Clinical trial and post-licensure safety profile of a prophylactic human papillomavirus (types 6, 11, 16, and 18) l1 virus-like particle vaccine

Safety and immunogenicity of a quadrivalent human papillomavirus vaccine in HIV-infected and HIV-negative adolescents and young adults

Human papillomavirus (HPV) infection is highly prevalent and can lead to cancer; the development of safe and efficacious vaccines for HPV is a major public health concern. The two licensed HPV vaccines contain recombinant virus-like particles of HPV 16 and 18; one of such vaccines also protects against HPV types 6 and 11 which cause genital warts. We determined safety and immunogenicity of quadrivalent HPV vaccine in HIV-infected and HIV-negative adolescents and young adults, aged 13-27 years. The seroconversion rate, assessed by antibody titers, 1 month after the administration of the third vaccine dose was 0.85 (95% CI 0.75-0.95) in the HIV-infected group and 0.91 (0.83-0.99) in the HIV-negative subjects (p=0.52). The vaccine was generally safe and well tolerated; the most common side effect was local pain and the most frequent systemic side effect was headache. This is the first report on response to HPV vaccination in both female and male HIV-infected adolescents and young adults and highlights that this population may benefit from HPV immunoprophylaxis. Further studies are needed to examine the long term efficacy of this vaccine in HIV-infected individuals.

Efficacy of the HPV-16/18 vaccine: final according to protocol results from the blinded phase of the randomized Costa Rica HPV-16/18 vaccine trial

BACKGROUND

A community-based randomized trial was conducted in Costa Rica to evaluate the HPV-16/18 AS04-adjuvanted vaccine (NCT00128661). The primary objective was to evaluate efficacy of the vaccine to prevent cervical intraepithelial neoplasia 2 or more severe disease (CIN2+) associated with incident HPV-16/18 cervical infections. Secondary objectives were to evaluate efficacy against CIN2+ associated with incident cervical infection by any oncogenic HPVs and to evaluate duration of protection against incident cervical infection with HPV-16/18. Vaccine safety and immunogenicity over the 4-year follow-up were also evaluated.

METHODS

We randomized (3727 HPV arm; 3739 control arm), vaccinated (HPV-16/18 or Hepatitis A) and followed (median 53.8 months) 7466 healthy women aged 18-25 years. 5312 women (2635 HPV arm; 2677 control arm) were included in the according to protocol analysis for efficacy. The full cohort was evaluated for safety. Immunogenicity was considered on a subset of 354 (HPV-16) and 379 (HPV-18) women. HPV type was assessed by PCR on cervical specimens. Immunogenicity was assessed using ELISA and inhibition enzyme immunoassays. Disease outcomes were histologically confirmed. Vaccine efficacy and 95% confidence intervals (95%CI) were computed.

RESULTS

Vaccine efficacy was 89.8% (95% CI: 39.5-99.5; N=11 events total) against HPV-16/18 associated CIN2+, 59.9% (95% CI: 20.7-80.8; N=39 events total) against CIN2+ associated with non-HPV-16/18 oncogenic HPVs and 61.4% (95% CI: 29.5-79.8; N=51 events total) against CIN2+ irrespective of HPV type. The vaccine had an acceptable safety profile and induced robust and long-lasting antibody responses.

CONCLUSIONS

Our findings confirm the high efficacy and immunogenicity of the HPV-16/18 vaccine against incident HPV infections and cervical disease associated with HPV-16/18 and other oncogenic HPV types. These results will serve as a benchmark to which we can compare future findings from the ongoing extended follow-up of participants in the Costa Rica trial.

TRIAL REGISTRATION

Registered with clinicaltrials.gov: NCT00128661.

