Data show Gilead's sofosbuvir has 'clean' safety profile

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The safety profile of Gilead's hep. C drug sofosbuvir appears to be clean. Physicians and analysts flagged that as a key takeaway from clinical trial data involving a couple of sofosbuvir-based therapies. The data release came ahead of a European medical meeting, where discussions are sure to focus on drug makers' ongoing effort to replace injectable therapies with oral drugs in the treatment of liver disease.

The Phase III findings appeared in the New England Journal of Medicine on the eve of the EASL (European Association for the Study of Liver) confab in Amsterdam, which kicks off today. In four clinical trials involving nearly 1,000 patients, sofosbuvir was found to be superior or non-inferior to currently available treatment options. SVR12 rates (sustained viral response 12 weeks after completing therapy) ranged from 50-90%. Once patients achieve SVR12, they are considered cured.

Moreover, only a small percentage of patients discontinued due to adverse events or were found to experience serious side effects. One of the regimens that paired the experimental pill with peginterferon and ribavirin showed it to be on par with the older treatments from a safety perspective.

While other drug makers have stumbled, these results should support Gilead's bid to get its drug approved for treating chronic hepatitis C virus (HCV). The Foster City, CA, company submitted sofosbuvir to FDA on April 8 and plans to file it in Europe later this year.

"While overall there were no big surprises in the new abstracts or press release updates, we believe an important takeaway is the clean safety profile of sofosbuvir (SOF) shown in the full publications," wrote Leerink Swann's Howard Liang, PhD, in a note yesterday.

The clean safety profile seen thus far, combined with efficacy in a variety of patient types, also meant that sofosbuvir remained the frontrunner in the biotech race to bring a strictly oral-based HCV regimen to market. “Nothing in the abstracts/articles should change the market's view that Gilead should be on track to launch its new Hep C drugs around the end of 2014," ISI Group analyst Mark Schoenebaum wrote in an investor note yesterday. "Gilead's initial hepatitis C launch will include an ‘all oral' regimen for patients with genotype 2/3 (around 30% of the US market)…GILD should be ready to launch an all oral genotype 1 regime around the end of 2014.”

KOLs extolled the drug, as well. In an editorial on, “No More Room for Interferonolgists?” author Joost Drenth, MD, PhD, wrote, “The low incidence of side effects, the relatively short duration of treatment and the pangenotypic properties of the drug are strong selling points of a sofosbuvir-ribavirin treatment and will probably lower the threshold for HCV for both patients and physicians.”

Gilead's therapy was successful in "reducing the need for interferon injections to 12 weeks, or eliminating interferon completely from the regimen," added Eric Lawitz, MD, a liver expert at the University of Texas Health Science Center.

The old paradigm for treating the disease centered on protease inhibitors paired with peginterferon and ribavirin. This form of treatment was suitable for only one of 11 possible genotypes and left some patients without options. New treatments, like the one Gilead is pursuing, are showing high SVR12 rates in up to six genotypes. They also offer the advantage of a treatment without peginteferon, which causes flu-like symptoms and is given intravenously.

Even if Gilead receives the FDA go-ahead for sofosbuvir before rivals, analysts say, it may not be alone in the market for long. Abbott's newly spun-off pharma arm AbbVie also released data on a oral five-drug combination yesterday, which cured 88% of patients within eight weeks.

And Bristol-Myers Squibb released data from a mid-stage clinical trial. Its three-drug combo achieved cure rates up to 94% when administered for 12 to 24 weeks. The BMS combo hep. C treatment achieves those rates without ribavirin. Ribavirin has been linked to hemolytic anemia which can worsen cardiac disease, lead to fatal myocardial infarctions and prohibits patients with a history of unstable cardiac disease from using it.

The BMS findings, while mostly positive, also showed two cases of the virus returning in patients, a hiccup not heard from Gilead's findings, RBC Capital Markets Micahel Yee pointed out, as reported by FierceBiotech.

Merck and BMS also announced yesterday a joint effort to conduct Phase II trials for the combined use of daclatasvir and protease inhibitor MK-5172 for use in patients with hep. C genotype 1.

If the competition among oral therapies comes down to which is the most convenient for patients to take, AbbVie's five-drug combo would appear to be at a disadvantage relative to other treatment options offering a cure with fewer pills. In addition, Merck and BMS have only announced plans for testing therapy on genotype 1 patients, while other firms are promising coverage for more patient types.

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