The impact of quadrivalent human papillomavirus (HPV; types 6, 11, 16, and 18) L1 virus-like particle vaccine on infection and disease due to oncogenic nonvaccine HPV types in sexually active women aged 16-26 years

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 of quadrivalent HPV vaccine against HPV Infection and disease in males

BACKGROUND

Infection with human papillomavirus (HPV) and diseases caused by HPV are common in boys and men. We report on the safety of a quadrivalent vaccine (active against HPV types 6, 11, 16, and 18) and on its efficacy in preventing the development of external genital lesions and anogenital HPV infection in boys and men.

METHODS

We enrolled 4065 healthy boys and men 16 to 26 years of age, from 18 countries in a randomized, placebo-controlled, double-blind trial. The primary efficacy objective was to show that the quadrivalent HPV vaccine reduced the incidence of external genital lesions related to HPV-6, 11, 16, or 18. Efficacy analyses were conducted in a per-protocol population, in which subjects received all three vaccinations and were negative for relevant HPV types at enrollment, and in an intention-to-treat population, in which subjects received vaccine or placebo, regardless of baseline HPV status.

RESULTS

In the intention-to-treat population, 36 external genital lesions were seen in the vaccine group as compared with 89 in the placebo group, for an observed efficacy of 60.2% (95% confidence interval [CI], 40.8 to 73.8); the efficacy was 65.5% (95% CI, 45.8 to 78.6) for lesions related to HPV-6, 11, 16, or 18. In the per-protocol population, efficacy against lesions related to HPV-6, 11, 16, or 18 was 90.4% (95% CI, 69.2 to 98.1). Efficacy with respect to persistent infection with HPV-6, 11, 16, or 18 and detection of related DNA at any time was 47.8% (95% CI, 36.0 to 57.6) and 27.1% (95% CI, 16.6 to 36.3), respectively, in the intention-to-treat population and 85.6% (97.5% CI, 73.4 to 92.9) and 44.7% (95% CI, 31.5 to 55.6) in the per-protocol population. Injection-site pain was significantly more frequent among subjects receiving quadrivalent HPV vaccine than among those receiving placebo (57% vs. 51%, P<0.001).

CONCLUSIONS

Quadrivalent HPV vaccine prevents infection with HPV-6, 11, 16, and 18 and the development of related external genital lesions in males 16 to 26 years of age. (Funded by Merck and others; ClinicalTrials.gov number, NCT00090285.).

Is human papillomavirus screening preferable to current policies in vaccinated and unvaccinated women? A cost-effectiveness analysis

Objectives

Italy was the first European nation to offer free vaccination against human papillomavirus (HPV) types 16 and 18. The vaccination is actively encouraged and is available free of charge to 11-year-old girls. The introduction of new technologies such as HPV DNA testing and HPV vaccination requires cost-effectiveness analysis of cervical cancer strategies in Italy for both vaccinated and unvaccinated women.

Methods

A calibrated Markov model was developed to describe the natural history of HPV infection and cervical carcinogenesis. We performed a microsimulation generating the life histories of 10 million women. Changes in these life histories occur as consequences of prevention strategies. We estimated costs of screening activities using an activity-based costing analysis. We assessed lifetime risk due to cervical cancer, lifetime costs and quality-adjusted life-expectancy (QALE) for 18 scenarios. Strategies varied by screening interval (three and five years), primary and triage test (Pap test and HPV DNA test), and HPV 16 and 18 vaccination.

Results

The current screening policy (Pap test every three years) is more costly and less effective than HPV DNA test and Pap test triage every five years. For unvaccinated women an HPV DNA test every five years with a Pap test triage was cost-effective (ICER €5753/QALE). Vaccination followed by the same screening strategy was cost-effective (ICER €23,951/QALE) for women who are eligible to be vaccinated.

Conclusions

Our findings strongly support changing the Pap screening policy to the use of HPV DNA as a primary test with Pap test triage for both vaccinated and unvaccinated women.

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.

Unresolved questions concerning human papillomavirus infection and transmission: a modelling perspective

Mathematical transmission models are widely used to forecast the potential impact of interventions such as vaccination and to inform the development of health policy. Effective vaccines are now available for the prevention of cervical cancer and other diseases attributable to human papillomavirus (HPV). Considerable uncertainties remain regarding the characterisation of HPV infection and its sequelae, infectivity, and both vaccine-conferred and naturally-acquired immunity. In this review, we discuss the key knowledge gaps that impact on our ability to develop accurate models of HPV transmission and vaccination.

Distribution of HPV genotypes in women with cervical cancer in Auckland, New Zealand; a review of 50 specimens between 2000-2006

BACKGROUND

In New Zealand, around two hundred women are diagnosed with cervical cancer annually, with approximately seventy deaths from cervical cancer per year.

AIM

Our aim was to determine the distribution of oncogenic HPV genotypes in biopsy specimens from women with diagnosed cervical cancers in the Auckland region of New Zealand between 2000-2006.