Factors impacting HPV vaccination: lessons for health care professionals

HPV infection leads to significant morbidity and mortality worldwide. The HPV vaccine is currently licensed and recommended for adolescents and young adults in many countries. Nonetheless, coverage levels remain low, especially in settings using a clinic-based rather than school-based delivery model. Health care professionals (HCPs) have the potential to strongly impact HPV vaccine acceptability and uptake, yet often fail to discuss and/or strongly recommend HPV vaccination. This article reviews the myriad factors that influence HPV vaccination, focusing, in particular, on those relevant to HCP communication with patients and families. It also provides a historical framework and highlights recent evidence related to HPV vaccination that may be valuable for these conversations. Lastly, it discusses strategies targeting HCPs and their practices that may increase HPV vaccination initiation and completion rates globally.

Autoimmune disorders and quadrivalent human papillomavirus vaccination of young female subjects

OBJECTIVES

The aim of this study was to investigate whether the quadrivalent human papillomavirus (HPV) vaccine Gardasil is associated with a change in the risk of autoimmune disorders (ADs) in young female subjects.

DESIGN

Systematic case-control study of incident ADs associated with quadrivalent HPV vaccination in young women across France.

PARTICIPANTS AND SETTING

A total of 113 specialised centres recruited (from December 2007 to April 2011) females aged 14-26 years with incident cases of six types of ADs: idiopathic thrombocytopenic purpura (ITP), central demyelination/multiple sclerosis (MS), Guillain-Barré syndrome, connective tissue disorders (systemic lupus erythematosus, rheumatoid arthritis/juvenile arthritis), type 1 diabetes mellitus and autoimmune thyroiditis. Control subjects matched to cases were recruited from general practice.

ANALYSIS

Multivariate conditional logistic regression analysis; factors included age, geographical origin, smoking, alcohol consumption, use of oral contraceptive(s) or vaccine(s) other than Gardasil received within 24 months before the index date and personal/family history of ADs.

RESULTS

Overall, 211 definite cases of ADs were matched to 875 controls. The adjusted odds ratio (OR) for any quadrivalent HPV vaccine use was 0.9 [95% confidence interval (CI) 0.5-1.5]. The individual ORs were 1.0 (95% CI 0.4-2.6) for ITP, 0.3 (95% CI 0.1-0.9) for MS, 0.8 (95% CI 0.3-2.4) for connective disorders and 1.2 (95% CI 0.4-3.6) for type 1 diabetes. No exposure to HPV vaccine was observed in cases with either Guillain-Barré syndrome or thyroiditis.

CONCLUSIONS

No evidence of an increase in the risk of the studied ADs was observable following vaccination with Gardasil within the time periods studied. There was insufficient statistical power to allow conclusions to be drawn regarding individual ADs.

Adverse events following immunization in Ontario's female school-based HPV program

BACKGROUND

In September 2007, a school-based human papillomavirus (HPV) vaccination program targeting grade 8 girls (approximately 13 years old) and delivered by public health was implemented in Ontario, Canada. We assessed reports of adverse events following immunization (AEFI) from the school-based program as part of quadrivalent HPV (HPV4) vaccine safety surveillance and to contribute to a comprehensive HPV vaccine program evaluation.

METHODS

AEFIs following HPV4 vaccine (Gardasil(®)) administered between September 1, 2007 and December 31, 2011 were extracted from the province's reportable disease system. Confirmed AEFI reports among females 12-15 years old (i.e. assumed to have received vaccine through the program) were included. Events were grouped according to provincial AEFI case definitions. Rates were calculated using doses distributed as the denominator.

RESULTS

Between 2007 and 2011, 133 confirmed AEFIs were reported while 691,994 HPV4 vaccine doses were distributed in the school-based program. The overall reporting rate was 19.2 HPV4 AEFI per 100,000 doses distributed. Annual reporting rates decreased from 30.0 to 18.3 per 100,000 doses distributed. Frequently reported events included 'allergic reaction-dermatologic/mucosa' (25%), 'rash' (22%), and 'local/injection site reaction' (20%); 26% of reports had a non-specific event of 'other severe/unusual events' selected. Ten serious AEFIs were reported (7.5% of reports) including 2 anaphylaxis, 2 seizures, 1 thrombocytopenia and 1 death. Further review found that the reports of anaphylaxis did not meet the Brighton anaphylaxis definition and the death was attributed to a preexisting cardiac condition.

