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Researchers are taking a hard look at the forgotten half of the transmission equation of human papillomavirus (HPV). Investigators are recruiting 3,000 healthy men, ages 18 to 44, in the United States, Mexico, and Brazil to determine men’s roles in spreading the sexually transmitted organism, which is linked to cervical cancer in women.
Anna Giuliano, PhD, a professor of interdisciplinary oncology at the University of South Florida College of Medicine and a program leader at the H. Lee Moffitt Cancer Center & Research Institute, both in Tampa, is heading the multinational investigation, which is funded through a $10 million grant from the National Institutes of Health. Study subjects will be followed every six months for four years at study sites in Tampa; Cuernavaca, Mexico; and São Paulo, Brazil.
According to the Centers for Disease Control and Prevention, at least half of all sexually active men and women acquire genital HPV infection at some point in their lives.1 However, most who have such an infection are unaware of it because the virus lives in the skin or mucous membranes and usually causes no symptoms.
If symptoms do appear, they usually are in the form of genital warts, soft pink or flesh-colored swellings. Warts can be raised or flat, single or multiple, small or large, and can appear on the vulva, in or around the vagina or anus, on the cervix, and on the penis, scrotum, groin, or thigh. (Get more information on counseling patients with HPV; see the latest edition of the Washington, DC-based Association of Reproductive Health Professionals’ publication, Health & Sexuality. Go to the organization’s web site, www.arhp.org, and click on "Health & Sexuality: Cervical Cancer Prevention and HPV DNA Testing.")
Exposure to HPV has significant health implications, particularly for women. Some strains of the virus, including HPV-16 and HPV-18, can trigger cancers of the cervix. Researchers believe HPV causes more than 90% of cervical cancer in the United States.2 Such disease continues to be a threat to women: About 10,370 cases of invasive cervical cancer will be diagnosed in the United States in 2005, according to the American Cancer Society (ACS).3 About 3,710 women will die from the disease in 2005, the society estimates.3
"The biggest obstacle is whether men will be interested in this study," says Giuliano. "If men are committed to making a difference in this issue, the study can succeed."
Is vaccine on the way?
A vaccine against HPV may hold the key to stemming its spread. Through development of recombinant DNA techniques, researchers have been able to produce viruslike particles that mirror the chemical structure of proteins found on the outer coat of HPV. These particles are tested for their ability to trigger an immune response, which signals viability as a potential vaccine candidate.
Merck & Co. in Whitehouse Station, NJ, is expected to file in the second half of 2005 for Food and Drug Administration approval of its multivalent vaccine, Gardasil. The vaccine is aimed at types 6, 11, 16, and 18 of HPV. Research of a component monovalent vaccine has shown effectiveness in reducing HPV incidence.4,5 In a study of 2,391 women ages 16-23, the monovalent vaccine was 100% effective in preventing the development of HPV 16-related high-grade cervical pre-cancer, the immediate precursor to invasive cervical cancer.5
Another vaccine, under development by GlaxoSmithKline (GSK) Biologicals in Rixensart, Belgium, is the focus of a large-scale Phase III study. Investigators at more than 90 sites in 14 countries are enrolling approximately 13,000 young women ages 15-25 in the four-year study of the vaccine. The investigational vaccine contains viruslike particles for HPV types 16 and 18, plus a substance called AS04, a novel proprietary adjuvant under development by GSK Biologicals in collaboration with Corixa Corporation of Seattle that increases the immune system’s response to a vaccine.
Researchers conducted a double-blind, controlled trial of the vaccine in which 1,113 young women in the United States, Canada, and Brazil were randomized to receive three doses formulated with AS04 adjuvant or placebo. Results indicate the vaccine prevented most HPV-16 and HPV-18 infections, as well as most abnormal Pap smears and cervical lesions associated with HPV-16 and HPV-18.6
1. Centers for Disease Control and Prevention. Genital HPV Infection. Atlanta; Dec. 2, 2004. Accessed at: www.cdc.gov/std/HPV/STDFact-HPV.htm.
2. National Cancer Institute. Research on Cervical Cancer Vaccines. Nov. 11, 2004. Accessed at: www.nci.nih.gov.
3. American Cancer Society. What Are the Key Statistics About Cervical Cancer? Atlanta; January 2005. Accessed at: www.cancer.org/docroot/CRI/content/CRI_2_4_1X_What_are_the_key_statistics_for_cervical_cancer_8.asp?sitearea=.
4. Koutsky LA, Ault KA, Wheeler CM, et al. A controlled trial of a human papillomavirus type 16 vaccine. N Engl J Med 2002; 347:1,645-1,651.
5. Mao C. Prophylactic human papillomavirus (HPV) 16 virus-like particle vaccine prevents HPV 16-related cervical intraepithelial neoplasia (CIN) 2-3. Presented at the 44th Interscience Conference on Antimicrobial Agents and Chemotherapy. Washington, DC; November 2004.
6. Harper DM, Franco EL, Wheeler C, et al. Efficacy of a bivalent L1 virus-like particle vaccine in prevention of infection with human papillomavirus types 16 and 18 in young women: A randomised controlled trial. Lancet 2004; 364:1,757-1,765.