MATERIALS AND METHODS

Confirmed cases of cervical carcinoma were identified from the local pathology register, and representative tissue samples were taken from these blocks. Sections were deparaffinised, and DNA was extracted according to standard protocols. Samples were subject to PCR amplification using L1 consensus primer sets MY09/11 and GP5/6. Further type-specific amplification was performed on positive samples, using an in-house primer sequence based on target sequences within the E6 gene. Remaining samples were typed by a Linear Array Assay, or by DNA sequencing.

RESULTS

HPV DNA was detected in 100% of cases. In 49/50 samples, the HPV genotype was identified, with a total of 14 different HPV genotypes detectable. Together HPV-16 and 18 were found in 41/49 cases (83.6%) either singly or in combination.

DISCUSSION

Our findings suggest that the distribution of HPV genotypes in New Zealand is similar to that of other geographic areas.

CONCLUSION

Ongoing surveillance is warranted to ensure appropriate genotype selection for prophylactic HPV vaccinations.

Human papillomavirus infection in women with and without cervical cancer in Ibadan, Nigeria

Background

Concerns have been raised that the proportion of cervical cancer preventable by human papillomavirus (HPV) 16/18 vaccines might be lower in sub-Saharan Africa than elsewhere.

Method

In order to study the relative carcinogenicity of HPV types in Nigeria, as well as to estimate the vaccine-preventable proportion of invasive cervical cancer (ICC) in the country, we compared HPV type prevalence among 932 women from the general population of Ibadan, Nigeria, with that among a series of 75 ICC cases diagnosed in the same city. For all samples, a GP5+/6+ PCR based assay was used for the detection of 44 genital HPV types.

Results

In the general population, 245 (26.3%, 95% confidence interval (CI) 23.5% - 29.2%) women were HPV-positive, among whom the prevalence of HPV35 and HPV16 were equally frequent (12.2%, 95% CI 8.4% - 17.0%). In ICC, however, HPV16 predominated strongly (67.6% of 68 HPV-positive cases), with the next most common types being 18 (10.3%, 95% CI 4.2% - 20.1%), 35, 45 and 56 (each 5.9%, 95% CI 1.6% - 14.4%). Comparing among HPV-positive women only, HPV16 and 18 were over-represented in ICC versus the general population (prevalence ratios 5.52, 95% CI 3.7 - 8.3 and 1.4, 95% CI 0.6 - 3.3, respectively). Other high-risk HPV types, as well as low-risk and multiple HPV infections were less common in HPV-positive women with ICC than from the general population.

Conclusions

Our study confirms that in Nigeria, as elsewhere, women infected with HPV16 and 18 are at higher risk of developing ICC than those infected with other high-risk types, and that current HPV16/18 vaccines have enormous potential to reduce cervical cancer in the region.

The age-specific relationships of abnormal cytology and human papillomavirus DNA results to the risk of cervical precancer and cancer

BACKGROUND

To estimate the relationship of human papillomavirus (HPV) detection and abnormal cytology with histologic diagnoses of cervical precancer and cancer.

METHODS

From 2003 to 2008 we examined the HPV, cytology, and diagnostic results from almost one million cervical cancer screenings done on women aged 30 and older who were members in Kaiser Permanente Northern California, a large health maintenance organization that introduced cotesting in 2003. Women were screened using conventional Pap tests and a DNA test for a pool of 13 high-risk HPV genotypes. Women with HPV-positive atypical squamous cells of undetermined significance and other abnormal cervical cytology, independent of their HPV results, routinely underwent colposcopy. Results were stratified by 5-year age groups from 30 to 64.

RESULTS

High-grade squamous intraepithelial lesions (HSIL), atypical squamous cells, cannot exclude HSIL (ASC-H), and atypical glandular cells were more strongly associated with cervical intraepithelial neoplasia grade 3 while low-grade squamous intraepithelial lesions (LSIL) and HPV-positive atypical squamous cells of undetermined significance were more strongly associated with cervical intraepithelial neoplasia grade 2 (CIN2). Cervical cancer was most commonly found in women with HSIL and atypical glandular cells cytology. Human papillomavirus-negative women with ASC-H cytology were at a reduced but significant risk of CIN2 or more severe (CIN2+) (10.6%) compared with HPV-positive women with ASC-H cytology. Human papillomavirus-negative women with LSIL were at a 4.0% risk of CIN2+, and among women 50 and older, at a 0.5% risk of CIN2+ with no cancers were diagnosed.

CONCLUSION

Human papillomavirus testing may be useful for triage for colposcopic referral for LSIL cytology in older women but not for ASC-H cytology at any age.

LEVEL OF EVIDENCE

II.

