Merck's Gardasil wins approval for anal cancer

Gardasil, a Human Papillomavirus vaccine, is displayed at the Girls to Women Health and Wellness clinic in Dallas, Texas March 6, 2007.

NEW YORK (Reuters) - Merck & Co's Gardasil vaccine won U.S. approval on Wednesday for preventing anal cancer, providing a new weapon against a rare but rising form of the disease.

Both the drugmaker and the U.S. Food and Drug Administration announced the approval, which applies to people ages 9 to 26.

Gardasil already is approved for the same age population for the prevention of cervical, vulvar and vaginal cancers.

It fights infection with the sexually transmitted human papillomavirus (HPV), best known as the primary cause of cervical cancer. HPV also can lead to cancers of the anus, penis, head and neck.

Gardasil's sales hit $1.1 billion last year, though the product has not reached initial expectations for even larger sales. Many young women already have been immunized with Gardasil, limiting the market size, while Gardasil faces competition from a rival vaccine from GlaxoSmithKline Plc.

As of the end of May, more than 65 million doses of Gardasil had been distributed worldwide since its approval in 2006.

Anal cancer is one of the one of the less common types of cancer, with an estimated 5,300 new U.S. cases diagnosed each year, but the incidence is increasing, the FDA said. The disease killed actress Farrah Fawcett in 2009 at age 62.

"Treatment for anal cancer is challenging; the use of Gardasil as a method of prevention is important as it may result in fewer diagnoses and the subsequent surgery, radiation or chemotherapy that individuals need to endure," said Karen Midthun, director of the FDA's Center for Biologics Evaluation and Research.

Deutsche Bank analyst Barbara Ryan said approval for the new use was unlikely to give Gardasil sales a significant boost.

Last month, members of a U.S. advisory panel said Gardasil appeared effective for preventing anal cancer.

The FDA on Wednesday cited data showing Gardasil was effective in a study of men who have sex with men, a group that has a higher incidence of anal cancer.

The agency said that because anal cancer is the same disease in both males and females, such data can support the use in females as well.

Merck is facing the impending patent expiration of its Singulair asthma drug, but is also thought to have one of the most enviable product pipelines in the drug industry, including potential big sellers for treating hepatitis C and preventing blood clots.

Merck shares closed up 4 cents at $36.22 on the New York Stock Exchange on Wednesday.

(Reporting by Lewis Krauskopf; additional reporting by Lisa Richwine in Washington; Editing by Gary Hill and Tim Dobbyn)