Evaluation of quadrivalent HPV 6/11/16/18 vaccine efficacy against cervical and anogenital disease in subjects with serological evidence of prior vaccine type HPV infection

Clinical and laboratorial study of HPV infection in men infected with HIV

OBJECTIVES

To determine the prevalence of precursor lesions of penile cancer, to establish the concordance of diagnostic techniques (PCR, Hybrid Capture (HC) and peniscopy with acetic acid 5%) in the diagnosis of Human Papilloma Virus (HPV) of the penis of men infected with HIV and to evaluate the influence of the immune status.

PATIENTS, METHODS AND RESULTS

276 men were studied, with a median age of 34.6 years. Prevalence of High Risk HPV, Low Risk HPV and infection with both, according to HC, was 43%, 32% and 22%, respectively. PCR showed 50% of positivity for HPV DNA. Peniscopy was positive in 27% of individuals. Peniscopy showed good specificity and low sensitivity for the detection of penile HPV, and low concordance with PCR. Men with white lesions had a 3.6 higher relative risk of positivity for HPV. The most common clinical lesion observed was vegetation, identified in 29% of patients. PCR and HC techniques showed high sensitivity for HPV DNA and there was an excellent correlation between them. Immunosuppressed individuals with CD4 < 200 cells/mm(3) had the highest prevalence of premalignant lesions that were observed in 10% of the studied individuals.

CONCLUSIONS

Peniscopy was important for identification and treatment of subclinical lesions. PCR and HC techniques were sensitive methods for the detection of HPV DNA with high concordance. Severely immunosuppressed individuals showed a higher prevalence of pre-malignant lesions of the penis.

A review of clinical trials of human papillomavirus prophylactic vaccines

End of study analyses of the phase III trials of prophylactic human papillomavirus (HPV) virus-like particle (VLP) vaccines in young women are now largely completed. Two distinct vaccines were evaluated, Gardasil(®) (Merck & Co., Whitehouse Station, NJ USA) a quadrivalent vaccine containing VLPs of types 6, 11, 16 and 18 and Cervarix(®) (GlaxoSmithKline Biologicals, Rixensart, Belgium), a bivalent vaccine containing VLPs of types 16 and 18. Both vaccines exhibited excellent safety and immunogenicity profiles. The vaccines also demonstrated remarkably high and similar efficacy against the vaccine-targeted types for a range of cervical endpoints from persistent infection to cervical intraepithelial neoplasia grade 3 (CIN3) in women naïve to the corresponding type at the time of vaccination. However, protection from incident infection or disease from non-vaccine types was restricted, and the vaccines had no effect on prevalent infection or disease. Gardasil(®) also demonstrated strong protection against genital warts and vulvar/vaginal neoplasia associated with the vaccine types. In other trials, Gardasil(®) protected mid-adult women from incident infection and CIN caused by the vaccine types and protected men for incident infection, genital warts and anal intraepithelial neoplasia by the vaccine types. Cervarix(®) protected against vaccine-targeted anal infections in women in an end of study evaluation. For practical reasons, efficacy studies have not been conducted in the primary target populations of current vaccination programs, adolescent girls and boys. However, immunogenicity bridging studies demonstrating excellent safety and strong immune responses in adolescence, coupled with the documentation of durable antibody responses and protection in young adults, leads to an optimistic projection of the effectiveness of the vaccines in adolescent vaccination programs. Taken together, the excellent clinical trial results strongly support the potential of the vaccines as high value public health interventions and justify their widespread implementation to prevent anogenital HPV infections and their associated neoplasia. This article forms part of a special supplement entitled "Comprehensive Control of HPV Infections and Related Diseases" Vaccine Volume 30, Supplement 5, 2012.

Human papillomavirus vaccine uptake, knowledge and attitude among 10th grade students in Berlin, Germany, 2010

PURPOSE

Since March 2007, the Standing Committee on Vaccination (STIKO) recommends HPV vaccination for all 12-17 y-old females in Germany. In the absence of an immunization register, we aimed at assessing HPV-vaccination coverage and knowledge among students in Berlin, the largest city in Germany, to identify factors influencing HPV-vaccine uptake.

METHODS

Self-administered questionnaires were distributed to 10th grade school students in 14 participating schools in Berlin to assess socio-demographic characteristics, knowledge, and statements on vaccinations. Vaccination records were reviewed. Multivariable statistical methods were applied to identify independent predictors for HPV-vaccine uptake among female participants.

RESULTS

Between September and December 2010, 442 students completed the questionnaire (mean age 15.1; range 14-19). In total 281/442 (63.6%) students specified HPV correctly as a sexually transmitted infection. Of 238 participating girls, 161 (67.6%) provided their vaccination records. Among these, 66 (41.0%) had received the recommended three HPV-vaccine doses. Reasons for being HPV-unvaccinated were reported by 65 girls: Dissuasion from parents (40.2%), dissuasion from their physician (18.5%), and concerns about side-effects (30.8%) (multiple choices possible). The odds of being vaccinated increased with age (Odds Ratio (OR) 2.19, 95% Confidence Interval (CI) 1.16, 4.15) and decreased with negative attitude toward vaccinations (OR = 0.33, 95%CI 0.13, 0.84).

CONCLUSIONS

HPV-vaccine uptake was low among school girls in Berlin. Both, physicians and parents were influential regarding their HPV-vaccination decision even though personal perceptions played an important role as well. School programs could be beneficial to improve knowledge related to HPV and vaccines, and to offer low-barrier access to HPV vaccination.

Human papillomavirus vaccination in low-resource countries: lack of evidence to support vaccinating sexually active women

Vaccines against the human papillomaviruses (HPV) that cause around 70% of cervical cancer cases worldwide are highly efficacious when administered before infection with the viruses, which occurs soon after initiation of sexual activity. Despite recommendations from key public health bodies that the primary target population for HPV vaccination should be young adolescent girls, numerous articles have suggested widening the target age group to include older adolescent girls and adult women. These articles cite evidence of efficacy and cost-effectiveness when making recommendations, and they rarely take into account the difficult resource-allocation issues faced by decision makers in low-income countries. Authors and sponsors of these articles are usually from high-income countries and sometimes include vaccine manufacturers. This review discusses the strengths and weaknesses of several types of evidence offered by these papers in support of vaccination of a broad age range of girls and women. It concludes that the greatest public health benefit and value for resources will come from vaccinating girls before sexual debut and exposure to HPV, particularly in low-resource areas.

