Washington Editor

Corixa Corp. won an appeal against an FDA decision issued earlier this year that required additional clinical trials in order to market the cancer drug Bexxar.

While biotechnology analysts cautioned that the appeal doesn't guarantee approval, it does give Corixa the opportunity to present its case before the FDA's Oncologic Drugs Advisory Committee (ODAC), possibly before the end of the year.

Had Corixa lost the appeal, the company likely would have been forced into additional, prospective trials to prove Bexxar's clinical and safety benefits.

"This is the first step in our process to take this product to the market and obviously we see this as a very positive opportunity to have the chance to present to ODAC," David Fanning, Corixa's chief operating officer, told BioWorld Today. "We are encouraged by the productive dialogue with the FDA and we look forward to continuing to work with them as we plan for the ODAC presentation."

Bexxar (tositumomab and iodine-131 tositumomab) is an investigational radioimmunotherapy being developed for the treatment of low-grade or transformed low-grade non-Hodgkin's lymphoma.

Corixa said the FDA has agreed to place Bexxar on ODAC's agenda "upon timely receipt of certain follow-up information requested." Specifically, the agency wants an integrated analysis of efficacy across multiple clinical trials and some other supporting materials.

"The FDA will determine when we go before ODAC, and we are optimistic that it will happen before the end of the year. There are two opportunities - there's a meeting in September and in December," Fanning said. "We're obviously working with the agency to do this as expeditiously as possible."

Brian Rye, a biotech analyst with Raymond James & Associates Inc. in Nashville, Tenn., told BioWorld Today that it's too early to determine whether Corixa will make it before ODAC this year. "But we certainly are encouraged by today's news. I know the company has long felt that if they could get in front of an ODAC panel that they could convince them that Bexxar is a drug that needs to be approved. As to the timing, once the company gets these few remaining items to the FDA, the FDA can review it at its own pace; there's really no time constraint on them."

Rye said Bexxar should be approved, and Thomas Dietz, an analyst with Pacific Growth Equities in San Francisco, released research notes Thursday saying ODAC would be likely to vote in favor of Bexxar.

Corixa and its partner, GlaxoSmithKline plc, of London, have faced some trying times on the road to gaining marketing clearance for Bexxar.

It was widely assumed that Bexxar would be the subject of an ODAC panel hearing in February, but the FDA didn't schedule the meeting because its reviewers were unable to study all the material submitted as part of the biologics license application. (See BioWorld Today, Jan. 11, 2002.)

By March, the agency had reviewed all the data and issued a letter stating that additional trials would be necessary for approval. (See BioWorld Today, March 14, 2002.)

Initially, the FDA said it had insufficient data to adequately evaluate the safety profile. Furthermore, the agency raised questions about approvability of the product, given that other drugs are available for this disease. (Similar products are Rituxan and Zevalin, both made by San Diego-based IDEC Pharmaceuticals Inc.)

"Our contention has always been that our drug is the only radioimmunotherapy that has demonstrated durable responses in patients who have relapsed, refractory NHL," Fanning said.

After a meeting in April to discuss the March decision, the FDA issued a letter stating it was able to assess the safety of Bexxar, but continued to question the clinical benefit. At that point, the agency suggested additional trials.

Corixa responded by filing an appeal under the Food and Drug Administration Modernization Act of 1997.

The Bexxar BLA was submitted in September 2000 by San Francisco-based Coulter Pharmaceuticals Inc., and then-partner SmithKlineBeecham plc. Corixa inherited Bexxar in late 2000 when it took over Coulter in a stock swap valued at more than $900 million. (See BioWorld Today, Oct. 17, 2000.)

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 cell surface, including non-Hodgkin's lymphoma B cells.

Delays associated with Bexxar prompted Corixa to restructure its South San Francisco operations by cutting the work force, from about 200 people down to 70, and by completing a $21 million agreement with Princeton, N.J.-based Medarex Inc. to sell some technology and preclinical therapeutic programs. (See BioWorld Today, May 28, 2002.)

The company's stock (NASDAQ:CRXA) headed upward Thursday, closing up 83 cents, or 14.8 percent, at $6.45.