Cervical nitric oxide release and persistence of high-risk human papillomavirus in women

Nitric oxide may serve as one cofactor for human papillomavirus (HPV)-induced development of cervical cancer. Therefore, we first assessed the levels of cervical fluid nitric oxide metabolite (NOx) in 283 women with and without high-risk (hr) HPV. The NOx level in women with hr HPV (48.4 μmol/L [95% CI: 39.4-56.6], n = 199) was higher (p < 0.001) than that in women without hr HPV (24.6 μmol/L [95% CI: 19.1-38.7], n = 84). Second, we evaluated if cervical fluid NOx levels could predict the persistence of hr HPV. Therefore, we followed up 113 women with detectable hr HPV without any treatment for 12 mo and repeated hr HPV test. High-risk HPV persisted in 72 women (64%) and disappeared in 41 women (36%). The median basal levels of NOx were higher (p = 0.02) in women with persistent hr HPV (56.9 μmol/L [95% CI: 48.7-81.0]) compared to those with eradicated hr HPV (37.7 μmol/L [95% CI: 27.0-58.0]). The NOx level higher than the 75th percentile (>87.0 μmol/L) predicted hr HPV persistence (OR = 4.1 [95% CI: 1.3-13.1]). This cutoff level of NOx showed 33% sensitivity and 90% specificity in predicting the persistence of hr HPV, but it failed to predict cytological progression or regression in 12 mo. In conclusion, high cervical fluid NOx appears to be connected to the persistence of hr HPV, but the low predictive capacity of NOx prevents its clinical use at this phase.

Monitoring of human papillomavirus vaccination

Persistent infection with oncogenic human papillomavirus (HPV) is a necessary causal factor in the development of cervical cancer. Moreover, HPV, predominately type 16 and to a lesser degree type 18, is linked causally to varying proportions of other anogenital cancers (vulva, vagina, penis, anus) as well as cancers elsewhere in the body (oropharynx, larynx, conjunctiva). HPV types 6 and 11 cause most of genital warts and recurrent respiratory papillomatosis. Effective prophylactic vaccines have been developed. In this review, we address briefly the immunological aspects of HPV infection and the results of HPV vaccination trials. Internationally standardized monitoring and evaluation of prophylactic HPV vaccination programmes will be essential for arriving at the most cost-effective strategies for cancer control.

HPV vaccine: an overview of immune response, clinical protection, and new approaches for the future

Although long-term protection is a key-point in evaluating HPV-vaccine over time, there is currently inadequate information on the duration of HPV vaccine-induced immunity and on the mechanisms related to the activation of immune-memory. Longer-term surveillance in a vaccinated population is needed to identify waning immunity, evaluating any requirements for booster immunizations to assess vaccine efficacy against HPV-diseases. Current prophylactic vaccines have the primary end-points to protect against HPV-16 and 18, the genotypes more associated to cervical cancer worldwide. Nevertheless, data from many countries demonstrate the presence, at significant levels, of HPVs that are not included in the currently available vaccine preparations, indicating that these vaccines could be less effective in a particular area of the world. The development of vaccines covering a larger number of HPVs presents the most complex challenge for the future. Therefore, long term immunization and cross-protection of HPV vaccines will be discussed in light of new approaches for the future.

Incidence, duration, and reappearance of type-specific cervical human papillomavirus infections in young women

BACKGROUND

We describe the incidence and duration of cervical human papillomavirus (HPV) infection episodes along with the risk of infection reappearance following a period of nondetection.

METHODS

Women (1,788) ages 16 to 23 years underwent cytologic testing and PCR-based testing of cervical swab samples for HPV DNA (HPV-16/18/31/33/35/45/52/58/59) at approximately 6-month intervals for up to 4 years in the context of a phase 3 clinical trial (placebo arm). HPV type-specific incidence rates were estimated per 100 person-years. Duration of type-specific cervical infection episodes and risk of reappearance following a period of nondetection were estimated using Kaplan-Meier methods.

RESULTS

HPV-16 exhibited the highest (5.9), and HPV-35 and HPV-33 exhibited the lowest (1.0) incidence rates per 100 person-years. Mean cervical infection durations ranged from 13 months for HPV-59 to 20 months for HPV-16 and 58 (with ongoing infections censored at the time of treatment, if done). The risk of cervical infection reappearance within approximately 3 years following a period of nondetection ranged from 0% to 16% across HPV types, with a mean of 8%. Limited evidence was found for a role of false-positive HPV tests, missed infections that were above the threshold for detection, or new acquisition of infection in accounting for patterns of infection reappearance.

CONCLUSIONS

Incidence of high-risk cervical infection was observed to vary considerably more across HPV types than infection duration. A nontrivial proportion of women exhibited infection reappearance following a period of nondetection, with a potential explanation for many such events observed within this analysis being a return to detectable levels of a previously acquired infection.

IMPACT

The risk of HPV infection reappearance following a period of nondetection has not been previously reported for individual HPV types, and this study finds that a nontrivial proportion of infected women exhibit reappearances. Future studies could ascertain subject-level factors that potentially modify the risk of infection reappearance.

Epidemiological study of anti-HPV16/18 seropositivity and subsequent risk of HPV16 and -18 infections

BACKGROUND

Infection with human papillomavirus (HPV) 16 or HPV18 elicits an antibody response, but whether the elicited antibodies protect women against subsequent infection by a homologous HPV type compared with seronegative women is unknown.