CONCLUSIONS

Overall these findings are consistent with the safety profile of HPV4 vaccine from pre-licensure clinical trials and post-marketing surveillance reports and importantly, no new safety signals were identified, especially no reports of VTE in this younger female population. Continued assessment of HPV4 AEFI surveillance data may be important to detect and investigate safety signals.

Autoimmune, neurological, and venous thromboembolic adverse events after immunisation of adolescent girls with quadrivalent human papillomavirus vaccine in Denmark and Sweden: cohort study

OBJECTIVE

To assess the risk of serious adverse events after vaccination of adolescent girls with quadrivalent human papillomavirus (qHPV) vaccine.

DESIGN

Register based cohort study.

SETTING

Denmark and Sweden, October 2006 to December 2010.

PARTICIPANTS

997,585 girls aged 10-17, among whom 296,826 received a total of 696,420 qHPV vaccine doses.

MAIN OUTCOME MEASURES

Incident hospital diagnosed autoimmune, neurological, and venous thromboembolic events (53 different outcomes) up to 180 days after each qHPV vaccine dose. Only events with at least five vaccine exposed cases were considered for further assessment. Rate ratios adjusted for age, country, calendar year, and parental country of birth, education, and socioeconomic status were estimated, comparing vaccinated and unvaccinated person time. For outcomes where the rate ratio was significantly increased, we regarded three criteria as signal strengthening: analysis based on 20 or more vaccine exposed cases (reliability), rate ratio 3.0 or more (strength), and significantly increased rate ratio in country specific analyses (consistency). We additionally assessed clustering of events in time and estimated rate ratios for a risk period that started on day 181.

RESULTS

Among the 53 outcomes, at least five vaccine exposed cases occurred in 29 and these were analysed further. Whereas the rate ratios for 20 of 23 autoimmune events were not significantly increased, exposure to qHPV vaccine was significantly associated with Behcet's syndrome, Raynaud's disease, and type 1 diabetes. Each of these three outcomes fulfilled only one of three predefined signal strengthening criteria. Furthermore, the pattern of distribution in time after vaccination was random for all three and the rate ratios for these outcomes in the period from day 181 after vaccination were similar to the rate ratios in the primary risk period. The rate ratios for five neurological events were not significantly increased and there were inverse associations with epilepsy (rate ratio 0.66, 95% confidence interval 0.54 to 0.80) and paralysis (0.56, 0.35 to 0.90). There was no association between exposure to qHPV vaccine and venous thromboembolism (0.86, 0.55 to 1.36).

CONCLUSIONS

This large cohort study found no evidence supporting associations between exposure to qHPV vaccine and autoimmune, neurological, and venous thromboembolic adverse events. Although associations for three autoimmune events were initially observed, on further assessment these were weak and not temporally related to vaccine exposure. Furthermore, the findings need to be interpreted considering the multiple outcomes assessed.

Counseling about the HPV vaccine: desexualize, educate, and advocate

Information is provided for clinicians who treat adolescents and adult women to use when counseling patients about human papillomavirus (HPV) vaccine. A literature search was done to determine: (1) reasons for refusal of the vaccine, including cost and concerns that immunization against HPV will lead to promiscuity; (2) potential for non-sexual transmission of HPV; (3) non-genital locations of HPV; (4) non-genital cancers associated with HPV. Vaccines for Children Program and the Affordable Care Act eliminate many costs.Neither biological nor behavioral evidence supports the idea that sexual behavior changes after immunization. HPV is transmitted from person to person by non-sexual routes including mother to child at birth and apparently by touch after birth. HPV is persistent in the environment, including medical environments. It has been found on apparently sterilized instruments used in vaginal exams. Pathogenic HPV has been recovered from breast tissue, sinonasal areas, and nipples as well as from hair follicles on arms, legs, scalps, eyebrows, and pubic hair. Pathogenic HPV was found in 6.5% of the oral cavities of a random sample of Americans. HPV is known to cause anal and oral cancers. It has also been associated with skin cancers, breast tumors, and prostate cancers. It is not known if the vaccine is protective against these cancers, but it is useful to educate about these other routes of transmission and non-genital HPV linked cancers so that patients/parents do not just focus on the sexual nature of the human papillomavirus.

