Benefits of cervical cancer vaccine confirmed

By Ben Hirschler

LONDON (Reuters) - The experimental cervical cancer vaccine, Cervarix, is 90 percent effective in preventing precancerous viral infection for most cases of cervical cancer. GlaxoSmithKline Plc reported in the Lancet.

Interim results from the biggest cervical cancer vaccine trial to date confirm previous promising data. Cervarix is a rival to Merck & Co. Inc.'s similar product Gardasil.

So far, the only major market where Cervarix has a green light is Australia. Glaxo expects to launch it in Europe in the second half of this year but in the United States -- the world's top market -- it will not go on sale before 2008.

Cervarix is designed to prevent infections with the sexually transmitted human papillomavirus (HPV) type 16 and 18, which are responsible for 70 percent of all cervical cancers. Gardasil targets two additional virus strains that cause genital warts, a less serious condition.

Results of the phase III study involving 18,644 women ages 15 to 25 years showed Cervarix was 90.4 percent effective against types 16 and 18, based on pre-specified analyses that only required detection of virus.

In practice, however, researchers found most growths contained multiple cancer-causing HPV types. When this was taken into account, Glaxo said the data showed Cervarix was actually 100 percent effective against strains 16 and 18.

CROSS-PROTECTION

Cervarix also provided significant cross-protection against infection caused by virus types 45, 31 and 52, which together account for another 12 percent of cervical cancer cases.

"To have up to 100 percent protection against two viruses that are responsible for more than 70 percent of cervical cancers and to confirm some preliminary findings on cross-protection, as well as the safety profile, is extremely exciting news for us," Philippe Monteyne, Glaxo's head of vaccine development, told reporters in a conference call.

In an accompanying comment in the Lancet, Jessica Kahn of the University of Cincinnati College of Medicine and Robert Burk of the Albert Einstein College of Medicine in New York, said the results were encouraging but it was still early days to assess efficacy, since cervical cancer can evolve over several decades.

They also highlighted some increases in adverse reactions among vaccinated women, including injection site symptoms and some general symptoms, although there were no clinically meaningful differences in safety outcomes.

Many governments around the world have endorsed the idea of vaccinating young girls around the age of puberty, on the basis that it will save lives and healthcare costs in the years ahead.