METHODS

Study participants were women aged 18-25 years at enrollment in the control group of the ongoing National Cancer Institute-sponsored, community-based, randomized HPV16/18 Costa Rica Vaccine Trial. At enrollment, 2813 participants were negative for cervical HPV16 DNA and 2950 for HPV18 DNA. Women were interviewed regarding sociodemographic data and medical and health history. Medical and pelvic examinations were conducted for all consenting sexually experienced women. Serum samples taken at enrollment were tested for total HPV16/18 antibodies with a polyclonal enzyme-linked immunosorbent assay, and cervical specimens were tested for type-specific HPV DNA over 4 years of follow-up. Using Poisson regression, we compared rate ratios of newly detected cervical HPV16 or HPV18 infection among homologous HPV-seropositive and HPV-seronegative women, adjusting for age, education, marital status, lifetime number of sexual partners, and smoking.

RESULTS

There were 231 newly detected HPV16 infections during 5886 person-years among HPV16-seronegative women compared with 12 newly detected HPV16 infections during 581 person-years among HPV16-seropositive women with the highest HPV16 sero-levels. There were 136 newly detected HPV18 infections during 6352 person-years among HPV18-seronegative women compared with six new infections detected during 675 person-years among HPV18 seropositives with the highest sero-levels. After controlling for risk factors associated with newly detected HPV infection, having high HPV16 antibody titer at enrollment was associated with a reduced risk of subsequent HPV16 infection (women in the highest tertile of HPV16 antibody titers, adjusted rate ratio = 0.50, 95% confidence interval = 0.26 to 0.86 vs HPV16-seronegative women). Similarly, having high HPV18 antibody titer at enrollment was associated with a reduced risk of subsequent HPV18 infection (women in the highest tertile of HPV18 antibody titers, adjusted rate ratio = 0.36, 95% confidence interval = 0.14 to 0.76 vs HPV18-seronegative women).

CONCLUSION

In this study population, having high antibody levels against HPV16 and HPV18 following natural infection was associated with reduced risk of subsequent HPV16 and HPV18 infections.

Most parents do not think receiving human papillomavirus vaccine would encourage sexual activity in their children

OBJECTIVE

To determine whether parents think receiving human papillomavirus (HPV) vaccine encourages sexual activity in their children.

MATERIALS AND METHODS

Parents of children 9 to 17 years old living in Georgia and South Carolina completed a 53-item questionnaire that evaluated their opinions about the HPV vaccine and their feelings about whether receiving it encourages sexual intercourse in their children. Fisher exact tests and t tests were used to identify differences between groups.

RESULTS

Participants tended to be white, protestant mothers, 30 to 39 years old with private health insurance. Most parents (301/322, 93.5%) did not believe receiving the HPV vaccine would encourage their child to have sex. Parents who believed the vaccine would encourage sex were more likely to have 15- to 17-year-old children (76% vs 37%, p =.0007), were 40 years or older (62% vs 35%, p =.019), have religious objections to vaccines in general (10% vs 0.3%, p =.01) and the HPV vaccine (14% vs 2%, p =.02), and believed the vaccine would not reduce the risk of cervical cancer in their daughters (50% vs 9%, p =.001).

CONCLUSIONS

Most parents do not think the HPV vaccine would actually encourage sexual activity in their children. Therefore, health care providers can be less hesitant in recommending the vaccine to young sexually naive girls. Additional education should help improve overall parental understanding about the HPV vaccine and, consequently, vaccination rates.

Population fraction of cervical neoplasia attributable to high-risk human papillomaviruses

AIMS

The efficacy of human papillomavirus (HPV) type 16 and 18 vaccines against cervical intraepithelial neoplasia grade II (CIN2+) has been verified, but the active follow-up of studies with invasive cervical cancer or cervical intraepithelial neoplasia grade III (CIN3) as primary end points are ethically not possible. Furthermore, ongoing registry-based passive follow-up studies with invasive cervical cancer as the end point will take time.

MATERIALS & METHODS

To evaluate the feasibility of CIN3 as a surrogate end point, we compared high-risk (hr) HPV-associated relative risk and population attributable fraction (PAF) of CIN3 and/or squamous cell carcinoma (SCC) estimated in a large serological case-cohort HPV study. Our case-cohort comprised 83 SCC and 389 CIN3 cases and a subcohort of 7862 out of 230,998 Finnish women, who at baseline were under 32 years of age and had undergone a minimum of two pregnancies within 5 years during 1983-1997.

RESULTS

PAFs of the case-cohort, approach-based, serologically defined and misclassification-corrected HPV16 and hrHPV (HPV types 16, 18, 31 and 33) exposures in the SCC samples were 61% (95% CI: 18-85) and 73% (95% CI: 13-93), respectively. Considerably lower HPV16 and hrHPV PAF estimates in CIN3 of 6% (95% CI: -19-35) and 36% (95% CI: -5-65), respectively, were obtained. A meta-analysis-derived, PCR-based, hrHPV-associated relative risk estimate of 20.3 in CIN2/3+ yielded a PAF estimate for hrHPV in CIN2/3+ of 86% (90% CI: 63-95) in our study population. The former, hrHPV serology-based CIN3 PAF estimates were biased owing to low sensitivity of HPV16 and/or HPV16/18/31/33 serology, most notably in cervical cancer precursor lesions, but the latter estimate overlapped with our hrHPV serology-based cervical cancer PAF estimate.

