from cirrhosis, typically among the sickest of hepatitis patients.
The study tested sofosbuvir in combination with the older oral hepatitis treatment ribavirin in patients who did not respond to prior treatments with ribavirin and injectable interferon.
No patients in the study discontinued treatment due to adverse side effects.
Fatigue, headache, insomnia and nausea were the most common adverse effects, reported in less than 15 percent of patients, Gilead said.
"With positive results from all four Phase 3 trials now in hand, Gilead is on track to meet its goal of filing regulatory applications in the United States and Europe in the second quarter," Gilead Chief Scientific Officer Norbert Bischofberger said in a statement.
Earlier this month, Gilead said the drug combination also achieved the main goals set in two other late-stage trials of patients who had not received prior treatment.
Sofosbuvir also showed promise in a late-stage study called Positron in patients who were unable or unwilling to take interferon, a standard hepatitis C drug known for its unpleasant side effects that lead many patients to delay or discontinue treatment.
With analysts estimating a multibillion-dollar annual market, new interferon-free treatment options for hepatitis C are among the hottest areas of pharmaceutical research.
Several other companies, including Abbvie Inc, Bristol-Myers Squibb Co and Vertex Pharmaceuticals Inc, are developing interferon-free treatment combinations for hepatitis C, with most focusing on by far the most common strain of the virus, genotype 1.
ISI Group analyst Mark Schoenebaum said Gilead needs to find ways to improve cure rates in Genotype 3 patients, possibly by combining sofosbuvir with other experimental drugs in its pipeline.
"Competition in the Genotype 2/3 space is sparse, so even with these data, Gilead probably has many years to optimize before they will face a serious threat," he said.
The SVR rates for genotype 3 was 30 percent with 12 weeks of treatment and 62 percent after 16 weeks of therapy. That compared with SVR rates of 86 percent and 94 percent for genotype 2.
Gilead said it will present full data from the four Phase III studies at a future scientific conference.
Shares of the company were up 70 cents, or 1.7 percent, at $42.30 in midday trading on the Nasdaq on Tuesday.
(Reporting by Bill Berkrot in New York and Pallavi Ail in Bangalore; Editing by Supriya Kurane and John Wallace)
Gilead ’s Sofosbuvir for Hepatitis C Meets Primary Endpoint in Fourth Pivotal Phase 3 Study
-- Initial Regulatory Filings Planned for Q2 2013 --
“This study demonstrates that all-oral therapy with sofosbuvir provides significant efficacy among difficult-to-treat hepatitis C patients who could not be cured by prior regimens containing pegylated interferon and now have limited treatment options,” said
In the FUSION study, HCV genotype 2 or 3 patients who failed prior interferon-based therapy were randomized (1:1) to receive either a 12-week (n=103) or 16-week (n=98) course of sofosbuvir 400 mg once daily plus RBV (1,000 or 1,200 mg/day). Sixty-three percent of patients were infected with genotype 3. In the 12-week arm, SVR12 rates were 86 percent among genotype 2 and 30 percent among genotype 3 patients. In the 16-week arm, SVR12 rates were 94 percent among genotype 2 and 62 percent among genotype 3 patients. Among the 34 percent of FUSION participants who had compensated cirrhosis at baseline, 31 percent achieved SVR12 in the 12-week arm, and 66 percent achieved SVR12 in the 16-week arm. All patients in the study became HCV negative on treatment, and relapse accounted for all virologic failures.
No patients discontinued sofosbuvir or RBV due to adverse events. The most common adverse events reported in ≥15 percent of patients in the study were fatigue, headache, insomnia and nausea.
Results from all four pivotal Phase 3 studies of sofosbuvir – FUSION, POSITRON, FISSION and NEUTRINO – will support the initial regulatory filing for sofosbuvir as part of all-oral therapy with RBV among genotype 2 and 3 treatment-naïve, treatment-experienced and interferon-intolerant HCV patients, and for sofosbuvir in combination with RBV and pegylated interferon among treatment-naïve patients with genotypes 1, 4, 5 and 6.
Full results from these studies will be presented at a future scientific conference. Additional information about these and other ongoing clinical studies of sofosbuvir can be found at www.clinicaltrials.gov. Sofosbuvir is an investigational product and its safety and efficacy have not yet been established.
This press release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to risks, uncertainties and other factors, including the possibility that the proportion of patients who maintain a sustained virologic response with longer follow up will not be as favorable as the sustained virologic response rates reported in this press release, and the possibility of unfavorable results from other clinical trials involving sofosbuvir. As a result, sofosbuvir may never be successfully commercialized. In addition, Gilead may make a strategic decision to discontinue development of the compound if, for example, Gilead believes commercialization will be difficult relative to other opportunities in its pipeline. Further, Gilead may be unable to file for regulatory approval of sofosbuvir in the currently anticipated timelines or at all. If marketing approval is granted for this product, there may be significant limitations on its use.
These risks, uncertainties and other factors could cause actual results to differ materially from those referred to in the forward-looking statements. The reader is cautioned not to rely on these forward-looking statements. These and other risks are described in detail in Gilead’s Quarterly Report on Form 10-Q for the quarter ended
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