Towards the eradication of HPV infection through universal specific vaccination

BACKGROUND

The Human Papillomavirus (HPV) is generally recognized to be the direct cause of cervical cancer. The development of effective anti-HPV vaccines, included in the portfolio of recommended vaccinations for any given community, led to the consolidation in many countries of immunization programs to prevent HPV-related cervical cancers. In recent years, increasing evidence in epidemiology and molecular biology have supported the oncogenic role of HPV in the development of other neoplasm including condylomas and penile, anal, vulvar, vaginal, and oro-pharyngeal cancers. Men play a key role in the paradigm of HPV infection: both as patients and as part of the mechanisms of transmission. Data show they are affected almost as often as women. Moreover, no screening procedures for HPV-related disease prevention are applied in men, who fail to undergo routine medical testing by any medical specialist at all. They also do not benefit from government prevention strategies.

DISCUSSION

A panel of experts convened to focus on scientific, medical, and economic studies, and on the achievements from health organizations' intervention programs on the matter. One of the goals was to discuss on the critical issues emerging from the ongoing global implementation of HPV vaccination. A second goal was to identify contributions which could overcome the barriers that impede or delay effective vaccination programs whose purpose is to eradicate the HPV infection both in women and men.

SUMMARY

The reviewed studies on the natural history of HPV infection and related diseases in women and men, the increasing experience of HPV vaccination in women, the analysis of clinical effectiveness vs economic efficacy of HPV vaccination, are even more supportive of the economic sustainability of vaccination programs both in women and men. Those achievements address increasing and needed attention to the issue of social equity in healthcare for both genders.

Answering human papillomavirus vaccine concerns; a matter of science and time

Since the introduction of the HPV vaccine, questions have been asked about its efficacy in preventing cancer linked with HPV. Concerns about the HPV vaccine safety profile have also been raised. This paper highlights the rapidly growing body of evidence (including clinical trials and post-marketing surveillance) illustrating both the safety of the HPV vaccine, through a detailed investigation of reported adverse events, and its efficacy in reducing both HPV infections rates and the resulting drop in cervical lesions, which have been demonstrated to be good predictors of cervical cancer risk.

Safety of human papillomavirus vaccines: a review

Vaccination to prevent human papillomavirus (HPV)-related infection leading to cancer, particularly cervical cancer, is a major public health breakthrough. There are currently two licensed HPV vaccines, both of which contain recombinant virus-like particles of HPV types 16 and 18 (which account for approximately 70 % of cervical cancer). One vaccine also protects against HPV types 6 and 11, which cause genital warts. The safety profile of both vaccines was assessed extensively in randomised controlled clinical trials conducted prior to licensure and has been further elucidated following licensure from surveillance and specific studies in large populations. This review aims to examine current evidence regarding the safety of HPV vaccines. In summary, both vaccines are associated with relatively high rates of injection site reactions, particularly pain, but this is usually of short duration and resolves spontaneously. Systemic reactions have generally been mild and self-limited. Post vaccination syncope has occurred, but can be avoided with appropriate care. Serious vaccine-attributable adverse events, such as anaphylaxis, are rare, and although not recommended for use in pregnancy, abnormal pregnancy outcomes following inadvertent administration do not appear to be associated with vaccination. HPV vaccines are used in a three-dose schedule predominantly in adolescent females: as such case reports linking vaccination with a range of new onset chronic conditions, including autoimmune diseases, have been made. However, well-conducted population-based studies show no association between HPV vaccine and a range of such conditions. Whilst this reassuring safety profile affirms the positive risk benefit of vaccination, as HPV vaccine use expands into more diverse populations, including males, ongoing safety assessment using well-conducted studies is appropriate.

