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Cervical Cancer Vaccine Shows Promise

Vaccine's Maker Plans to File for FDA Review by Year's End

By Miranda Hitti

WebMD Medical News Reviewed By Louise Chang, MD

on Thursday, October 06, 2005

Oct. 6, 2005 -- An experimental vaccine that targets viruses responsible for

most cervical cancers will soon be sent to the FDA for review.

The vaccine is called Gardasil. It's made by Merck & Co. Merck spokeswoman

Janet Skidmore tells WebMD that Merck will submit Gardasil for the FDA's

review by the end of 2005. Merck is a WebMD sponsor.

In phase III clinical trials -- the last step before application for FDA

review -- Gardasil was 100% effective against two forms of the human

papillomavirus (HPV), according to a Merck news release.

Those two forms of HPV are HPV 16 and 18. They are transmitted through sex.

Together, they cause about 70% of all cervical cancers. The CDC estimates

that 20 million people are infected with HPV, and 6.2 million people in the

U.S.

get a new infection of HPV each year. Unfortunately most people will be

unaware that they are infected as most will not have any symptoms.

Nearly 10,370 cases of invasive cervical cancer will be diagnosed and an

estimated 3,710 American women will die from cervical cancer in 2005, predicts

the American Cancer Society (ACS). However, HPV infection can be the cause of

a much higher number of abnormalities, which can be discovered on routine Pap

test screening.

The Pap test can screen for cervical abnormalities that may be cancerous or

precancerous. The American Cancer Society recommends that screening starts

three years after the start of vaginal intercourse and no later than the age of

21.

It is important to note that HPV infection and/ or an abnormal Pap test

don't always indicate cancer. Most cases will resolve on their own, but it is

important to follow up with a gynecologist for the necessary treatment to

prevent the progression to invasive cervical cancer.

Results from Gardasil's phase III studies are due for presentation in San

Francisco at the Infectious Diseases Society of America.

Not Total Protection

The vaccine doesn't prevent all cervical cancer. Some cervical cancers are

caused by other factors.

The vaccine would likely target women who haven't been exposed to HPV. The

most likely candidates would be young women prior to the onset of sexual

activity.

" At this point, there is no data suggesting that the vaccine works on women

who already have the infection, " National Cancer Institute epidemiologist

Allan Hildesheim, PhD, tells WebMD.

It's not yet known how long the protection lasts, and if booster vaccines

could extend the protection, says Hildesheim.

Experts React

" It seems like a very important advancement to me, from what I've seen.

There's limited information at this point. [but] it looks very promising, " says

Hildesheim.

" I think it has a good potential, " says Flowers, MD, assistant

professor of obstetrics and gynecology at Emory University's medical school.

" This is another exciting study which points to the likely availability of a

vaccine for HPV, but it is critical [that] the data be peer-reviewed and

published, " states Debbie Saslow, PhD, in a statement emailed to WebMD.

Saslow is the director of breast and gynecological cancers for the American

Cancer Society (ACS).

Next Steps

" If and when the FDA approves the vaccine, federal advisory groups will

decide whether to recommend the vaccine and if so under what conditions (e.g.:

at

what age, etc.), " states Saslow.

The Gardasil phase III study participants were more than 12,000 women aged

16-26 years in 13 countries, states Merck's news release.

" In the U.S., most women will have been exposed (through sexual activity) to

HPV by age 23 and many by age 16, " states Saslow. " It is likely that the

vaccine will be more effective if given to younger girls, before the onset of

sexual activity, but we have very little data from this age group. "

" While we have high rates of vaccination for infants and young children, it

is more difficult to achieve wide participation in vaccination of older

children and adolescents. This will be further complicated by the need for

three

doses, " says Saslow.

" Other questions being discussed relate to whether boys should be

vaccinated, and whether young women who have been exposed to HPV, and women in

their

20s and 30s who also have likely been exposed, can get any benefit from

vaccination, " she continues.

Obviously, males don't get cervical cancer, since the cervix is part of the

female reproductive system. But men can spread the HPV virus to women through

sex.

" Most important will be to ensure that women who are most at risk for

cervical cancer (women who do not get routine screening) receive any vaccine

that

is approved and recommended, " Saslow continues.

Pap Test Here to Stay

Flowers lists these steps women can take right now:

Get Pap tests on a regular basis (every year).

If the Pap test has abnormal results, follow up and get treatment, if

needed.

Use condoms and limit sexual partners, which may help. But only abstinence

is 100% effective against sexually transmitted disease.

Don't smoke.

Women should " continue on with screening until it's felt by their physician

that screening is no longer necessary, based on their profile, " says Flowers.

A lot of women don't do that.

" In the U.S., at least 80% of adult women get Pap tests; this is a very

effective way to prevent cervical cancer and deaths from cervical cancer, "

states

Saslow.

" We also know that most women in the U.S. who do get cervical cancer have

either never had a Pap test, or have not had one in five years or more. Most

but not all cervical cancer can be prevented or detected early enough to

prevent lives lost, " Saslow continues.

Global Impact?

" Cervical cancer is a major problem, especially in developing countries,

where they don't have the screening capabilities the way we do for the Pap

test.

This is something that could be helpful as far as saving lives, " says

Flowers.

" The study of HPV vaccines is important because cervical cancer is a leading

cancer killer of women in many countries, and in many countries cervical

screening is not available or feasible to introduce. There are other benefits

as

well, but this is the biggest one, " states Saslow.

It's not yet clear if developing countries will have access to the vaccine,

notes Hildesheim.

" An HPV vaccine would have the greatest impact in the U.S if it was targeted

at the population that is least likely to get screened and therefore most at

risk from cervical cancer, " Saslow notes.

Maker's Reaction

" We're really quite excited about these results, " Skidmore tells WebMD.

" This is a vaccine that we have been working on for more than a decade, and it

has the potential to improve the health of women around the world. "

Another Vaccine in the Works

Another cervical cancer vaccinecervical cancer vaccine -- Cervarix, made by

GlaxoKline -- is also in the works. GlaxoKline is a WebMD sponsor.

" We've completed phase II studies and that data was published in The Lancet

last year, " GlaxoKline spokeswoman le Halstrom tells WebMD. " In

that study, we showed 100% protection against persistent infection of HPV 16

and 18. "

Phase III studies of Cervarix are now underway. They will include about

35,000 women in 14 countries. " We have completed enrollment of those studies.

The

studies are progressing nicely, " says Halstrom.

SOURCES: News release, Merck. Allan Hildesheim, PhD, epidemiologist,

National Cancer Institute. Flowers, MD, assistant professor of obstetrics

and

gynecology, Emory University School of Medicine. Debbie Saslow, PhD, director,

breast and gynecological cancers, American Cancer Society. Janet Skidmore,

spokeswoman, Merck. WebMD Medical News: " Cervical Cancer Vaccine Passes Major

Hurdle. " le Halstrom, spokeswoman, GlaxoKline. Associated Press.