Human papillomavirus 16 L1-E7 chimeric virus like particles show prophylactic and therapeutic efficacy in murine model of cervical cancer

Cervical cancer is found to be associated with human papillomavirus (HPV) infection, with HPV16 being the most prevalent. An effective vaccine against HPV can thus, be instrumental in controlling cervical cancer. An ideal HPV vaccine should aim to generate both humoral immune response to prevent new infection as well as cell-mediated immunity to eliminate established infection. In this study, we have generated a potential preventive and therapeutic candidate vaccine against HPV16. We expressed and purified recombinant HPV16 L1(ΔN26)-E7(ΔC38) protein in E. coli which was assembled into chimeric virus like particles (CVLPs) in vitro. These CVLPs were able to induce neutralizing antibodies and trigger cell-mediated immune response, in murine model of cervical cancer, exhibiting antitumor efficacy. Hence, this study has aimed to provide a vaccine candidate possessing both, prophylactic and therapeutic efficacy against HPV16 associated cervical cancer.

Cervical, anal and oral HPV in an adolescent inner-city health clinic providing free vaccinations

Objectives

Published human papillomavirus (HPV) vaccine trials indicate efficacy is strongest for those naive to the vaccine-types. However, few high-risk young women have been followed and cervical HPV has been the predominant outcome measure.

Methods

We collected cervical and anal swabs, as well as oral rinse specimens from 645 sexually active inner-city young females attending a large adolescent health-clinic in New York City that offers free care and HPV vaccination. Specimens were tested for HPV-DNA using a MY09/MY11-PCR system. Type-specific prevalence of HPV at each anatomic site was compared for individuals by vaccination dose using generalized estimating equation logistic regression models.

Results

The majority of subjects reported being of non-Caucasian (92%) and/or Hispanic ethnicity (61%). Median age was 18 years (range:14–20). All had practiced vaginal sex, a third (33%) practiced anal sex, and most (77%) had also engaged in oral sex. At enrollment, 21% had not received the vaccine and 51% had received three doses. Prevalent HPV infection at enrollment was detected in 54% of cervical, 42% of anal and 20% of oral specimens, with vaccine types present in 7%, 6% and 1% of specimens, respectively. Comparing prevalence for vaccine types, the detection of HPV in the cervix of vaccinated compared to unvaccinated adolescents was significantly reduced: HPV6/11 (odds ratio [OR] = 0.19, 95%CI:0.06–0.75), HPV16 (OR = 0.31, 95%CI:0.11–0.88) and HPV18 (OR = 0.14, 95%CI:0.03–0.75). For anal HPV, the risk of detecting vaccine types HPV6/11 (OR = 0.27, 95%CI:0.10–0.72) and HPV18(OR = 0.12, 95%CI:0.01–1.16) were significantly reduced for vaccinated adolescents however, the risk for HPV16 was not significantly decreased (OR = 0.63, 95%CI:0.18–2.20).

Conclusion

HPV Prevalence is extremely high in inner-city female adolescents. Administration of the HPV vaccine reduced the risk for cervical HPV; however continued follow-up is required to assess the protection for HPV at all sites in young women with high exposure.

Prevalence of human papillomavirus (HPV) infections in sexually active adolescents and young women in England, prior to widespread HPV immunisation

INTRODUCTION

The introduction of an HPV immunisation programme in England should result in a significant reduction in the prevalence of vaccine type infections in young women. Here we describe type-specific HPV prevalence in three samples of the young female population in England, prior to the beginning of mass immunisation in 2008.

METHODS

Residual vulva-vaginal swab samples from females aged under 25 years undergoing chlamydia testing as part of the National Chlamydia Screening Programme (NCSP) or Prevention of Pelvic Infection (POPI) trial were collected from sites across England, together with available demographic and sexual behaviour data. Residual samples were screened for HPV infection using the Hybrid Capture 2 (hc2) HPV DNA Test, including the high-risk (HR) and low-risk (LR) probes. Hc2 positive samples were genotyped using the Roche Linear Array (LA) HPV Genotyping Test.

RESULTS

A total of 3829 samples were included: 2369 from 16 to 24 year old NCSP participants, 275 from 13 to 15 year old NCSP participants and 1185 from 16 to 24 year old POPI participants. Variations in HPV prevalence between and within the different samples followed a pattern largely consistent with differences in sexual behaviour. The prevalence of total HR HPV infection, of HPV 16 and/or 18 (16/18) infection and of five HR HPV types closely related to HPV 16/18 (HPV 31, 33, 45, 52 or 58) amongst 16-24 year old NCSP participants was 35% (95% CI 33-37%), 18% (95% CI 16-19%), and 16% (95% CI 14-18%), respectively. Risk of HR HPV infection increased with age during the teen years and was higher in women who reported two or more sexual partners in the last year and in women with chlamydia infection. Approximately half of women with HPV 16/18 infection also had another non-vaccine HR HPV type present.

CONCLUSIONS

Prior to HPV immunisation, there was a high prevalence of HPV infections in the lower genital tract of young, sexually active females in England. The overall, type-specific, and multiple infection prevalence closely reflected age and sexual activity. These data provide a baseline against which the early impact of HPV immunisation on the prevalence of HPV 16/18 and closely related types in young women can be measured, in order to inform immunisation and cervical screening policies.

Spotlight on quadrivalent human papillomavirus (types 6, 11, 16, 18) recombinant vaccine(Gardasil®) in the prevention of premalignant genital lesions, genital cancer, and genital warts in women

Quadrivalent human papilloma virus (HPV) [types 6, 11, 16, 18] recombinant vaccine (Gardasil®; Silgard®) is composed of virus-like particles (VLPs) formed by self-assembly of recombinant L1 capsid protein from each of HPV types 6, 11, 16, and 18. The VLPs are noninfectious, containing no DNA, and are highly immunogenic, inducing high levels of neutralizing antibodies against the particular HPV types when administered to animals or humans. Quadrivalent HPV vaccine is indicated for use from the age of 9 years for the prevention of premalignant genital lesions (cervical, vulvar, and vaginal), cervical cancer, and external genital warts (condyloma acuminata) causally related to certain oncogenic or specific HPV types. In placebo-controlled clinical trials, quadrivalent HPV vaccine administered as three doses over 6 months provided high-level protection against infection or disease caused by the vaccine HPV types over 2-4 years of follow-up in females aged 15-45 years who were naive to the vaccine HPV types. A degree of cross-protection against certain other non-vaccine high-risk HPV types was also observed. The vaccine is not effective against current infection with a vaccine HPV type. Girls or women with current infection with one or more of the vaccine HPV types gained protection from infection or disease caused by the remaining vaccine HPV types and they were also protected against reinfection with the same HPV type after clearance of an infection caused by a vaccine HPV type. High seroconversion rates and high levels of anti-HPV antibodies were observed in all vaccinated individuals of all age ranges from 9 to 45 years. No correlation was found between antibody levels and protective efficacy of the vaccine. Rechallenge with quadrivalent HPV vaccine produced a potent anamnestic humoral immune response. The vaccine is generally well tolerated and is projected to be cost effective in most pharmacoeconomic models. Therefore, quadrivalent HPV vaccine offers an effective means, in combination with screening programs, to substantially reduce the burden of HPV-related precancerous lesions and cancer, particularly cervical cancer, as well as anogenital warts.

