By Kim Coghill
Neither Genzyme General nor Transkaryotic Therapies Inc. (TKT) will have to go before an advisory committee review as they seek approval of their Fabry disease products.
Fabrazyme is Genzyme's experimental enzyme replacement therapy for patients with Fabry disease. The marketing request has been accepted for priority review, speeding up the process to six months from the usual 12 months. Genzyme anticipates approval in mid-January.
"It would be hard for me to elaborate further on this," said Bo Piela, spokesman for Cambridge, Mass.-based Genzyme. "We talk to the FDA almost daily and they simply informed us that there would not be a need to review our BLA at their December panel meeting. The review of the BLA is on schedule."
The FDA often uses advisory committees to provide guidance for clinical issues related to marketing applications.
Also on schedule for priority review is TKT's Replagal, an enzyme replacement therapy drug produced by the Cambridge, Mass., company.
Genzyme and TKT filed biologics license applications (BLAs) with the FDA for their products June 23 and June 16, respectively. The first product to gain approval could get orphan status, which gives it seven years of market exclusivity. (See BioWorld Today, June 19, 2000; June 26, 2000; and Oct. 6, 2000.)
Justine Koenigsberg, spokeswoman for TKT, would not say when the FDA informed the company that it will bypass that step, but said, "We have no expectation of having an advisory committee. Our submission was done in mid-June, we have priority review and we would expect to hear early next year."
Fabry disease is a rare, inherited genetic disorder caused by deficient activity of the lysosomal enzyme alpha-galactosidase A, which leads to accumulations in the body of ceramidetrihexoside, resulting in extreme pain, serious renal and cardiovascular disease and stroke. It affects about one in 40,000 men worldwide, and death typically occurs around age 40 or 50. Between 1,000 and 2,000 patients in the U.S. are afflicted.
The rarity of the disease may be one reason the FDA isn't requiring an advisory committee.
According to Elise Wang, biotechnology analyst with PaineWebber in New York, it often is difficult for the FDA to seat an appropriate panel given the limited number of Fabry disease experts and the potential for conflict of interests. "That's a potential reason for not having the advisory committee," she said. "The other potential reason is that the FDA may have sufficient data to make their analysis and make their determination. They may not need the advice of an advisory panel."
Regarding which drug will receive approval first, Wang said, "These were filed so close together, we are talking about a week in terms of the time of separation of the two filing. I don't think the FDA is going to give one or the other the lead, so to speak.
"My guess is that the FDA will review them simultaneously; it only makes rational sense," Wang said.
PaineWebber predicted Genzyme may have an advantage because its Phase III study included more patients across multiple sites (58 patients in eight sites), as compared to TKT's two Phase II studies, each conducted at a single site, that included an aggregate of 41 patients, according to a statement released by the company.
"It has been acknowledged that the endpoint Genzyme used in their study was FDA approved," Wang said. "We don't have the full data on TKT; we've only seen one study. But our general feeling is that Genzyme might have an advantage."
Other analysts have given TKT a good chance in the case.
Genzyme filed a complaint in July against TKT in U.S. District Court, alleging that the latter's manufacture and use of Replagal infringes on a patent licensed to Genzyme. Two months later, TKT filed papers against Genzyme, seeking declaratory judgment of patent non-infringement and invalidity. (See BioWorld Today, Oct. 6, 2000.)
Genzyme's stock (NASDAQ:GENZ) closed Thursday at $80, up $6.75, or 9 percent. TKT's stock (NASDAQ:TKTX) closed Thursday at $43.375, up $4.187, or 10 percent.