) and its American rival, Merck & Co. (MRK
), have been racing to develop a vaccine against the human papilloma virus (HPV), which causes almost all cervical cancer.
The race just got tighter. On Nov. 12, GSK's experimental vaccine Cervarix got a significant boost. A study published in British medical journal The Lancet reported Cervarix was the first vaccine to be 100% effective in protecting women against two strains of HPV that are linked to more than 70% of all cases of cervical cancer. The results led GSK to announce it will file for regulatory approval for Cervarix in Europe and countries outside the U.S. in 2006, two years ahead of schedule. "Over the last 20 years there has been nothing else developed that will make such a huge impact on women's health," says Dr. Diane Harper, a director of gynecological cancer-prevention research at Norris Cotton Cancer Center in Lebanon, N.H., and the author of the GSK-funded study.
The market potential could be huge. HPV is the most common sexually transmitted disease worldwide, infecting 75% of sexually active women at some point in their lives. For the majority of women who contract HPV, the body's defenses are enough to beat the virus. Some strains cause genital warts, which pose no real health risk. But persistent infections from others can lead to cervical lesions that ultimately turn cancerous. There is often an interval of up to two decades between infection and cancer. With that in mind, both GSK and Merck are considering aiming their vaccines at girls as young as 10 to ensure they are vaccinated before the onset of sexual activity. Scientists are still researching whether or not booster shots will be needed after the initial inoculation in order to guarantee lifetime protection against HPV.POOR COUNTRIES
It's not just a question of life and death. In the U.S., deaths from cervical cancer are relatively low, but the costs of screening for the HPV virus and treating infections and cervical cancer add up to $6 billion a year. An estimated 80% of deaths from cervical cancer occur in the developing world, where pap tests and cancer screening are rare.
But burdened as poor countries are by other mass killers -- from AIDS to malaria -- it's hard to imagine how they will be able to pay for this vaccine. Public-private partnerships, such as those that have emerged to treat HIV, could help defray some of the costs for cash-strapped national health systems.
The Bill & Melinda Gates Foundation, endowed by Microsoft (MSFT
) founder Bill Gates, has earmarked $50 million for the prevention of cervical cancer. "But it remains to be seen whether the developing world will be willing to invest in a vaccine where the reduction in cancer will not be seen for many years because of [the] long interval between infection and development of the cancer," says Dr. Douglas R. Lowy. He headed the research team at the National Institutes of Health in Bethesda, Md., whose original discovery is the basis of both the Merck and GSK vaccines.
In the meantime, GSK and Merck are engaged in the late-stage trials needed to bring their vaccines to market. Both companies introduced vaccines for Hepatitis B, a disease linked to liver cancer, more than a decade ago. Their competing cervical-cancer vaccines operate on a similar principle. Patients are injected with virus-sized particles that have the molecular shell of HPV-16 and 18 but no infectious DNA inside, making them harmless mimics of the real thing.
Still, there are some crucial differences between the GSK and Merck drugs. While Cervarix targets two cancer-causing strains of HPV, Merck's shot will also ward off genital warts in both men and women. Merck, which began its phase II efficacy trials a year ahead of GSK, reckons it will be ready to file its vaccine for U.S. approval by the end of next year. Because Merck's vaccine has been in trials longer than GSK's, the company has been able to show a greater reduction in precancerous lesions, a condition the FDA is thought to consider necessary for approval. Dr. Eliav Barr, head of Merck's HPV vaccine clinical-trial program, also believes that his company's broader vaccine will encourage young women -- and, down the road, young men -- to get vaccinated, since many young people are more worried about unsightly genital warts than the risk of getting cancer.
Both companies badly need the boost the new vaccine could bring. GSK has lost two of its best-selling drugs, antidepressants Paxil and Wellbutrin, to generic competition, and it will be at least two years before any of its most promising new medicines hit the market. Merck, which has had several drugs fail in clinical trials, is desperate for good news after it pulled its blockbuster painkiller Vioxx from the market in September because of a link to heart attacks and stroke.MORAL HURDLES
Even if Merck is first to market, GSK CEO Jean-Pierre Garnier figures there is room for both companies' versions. "It's a vaccine every woman should take," says Garnier. Analysts agree. They estimate the market could be worth more than $3 billion annually by 2008. "This is groundbreaking stuff," says Adrian Howd, pharmaceutical analyst with ABN Amro (ABN
) in London. "The market is certainly big enough for more than one player."
The recent flu-vaccine shortage also underscores the importance of having more than one manufacturer making the drug. Although neither GSK nor Merck has indicated how they intend to price their vaccines, analysts say they will be much more expensive than flu shots. Howd estimates that a cervical-cancer vaccine could cost as much as $300 for the expected course of three injections over a six-month period. This means the drugs have a good chance of becoming blockbusters for both companies.
Despite the obvious benefits, the vaccines may not be an easy sell: There are social and moral hurdles to overcome. "The biggest problem for companies will be convincing society of the need to vaccinate young girls against what is essentially a sexually transmitted disease," says Dr. Anne Szarewski, a clinical consultant at Cancer Research UK, which is conducting phase iii trials of Cervarix at Margaret Pyke Centre in London. Women worldwide had better hope Merck and GSK succeed. By Kerry Capell in London, with Amy Barrett in Philadelphia