New Vaccine Prevents Cervical Cancer
The Food and Drug Administration has approved Gardasil, the first vaccine developed to prevent cervical cancer and precancerous genital lesions and genital warts due to certain types of human papillomavirus (HPV). The vaccine is approved for use in females ages 9 years to 26 years. Gardasil was evaluated and approved in six months under the FDA's priority review process--a process for products with potential to provide significant health benefits.
HPV is the most common sexually transmitted infection in the United States. The Centers for Disease Control and Prevention estimates that more than 6 million Americans become infected with genital HPV each year and that more than half of all sexually active men and women become infected at some time during their lifetimes. On average, there are 9,710 new cases of cervical cancer and 3,700 deaths attributed to it in the United States each year. Worldwide, cervical cancer is the second most common cancer in women and is estimated to cause over 470,000 new cases and 233,000 deaths each year.
For most women, the body's own defense system will clear the virus, and infected women do not develop related health problems. Some HPV types, however, can cause abnormal cells on the lining of the cervix that can turn into cancer years later. Other HPV types can cause genital warts. The vaccine is effective against HPV types 16 and 18, which cause about 70 percent of cervical cancers, and against HPV types 6 and 11, responsible for about 90 percent of genital warts.
--This vaccine is a significant advance in the protection of women's health in that it strikes at the infections that are the root cause of many cervical cancers," says Acting FDA Commissioner Andrew C. von Eschenbach, M.D. "The development of this vaccine is a product of extraordinary work by scientists as well as by FDA's review teams to help facilitate the development of very novel vaccines to address unmet medical needs."
Gardasil is given as three injections over a six-month period. Immunization is expected to prevent most cases of cervical cancer due to HPV types included in the vaccine. Females, however, are not protected if they have been infected with the HPV types prior to vaccination. Also, Gardasil does not protect against less common HPV types not included in the vaccine; therefore, regular Pap screening remains critically important to detect precancerous changes in the cervix to allow treatment before cervical cancer develops.
Four studies, one in the United States and three multinational, were conducted in 21,000 women to examine how well Gardasil worked in women ages 16 to 26 by giving them either the vaccine or an inactive injection (placebo). In women who had not already been infected, Gardasil was nearly 100 percent effective in preventing precancerous cervical lesions, precancerous vaginal and vulvar lesions, and genital warts caused by infection with the HPV types against which the vaccine is directed. While the study period was not long enough for cervical cancer to develop, the prevention of these cervical precancerous lesions is believed highly likely to result in the prevention of those cancers.
The studies also evaluated whether the vaccine can protect women already infected with some HPV types included in the vaccine from developing diseases related to those viruses. The results show that the vaccine is only effective when given prior to infection.
Two studies were also performed to measure the immune response to the vaccine among younger females ages 9 years to 15 years. Their immune response was as good as that found in 16 to 26 year olds, indicating that the vaccine should have similar effectiveness when used in younger females.
The safety of the vaccine was evaluated in about 11,000 individuals. Most adverse experiences in study participants who received Gardasil included mild or moderate local reactions, such as pain or tenderness at the site of injection.
The manufacturer Merck & Co. Inc. of Whitehouse Station, N.J., has agreed to conduct additional studies to further evaluate general safety and long-term effectiveness. Merck also will monitor the pregnancy outcomes of women who receive Gardasil while unknowingly pregnant. Also, the manufacturer has an ongoing study to evaluate the safety and effectiveness of Gardasil in males.