CONCLUSION

CIN3 may be a valid surrogate efficacy end point for HPV vaccination studies, but the associated causality of multiple hrHPV exposures needs to be unambigously defined.

Randomized controlled trials of interventions to prevent sexually transmitted infections: learning from the past to plan for the future

Globally, sexually transmitted infections (STIs) represent a significant source of morbidity and disproportionately impact the health of women and children. The number of randomized controlled trials testing interventions to prevent STIs has dramatically increased over time. To assess their impact, the authors conducted a systematic review of interventions to prevent sexual transmission or acquisition of STIs other than human immunodeficiency virus, published in the English-language, peer-reviewed literature through December 2009. Ninety-three papers reporting data from 74 randomized controlled trials evaluating 75 STI prevention interventions were identified. Eight intervention modalities were used: behavioral interventions (36% of interventions), vaginal microbicides (16%), vaccines (16%), treatment (11%), partner services (9%), physical barriers (5%), male circumcision (5%), and multicomponent (1%). Overall, 59% of interventions demonstrated efficacy in preventing infection with at least 1 STI. Treatment interventions and vaccines for viral STIs showed the most consistently positive effects. Male circumcision protected against viral STIs and possibly trichomoniasis. Almost two-thirds of behavioral interventions were effective, but the magnitude of effects ranged broadly. Partner services yielded similarly mixed results. In contrast, vaginal microbicides and physical barrier methods demonstrated few positive effects. Future STI prevention efforts should focus on enhancing adherence within interventions, integrating new technologies, ensuring sustainable behavior change, and conducting implementation research.

Establishment of the 1st World Health Organization international standards for human papillomavirus type 16 DNA and type 18 DNA

A World Health Organization collaborative study was conducted to evaluate candidate international standards for human papillomavirus (HPV) Type 16 DNA (NIBSC code 06/202) and HPV Type 18 DNA (NIBSC code 06/206) for use in the amplification and detection steps of nucleic acid-based assays. The freeze-dried candidate international standards were prepared from bulk preparations of cloned plasmid containing full-length HPV-16 or HPV-18 genomic DNA. Nineteen laboratories from 13 countries participated in the study using a variety of commercial and in-house quantitative and qualitative assays. The data presented here indicate that, upon freeze-drying, there is no significant loss in potency for the candidate HPV-18 DNA and a slight loss in potency for the candidate HPV-16 DNA; although this is likely not scientifically relevant when assay precision is considered. In general, the individual laboratory mean estimates for each study sample were grouped +/- approximately 2 log(10) around the theoretical HPV DNA concentration of the reconstituted ampoule (1 x 10(7) HPV genome equivalents/mL). The agreement between laboratories is improved when potencies are made relative to the candidate international standards, demonstrating their utility in harmonizing amplification and detection steps of HPV-16 and -18 DNA assays. Degradation studies indicate that the candidate international standards are extremely stable and suitable for long-term use. Based on these findings, the candidate standards were established as the 1st WHO international standards for HPV-16 DNA and HPV-18 DNA, each with a potency of 5 x 10(6) international units (IU) per ampoule or 1 x 10(7) IU mL(-1) when reconstituted as directed.

HPV vaccine: Cervarix

IMPORTANCE OF THE FIELD

Cervical cancer is a major cause of morbidity and mortality worldwide and is common in relatively young women. Cervical screening programs, while successful if properly carried out, are difficult and expensive to implement, and offer secondary, not primary prevention. Vaccination against the human papillomavirus (HPV), which is the major cause of cervical cancer, is a significant step forward.

AREAS COVERED IN THIS REVIEW

The data on Cervarix, the GSK HPV vaccine, are reviewed and placed in the context of HPV vaccination as a whole. A literature review using PubMed listed publications and official product websites has been carried out.

WHAT THE READER WILL GAIN

The reader will gain an understanding of the issues involved in HPV vaccination and of the data to date.

TAKE HOME MESSAGE

Cervarix has been shown to have high efficacy against disease associated with both HPV-16 and HPV-18. Its antibody response profile allows for optimism regarding the duration of immunity. The fact that it is a virus-like particle, rather than a live-virus vaccine, is reassuring regarding safety, as are the reasonably extensive safety data for the vaccine preparation so far accrued. Cross protection against oncogenic non-vaccine HPV types, in particular HPV-45, may be important in the prevention of cervical adenocarcinoma, which is currently not well served by screening.

The Psychosocial Burden of HPV

Despite an increased awareness and ‘normalization’ of Human Papillomavirus (HPV) following the release of the HPV vaccine, the psychosocial impact of an HPV infection, the most common sexually transmissible infection (STI), must not be overshadowed. This study employed in-depth interviews ( N = 52) and quantitative surveys ( N = 154) to assess the knowledge, emotional impact and behavioral consequences of an HPV-related diagnosis in women who had received abnormal Pap test results. Findings revealed confusion over test results and themes related to stigma, fear, self-blame, powerlessness and anger emerged. The promotion of the HPV vaccine should not obfuscate the psychosocial burden associated with an HPV diagnosis.

