Eliav Barr1, Lisa M. Lupinacci
1, Kathrin U. Jansen
2, Kevin A. Ault
3, Cosette Wheeler
4, Darron R. Brown
5, Frances A. Alvarez
1, and Laura A. Koutsky
6. (1) Biologics Clinical Research, Merck Research Laboratories, POB 4 141C, West Point, PA, USA, (2) Vaccine and Cell Biology, Merck Research Laboratories, POB 4, West Point, PA, USA, (3) Department of Obstetrics and Gynecology, University of Iowa, Iowa City, IA, USA, (4) Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM, USA, (5) Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA, (6) Epidemiology, University of Washington, Seattle, WA, USA
KEYWORDS:
Human Papillomavirus, Cervical Cancer, Virus-like Particle Vaccine, Adolescent Vaccination
BACKGROUND:
About 20% of sexually-active adults become infected with HPV16. Although most infections resolve without sequelae, some will progress to anogenital cancer.
OBJECTIVE:
To determine the efficacy of a prophylactic HPV16 vaccine as proof of concept for the development of a multivalent vaccine.
METHOD:
2,392 16 to 23 year old women were enrolled in a double-blind, multicenter clinical trial. Women were randomized to receive a 3-dose regimen (0, 2, and 6 months) of either 40 mcg of HPV16 L1 VLP vaccine or placebo. Cervicovaginal samples for HPV DNA, sera for anti-HPV, and Pap tests were obtained at baseline and every 6 months. Referral to colposcopy/biopsy was determined by protocol-specified criteria. Biopsy tissue was evaluated for cervical intraepithelial neoplasia (CIN) and analyzed by PCR for HPV16 DNA. The primary endpoint was detection of HPV16 DNA in cervicovaginal samples during at least 2 consecutive visits (persistent HPV16 infection).
RESULT:
Of the 2,392 subjects, 1,533 HPV16-naive subjects who were not protocol violators (identified prior to unblinding) were followed for a median of 17.4 months after completing the vaccination regimen. The incidence of persistent HPV16 infection was 3.8/100 subject-years at risk (SYR) in the placebo group and 0.0/100 SYR in the vaccine group (efficacy 100%, 95% confidence interval 90%, 100%, p<0.001). All 41 cases of persistent HPV 16 infection, including 9 cases of HPV16-related CIN, occurred among placebo recipients.
CONCLUSION:
In this study, administration of HPV16 L1 VLP vaccine prevented HPV16 infection and development of HPV16-related CIN.
LEARNING OBJECTIVES:
This study was the first demonstration of efficacy for a prophylactic HPV vaccine. Future studies to evaluate the impact of a quadrivalent HPV (Types 6, 11, 16, 18) L1 VLP vaccine on risk of CIN 2/3 and genital warts are underway.
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