Girls aged 10 to 14 who received GlaxoSmithKline Plc’s vaccine to
prevent infection with the virus that causes cervical cancer had immune
responses twice as strong as women 15-25 years old given the vaccine,
the company said on Saturday, describing results of a late-stage trial.

Glaxo
said the first published data from a Phase III trial of its Cervarix
vaccine suggest it may provide the strongest and most-prolonged
protection if given to girls at very young ages, long before they
encounter the sexually transmitted virus.

"The concentrations of
antibodies to the virus were twice as high in the bloodstreams of the
young girls," said Gary Dubin, a senior research official at Glaxo who
was the lead author on the study.

Antibodies are immune-system
proteins that seek out and destroy bacteria and viruses. Vaccines, by
introducing the body to snippets of specific bacteria or viruses, train
the body to crank out tailor-made antibodies that attack them.

Dubin
said the trial was not designed to confirm actual effectiveness of the
vaccine because few girls in the 10 to 14 age group are yet sexually
active. Instead, he said the immune response is the best "surrogate"
indicator of the vaccine’s potential ability to protect them from
prolonged infection with the virus.

Results of the trial were
presented at the Interscience Conference on Antimicrobial Agents and
Chemotherapy (ICAAC) in Washington, D.C.

The Glaxo-financed
trial, conducted in Europe and Russia, involved 158 healthy girls aged
10-14 and 458 women aged 15-25 who received three doses of the vaccine
over a six month period.

Cervarix, which has not yet been
submitted for regulatory approvals, is one of the most important
experimental products being developed by the British drugmaker. It is
expected to eventually compete with a similar Merck and Co. vaccine,
Gardasil, that is already awaiting approval from U.S. and European
regulators.

Like Gardasil, the Glaxo product blocks infection
with two strains of human papillomavirus that are responsible for about
70 percent of cases of cervical cancer. It is the second most common
fatal cancer in women.

By Ransdell Pierson

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