The FDA will delay action up to three months on Corixa Corp.'s biologics license application for Bexxar, a radioimmunotherapy for the treatment of non-Hodgkin's lymphoma.
Corixa and partner GlaxoSmithKline plc, of London, received notification that the FDA intends to extend the Prescription Drug User Fee Act (PDUFA) date to Aug. 1. PDUFA guidelines compel the agency to act on a drug application within a certain time frame.
Importantly, the FDA has not sought additional trials, Jim DeNike, spokesman for Seattle-based Corixa, told BioWorld Today. "They didn't ask for anything, they just simply notified us that they were extending for three months," he said.
In a conference call with analysts, reporters and investors Monday morning, Steven Gillis, chairman and CEO of Corixa, said the three-month extension provides additional time to further discuss post-marketing commitments and package inserts, and to ensure that they are consistent with updated safety data submitted in April.
When Corixa presented its application to the Oncologic Drugs Advisory Committee (ODAC) in December, the company submitted safety data including 620 patients. The updated data includes 995 patients with up to 9.5 years of follow-up, Gillis said. The new data do not change the overall safety profile, he said.
In a 10-3 vote, ODAC agreed that Bexxar showed substantial clinical benefit in rituximab-refractory follicular non-Hodgkin's lymphoma (NHL). And the panel voted unanimously that Bexxar (tositumomab and iodine-131 tositumomab) showed benefit in chemotherapy-refractory patients with low-grade and follicular NHL. (See BioWorld Today, Dec. 18, 2002.)
Specifically, the companies are seeking approval for the treatment of patients with B-cell, follicular NHL, with and without transformation, whose disease has relapsed following or is refractory to chemotherapy and is refractory to rituximab.
Bexxar is an antibody specific to the CD20 antigen on B cells conjugated to radioactive iodine-131. It attaches to a protein found only on the surface of B cells, including NHL B cells.
While Corixa clearly stated that the agency has not asked for additional information as part of the extension, analysts interpret it as being time to finish the package insert and finalize details on the post-marketing commitment.
"Those are issues you would be concerned about if you were going to approve a drug," Brian Rye, a biotech analyst with Raymond James & Associated Inc. in Nashville, Tenn., told BioWorld Today. "They are not requesting any additional data or a new trial, but obviously a delay is a delay. But in this case, it is only a three-month pushback and I don't think there's anything that's going to prevent the drug from being approved. It is a question of when rather than if."
Upon FDA approval, it would take the companies about 30 days to launch Bexxar. In preparation, Kevin Lokay, vice president of oncology at GSK, said the company has nearly doubled its sales staff. Even when pressed by analysts, Lokay would not disclose the size of the staff.
Raymond James' model indicates that peak worldwide sales of Bexxar will reach about $250 million. And a research note released by Phil Nadeau, an analyst with SG Cowen Securities Corp. in New York, estimates peak (2007) U.S. sales to reach $135 million.
Cowen, though, cautioned that Bexxar alone will not make Corixa an outperformer because the company has to split the profits with GSK.
Corixa inherited Bexxar in late 2000 when it took over San Francisco-based Coulter Pharmaceuticals Inc. in a stock swap. Coulter was partnered with SmithKline Beecham plc in the development of Bexxar. (See BioWorld Today, Oct. 17, 2000.)
According to Corixa, the partnership between Coulter and SKB was amended in April 2000 to reduce what was then SKB's territory to the U.S. Upon regulatory approval, SKB (now GSK) would be required to pay Coulter (now Corixa) a milestone. The companies will co-promote Bexxar in the U.S., with each company contributing to the sales force and both companies sharing profits equally.
GSK also provided a $15 million credit line that was fully drawn by Coulter in December 2000. It may be repaid in cash or shares of common stock on or prior to the October 2003 maturity date.
All companies involved in the development of Bexxar have faced a series of setbacks, including one a little more than a year ago when the FDA refused to set a panel hearing because the reviewers couldn't make it through the extensive product-related material submitted by the company. (See BioWorld Today, March 14, 2002.)
Sometime thereafter, the FDA told Corixa it had failed to provide sufficient evidence of safety and clinical benefit, and likely would need additional studies. The company responded by filing and winning an appeal against the agency. (See BioWorld Today, May 16, 2002, and June 28, 2002.)
Corixa's stock (NASDAQ:CRXA) closed Monday at $6.88, down 12 cents.