By Randall Osborne
West Coast Editor
In a year of influenza vaccine shortages, Gilead Sciences Inc. and partner Hoffmann-La Roche Inc. have won marketing approval for Tamiflu (oseltamivir phosphate) for flu prevention.
Studies have shown is Tamiflu up to 92 percent effective in flu prevention in adolescents, adults and the elderly, but Sheryl Meredith, director of corporate communications for Foster City, Calif.-based Gilead, said the drug is not to be used as a vaccine substitute.
"Clearly, [the approval is] really timely, but people need to be talking to their physicians to find out whether Tamiflu is appropriate for them," she said. "Hopefully, the vaccine supply will come up to par before flu season hits."
Tamiflu is intended for flu prophylaxis - that is, for taking after exposure to the virus. The new label calls for a week's worth of once-a-day pills after exposure. But, because the patient is said to be protected for as long as the drug is taken and it is also intended to deal with community outbreaks, the number of days it's actually used is likely to be more, said Gordon Cohen, an analyst with Banc of America Securities in New York.
"High-risk patients should [still] get the vaccine," Cohen said. "It protects you for the whole season, and this only protects you while the flu is in your area."
He said the new label likely will double Tamiflu sales this year, to $80 million, and is expected to boost awareness of the drug - which, last season among physicians, was only about 3 percent.
"Roche is launching a large advertising campaign, direct to consumer," Cohen said. "[Tamiflu] is going to be used more as people get to know about it, especially if the incidence of flu goes up" because of the vaccine shortage caused by this year's manufacturing problems, he added.
The shortage means up to 30 percent of flu vaccinations will be delayed until December, according to the Centers for Disease Control, and it's the middle of December when flu outbreaks typically increase.
Cohen said the reduced number of flu shots available before December could result in 10 percent to 15 percent more cases of flu. Since more people will know about Tamiflu, the patient population should jump by about 45 percent, he estimated.
Tamiflu already is doing well. An oral neuraminidase inhibitor cleared in October 1999 as a treatment for flu strains A and B, it has taken 58 percent of the neuraminidase inhibitor market, where its sole competitor is Relenza (zanamivir), marketed by London-based Glaxo Wellcome plc, and 30 percent of the flu market, which includes other drugs for relief of the troublesome seasonal ailment. (See BioWorld Today, Oct. 29, 1999.)
Providing Tamiflu with even more of an edge, Cohen said, was the problem that Relenza, which is an inhaled drug, had over the summer, when it was hit with a warning label because it was causing respiratory failure and deaths in some patients with pre-existing lung conditions.
Another potential competitor in the oral neuraminidase inhibitor market, RWJ-270201, was stalled last month when Birmingham, Ala.-based BioCryst Pharmaceutical Inc.'s partner, R.W. Johnson Pharmaceutical Research Institute, said it would not go ahead with its plan to start two clinical studies in high-risk elderly patients of the drug. (See BioWorld Today, Oct. 13, 2000.)
Also on the flu horizon: Aviron Inc.'s FluMist, an intranasally delivered, attenuated live flu vaccine. Mountain View, Calif.-based Aviron submitted a biologics license application for FluMist earlier this month, so the drug won't be available until the 2001 flu season. (See BioWorld Today, Nov. 1, 2000.)
Meanwhile, Gilead and Roche, of Nutley, N.J., will be promoting Tamiflu - and Gilead, having won fast-track status for tenofovir, its HIV drug, will be gathering data from the Phase III trial that began in June. Tenofovir is a nucleotide analogue for HIV that blocks the reverse transcriptase enzyme. (See BioWorld Today, June 13, 2000.)
"We expect [an application for marketing approval of tenofovir] to be filed with 24-week data from the Phase III trial, which should be mid-2001, earlier than people expected a few months ago," when it seemed the FDA would require six-month data, Cohen said. Sales of tenofovir are expected to peak at about $400 million, he said.
Gilead's stock (NASDAQ: GILD) closed Monday at $64.625, down $5.625.