UPDATED: Zepatier beats Harvoni, Sovaldi in hep C clinical-data safety showdown: Advera Health Analytics

It's still early days for Merck's ($MRK) hep C combo Zepatier, but the drug could be a frontrunner in terms of safety. In a new data analysis, Zepatier turned up proportionally fewer serious side effects than Gilead Sciences' ($GILD) hep C combo treatment Harvoni and its veteran hep C med Sovaldi.

Healthcare informatics firm Advera Health Analytics looked at clinical trial data for the three drugs and found that while Harvoni and Sovaldi's labels have worrisome side effects such as cardiac arrest and suicidal ideation, Zepatier does not have the same side effects listed. Zepatier is less risky than Sovaldi, according to Advera's report, but the drug's safety is on par with Harvoni, Advera said.

Zepatier and Harvoni worked almost equally well in treating individuals in clinical trials who had already undergone treatment. Harvoni was more effective than Zepatier and Sovaldi in patients who hadn't been treated previously, though, according to the report.

"Our clinical development program for Zepatier is among the largest and most comprehensive for chronic HCV treatment. It included studies dedicated to patient populations where significant unmet medical need still exists, such as prior treatment failures, as well as those living with co-morbid conditions, including HIV infection and advanced chronic kidney disease," Merck spokeswoman Sarra Herzog told FiercePharma in an email. "We believe our clinical data and FDA-approved prescribing information demonstrate the value of Zepatier."

Sovaldi turned up the most serious side effects of the three drugs. Advera flagged a few side effects that the FDA might require to be on the drug's label in the future, including progressive multifocal leukoencephalopathy, a rare brain infection; Stevens-Johnson syndrome, a rare but serious skin disorder that exhibits through flu-like symptoms; and drug-induced liver injury.

"The general conclusion is that Zepatier looks safer than Sovaldi, just based on clinical trial information," Advera Chief Product Officer Bob Kyle told FiercePharma. But "anything can change once the real world data starts to come through," Kyle said. "It's something to keep an eye on in post-marketing data."

Gilead is singing a different tune. The company took issue with Advera's report, saying that the analysis was "deeply flawed for a number of reasons," spokeswoman Cara Miller said in an email to FiercePharma. The analysis is not based on head-to-head data comparing Zepatier, Sovaldi and Harvoni, Miller said. Plus, the report compares Zepatier's label at the time of launch with those for Harvoni and Sovaldi, which have been on the market longer.

And "no consideration was given" for the underlying condition of patients taking Harvoni and Sovaldi, or for drugs given with Sovaldi that carry their own serious side effects, Miller said. "Patient safety is of the utmost importance to Gilead. The company monitors the safety of all its medications, reports adverse events in a timely manner and is compliant with FDA and other Health Authority safety reporting requirements."

Still, the report is music to Merck's ears as it competes in the contentious hep C sphere. The New Jersey pharma titan won FDA approval for Zepatier back in January, and quickly set the drug's list price at $54,600 for a 12-week regimen--far lower than its hep C peers. Harvoni runs at about $94,600 and AbbVie's ($ABBV) Viekira Pak has an $83,319 list price. None of these prices accounts for discounts or rebates offered to payers.

Merck's price-setting move did not escape the attention of leading PBM Express Scripts ($ESRX), which set off a pricing war last year after selecting AbbVie's Viekira Pak as its preferred hep C treatment. Steve Miller, Express Scripts' CMO, recently said that he "can't say enough good things" about Merck's approach to hep C pricing. The tactic "sends a very loud message to the marketplace," Miller said, one that competitors might not be able to ignore.

- here's a link to the report

Special Reports: The new drug approvals of 2014 - Harvoni - Viekira Pak |The new drug approvals of 2013 - Sovaldi - Gilead

Editor's note: This article was updated with a statement from Gilead Sciences.

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