By Randall Osborne
West Coast Editor
Like one half of a closely fought Super Bowl fight, Transkaryotic Therapies Inc. (TKT) lost yardage in its contest to get its treatment approved by the FDA for Fabry disease - a week after the other "team" in the battle, Genzyme General, was dealt a "penalty" by the agency.
The FDA is asking for more information before it will give the nod to Cambridge, Mass.-based TKT's biologics license application (BLA) for the enzyme replacement therapy Replagal (agalsidase alfa).
In a news release, TKT said the FDA "has asked for further explanation in several areas and requested additional data." Neither the nature of the information sought nor the time likely required to assemble it will be disclosed, Justine Koenigsberg, manager of corporate communications for TKT, told BioWorld Today.
"We've initiated collection of the data, and we'll have further discussion with the FDA," she said, declining further comment.
Last week, the FDA told Genzyme General, also of Cambridge, that its BLA for Fabrazyme (agalsidase beta) also is not approvable without more data. Genzyme would not be more specific, either, but said it already has gathered most of the data sought. (See BioWorld Today, Dec. 28, 2000.)
Both products have been granted orphan drug status, which normally guarantees seven years of market exclusivity. Because the two BLAs were filed at almost the same time, the agency could either make a judgment regarding which of the drugs is better and decide in its favor, or - if the regulations can be interpreted to allow it - could grant "co-orphan" status to both drugs, and let patients decide which to use.
"Politically, the FDA wants to get at least one drug on the market," said Thomas Dietz, an analyst with Pacific Growth Equities in San Francisco, who gave a "strong buy" rating to TKT.
"Genzyme ran a biochemical surrogate marker study, and during the course of running that, clinical benefit was shown by [TKT's] drug," Dietz told BioWorld Today. "In the regulations, it says that if clinical benefit, or the definition for showing success changes, the FDA can make you go back and re-run your study - even if it took you five years to run it, and they approved your drug. If they're going to pick just one, I can't believe they wouldn't pick the one that had clinical benefit."
Beyond this, Dietz said, he was stymied by the lack of detail provided by the companies.
"You can have two drugs in a category approved if you have a different profile, different safety," he said. "But we don't know what's been requested [by the FDA] from the companies. I don't know how to handicap them anymore."
TKT's stock (NASDAQ: TKTX) closed Thursday at $33.25, down $3.312. Genzyme's shares (NASDAQ: GENZ) ended the day at $82.687, down $4.875.