Science eyes HPV vaccine use in men — Will shot be approved for U.S. males?
Vaccine prevented 90% of external genital lesions caused by 4 HPV types
Family planning clinicians have become familiar with providing Gardasil (Merck & Co.), the quadrivalent vaccine for human papillomavirus (HPV), to young women. Will their practice extend to include young men if the vaccine is approved by the Food and Drug Administration (FDA)?
The FDA has accepted Merck's supplemental Biologics License Application for Gardasil for use in boys and men ages 9 to 26 for the prevention of external genital lesions caused by HPV types 6, 11, 16, and 18, says Jennifer Allen, Merck spokeswoman. The company expects to hear back from the FDA this fall, she states. Results from a Phase III study in men ages 16 to 26 indicate that the vaccine prevented 90% of external genital lesions caused by types 6, 11, 16, and 18 of HPV.1
The Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention (CDC) is set to review the cost-effectiveness of male vaccination with the quadrivalent vaccine. How does cost-effectiveness factor into the equation when examining potential use of such a vaccine? As for all vaccines, ACIP will review a variety of data when considering HPV vaccine recommendations for males, including vaccine efficacy, immunogenicity and safety, epidemiology and burden of disease, and cost-effectiveness, explains Lauri Markowitz, MD, a CDC medical epidemiologist.
"Cost-effectiveness analyses provide helpful information for ACIP deliberations and are one of several factors considered," she reports. "There is no absolute level of cost-effectiveness that is required before recommendations can be made."
ACIP's input plays an important factor in the potential use of the vaccine, says Khalil Ghanem, MD, PhD, assistant professor of medicine and associate fellowship program director in the Division of Infectious Diseases at Johns Hopkins University School of Medicine. While ACIP will not make recommendations unless the vaccine gets FDA approval, its final consideration plays an important role in vaccine use, he explains.
If the committee does not endorse use of the shot in males, the uptake of the vaccine in that population will be significantly hindered because the federally funded Vaccines for Children (VFC) program might not pick it up, says Ghanem. VFC provides funding for children ages 18 years and younger who cannot afford to pay for vaccines; the program covers funding for almost 50% of children's vaccinations in the United States, Ghanem states. If the ACIP endorses a vaccine, the VFC is obliged to include it in its coverage. If the committee does not endorse the vaccine, many insurance companies will not cover its cost, he explains. The vaccine is given in three injections over six months. The series costs about $360.
"In other words, if FDA approves it, but ACIP does not endorse it, most people who will get the vaccine are those who can pay for it out of pocket," Ghanem notes. "That would mean a very small number of people."
Robert Hatcher, MD, MPH, professor of obstetrics and gynecology at Emory University in Atlanta, makes the following prediction: "If public health agencies fail to actively endorse a vaccine that is proven to be effective against HPV infection, the storm of criticism from feminists, like me, who are fully aware that there are men whose reproductive health activities cause cancer in women, is going to be strident and relentless."
Why immunize men?
There are probably two good reasons to think about HPV vaccination in men, says Joel Palefsky, MD, professor of medicine at the University of California San Francisco. Palefsky is one of the principal leaders of the study of Gardasil's use in men.
"The first is that men are the way that the virus spreads to women, and if one can improve or reduce the rates of HPV infection in the male population, it has the benefit of protecting unvaccinated women," he explains.
This technique is known as "herd immunity." If large numbers of girls and women do not obtain HPV immunization, then vaccination of men and boys could play a significant role in lowering infection rates among males and females. "If we were dealing with a situation where 100% of eligible women were vaccinated, then it wouldn't be much of a factor," Palefsky observes. "But that's not the reality."