Prophylactic human papillomavirus vaccines: will they do their job?

The prophylactic HPV L1 virus like particle vaccines are highly efficacious preventing >98% of HPV 16/18 caused high grade cervical intra-epithelial neoplasia (CIN2/3) according to protocol group in phase III randomized clinical trials over approximately 4 years. Data from the trials together with postvaccine surveillance indicates that they have a good safety profile. As the current HPV vaccines include only two of the 15 oncogenic HPVs, they will not eliminate cervical cancer or the other HPV associated ano-genital diseases but could reduce, for example, the incidence of cervix cancer by up to 70-80%, if effectively delivered to adolescent females.

Currently approved prophylactic HPV vaccines

Cervarix and Gardasil are two prophylactic HPV vaccines designed primarily for cervical cancer prevention. Cervarix is effective against HPV-16, -18, -31, -33 and -45, the five most common cancer-causing types, including most causes of adenocarcinoma for which we cannot screen adequately. Gardasil is effective against HPV-16, 18 and 31, three common squamous cell cancer-causing types. In addition, Gardasil is effective against HPV-6 and -11, causes of genital warts and respiratory papillomatosis. The most important determinant of vaccine impact to reduce cervical cancer is its duration of efficacy. To date, Cervarix's efficacy is proven for 6.4 years and Gardasil's for 5 years.

Predicted impact of vaccination against human papillomavirus 16/18 on cancer incidence and cervical abnormalities in women aged 20-29 in the UK

Background:

Human papillomavirus (HPV) vaccination has been approved in more than 90 countries and is being implemented in many of these. In the UK, vaccination for girls aged 12–13 with catch-up for girls up to age 18 was introduced in 2008, using the bivalent GSK vaccine (Cervarix).

Methods:

We modelled the proportion of abnormal smears, cervical intraepithelial neoplasia grade 3 (CIN3) and invasive cancer, which will be prevented in women aged 20–29 in the UK as a result of HPV vaccination.

Results:

It will take many years for the full benefit of vaccination to be achieved. The earliest effects will be seen in women aged 20–29. With 80% coverage in women aged 12–13, we project an eventual 63% reduction in invasive cancer, a 51% reduction in CIN3 and a 27% reduction in cytological abnormalities before age 30. The full effect in this age group will not be seen until 2025, although half of the benefit will be seen by 2019 in England, where screening starts at age 25. However in Scotland and Wales, where screening starts at age 20, 50% of the benefit for CIN3 and abnormal smears (but not cancer) will be seen earlier.

Conclusion:

Substantial reductions in disease can be anticipated by vaccination, but most of the benefit will not be apparent for at least another decade. High vaccine coverage is the key factor for achieving these benefits.

EUROGIN 2008 roadmap on cervical cancer prevention

The EUROGIN 2008 Roadmap represents a continuing effort to provide updated information on primary and secondary prevention of cervical cancer. The report addresses several areas including the progress made toward global implementation of currently licensed human papillomavirus (HPV) vaccines, the possibilities and value of future-generation HPV vaccines, endpoints under consideration for evaluation of candidate HPV vaccines, and monitoring impact of HPV vaccination programmes that can be implemented within developed and less-developed countries. For the sake of completeness, a short update on the evolution of HPV testing in primary screening programmes at present and after HPV vaccine introduction has also been included. The report is available on the EUROGIN website (www.eurogin.com).

Clinical update of the AS04-adjuvanted human papillomavirus-16/18 cervical cancer vaccine, Cervarix

Persistent infection with human papillomavirus (HPV) is a necessary cause of cervical cancer, resulting annually in 274,000 deaths worldwide. Two prophylactic HPV vaccines are licensed in >100 countries, and immunization programs in young, adolescent girls have been widely implemented. HPV-16/18 AS04-adjuvanted vaccine (Cervarix; GlaxoSmithKline Biologicals, Rixensart, Belgium) has demonstrated type-specific protection against the five most frequent cancer-causing types (16, 18, 31, 33, and 45) that are responsible for 82% of invasive cervical cancers globally. Cervarix has demonstrated efficacy against HPV-45, which is the third most common HPV type in cervical cancer and adenocarcinoma. Final results of a large phase 3 trial recently showed Cervarix substantially reduced the overall burden of cervical precancerous lesions (cervical intraepithelial neoplasia 2+) by 70.2% in an HPV-naïve population approximating young girls prior to sexual debut, the target of most current vaccination programs. Protection offered by Cervarix against nonvaccine types (mainly 31, 33, and 45) might potentially allow for 11%-16% additional protection against cervical cancers, compared to a vaccine only offering protection against HPV-16/18. Another recent study directly compared the antibody response of Cervarix to that of quadrivalent HPV-6/11/16/18 vaccine (Gardasil; Merck, Whitehouse Station, NJ, USA). Cervarix induced significantly superior neutralizing antibody levels as compared with Gardasil for HPV-16 and HPV-18 in all age groups studied. This may translate into more women having detectable (neutralizing) antibodies in cervicovaginal secretions for HPV-16 and HPV-18 after vaccination with Cervarix when compared with Gardasil. Cervarix induced significantly higher frequencies of antigen-specific memory B-cells and T-cells in responders for HPV-16 and HPV-18 as compared with Gardasil. Cervarix continues to show sustained high levels of total and neutralizing antibodies for HPV-16 and HPV-18, 7.3 years after vaccination. This is associated with high efficacy and no breakthrough cases in the HPV-naïve population, and is the longest duration follow-up for safety, immunogenicity, and efficacy for any licensed HPV vaccine to date.

