Shares in Regeneron Pharmaceuticals took a downward tumble in after-hours trading last night (Tuesday) after it emerged that a panel of FDA advisors had failed to back its drug Arcalyst for gout.

The US Food and Drug Administration's advisory panel voted unanimously (11-0) against recommending Arcalyst (rilonacept) for the prevention of gout flare-ups when patients start uric acid-lowering therapy, on concerns over a lack of data to support its use in this setting.

Arcalyst was first approved in 2008 to treat a rare genetic disorder called Cryopyrin-Associated Periodic Syndromes, and Regeneron is seeking to expand the scope of its use with a gout indication.

However, things were already looking bleak last week after a report posted on the FDA's website ahead of the advisory panel meeting highlighted Arcalyst's potential to boost the risk of infections and malignancies, and questioned whether data from the 16-week trial submitted in the application was sufficient to determine safety.

The company only studied the drug for 16 weeks because that is the expected treatment duration for Arcalyst in the gout prevention setting, but the FDA's advisors said they would like to see a longer stretch of data to rule out any risk of cancer. 

“There is a role for this drug or this type of drug...I just don’t think we have the data yet,” Lenore Buckley, the chairwoman of the panel and a professor of internal medicine and pediatrics at Virginia Commonwealth University School of Medicine in Richmond, said following the vote, according to Bloomberg.

The FDA now has until July 30 to make its decision.

Eylea co-promotion agreement

Meantime, Regeneron and partner Bayer have linked up with Santen Pharmaceutical Co to co-promote Eylea (aflibercept) in Japan for the treatment of neovascular age-related macular degeneration (wet AMD).

The German firm's Japanese subsidiary, Bayer Yakuhin, filed for approval in that country last year. Sebastian Guth, chief executive of Bayer Yakuhin, said "we expect that the combined resources of the two companies will allow Eylea to achieve a broader and faster reach into the Japanese ophthalmology community".