Effect of the human papillomavirus (HPV) quadrivalent vaccine in a subgroup of women with cervical and vulvar disease: retrospective pooled analysis of trial data

OBJECTIVES

To determine the effect of human papillomavirus (HPV) quadrivalent vaccine on the risk of developing subsequent disease after an excisional procedure for cervical intraepithelial neoplasia or diagnosis of genital warts, vulvar intraepithelial neoplasia, or vaginal intraepithelial neoplasia.

DESIGN

Retrospective analysis of data from two international, double blind, placebo controlled, randomised efficacy trials of quadrivalent HPV vaccine (protocol 013 (FUTURE I) and protocol 015 (FUTURE II)).

SETTING

Primary care centres and university or hospital associated health centres in 24 countries and territories around the world.

PARTICIPANTS

Among 17,622 women aged 15-26 years who underwent 1:1 randomisation to vaccine or placebo, 2054 received cervical surgery or were diagnosed with genital warts, vulvar intraepithelial neoplasia, or vaginal intraepithelial neoplasia.

INTERVENTION

Three doses of quadrivalent HPV vaccine or placebo at day 1, month 2, and month 6.

MAIN OUTCOME MEASURES

Incidence of HPV related disease from 60 days after treatment or diagnosis, expressed as the number of women with an end point per 100 person years at risk.

RESULTS

A total of 587 vaccine and 763 placebo recipients underwent cervical surgery. The incidence of any subsequent HPV related disease was 6.6 and 12.2 in vaccine and placebo recipients respectively (46.2% reduction (95% confidence interval 22.5% to 63.2%) with vaccination). Vaccination was associated with a significant reduction in risk of any subsequent high grade disease of the cervix by 64.9% (20.1% to 86.3%). A total of 229 vaccine recipients and 475 placebo recipients were diagnosed with genital warts, vulvar intraepithelial neoplasia, or vaginal intraepithelial neoplasia, and the incidence of any subsequent HPV related disease was 20.1 and 31.0 in vaccine and placebo recipients respectively (35.2% reduction (13.8% to 51.8%)).

CONCLUSIONS

Previous vaccination with quadrivalent HPV vaccine among women who had surgical treatment for HPV related disease significantly reduced the incidence of subsequent HPV related disease, including high grade disease.

TRIAL REGISTRATIONS

NCT00092521 and NCT00092534.

Randomized trial of HPV4 vaccine assessing the response to HPV4 vaccine in two schedules among Peruvian female sex workers

Two hundred female sex workers (FSWs) in Lima, Peru were randomized to receive HPV4 vaccine in the standard (0, 2, 6 months) or a modified schedule (0, 3, 6 months). One hundred and eighty four (92%) participants completed 3 doses of vaccine. Baseline seropositive rates were 58% for HPV6, 22.5% for HPV11, 41.5% for HPV16, and 13% for HPV18. The final geometric mean antibody titer (GMT) following vaccination was significantly greater for women who were seropositive at baseline compared to seronegative women: HPV6 (GMT ratio=2.3, p<0.01), HPV11 (GMT ratio=2.7, p<0.01), HPV16 (GMT ratio=1.3, p=0.04), and HPV18 (GMT ratio=2.4, p<0.01). Antibody titers in the modified schedule were not inferior to those in the standard schedule, suggesting the modified schedule may be paired with required STD visits. Although all women benefit from vaccination, administration at a younger age and before sexual debut is needed to achieve maximum protection from vaccine.

Cervical cancer in the human papillomavirus vaccination era

PURPOSE OF REVIEW

To evaluate the potential changes in the epidemiology of cervical cancer based on recently emerged information from mass vaccination programs beyond clinical trials.

RECENT FINDINGS

Limited sensitivity and unequal access to screening have resulted in an imbalance in distribution of the burden of cervical cancer between developed and developing countries, between metropolitan and rural areas in developed countries, and among women from different ethnic groups. In screened populations, there is a relative increase in incidence of cervical cancer in young and elderly women, and an increased proportion of adenocarcinoma. A high coverage of the target population has been achieved in human papillomavirus (HPV) vaccination programs in many countries. After 3 years of mass vaccination of adolescent girls, surveillance data in Australia confirmed a significant reduction in high-grade abnormalities for girls aged 18 years and below.

SUMMARY

HPV vaccination is more feasible than cytology screening for universal implementation across geographic sectors and demographic groups within individual countries and over the world. The high vaccine efficacy should significantly reduce the total burden and unequal distribution of invasive cervical cancer, including adenocarcinoma hitherto observed. These epidemiological changes provoke consideration for appropriate modifications of the current screening program.

Age-specific human papillomavirus antibody and deoxyribonucleic acid prevalence: a global review

PURPOSE

Global data on human papillomavirus (HPV) serological and deoxyribonucleic acid (DNA) prevalence are essential to optimize HPV prophylactic vaccination strategies.

METHODS

We conducted a global review of age-specific HPV antibody and studies with both antibody and DNA prevalence for HPV-16, -18, -6, and -11.

RESULTS

One hundred seventeen studies were included; participants' ages ranged from several hours to >90 years. HPV-16 seroprevalence was generally higher in Africa, Central and South America, and North America, more prevalent among women than among men, and peaked around ages 25-40 years. HPV-18 seroprevalence was generally lower than HPV-16 with a later age peak. Data were limited for HPV-6 and -11, both of which peaked at ages similar to HPV-18. Among 9-26-year-old females, HPV-16 seroprevalence ranged from 0%-31% in North America, 21%-30% in Africa, 0%-23% in Asia/Australia, 0%-33% in Europe, and 13%-43% in Central and South America. HPV-16/-18 DNA prevalence peaked 10-15 years before corresponding HPV-16/-18 antibody prevalence.

CONCLUSIONS

Females within the HPV vaccine-eligible age-group (9-26 years) had a range of dual HPV-16 DNA and serology negativity from 81%-87%, whereas 90%-98% were HPV-16 DNA negative. Serology and DNA data are lacking worldwide for females younger than age 15 years, the prime target group for vaccination.