Bovine papillomavirus type 1 (BPV1) and BPV2 are closely related serotypes

Infection with bovine papillomavirus type 1 (BPV1) or BPV2 induces fibropapillomas in cows and skin sarcoids in horses. Prophylactic vaccination targeting BPV1 and BPV2 may reduce the incidence of these economically important diseases. The L1 major capsid proteins of BPV1 and BPV2 were expressed in Sf-9 insect cells and both self-assembled into virus-like particles (VLPs). Using conformation-dependent monoclonal antibodies (mAb) both type-specific and shared epitopes were detected. Antisera were raised against BPV1 or BPV2 VLP using alum adjuvant, and their (cross)neutralization capacity was tested by C127 neutralization assays using native BPV1 and BPV2 virions, or by BPV1 pseudovirion assay. Antisera induced by either VLP vaccine were able to robustly (cross-)neutralize heterologous as well as homologous types, indicating that BPV1 and BPV2 are closely related serotypes. These results suggest that a monovalent BPV1 (or BPV2) VLP vaccine may potentially protect against both BPV1 and BPV2 infections and associated diseases.

Human papillomavirus types 16 and 18 DNA load in relation to coexistence of other types, particularly those in the same species

BACKGROUND

Infection with multiple human papillomavirus (HPV) types is common. However, it is unknown whether viral DNA load is related to the coexistence of other types.

METHODS

Study subjects were 802 and 303 women who were positive for HPV16 and HPV18, respectively, at enrollment into the Atypical Squamous Cells of Undetermined Significance and Low-Grade Squamous Intraepithelial Lesion Triage Study. HPV16 and HPV18 E7 copies per nanogram of cellular DNA in cervical swab samples were measured by real-time PCR in triplicate.

RESULTS

Concurrent coinfection was common in this population of women with minor cervical lesions; multiple HPV types were detected in 573 (71.4%) of 802 HPV16-positive women and 227 (74.9%) of 303 HPV18-positive women. The adjusted odds ratio associating coinfection with per 1 log unit increase in HPV16 DNA load was 0.78 (95% confidence interval, 0.68-0.89); it was 0.64 (95% confidence interval, 0.52-0.79) for a similar analysis of HPV18 DNA load. Women with, compared with without, coinfection of A9 species types possessed a significantly lower HPV16 DNA load (P < 0.001), whereas women with, compared with without, coinfection of A7 species types possessed a significantly lower HPV18 DNA load (P = 0.001). A trend of decrease in HPV16 DNA load with increasing number of the coexisting non-HPV16 A9 species types was statistically significant (P(trend) = 0.001).

CONCLUSION

Coinfection with other types was associated with lower HPV16 and HPV18 DNA load. The extent of reduction was correlated to phylogenetic distance of the coexisting types to HPV16 and HPV18, respectively.

Chimeric L1-L2 virus-like particles as potential broad-spectrum human papillomavirus vaccines

The amino (N) terminus of the human papillomavirus (HPV) minor capsid protein L2 can induce low-titer, cross-neutralizing antibodies. The aim of this study was to improve immunogenicity of L2 peptides by surface display on highly ordered, self-assembled virus-like particles (VLP) of major capsid protein L1, and to more completely characterize neutralization epitopes of L2. Overlapping peptides comprising amino acids (aa) 2 to 22 (hereafter, chimera or peptide 2-22), 13 to 107, 18 to 31, 17 to 36, 35 to 75, 75 to 112, 115 to 154, 149 to 175, and 172 to 200 of HPV type 16 (HPV16) L2 were genetically engineered into the DE surface loop of bovine papillomavirus type 1 L1 VLP. Except for chimeras 35-75 and 13-107, recombinant fusion proteins assembled into VLP. Vaccination of rabbits with Freund's adjuvanted native VLP induced higher L2-specific antibody titers than vaccination with corresponding sodium dodecyl sulfate-denatured proteins. Immune sera to epitopes within residues 13 to 154 neutralized HPV16 in pseudovirion neutralization assays, whereas chimera 17-36 induced additional cross-neutralization to divergent high-risk HPV18, -31, -45, -52, and -58; low-risk HPV11; and beta-type HPV5 (titers of 50 to 10,000). Aluminum hydroxide-monophosphoryl lipid A (Alum-MPL)-adjuvanted VLP induced similar patterns of neutralization in both rabbits and mice, albeit with 100-fold-lower titers than Freund's adjuvant. Importantly, Alum-MPL-adjuvanted immunization with chimeric HPV16L1-HPV16L2 (peptide 17-36) VLP induced neutralization or cross-neutralization of HPV16, -18, -31, -45, -52, and -58; HPV6 and -11; and HPV5 (titers of 50 to 100,000). Immunization with HPV16 L1-HPV16 L2 (chimera 17-36) VLP in adjuvant applicable for human use induces broad-spectrum neutralizing antibodies against HPV types evolutionarily divergent to HPV16 and thus may protect against infection with mucosal high-risk, low-risk, and beta HPV types and associated disease.

