Washington Editor

While The Street is leaning toward a favorable vote for MedImmune Inc.'s FluMist as an intranasal influenza vaccine, it's not so clear whether Seattle-based Corixa Inc. will get the nod for its cancer drug, Bexxar.

MedImmune and Corixa - and their partners - have fought uphill battles on the road to regulatory approval, and likely will learn their fate today in Bethesda, Md.

The Vaccine and Related Biologics Products Advisory Committee will hear the case for FluMist, while the Oncologic Drugs Advisory Committee will discuss the merits of Bexxar.

Both biologics ended up in the hands of their respective owners through expensive corporate mergers and acquisitions that are now in a position to begin paying off.

The larger of the deals was the $1.5 billion merger between Aviron Inc., of Mountain View, Calif., and MedImmune, of Gaithersburg, Md. The companies came together for FluMist several months after Aviron failed to win a clear victory in its first appearance before an FDA panel. (See BioWorld Today, July 30, 2001, and Dec. 4, 2001.)

But the good news is, on studying the FDA's briefing document released in advance of the hearing, Dennis Harp, a biotechnology analyst with Deutsche Bank in New York, said the agency had not raised any new issues.

FluMist, a potential blockbuster, was the subject of a two-day panel meeting in July 2001 that got hung up when members said the safety data were not sufficient for approval. And while the FDA is not bound by the committee's recommendation, in this case, the issues surrounding safety data in children 5 years and younger and the insufficient efficacy data in patients 50 to 64 years of age were enough to stop the intranasal vaccine from making it to market. (See BioWorld Today, July 30, 2001.)

This time around though, Harp told BioWorld Today, he expects FluMist to win approval. "The first time the panel reviewed the product, it appeared that they were favorably impressed with the efficacy and had some residual concerns for safety. We think much of the safety concerns have now been addressed with the expanded database and the fact that the company is now seeking a label indication that would not include children under 5," he said.

Specifically, the earlier panel raised concerns about the risk of asthma in children under 5, and whether FluMist would interfere with other childhood vaccinations.

Referencing the insufficient data for the 50- to 64-year-old population, Harp said in a research note that "although FluMist did not reduce the number of days of flu-like illness in the 50-64 population, we are encouraged by significant reductions that were observed in days of missed work, physician visits and prescription drug usage."

FluMist is a cold-adapted trivalent vaccine containing two different influenza A strains and one influenza B strain selected each year based on worldwide surveillance. The internal flu proteins from the master strains of influenza A and B virus grow at cooler temperatures and combine with hemaglutinin and neuraminidase, the surface proteins found on contemporary circulatory viruses. FluMist stimulates the mucosal immune system as well as the systemic immune system, resulting in a strong cytotoxic T-cell response.

As a carry-over from the Aviron ownership, FluMist remains partnered with Wyeth-Lederle Vaccines, a business unit of Wyeth, of Madison, N.J., for U.S. marketing rights (See BioWorld Today, Dec. 4, 2001.)

MedImmune's stock (NASDAQ:MEDI) closed Monday at $24.99, down $1.65.

Corixa Seeks Approval After Recent FDA Support

Seattle-based Corixa enters its panel meeting within weeks of the FDA's decision to return Bexxar to active status, prompting the company to drop its pending dispute against the agency.

The decisions were reached after the FDA said additional data as well as responses to concerns previously raised about the biologics license application (BLA) for Bexxar were sufficient. (See BioWorld Today, Dec. 4, 2002.)

Corixa today will seek recommended approval of Bexxar (tositumomab and iodine-131 tositumomab) as an investigational radioimmunotherapy for the treatment of low-grade or transformed low-grade non-Hodgkin's lymphoma (NHL). Also, Corixa will seek registration for use of Bexxar in low-grade NHL patients who do not respond or progress following rituximab therapy.

While the agency has criticized Corixa for the design of its trials, in its briefing document released in advance of the meeting, the FDA said, "The results of the major efficacy trial demonstrated a significantly higher proportion of patients with a longer duration of response following iodine I-131 tositumomab therapy as compared to the most recent standard chemotherapy regimen (p<0.001, McNemar's test)."

Corixa and its partner, London-based GlaxoSmithKline plc, have faced a series of setbacks with Bexxar beginning around last winter when the agency refused to schedule a panel meeting because 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, March 14, 2002; May 16, 2002; and June 28, 2002.)

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 non-Hodgkin's lymphoma B cells.

Bexxar's primary competition is Zevalin, also a radioimmunotherapeutic agent, made by San Diego-based IDEC Pharmaceuticals Corp.

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, 2002.)

Corixa's stock (NASDAQ:CRXA) closed Monday at $6.98, up 23 cents.