Population-based human papillomavirus 16, 18, 6 and 11 DNA positivity and seropositivity in Chinese women

To optimize HPV vaccination implementation at the population-level in China, data are needed on age-specific HPV 16, 18, 6 and 11 prevalence. This cross-sectional, population-based study evaluated the age- and type-specific HPV 16, 18, 6 and 11 prevalence of DNA and serum antibodies among women in China. From July 2006 to April 2007, 17-54 year old women from three rural provinces (Xinjiang, Shanxi and Henan) and two cities (Beijing and Shanghai) provided cervical exfoliated cells for HPV DNA and liquid-based cervical cytology (SurePath). High- and low-risk HPV types were detected with HC-II (Qiagen), with genotyping of HPV-positive samples using Linear Array (Roche). HPV 16, 18, 6 and 11 serum antibodies were detected using a Luminex-based, competitive immunoassay (Merck). A total of 4,206 women with DNA and serum antibody results were included. HPV 16 DNA prevalence peaked in women aged 30-34 (4.2%) and 45-49 yr (3.8%), while HPV 18 DNA prevalence peaked at ages 40-44 yr (1.3%). Most women were dually DNA and serum antibody negative: HPV 16 (92.2%), 18 (97.2%), HPV 16 and 18 (90.2%), 6 (92.0%), 11 (96.6%), 6 and 11(89.9%) and HPV 16, 18, 6 and 11 (82.5%). Future national HPV vaccination programs in China should target younger women due to increased exposure to HPV types 16, 18, 6 and 11 with increasing age. Cumulative exposure of HPV may be underreported in this population, as cross-sectional data do not accurately reflect exposure to HPV infections over time.

Behavioral and sociodemographic risk factors for serological and DNA evidence of HPV6, 11, 16, 18 infections

INTRODUCTION

Risk for HPV6/11/16/18 infections in young sexually active, behaviorally low-risk females is not well described and may inform public policy.

METHODS

To assess exposure risk for HPV/6/11/16/18 among 16-23 year old low-risk females, data for 2409 female clinical trial participants were evaluated. Baseline visit self-reported sexual, behavioral and demographic characteristics; and results from HPV genotyping and serology, and other clinical laboratory assays were analyzed. All subjects reported <5 lifetime male sexual partners and no prior abnormal cytology at baseline.

RESULTS

While 98% (2211/2255) were naïve to HPV16 or 18 and 99.6% (2246/2255) were naïve for 1-3 index HPVs, 27% (616/2255) showed antibody, DNA or both for ≥1 index HPV. While 18% (409/2255) tested HPV16- or -18-antibody- or -DNA-positive, only 2% (44/2255) tested positive for both types. Against this high background, other sexually transmitted infections (STIs) were uncommonly detected, suggesting low sexual risk-taking behavior. The adjusted analyses showed race, age, alcohol consumption, current Chlamydia trachomatis (chlamydia) and Trichamonas vaginalis (trichomoniasis), bacterial vaginosis (BV), number of lifetime male sex partners predicted positive index-HPV antibody test results. However, only the number of male sex partners predicted positivity for HPV6/11- and 16/18-DNA, and chlamydia infection predicted positivity for HPV6/11-DNA alone.

CONCLUSIONS

Taken together, type-specific HPV-DNA and -antibody evidence of HPV6/11/16/18 infections among behaviorally low-risk 16-23 year old females is high. Since almost all participants would have benefited by either currently available bivalent or quadrivalent vaccine strategies, delaying vaccination beyond menarche may be a missed opportunity to fully protect young females against HPV6/11/16/18 infections and related dysplasias. Early diagnosis and treatment of chlamydia and trichomonas may be important in HPV pathogenesis.

Use of human papillomavirus vaccines among young adult women in the United States: an analysis of the 2008 National Health Interview Survey

BACKGROUND

The Centers for Disease Control and Prevention recommends catch-up administration of human papillomavirus (HPV) vaccines to girls and women ages 13 to 26 who have not been vaccinated previously. In response to debate regarding catch-up vaccination of young adult women, this study examined whether 18- to 26-year-old women most likely to benefit from catch-up vaccination were aware of the HPV vaccine, and initiated the vaccine series by the end of 2008.

METHODS

We used data from the 2008 National Health Interview Survey to assess HPV vaccine awareness and use, and reasons for not vaccinating, among women aged 18-26 years (n = 1583). Sociodemographic, health care access, and health history factors associated with vaccine initiation were assessed using multivariate logistic regression.

RESULTS

Overall, 11.7% of women aged 18-26 years reported receiving at least 1 dose of the HPV vaccine by the end of 2008. In multivariate analyses, younger age, history of previous HPV infection, unmarried status, health insurance, flu shot in the past year, and receipt of 1 or more recommended lifetime vaccines were significantly associated with HPV vaccine initiation. Two-fifths (39.6%) of unvaccinated women were interested in receiving the HPV vaccine (n = 1327). Primary reasons for lack of interest in the vaccine were belief that it was not needed, not knowing enough about it, concerns about safety, and not being sexually active.

CONCLUSION

HPV vaccine coverage among young adult women was low, and lower among the uninsured than the insured. Public financing and care provision programs have the potential to expand vaccine coverage among uninsured women, who are at increased risk of cervical cancer.

Health economics of screening for gynaecological cancers

In this chapter, we summarise findings from recent cost-effectiveness analyses of screening for cervical cancer and ovarian cancer. We begin with a brief summary of key issues that affect the cost-effectiveness of screening, including disease burden, and availability and type of screening tests. For cervical cancer, we discuss the potential effect of human papilloma virus vaccines on screening. Outstanding epidemiological and cost-effectiveness issues are included. For cervical cancer, this includes incorporating the long-term effect of treatment (including adverse birth outcomes in treated women who are of reproductive age) into cost-effectiveness models using newly available trial data to identify the best strategy for incorporating human papilloma virus tests. A second issue is the need for additional data on human papilloma virus vaccines, such as effectiveness of reduced cancer incidence and mortality, effectiveness in previously exposed women and coverage. Definitive data on these parameters will allow us to update model-based analyses to include more realistic estimates, and also potentially dramatically alter our approach to screening. For ovarian cancer, outstanding issues include confirming within the context of a trial that screening is effective for reducing mortality and incorporating tests with high specificity into screening into screening algorithms for ovarian cancer.

Next Generation Cancer Protection: The Bivalent HPV Vaccine for Females

Nearly a half a million women throughout the world develop cervical cancer every year Parkin and Bray ("Chapter 2. The burden of HPVrelated cancers," Vaccine, vol. 24, no. 3, pp. S11-S25, 2006); 80% of these women are in countries without a quality-assured cytology screening program. It is in this setting that Cervarix could reduce the incidence of cervical cancer to about 9.5/100,000 women. New evidence indicates that this might be able to be accomplished with a single dose of Cervarix, a great advantage to public health implementation programs Kreimer et al. ("Proof-of-principle evaluation of the efficacy of fewer than three doses of a bivalent HPV16/18 vaccine, The Journal of the National Cancer Institute, vol. 103, no. 19, pp. 1444-1451, 2011). In countries with screening programs, adenocarcinoma is the most difficult to detect and treat with later-stage presentation and higher mortality Smith et al. ("The rising incidence of adenocarcinoma relative to squamous cell carcinoma of the uterine cervix in the United States-a 24-year population-based study," Gynecologic Oncology, vol. 78, no. 2, pp. 97-105, 2000) and Gunnell et al. ("A longitudinal Swedish study on screening for squamous cell carcinoma and adenocarcinoma: evidence of effectiveness and overtreatment," Cancer Epidemiology Biomarkers and Prevention, vol. 16, no. 12, pp. 2641-2648, 2007). With additional cross-protection to HPV 31, 33, and 45 and protection against HPV 16 and 18 lasting at least 9.4 years, Cervarix may reduce adenocarcinomas in screened populations by more than 90%. This paper will detail the evidence about the efficacy, immunogenicity, and safety of Cervarix in the studied populations contrasting public health goals with individual health options.

