By Lisa Seachrist
Last flu season, patients suffering from the seasonal viral infection had for the first time two FDA-approved drugs to treat their illness. This coming flu season, they may have a drug to protect them from getting the infection in the first place.
Hoffmann-La Roche Inc. has submitted an application to FDA to have the Tamiflu label expanded to include the prevention of naturally occurring influenza in adults and adolescents 13 years and older. Tamiflu (oseltamivir phosphate), an oral neuraminidase inhibitor originally developed by Gilead Sciences Inc., of Foster City, Calif., is marketed worldwide by Roche.
"Roche is excited about this new filing," said Charles Alfaro, director of public affairs for Roche. "We see this prevention indication as an additional weapon in the arsenal people have for fighting the flu. Tamiflu is never going to be a replacement for vaccination; it's a supplement that can provide additional safeguards."
Alfaro pointed out the drug could be particularly useful for people who aren't vaccinated, in cases where the vaccine does not match the influenza strain of the season, or for high-risk patients who might need additional protection. The prevention indication will allow Roche to market the drug for people exposed to influenza in the normal course of daily life. But, timing will be key because the drug must be taken within 48 hours of exposure to prevent infection.
London-based Glaxo Wellcome plc's inhaled neuraminidase inhibitor, Relenza, beat Tamiflu to the market last year by about a month. Nutley, N.J.-based Roche, in turn, has beaten Glaxo to filing a request for an expanded indication. Glaxo, however, is planning to file for a prophylaxis indication for Relenza sometime this year. Should both products attain approval for preventing flu, the two companies will continue their battle for market share on relatively even footing.
A prophylaxis label will make it possible for patients to have the drug sitting in the medicine cabinet at the ready in anticipation of the flu season.
"Early last year, Relenza had the advantage," said Al Rauch, senior vice president and biotech analyst at First Union Securities Inc. in Chicago. "By the end of the year Tamiflu had about 80 percent of the market. People seemed to prefer the pill formulation. I think Tamiflu is going to be the big winner next year."
The Roche filing is based on three separate Phase III randomized, double-blind, placebo-controlled clinical trials involving 3,434 healthy patients including adolescents, adults and the elderly. In one trial, patients took 75 milligrams of Tamiflu once a day for seven days after coming into contact with a flu-infected household member. Tamiflu reduced the incidence of influenza by 92 percent.
Tamiflu also reduced the incidence of laboratory-confirmed influenza by 76 percent in healthy adults during a community outbreak and by 92 percent among elderly patients in a nursing home setting. The drug also reduced the incidence of influenza-associated bronchitis, pneumonia and sinusitis by 86 percent. The most frequently reported side effects included nausea, vomiting, diarrhea and headache.
"Tamiflu could be very useful as a prophylaxis if the flu vaccine doesn't have the right antigens, which happens sometimes," Rauch said. "And, if you haven't been vaccinated, pretreatment is the best way to go."
Both Tamiflu and Relenza are neuraminidase inhibitors. Neuraminidase is an enzyme on the surface of all strains of influenza that facilitates the virus' ability to spread from cell to cell in the respiratory tract. Relenza was approved as a treatment for the flu in July 1999, while Tamiflu was approved in October 1999. (See BioWorld Today, July 28, 1999, p.1; and Oct. 29, 1999, p. 1.)
Each year, up to 40 million Americans develop the flu, resulting in an annual cost of $14.6 billion in physician visits, lost productivity and lost wages. In addition, nearly 300,000 people are hospitalized and 20,000 to 40,000 people die from influenza and its complications.
Gilead's stock (NASDAQ:GILD) closed Tuesday at $60.562, up 81.25 cents.