GlaxoSmithKline said May 31st that the U.S. Food and Drug Administration has declined to grant a priority review to its experimental cervical cancer vaccine Cervarix, meaning the biologic will go through a standard 10-month review delaying marketing of the vaccine in the U.S. until at least sometime in 2008.

The Glaxo biologic, which was approved earlier this month in Australia for use in females aged 10 to 45 years old, is a competitor for Merck's human papilloma virus and cervical cancer vaccine, Gardasil, which was approved by the FDA in June, 2006.

Both vaccines target HPV strains 16 and 18, which are responsible for 70 percent of all cervical cancers.

But whereas Merck's vaccine also protects against HPV strains 6 and 11, which cause 90 percent of all genital warts, GSK's vaccine is focused on cancer-causing HPV and also offers protection against HPV strains 45 and 31, which are responsible for another 10 percent of cervical cancers.

Cervarix also provides protection for women up to age 55 years, while Gardasil is targeted at somen up to the age of 25.

The outlook for Cervarix looks somewhat brighter in Europe where analysts expect the biologic to get a positive recommendation in June from the European Medicines Agency's Committee for Medicinal Products for Human Use.