FDA says Sanofi and Regeneron's cardio contender looks approvable. But for whom?

A potential blockbuster from Sanofi ($SNY) and Regeneron ($REGN) has proven its ability to slash rates of cholesterol, the FDA said, but questions remain regarding just how widely the treatment should be used.

In documents released ahead of a key panel meeting slated for next week, regulators noted that the antibody, alirocumab, met its goals across 10 Phase III trials, cutting LDL, or bad, cholesterol in patients with dangerously high rates of the waxy buildup. And the injection was generally well-tolerated, FDA staff pointed out, charting a safety profile in line with placebo.

Now the question facing the agency's independent advisors centers on which patient populations should get alirocumab. The antibody is widely expected to win approval alongside a rival treatment from Amgen ($AMGN), and analysts expect each to bring in as much as $3 billion a year at its peak. But the ultimate impact of the antibodies, which target a protein called PCSK9, will depend on their final labels and how well they perform in long-term outcomes studies currently underway.

On Tuesday, the FDA's Endocrinologic and Metabolic Drugs Advisory Committee will review Sanofi and Regeneron's data, voting whether to recommend the alirocumab for approval. The agency is not required to follow the recommendations of its committees, though it most commonly does, and the FDA has promised to hand down a final decision on alirocumab by July 24. Amgen's antibody, evolocumab, will go before the same committee on Wednesday, and the agency plans to weigh in on it by Aug. 27.

For alirocumab, Sanofi and Regeneron are seeking approval in patients with a genetic disorder that predisposes them to high cholesterol, those whose LDL levels are insufficiently controlled by generic statins and patients who can't handle statin therapy. But that latter population is murky at best, FDA staff said, pointing to a data suggesting "statin-intolerance" is quite often just a stubborn aversion on behalf of patients and warning that including it in alirocumab's label "could promote a condition that is not well-understood and encourage some patients to prematurely abandon statins."

But, looking at the data as a whole, FDA reviewers had little negative to say about the injection. Alirocumab significantly beat out placebo and Merck's ($MRK) Zetia at lowering LDL cholesterol, which the FDA accepts as a surrogate endpoint for improving patients' lives. The aforementioned outcomes studies will determine alirocumab's actual effect on rates of heart failure and stroke when data are available in 2017, but the agency has no plans on holding off approval until then.

On the safety side, the most common problems were injection site reactions, the agency said. And, addressing a lingering concern for all PCSK9 therapies, alirocumab didn't significantly increase the rate of neurocognitive issues, or "fuzzy thinking," compared to placebo and Zetia.

In the meantime, the two leading PCSK9 factions are preparing for a near-term fight to differentiate themselves as they march toward the market. Express Scripts ($ESRX), the pharmacy benefit manager that successfully spurred a price war among competing hepatitis C therapies last year, has identified PCSK9 blockers as its next target, figuring it can squeeze some savings by pitting fairly comparable drugs against one another. None of the companies has explicitly discussed expected pricing for the injected therapies, but it's sure to be contentious topic later this summer.

- read the briefing (PDF)

Special Report: Tomorrow's cardio blockbusters: Inside 'the next big leap' in controlling cholesterol

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