Efficacy of human papillomavirus (HPV)-16/18 AS04-adjuvanted vaccine against cervical infection and precancer caused by oncogenic HPV types (PATRICIA): final analysis of a double-blind, randomised study in young women

BACKGROUND

The human papillomavirus (HPV)-16/18 AS04-adjuvanted vaccine was immunogenic, generally well tolerated, and effective against HPV-16 or HPV-18 infections, and associated precancerous lesions in an event-triggered interim analysis of the phase III randomised, double-blind, controlled PApilloma TRIal against Cancer In young Adults (PATRICIA). We now assess the vaccine efficacy in the final event-driven analysis.

METHODS

Women (15-25 years) were vaccinated at months 0, 1, and 6. Analyses were done in the according-to-protocol cohort for efficacy (ATP-E; vaccine, n=8093; control, n=8069), total vaccinated cohort (TVC, included all women receiving at least one vaccine dose, regardless of their baseline HPV status; represents the general population, including those who are sexually active; vaccine, n=9319; control, n=9325), and TVC-naive (no evidence of oncogenic HPV infection at baseline; represents women before sexual debut; vaccine, n=5822; control, n=5819). The primary endpoint was to assess vaccine efficacy against cervical intraepithelial neoplasia 2+ (CIN2+) that was associated with HPV-16 or HPV-18 in women who were seronegative at baseline, and DNA negative at baseline and month 6 for the corresponding type (ATP-E). This trial is registered with ClinicalTrials.gov, number NCT00122681.

FINDINGS

Mean follow-up was 34.9 months (SD 6.4) after the third dose. Vaccine efficacy against CIN2+ associated with HPV-16/18 was 92.9% (96.1% CI 79.9-98.3) in the primary analysis and 98.1% (88.4-100) in an analysis in which probable causality to HPV type was assigned in lesions infected with multiple oncogenic types (ATP-E cohort). Vaccine efficacy against CIN2+ irrespective of HPV DNA in lesions was 30.4% (16.4-42.1) in the TVC and 70.2% (54.7-80.9) in the TVC-naive. Corresponding values against CIN3+ were 33.4% (9.1-51.5) in the TVC and 87.0% (54.9-97.7) in the TVC-naive. Vaccine efficacy against CIN2+ associated with 12 non-vaccine oncogenic types was 54.0% (34.0-68.4; ATP-E). Individual cross-protection against CIN2+ associated with HPV-31, HPV-33, and HPV-45 was seen in the TVC.

INTERPRETATION

The HPV-16/18 AS04-adjuvanted vaccine showed high efficacy against CIN2+ associated with HPV-16/18 and non-vaccine oncogenic HPV types and substantial overall effect in cohorts that are relevant to universal mass vaccination and catch-up programmes.

FUNDING

GlaxoSmithKline Biologicals.

Age-appropriate use of human papillomavirus vaccines in the U.S

Cervical infections by approximately 15 cancer-associated (carcinogenic) human papillomavirus (HPV) genotypes cause virtually all cervical cancer and its immediate precursor lesions worldwide. Prophylactic vaccines against human papillomavirus (HPV) types HPV16 and HP18, which cause 70% of cervical cancer worldwide, hold great promise for reducing the burden of cervical cancer worldwide. However, current HPV vaccines prevent future infections and related cervical abnormalities and do not treat pre-existing HPV infections. In the U.S., HPV vaccine introduction should be considered in the context of a very successful cervical cancer screening program that has reduced the rates of cervical cancer by 75% or more. Thus, HPV vaccines will only prevent an incremental number of additional cervical cancers in the U.S. The introduction of HPV vaccines can also prevent other HPV-related sequelae, most importantly cervical intraepithelial neoplasia grade 2 or 3 (CIN2/3), which precede the development of cervical cancer and require clinical follow-up and treatment. Examining data from 7 clinical centers in the U.S., the median age of CIN2/3 is typically between 25 and 30 years of age in 2007; if screen-detected CIN2/3 develops on average 5-10 years after the causal infection is acquired, HPV vaccination will only prevent a significant proportion of CIN2/3 if it is given to women before the age of 26 and more so if given to women 18 and younger. It is increasingly evident that prophylactic HPV vaccines will provide the greatest public health or population benefit only when delivered to adolescent, mostly HPV-naive women.