Monitoring human papillomavirus prevalence in urine samples: a review

Human papillomavirus (HPV) is the main cause of cervical cancer, and many countries now offer vaccination against HPV to girls by way of government-funded national immunization programs. Monitoring HPV prevalence in adolescents could offer a near-term biological measure of vaccine impact, and urine sampling may be an attractive large-scale method that could be used for this purpose. Our objective was to provide an overview of the literature on HPV DNA detection in urine samples, with an emphasis on adolescents. We searched the PubMed database using the terms “HPV” and “urine” and identified 21 female and 14 male study populations in which HPV prevalence in urine samples was reported, four of which included only asymptomatic female adolescents. We provide herein an overview of the recruitment setting, age, urine sampling procedure, lesion type, HPV assay, and HPV prevalence in urine samples and other urogenital samples for the studies included in this review. In female study populations, concordance for any HPV type and type-specific concordance in paired urine and cervical samples are provided in addition to sensitivity and specificity. We concluded that few studies on HPV prevalence in urine samples have been performed in asymptomatic female adolescent populations but that urine samples may be a useful alternative to cervical samples to monitor changes in HPV prevalence in females in the post-HPV vaccination era. However, care should be taken when extrapolating HPV findings from urine samples to the cervix. In males, urine samples do not seem to be optimal for monitoring HPV prevalence due to a low human genomic DNA content and HPV DNA detection rate compared to other urogenital sites. In each situation the costs and benefits of HPV DNA detection in urine compared to alternative monitoring options should be carefully considered.

Trends in HPV vaccine initiation among adolescent females in North Carolina, 2008-2010

BACKGROUND

To better target future immunization efforts, we assessed trends and disparities in human papillomavirus (HPV) vaccine initiation among female adolescents in North Carolina over 3 years.

METHODS

We analyzed data from a stratified random sample of 1,427 parents who, between 2008 and 2010, completed two linked telephone surveys: the Behavioral Risk Factor Surveillance System and the Child Health Assessment and Monitoring Program surveys. Weighted analyses examined HPV vaccine initiation for girls ages 11 to 17 years.

RESULTS

HPV vaccine initiation increased modestly over time (2008, 34%; 2009, 41%; 2010, 44%). This upward trend was present within 11 subpopulations of girls, including those who lived in rural areas, were of minority (non-black/non-white) race, or had not recently received a preventive check-up. Looking at differences between groups, HPV vaccine initiation was less common among girls who attended private versus public school, were younger, or lacked a recent check-up. However, the latter difference narrowed over time. The low level of initiation among girls without recent check-ups increased substantially (from 11% to 41%), whereas initiation among girls with recent visits improved little (from 39% to 44%, P(interaction) = 0.007).

CONCLUSIONS

Although HPV vaccine initiation improved among several groups typically at higher risk for cervical cancer, the lack of progress among girls with recent check-ups suggests that missed opportunities for administration have hampered broader improvements.

IMPACT

Achieving widespread coverage of HPV vaccine will require redoubled efforts to vaccinate adolescents during routine care.

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.

Surveillance of autoimmune conditions following routine use of quadrivalent human papillomavirus vaccine

OBJECTIVE

An observational safety study of the quadrivalent human papillomavirus vaccine (HPV4) in women was conducted. This report presents findings from autoimmune surveillance. Design.  Subjects were followed for 180days after each HPV4 dose for new diagnoses of 16 prespecified autoimmune conditions.

SETTING

Two managed care organizations in California. Subjects.  Number of 189,629 women who received ≥1 dose of HPV4 between 08/2006 and 03/2008.

OUTCOME

Potential new-onset autoimmune condition cases amongst HPV4 recipients were identified by electronic medical records. Medical records of those with ≥12-month health plan membership prior to vaccination were reviewed by clinicians to confirm the diagnosis and determine the date of disease onset. The incidence of each autoimmune condition was estimated for unvaccinated women at one study site using multiple imputations and compared with that observed in vaccinated women. Incidence rate ratios (IRR) were calculated. Findings were reviewed by an independent Safety Review Committee (SRC).