A second reason for immunization in males is that men actually get disease through HPV themselves and would benefit in reduction of such diseases, just as women do, he states. Gardasil use in males is designed to protect against genital warts and less common HPV-related malignancies, such as penile and anal cancer, as well as cancer of the mouth and throat.2 The virus causes at least 250,000 new cases of genital warts and an estimated 7,500 cancers in males each year, and it causes about 1,000 deaths.2
Another consideration for HPV immunization in men is for men who have sex with men and therefore would not benefit from female vaccination, notes Palefsky. Palefsky and research associates recently presented data indicating that the quadrivalent HPV vaccine is effective in reducing the burden of anogenital HPV infection and external genital lesions in young men who have sex with men.3
Researchers at Roswell Park Cancer Institute in Buffalo, NY, are strongly advocating a national discussion about the need to vaccinate young men and women against HPV 16 to prevent head and neck cancers. Over the past 10 years, members of the facility's head and neck department have seen a threefold increase in the number of throat cancers. Researchers began testing all head and neck tumors treated at the comprehensive cancer center for the presence of HPV DNA in 2007, says Saurin Popat, MD, FRCSC, FACS, attending surgeon in head & neck and plastic & reconstructive surgery at the facility.
The decision to test all tumors was made based on the significant prevalence of HPV 16 in cancers of the oropharynx (tonsil and base of tongue) of 50%-60% of the retrospective studies conducted by the Buffalo facility, and the known presence of HPV-16 in other head and neck sites, explains Popat. Researchers are compiling a database to develop a full picture of the degree of HPV-16 infections associated with head and neck mucosal squamous cell cancers, he states. "If the vaccine in use [Gardasil] and the one[s] in development are able to minimize the long-term persistence of HPV 16 in the bodies of men and women, then perhaps in the decades to come, HPV-16 associated head and neck squamous cell carcinomas, which account for 50%-60% of cancers in the oropharynx, would be reduced by that percentage," says Popat. "This would be a very successful public health outcome for an initiative that recommends vaccinations for young women and men."
Will men line up?
If the vaccine is approved for use in men, what will draw them to receive the shot? Results from a new study indicate that informing men that an HPV shot also would help protect their female partners against developing cervical cancer did not increase their interest in getting the vaccine.4
To conduct the study, investigators randomly divided 356 male college students into groups and gave one group a self-protection message that focused on the benefits of HPV vaccination for men and the other a partner-protection message that focused on the benefits of HPV vaccination for men and their female partners. Participants were asked to rate, on a scale of 1 to 6, the likelihood that they would get the vaccine, with 1 equaling "very unlikely" and 6 equaling "very likely."
Researchers report there was little difference between the groups, with both expressing only moderate interest in getting the vaccine. Those who received the self-protection message had a mean response of 3.9 on the 6-point scale, while the mean response from the group who got the partner-protection message was 3.8. Men who identified themselves as being in a committed relationship also did not indicate a higher degree of interest in the vaccination, researchers note.4
What might propel men to get vaccinated? In a study of some 500 men, the main reasons for wanting the vaccine included a desire to stay healthy (67.4%); prevention of cancer in sexual partner(s) (52.9%); prevention of anal, penile, and head and neck cancer (41%); fear of cancer (33.4%); and prevention of genital warts (32.8%).5 "Although many men want to receive the HPV vaccine, more remain undecided," state the researchers. "Pending favorable safety and efficacy results from a clinical trial for men, substantial factual education will likely convince many ambivalent men to receive the HPV vaccine."
References
- Palefsky J, Giuliano A on behalf of the Male Quadrivalent HPV Vaccine Efficacy Trial Study Group. Efficacy of the quadrivalent HPV vaccine against HPV 6/11/16/18-related genital infection in young men. Presented at the European Research Organization on Genital Infection and Neoplasia International Multidisciplinary Conference. Nice, France; November 2008.
- Stein R. A vaccine debate once focused on sex shifts as boys join the target market. Washington Post, March 26, 2009:A01.
- Palefsky J, Giuliano A. Quadrivalent HPV vaccine efficacy in men having sex with men. Presented at the 25th International Papillomavirus Conference. Malmö, Sweden; May 2009.
- Gerend MA, Barley J. Human papillomavirus vaccine acceptability among young adult men. Sex Transm Dis 2009; 36:58-62.
- Ferris DG, Waller JL, Miller J, et al. Men's attitudes toward receiving the human papillomavirus vaccine. J Low Genit Tract Dis 2008; 12:276-281.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content