An experimental cervical vaccine under development by GlaxoSmithKline (GSK) induces at least twice as many antibodies against cancer-causing viruses in females 10 to 14 years old compared to females 15 to 25 years old.

"The elevated levels demonstrated in this younger age range may result in longer duration of protection," GSK said recently.

The findings stem from a Phase III study by GSK that compared how many antibodies its vaccine, Cervarix, produced in each age group against the two most common types of cancer-causing human papilloma virus (HPV), HPV 16 and HPV 18. Approximately 70 percent of all cervical cancers are connected with HPV 16 and 18, GSK said.

GSK earlier this year also presented other study results that show its proprietary immune response-boosting adjuvant, AS04, induces a stronger, sustained immune response in patients who received Cervarix plus AS04 compared to those that received vaccine with a different adjuvant.

Cervarix is one of five vaccines GSK plans to launch over the next five years to tap what GSK predicts will be a multibillion-dollar market for preventative drugs. GSK's announcement also fuels competition between it and Merck, who is working on its own cervical cancer vaccine, Gardasil. GSK has not set a timeline for when it will apply to market Cervarix in the U.S., but Merck recently filed its biologic drug application and is seeking priority review for the drug, which if granted would result in a decision within six months instead of the standard 10 months.

Gardasil is designed to protect against four strains of human papillomavirus (HPV) -- Types 16 and 18, which account for an estimated 70 percent of cervical cancer cases, and Types 6 and 11, which account for an estimated 90 percent of genital wart cases.

Both drugs look promising. In November 2004, a study published in British medical journal The Lancet showed GSK's vaccine Cervarix to be virtually 100 percent effective against HPV 16 and 18. In October, Merck unveiled study results showing Gardasil prevented 100 percent of cervical growths caused by HPV 16 and 18.