The efficacy and safety of the quadrivalent human papillomavirus 6/11/16/18 vaccine gardasil

Human papillomavirus (HPV) infection causes cervical cancer, a significant portion of anal, genital, and oropharyngeal cancers, genital warts, and recurrent respiratory papillomatosis. In June 2006, a quadrivalent HPV-6/11/16/18 vaccine (Gardasil/Silgard) was licensed in the United States, and subsequently in the European Union (September 2006). It has since been approved in 121 countries, with >74 million doses distributed globally as of March 2011. As the incidence of HPV infection peaks 5-10 years after the onset of sexual activity, preadolescents and adolescents represent an appropriate target group to implement HPV vaccination programs so as to achieve the maximal public health benefit. In this article, we provide an overview of the prophylactic efficacy of the vaccine in young women who were found to be negative to at least one of the four vaccine HPV types, thus approximating sexually naive adolescents. Because adolescents are also at high risk for other infections which are preventable by currently available vaccines, the development of concurrent immunization strategies may lead to better compliance, thereby contributing to the overall goal of protection against preventable diseases. We also summarize concomitant administration studies with meningococcal, diphtheria, tetanus, and pertussis vaccines, which were conducted in adolescents aged 9-15 years. Prophylactic efficacy in other populations (males aged 16-26 years) is also summarized along with long-term safety and efficacy studies.

Efficacy of the human papillomavirus (HPV)-16/18 AS04-adjuvanted vaccine in women aged 15-25 years with and without serological evidence of previous exposure to HPV-16/18

In the Phase III PATRICIA study (NCT00122681), the human papillomavirus (HPV)-16/18 AS04-adjuvanted vaccine (Cervarix(®), GlaxoSmithKline Biologicals) was highly efficacious against HPV-16/18 infections and precancerous lesions in women HPV-16/18 deoxyribose nucleic acid (DNA) negative and seronegative at baseline. We present further data on vaccine efficacy (VE) against HPV-16/18 in the total vaccinated cohort including women who may have been exposed to HPV-16/18 infection before vaccination. In women with no evidence of current or previous HPV-16/18 infection (DNA negative and seronegative), VE was 90.3% (96.1% confidence interval: 87.3-92.6) against 6-month persistent infection (PI), 91.9% (84.6-96.2) against cervical intraepithelial neoplasia (CIN)1+ and 94.6% (86.3-98.4) against CIN2+ [97.7% (91.1-99.8) when using the HPV type assignment algorithm (TAA)]. In women HPV-16/18 DNA negative but with serological evidence of previous HPV-16/18 infection (seropositive), VE was 72.3% (53.0-84.5) against 6-month PI, 67.2% (10.9-89.9) against CIN1+, and 68.8% (-28.3-95.0) against CIN2+ [88.5% (10.8-99.8) when using TAA]. In women with no evidence of current HPV-16/18 infection (DNA negative), regardless of their baseline HPV-16/18 serological status, VE was 88.7% (85.7-91.1) against 6-month PI, 89.1% (81.6-94.0) against CIN1+ and 92.4% (84.0-97.0) against CIN2+ [97.0% (90.6-99.5) when using TAA]. In women who were DNA positive for one vaccine type, the vaccine was efficacious against the other vaccine type. The vaccine did not impact the outcome of HPV-16/18 infections present at the time of vaccination. Vaccination was generally well tolerated regardless of the woman's HPV-16/18 DNA or serological status at entry.

Next-generation treatment strategies for human papillomavirus-related head and neck squamous cell carcinoma: where do we go?

Oncogenic human papillomavirus (HPV) is currently recognised as a major risk factor for the development of head and neck squamous cell carcinomas (HNSCC). HPV is mostly detected in tumours arising from the oropharynx and more specifically from the tonsil. HPV-related tumours display clinical and molecular characteristics that are distinct from HPV-unrelated tumours, which are generally induced by alcohol and tobacco abuse. Detection of biologically active HPV in HNSCC has prognostic relevance, which warrants the separate classification of HPV-induced tumours and is a prerequisite for further optimisation of treatment protocols for this distinct group. Current guidelines for the treatment of oropharyngeal squamous cell carcinoma (OPSCC) have not incorporated specific treatment modalities for HPV-related tumours. The development of such treatment options is still in a preclinical phase or in early clinical trials. Recent data on treatment response of OPSCC have been obtained by retrospectively analysing HPV-status and indicate that patients with HPV-related tumours show a favourable prognosis, independent of the type of treatment. These patients may benefit from de-intensified treatment, which should be assessed in prospective clinical trials. The development and future use of new antiviral and immunomodulatory therapeutics may be instrumental in this approach to improve survival rates and decrease disease-and-treatment-related morbidity. In this review we will focus on present therapeutic HPV-targeting strategies and discuss future directions for de-intensified treatment of HPV-positive HNSCC.

Paradigm shifting vaccines: prophylactic vaccines against latent varicella-zoster virus infection and against HPV-associated cancer

We compare the design, mechanism of action, and clinical efficacy of two recently licensed paradigm shifting vaccines. Zostavax is the first vaccine licensed to prevent disease in patients already infected with a pathogen, and is contrasted with Gardasil and Cervarix, the first vaccines designed and licensed specifically to prevent cancers.

Prevention and treatment of papillomavirus-related cancers through immunization

Cervical and other anogenital cancers are initiated by infection with one of a small group of human papillomaviruses (HPV). Virus-like particle-based vaccines have recently been developed to prevent infection with two cancer-associated HPV genotypes (HPV16, HPV18) and have been ∼95% effective at preventing HPV-associated disease caused by these genotypes in virus-naive subjects. Although immunization induces virus-neutralizing antibody sufficient to prevent infection, persistence of antibody as measured by current assays does not appear necessary to maintain protection over time. Investigators have not identified a reliable surrogate immunological marker of protection against disease following immunization. The prophylactic vaccines are not therapeutic for existing infection. Trials of HPV-specific immunotherapy have shown some efficacy for existing disease, although animal modeling suggests that a combination of immunization and local enhancement of innate immunity may be necessary for optimal therapeutic outcome. HPV prophylactic vaccines are the first vaccines designed to prevent a human cancer and are the practical outcome of a global collaborative effort between basic and applied scientists, clinicians, and industry.