RESULTS

Overall, 1014 potential new-onset cases were electronically identified; 719 were eligible for case review; 31-40% were confirmed as new onset. Of these, no cluster of disease onset in relation to vaccination timing, dose sequence or age was found for any autoimmune condition. None of the estimated IRR was significantly elevated except Hashimoto's disease [IRR=1.29, 95% confidence interval: 1.08-1.56]. Further investigation of temporal relationship and biological plausibility revealed no consistent evidence for a safety signal for autoimmune thyroid conditions. The SRC and the investigators identified no autoimmune safety concerns in this study.

CONCLUSIONS

No autoimmune safety signal was found in women vaccinated with HPV4.

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.

The human papillomavirus (HPV) vaccine and cervical cancer: uptake and next steps

Infection with a high-risk type of the human papillomavirus (HPV) is a major contributing factor in the vast majority of cervical cancers. Dissemination of the HPV vaccine is critical in reducing the risk of the disease. This descriptive review of HPV vaccine uptake in papers published between 2006 and 2011 focuses on studies conducted in girls and young women. In the United States, rates of immunization as per the protocol for teens (age 13-17 years) range from 6% to 75% and those for young women (age 18-26 years) range from 4% to 79%, although the samples and data collection methods vary. The epidemiology of HPV, the mechanisms of action, protocols for vaccine immunization, rates of uptake, and barriers to vaccination at the policy, provider, and patient levels are reviewed. Various intervention techniques are described, and policy-level programs, such as legislation supporting mandates, subsidized public education, and cost-reduction initiatives, are also explored. Increased distribution of the HPV vaccine in school-based clinics, evidencebased scripts for provider counseling of young patients and their parents, concurrent immunizations to adolescents, prevention visits, greater patient education and outreach, and the dissemination of academic detailing can help to boost vaccine uptake, particularly in underresourced communities. Population-based surveillance is necessary for robust estimates of uptake over time. Additional research is needed to comprehensively examine socio-demographic, psychosocial, and sociocultural factors that predict vaccine uptake according to the protocol. Increased study of the vaccine's long-term effectiveness, in both males and females and among extended age groups, is warranted.

Quadrivalent human papillomavirus (HPV) types 6, 11, 16, 18 vaccine: for the prevention of genital warts in males

The quadrivalent HPV types 6, 11, 16, 18 vaccine (Gardasil®) is a recombinant vaccine comprising purified virus-like particles derived from the L1 capsid proteins of HPV types 6, 11, 16 and 18. The vaccine was highly immunogenic. Geometric mean titres (GMTs) and seroconversion rates for all four HPV types at month 7 in males aged 10-15 years were noninferior to those in females aged 16-23 years, and those in males aged 9-15 years were noninferior to those in females aged 9-15 years. In addition, GMTs and seroconversion rates in males aged 16-26 years receiving the vaccine were higher than those receiving amorphous aluminium hydroxyphosphate sulfate adjuvant (AAHS) control. The quadrivalent HPV vaccine was significantly more effective than AAHS control at decreasing the incidence of HPV 6-, 11-, 16- or 18-related external genital lesions (primary endpoint) in a randomized, double-blind, placebo-controlled, multicentre study in males aged 16-26 years. The most common clinical endpoint was HPV 6- and 11-related condyloma; efficacy was robust against these lesions. The vaccine is also expected to be protective against genital warts in males aged 9-15 years, as the immune response in males of this age group was noninferior to that in males aged 16-26 years. The quadrivalent HPV vaccine was generally well tolerated in males aged 9-26 years. The most common adverse events reported were injection-site related, and most of these were of mild to moderate severity.

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.

Lack of effects on male fertility from a quadrivalent HPV vaccine in Sprague-Dawley rats

BACKGROUND

Human papillomavirus (HPV) infection is one of the most common sexually transmitted diseases in both men and women. A recently developed quadrivalent HPV vaccine, Gardasil, has been shown to be highly effective in the prevention of several HPV-mediated diseases. The objective of the present study was to evaluate the potential effects of the vaccine on male fertility including reproductive performance, sperm evaluations, and histology of the testes. In addition, anti-HPV antibodies were measured during the study.

