Sanofi and Regeneron's would-be blockbuster clears FDA hurdle, but questions remain

A cholesterol-slashing treatment from Sanofi ($SNY) and Regeneron ($REGN) won over a key FDA panel, signaling a likely approval but leaving unclear just which patients should get the new medicine, believed to be a blockbuster in the making.

The agency's independent cardiovascular committee voted 13 to 3 that the antibody, alirocumab, had benefits that outweighed its safety risks, heralding the treatment's ability to drive down LDL--or bad--cholesterol in patients with few other options.

But the panelists expressed concerns about whether cutting LDL truly makes patients' lives better in the long term, warning the FDA that approving alirocumab could lead to widespread use of a treatment that isn't fully understood. Many backed the antibody's use in patients genetically predisposed to severely high LDL but hesitated to recommend it for larger populations. Only 7 of the experts were agreeable to approving the drug for patients who can't tolerate statins, setting up a potential regulatory road block that could come back to haunt the developers, who have a lot riding on the fate of this therapy. 

Despite their concerns, though, the question before the group was simply whether alirocumab should be approved for any population, and the majority bought into its potential. The FDA isn't required to follow the advice of its advisers, though it commonly does, and regulators are scheduled to make a final decision on alirocumab by July 24.

Sanofi's share shot up 6% on the positive vote, getting some much-needed support for the biggest new drug in its pipeline.

The treatment, to be sold as Praluent, is widely expected to win approval alongside a rival treatment from Amgen ($AMGN), which will be the topic at the same panel on Wednesday. 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.

Sanofi and Regeneron are seeking approval in patients with familial hypercholesterolemia, the aforementioned genetic disorder; patients whose LDL levels are insufficiently controlled by generic statins; and patients who can't handle statin therapy. Just how many of those groups will end up on alirocumab's label remains up to the FDA, and it's not impossible the agency will approve the PCSK9 antibodies for smaller populations and then hold out for long-term cardiovascular outcomes data, likely not available until 2017, before considering a wider nod.

One of the panel's biggest concerns focused on the threat to patients whose LDL levels drop too low. If it comes down to a head-to-head between Praluent and Repatha, that could play out in favor of Regeneron and Sanofi, as they plan to start patients on a 75-mg dose, where low LDL levels are likely to be of less concern, and then move up to 150 mg when necessary. Amgen, in contrast, plans to start patients on a 140-mg biweekly jab with a monthly 420-mg dose also available.

Payers are also expecting Regeneron and Sanofi to come out gunning for market share with a lower price for the low dose as they angle for a first-mover advantage that may give them a better position to work deals with payers who cover big patient populations.

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

John Carroll contributed to this report.

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