Effect of Pap smear collection and carrageenan on cervicovaginal human papillomavirus-16 infection in a rhesus macaque model

BACKGROUND

Human papillomavirus (HPV) infection of the genital mucosa is thought to require trauma to the cervicovaginal epithelium. Therefore, we determined whether a cytology specimen collection procedure (Pap smear), which disrupts the epithelium by design, renders the cervix more susceptible to HPV infection in a primate model.

METHODS

In a series of female rhesus macaques, a speculum examination was performed with (n = 8) or without (n = 4) a cytology specimen collection procedure as it is commonly practiced in a gynecology clinic. An internal digital examination was performed after specimen collection using Surgilube (n = 4) or 1% iota-carrageenan, a previously indentified HPV inhibitor (n = 4) as the lubricant. The cervix was then inoculated with HPV16 pseudovirions expressing red fluorescent protein. After 3 days, the reproductive tracts were excised and the cervix was cryosectioned. Sections were analyzed by fluorescent confocal microscopy for the number of red fluorescent protein-positive keratinocytes.

RESULTS

Substantial infection of the ectocervix, the transformation zone, and the endocervix was detected, but only in conjunction with the cytology specimen collection procedure (cytology using Surgilube vs without cytology using Surgilube, mean = 84 infectious events per section vs mean = 0.05 infectious events per section, difference = 84 infectious events per section, 95% confidence interval = 19 to 384 infectious events per section). When the carrageenan gel was substituted for Surgilube for an internal digital examination, the mean number of infectious events decreased (carrageenan gel vs Surgilube, mean = 3.5 events per section vs mean = 84 infectious events per section difference = 81 events per section, 95% confidence interval = 33 to 213 events per section).

CONCLUSIONS

These findings indicate that cytology screening in women might lead to a transient enhancement of susceptibility to HPV infection and that use of a carrageenan-based gel during the examination might mitigate this enhancement.

Impact of an HPV6/11/16/18 L1 virus-like particle vaccine on progression to cervical intraepithelial neoplasia in seropositive women with HPV16/18 infection

The impact of a human papillomavirus (HPV) vaccine on development of cervical intraepithelial neoplasia grade 2-3 or adenocarcinoma in situ (CIN2-3/AIS) in women with ongoing HPV16 or 18 infections prevaccination is reported. Seventeen thousand six-hundred and twenty-two women aged 16-26 were enrolled in 1 of 2 randomized, placebo-controlled, efficacy trials (Protocols 013 and 015). Vaccine or placebo was given at day 1, month 2 and 6. Women were tested for HPV6/11/16/18 DNA and antibodies at day 1. We focus on the subset of women who were seropositive and DNA positive to HPV16 or HPV18 prevaccination. Incidence is expressed as the number of women with an endpoint per 100 person-years-at-risk. In total, 419 vaccine and 446 placebo recipients were both seropositive and DNA positive to HPV16 or HPV18 prevaccination and had at least one follow-up visit. In Protocol 013, the incidence of HPV16/18-related CIN2-3/AIS among these women was 10.9 in the vaccine arm and 7.0 in the placebo arm (vaccine efficacy = -54.9; 95% CI: -181.7, 13.0). In Protocol 015, the incidence of HPV16/18-related CIN2-3/AIS was 5.5 in the vaccine arm and 6.2 in the placebo arm (vaccine efficacy = 12.2%; 95% CI: -29.8, 40.9). These data suggest HPV vaccination neither reduces nor enhances progression to HPV16/18-related high grade cervical lesions, and cervical cytology screening and corresponding management should continue as per local recommendations. Ultimately, population-based surveillance of vaccinated individuals beyond these clinical trials will be required to further address questions regarding the impact of vaccination in women exposed to vaccine HPV types before vaccination.

Quadrivalent human papillomavirus (types 6, 11, 16, 18) recombinant vaccine (Gardasil®): a review of its use in the prevention of premalignant genital lesions, genital cancer and genital warts in women

Quadrivalent human papilloma virus (HPV) [types 6, 11, 16, 18] recombinant vaccine (Gardasil®; Silgard®) is composed of virus-like particles (VLPs) formed by self-assembly of recombinant L1 capsid protein from each of HPV types 6, 11, 16 and 18. The VLPs are noninfectious, containing no DNA, and are highly immunogenic, inducing high levels of neutralizing antibodies against the particular HPV types when administered to animals or humans. Quadrivalent HPV vaccine is indicated for use from the age of 9 years for the prevention of premalignant genital lesions (cervical, vulvar and vaginal), cervical cancer and external genital warts (condyloma acuminata) causally related to certain oncogenic or specific HPV types. In placebo-controlled clinical trials, quadrivalent HPV vaccine administered as three doses over 6 months provided high-level protection against infection or disease caused by the vaccine HPV types over 2-4 years of follow-up in females aged 15-45 years who were naive to the vaccine HPV types. A degree of cross-protection against certain other non-vaccine high-risk HPV types was also observed. The vaccine is not effective against current infection with a vaccine HPV type. Girls or women with current infection with one or more of the vaccine HPV types gained protection from infection or disease caused by the remaining vaccine HPV types and they were also protected against reinfection with the same HPV type after clearance of an infection caused by a vaccine HPV type. High seroconversion rates and high levels of anti-HPV antibodies were observed in all vaccinated individuals of all age ranges from 9 to 45 years. No correlation was found between antibody levels and protective efficacy of the vaccine. Rechallenge with quadrivalent HPV vaccine produced a potent anamnestic humoral immune response. The vaccine is generally well tolerated and is projected to be cost effective in most pharmacoeconomic models. Therefore, quadrivalent HPV vaccine offers an effective means, in combination with screening programmes, to substantially reduce the burden of HPV-related precancerous lesions and cancer, particularly cervical cancer, as well as anogenital warts.

Efficacy and safety of prophylactic vaccines against cervical HPV infection and diseases among women: a systematic review & meta-analysis

Background

We conducted a systematic review and meta-analysis to assess efficacy and safety of prophylactic HPV vaccines against cervical cancer precursor events in women.

Methods

Randomized-controlled trials of HPV vaccines were identified from MEDLINE, Cochrane Central Register of Controlled Trials, conference abstracts and references of identified studies, and assessed by two independent reviewers. Efficacy data were synthesized using fixed-effect models, and evaluated for heterogeneity using I² statistic.