METHODS

Group 1 (30 male rats) received the full human dose of vaccine (0.5 mL, ∼200-fold excess based on body weight) by intramuscular injection at 6 weeks, 3 weeks, and 3 days prior to cohabitation. Group 2 males received only 1 dose at 3 days prior to cohabitation. Additional groups (20 male rats each) were administered PBS or Merck Aluminum Adjuvant similarly to Group 1. Ten males in the vaccine-treated groups were bled for immunogenicity assays after each dose. Twenty males per group were mated to untreated female rats. Cesarean sections were performed on Gestation Day 15 or 16. Cohabited males were necropsied and sperm count and motility were evaluated.

RESULTS

There were no unscheduled deaths during the study and no evidence of toxicity in vaccine-treated male rats. The vaccine induced a specific antibody response to the 4 HPV types after each injection. There were no effects on the cesarean-section parameters of females or reproductive parameters of the cohabited male rats, including histomorphology of testes and epididymis, sperm count, and sperm motility.

CONCLUSIONS

These results demonstrate that this quadrivalent HPV vaccine had no detectable adverse effects on routine measures of male fertility in rats.

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.

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.

Lassa virus-like particles displaying all major immunological determinants as a vaccine candidate for Lassa hemorrhagic fever

BACKGROUND

Lassa fever is a neglected tropical disease with significant impact on the health care system, society, and economy of Western and Central African nations where it is endemic. Treatment of acute Lassa fever infections has successfully utilized intravenous administration of ribavirin, a nucleotide analogue drug, but this is not an approved use; efficacy of oral administration has not been demonstrated. To date, several potential new vaccine platforms have been explored, but none have progressed toward clinical trials and commercialization. Therefore, the development of a robust vaccine platform that could be generated in sufficient quantities and at a low cost per dose could herald a subcontinent-wide vaccination program. This would move Lassa endemic areas toward the control and reduction of major outbreaks and endemic infections. To this end, we have employed efficient mammalian expression systems to generate a Lassa virus (LASV)-like particle (VLP)-based modular vaccine platform.

RESULTS

A mammalian expression system that generated large quantities of LASV VLP in human cells at small scale settings was developed. These VLP contained the major immunological determinants of the virus: glycoprotein complex, nucleoprotein, and Z matrix protein, with known post-translational modifications. The viral proteins packaged into LASV VLP were characterized, including glycosylation profiles of glycoprotein subunits GP1 and GP2, and structural compartmentalization of each polypeptide. The host cell protein component of LASV VLP was also partially analyzed, namely glycoprotein incorporation, though the identity of these proteins remain unknown. All combinations of LASV Z, GPC, and NP proteins that generated VLP did not incorporate host cell ribosomes, a known component of native arenaviral particles, despite detection of small RNA species packaged into pseudoparticles. Although VLP did not contain the same host cell components as the native virion, electron microscopy analysis demonstrated that LASV VLP appeared structurally similar to native virions, with pleiomorphic distribution in size and shape. LASV VLP that displayed GPC or GPC+NP were immunogenic in mice, and generated a significant IgG response to individual viral proteins over the course of three immunizations, in the absence of adjuvants. Furthermore, sera from convalescent Lassa fever patients recognized VLP in ELISA format, thus affirming the presence of native epitopes displayed by the recombinant pseudoparticles.

CONCLUSIONS

These results established that modular LASV VLP can be generated displaying high levels of immunogenic viral proteins, and that small laboratory scale mammalian expression systems are capable of producing multi-milligram quantities of pseudoparticles. These VLP are structurally and morphologically similar to native LASV virions, but lack replicative functions, and thus can be safely generated in low biosafety level settings. LASV VLP were immunogenic in mice in the absence of adjuvants, with mature IgG responses developing within a few weeks after the first immunization. These studies highlight the relevance of a VLP platform for designing an optimal vaccine candidate against Lassa hemorrhagic fever, and warrant further investigation in lethal challenge animal models to establish their protective potential.