Results

Seven unique trials enrolling 44,142 females were included. The fixed-effect Relative Risk (RR) and 95% confidence intervals were 0.04 (0.01-0.11) and 0.10 (0.03-0.38) for HPV-16 and HPV 18-related CIN2+ in the per-protocol populations (PPP). The corresponding RR was 0.47 (0.36-0.61) and 0.16 (0.08-0.34) in the intention-to-treat populations (ITT). Efficacy against CIN1+ was similar in scale in favor of vaccine. Overall vaccines were highly efficacious against 6-month persistent infection with HPV 16 and 18, both in the PPP cohort (RR: 0.06 [0.04-0.09] and 0.05 [0.03-0.09], respectively), and the ITT cohorts (RR: 0.15 [0.10-0.23] and 0.24 [0.14-0.42], respectively). There was limited prophylactic effect against CIN2+ and 6-month persistent infections associated with non-vaccine oncogenic HPV types. The risk of serious adverse events (RR: 1.00, 0.91-1.09) or vaccine-related serious adverse events (RR: 1.82; 0.79-4.20) did not differ significantly between vaccine and control groups. Data on abnormal pregnancy outcomes were underreported.

Conclusions

Prophylactic HPV vaccines are safe, well tolerated, and highly efficacious in preventing persistent infections and cervical diseases associated with vaccine-HPV types among young females. However, long-term efficacy and safety needs to be addressed in future trials.

HPV prophylactic vaccination: The first years and what to expect from now

New prophylactic HPV vaccines have the power to prevent many HPV infections, thus reducing the burden of HPV-associated diseases. Two vaccines composed of HPV L1 proteins self assembled into virus-like particles (VLPs) have been developed: one containing VLPS of HPV types 6, 11, 16 and 18, while the other vaccine is composed of HPV 16 and 18 VLPs. Large phase II and III clinical trials to assess prophylactic efficacy have been conducted in which both HPV infection endpoints and disease endpoints were evaluated, particularly high-grade cervical intraepithelial neoplasia--CIN2 or CIN3--as well as vulvar and vaginal intraepithelial neoplasias--VIN or VaIN--and genital warts for the quadrivalent vaccine. Very high efficacy rates were observed in different populations that included young women between 16 and 26 years of age, and older (up to 55). More recently, the quadrivalent vaccine has been shown to be efficacious in men to prevent genital and anal infection and disease caused by the types included in the vaccine. Based on demonstrated clinical efficacy and favorable safety profile, HPV prophylactic vaccine are being introduced worldwide aiming the reduction of the morbidity and mortality of tumors caused by HPV. From 2006 when first approved in the USA, hundreds of countries have licensed the HPV vaccines, a significant proportion of which are offering the vaccine to young women in national immunization programs supported by the government. The ultimate goal is to implement worldwide cervical cancer control programs to include HPV vaccination and screening with cytology and HPV DNA testing, particularly in less-developed countries where it is most needed.

Towards a Chlamydia trachomatis vaccine: how close are we?

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections and preventable blindness worldwide. The incidence of chlamydial sexually transmitted infections has increased rapidly and current antibiotic therapy has failed as an intervention strategy. The most accepted strategy for protection and/or control of chlamydial infections is a vaccine that induces both local neutralizing antibodies to prevent infections by the extracellular elementary bodies and a cell-mediated immune response to target the intracellular infection. This article will discuss the challenges in vaccine design for the prevention of chlamydial urogenital infection and/or disease, including selection of target antigens, discussion of effective delivery systems, immunization routes and adjuvants for induction of protective immunity at the targeted mucosal surface whilst minimizing severe inflammatory disease sequelae.

Benefits of vaccinating young adult women with a prophylactic quadrivalent human papillomavirus (types 6, 11, 16 and 18) vaccine

Cervical cancer is a leading cause of cancer-related deaths worldwide. The causal role of human papillomavirus (HPV) infection in the pathogenesis of cervical cancer has prompted the development of vaccines against HPV. The highest risk of HPV infection is in women aged 16-25 years. Almost all young adult women can benefit from HPV vaccination. There is strong epidemiological and clinical support for vaccination programmes that target sexually active women in this age group to prevent HPV infection, and thus avert the development of HPV-related disease. Furthermore, the implementation of HPV vaccination programmes may benefit the development or awareness of cervical cancer prevention strategies and ultimately reduce the burden of cervical cancer and improve cervical cancer control.

Targeted human papillomavirus vaccination of men who have sex with men in the USA: a cost-effectiveness modelling analysis

BACKGROUND

A vaccine targeting human papillomavirus (HPV) types 16 and 18, which are associated with 80% of anal cancers, is efficacious in men. High-risk populations such as men who have sex with men (MSM) might especially benefit from vaccination. I aimed to estimate the cost-effectiveness of HPV vaccination of MSM in the USA.

METHODS

I constructed decision-analytic models to estimate the direct health and economic outcomes of HPV vaccination (against types 6, 11, 16, and 18) for prevention of HPV-related anal cancer and genital warts. The model parameters that were varied were age at vaccination (12 years, 20 years, and 26 years), previous exposure to vaccine-targeted HPV types, and prevalence of HIV-1. I used the models to conduct sensitivity analyses, including duration of vaccine protection, vaccine cost, and burden of anal cancer and genital warts.

FINDINGS

In a scenario of HPV vaccination of MSM at 12 years of age without previous exposure to HPV, compared with no vaccination, vaccination cost US$15,290 per quality-adjusted life-year gained. In scenarios where MSM are vaccinated at 20 years or 26 years of age, after exposure to HPV infections, the cost-effectiveness ratios worsened, but were less than $50,000 per quality-adjusted life-year under most scenarios. For example, HPV vaccination of MSM at 26 years cost $37,830 per quality-adjusted life-year when previous exposure to all vaccine-targeted HPV types was assumed to be 50%. Outcomes were most sensitive to variations in anal cancer incidence, duration of vaccine protection, and HIV prevalence in MSM.

INTERPRETATION

HPV vaccination of MSM is likely to be a cost-effective intervention for the prevention of genital warts and anal cancer.

FUNDING

US National Cancer Institute.

Human papillomavirus infection and reinfection in adult women: the role of sexual activity and natural immunity

There is a paucity of data on whether or not women can be reinfected with human papillomavirus (HPV) types to which they were exposed to earlier in life and on the role of natural immunity. The observation of HPV infection at older ages may be explained by the reactivation of a latent infection or new exposure from sexual activity. Our objective was to analyze the association between reinfection and sexual activity. We analyzed data from 2,462 women enrolled in the Ludwig-McGill cohort and followed every 4 to 6 months for up to 10 years. We performed HPV typing and viral load measurements via PCR and determined HPV-16 seroreactivity at enrollment. Incidence of infection and reinfection were estimated for individual types. Adjusted relative risks (RR) for the association between infection/reinfection and new sexual partners were calculated using Cox regression. Rates of initial infection and reinfection postclearance were statistically comparable. RRs of initial infection or reinfection were consistently associated with new sexual partners [2.4 (95% confidence intervals; 95% CI, 2.0-3.1) for first infection, 3.7 (1.1-13.8) for reinfection with the same type, and 2.3 (1.5-3.7) for reinfection with a different type]. Reinfection in older women was also associated with new sexual partners (RR, 2.8; 95% CI, 1.4-5.3) as were new infections with HPV-16 among women with serologic evidence of prior HPV-16 exposure (RR, 3.0; 95% CI, 1.6-5.3). Viral loads at initial infection and at reinfection were comparable. HPV infection and reinfection were strongly associated with sexual activity. This study suggests that natural immunity does not play a role in controlling the extent of reinfections.

HPV - immune response to infection and vaccination

HPV infection in the genital tract is common in young sexually active individuals, the majority of whom clear the infection without overt clinical disease. However most of those who develop benign lesions eventually mount an effective cell mediated immune (CMI) response and the lesions regress.

Failure to develop effective CMI to clear or control infection results in persistent infection and, in the case of the oncogenic HPVs, an increased probability of progression to CIN3 and invasive carcinoma. The prolonged duration of infection associated with HPV seems to be associated with effective evasion of innate immunity thus delaying the activation of adaptive immunity.

Natural infections in animals show that neutralising antibody to the virus coat protein L1 is protective suggesting that this would be an effective prophylactic vaccine strategy. The current prophylactic HPV VLP vaccines are delivered i.m. circumventing the intra-epithelial immune evasion strategies. These vaccines generate high levels of antibody and both serological and B cell memory as evidenced by persistence of antibody and robust recall responses. However there is no immune correlate - no antibody level that correlates with protection. Recent data on how HPV infects basal epithelial cells and how antibody can prevent this provides a mechanistic explanation for the effectiveness of HPV VLP vaccines.

Meta-analysis of human papillomavirus infection concordance

BACKGROUND

Estimates of human papillomavirus (HPV) concordance among sexual partners are important for various public health activities, from counseling individual patients to predicting the effect of HPV vaccination.

METHODS

We systematically searched the PubMed and EMBASE databases for studies of HPV concordance among heterosexual couples published through 2008 in English. Two coders independently abstracted data using standardized forms. We integrated concordance data using random-effects meta-analysis.

RESULTS

Thirty studies (33 study populations) that met inclusion criteria reported concordance data for 2,972 couples. Most studies were cross-sectional cohort studies conducted in Europe or Asia that used DNA hybridization to test for HPV, sometimes in conjunction with PCR. Overall, 25.5% (95% confidence interval, 17.2-36.1%) of couples were infected with 1 or more of the same HPV types. Among couples with both members HPV-positive, 63.2% (95% confidence interval, 49.1-75.3%) were infected with 1 or more of the same viral types. Positive concordance was higher for female partners of men with HPV infections than for male partners of women with HPV infections. Positive concordance was also higher for studies using PCR and for the few studies that recruited men with HPV-related disease.

CONCLUSIONS

Sexual partners of HPV-infected individuals had high rates of HPV infection, suggesting a need for increased attention to this group.

IMPACT

Our refined estimates of HPV concordance can inform clinical encounters and public health planning. Future HPV concordance studies should use more rigorous research designs, characterize their participants in greater detail, and study more meaningful populations.

Human papillomavirus vaccines: current status and future prospects

Worldwide, cervical cancer is the second most common cancer of women. Less-developed countries bear the greatest burden in terms of morbidity and mortality, largely due to the lack of organized screening programmes. Cervical cancer is the first cancer shown to be caused solely by virological agents: oncogenic genotypes of human papillomavirus (HPV). Two recently developed prophylactic cervical cancer vaccines, which are based on viral-like particle (VLP) technology of HPV, have the capacity to diminish a large proportion of cervical cancer cases worldwide. However, to be successful public health tools, they need to be widely implemented to the appropriate target population, preferably prior to first sexual intercourse. To increase vaccination coverage, national programmes in some countries have also included catch-up vaccination, for a limited time period, to young adult women aged up to 26 years. Despite the excellent efficacy for high-grade dysplasia due to vaccine-related HPV types (near to 100%) and immunogenicity induced against the HPV types 16 and 18 in females naive to those HPV types pre-vaccination, some form of cervical precancer screening will still be necessary. Immunity to HPV is primarily type specific, and thus protection induced by the current generation of vaccines, based on a limited number of HPV VLP types, cannot provide complete protection against all oncogenic HPV types. Both these vaccines translate to protection of cervical cancer in the order of 70-75%, which represents the percentage of invasive cancers attributable to HPV-16 and -18. Challenges to ensuring the successful control of this largely preventable disease include endorsement by governments and policy makers, affordable prices, education at all levels, overcoming barriers to vaccination and continued adherence to screening programmes.

Cross-protective responses to human papillomavirus infection

Human papillomavirus (HPV) infections with oncogenic types account for approximately 500,000 deaths per year worldwide, predominantly in underdeveloped countries. The major cause of death is cervical cancer in women, but some additional cancers of the head and neck and anogenital sites also have an HPV etiology. Current virus-like particle-based vaccines are in clinical trials, and show very strong, long-lasting protection against vaccine-matched HPV types. These vaccines currently contain virus-like particles for the HPV types 6, 11, 16 and 18 (Gardasil®) and HPV16 and -18 (Cervarix®). Although type-specific neutralizing antibodies develop from immunizations with these virus-like particle vaccines, promising evidence for cross-protection against related but nonvaccine HPV types is emerging. Strategies to increase cross-protection to cover all oncogenic HPV types (currently approximately 20 types) are underway. These strategies include increasing the number of HPV types in the virus-like particle vaccine, and to the development of second-generation HPV vaccines that include the minor coat protein.

Review of Gardasil

Human papillomavirus (HPV) is necessary for the development of cervical cancer. Cervical cancer is the second most common cancer in women worldwide but 80% occurs in developing countries, not countries with Pap screening programs. Pap screening programs in industrialized countries have reduced the incidence of cervical cancer to 4-8/100,000 women. HPV vaccines may be a promising strategy for cervical cancer in women without access to screening programs. In industrialized countries, the benefit of HPV vaccines focuses on individual abnormal Pap test reduction not cancer prevention. The focus of this review is to cover the side effects of Gardasil in perspective with the limited population benefit cervical cancer reduction in countries with organized Pap screening programs. In addition, information about Gardasil benefits, risks and unknowns for individual patient decision making for vaccination is presented. Gardasil offers protection against CIN 2+ lesions caused by HPV 16/18 and against genital warts caused by HPV 6/11 for at least 5 years. Combining Gardasil with repeated cytology screenings may reduce the proportion of abnormal cytology screens and hence reduce the associated morbidity with the subsequent colposcopies and excisional procedures.

Cervical cancer vaccine development

Cervical cancer is initiated by infection of cervical epithelium with human papillomavirus. Vaccines have been developed, incorporating papillomavirus viral capsids and alum based adjuvants. In extensive clinical trials these vaccines have been shown safe and effective in preventing infection with, and disease caused by, the papillomavirus genotypes they incorporate, in women not already infected. These vaccines have the potential to reduce the global burden of cervical cancer by up to 70%.