Prophylactic human papillomavirus vaccines: the beginning of the end of cervical cancer

Persistent infection with one of the oncogenic human papillomavirus (HPV) types is a necessity for the development of cervical cancer. By HPV vaccination, cervical cancer could become a very rare disease. Two types of HPV vaccines can be distinguished: (i) therapeutic vaccines which induce cellular immunity targeted against epithelial cells infected with HPV and (ii) prophylactic vaccines inducing virus-neutralizing antibodies protecting against new but not against established infections. At present, several vaccines have been developed and tested in clinical trials. The vaccines are generally well tolerated and highly immunogenic. The current clinical data indicate that prophylactic vaccines are very effective against new persistent infections and the development of cervical intraepithelial lesions. The protection is type specific. However, the follow-up of the vaccination trials is still short. The effect of HPV vaccines on future cancer incidence will only be known after decades of follow-up. This article will address the status of recently terminated phase II and currently running phase III trials with prophylactic HPV vaccines.     

Human papillomavirus vaccines and adolescents

PURPOSE OF REVIEW: This review will describe human papillomavirus (HPV) vaccines in development, summarize data regarding safety and efficacy of these vaccines, and discuss key issues related to HPV vaccine implementation. RECENT FINDINGS: Evidence from epidemiologic and genetic studies has confirmed that HPV infection is a necessary cause of cervical cancer and contributes to the development of other cancers. HPV infection also may cause nonmalignant conditions such as external genital warts and recurrent respiratory papillomatosis. Over the past decade, several vaccines that target common HPV types have entered clinical trials. These vaccines are classified as prophylactic or therapeutic. The goal of prophylactic vaccines is to prevent primary or persistent HPV infections, and thus prevent cervical cancer and/or genital warts. Recent evidence indicates that prophylactic vaccines are well tolerated, highly immunogenic and effective in preventing persistent HPV infection and cervical intraepithelial neoplasia (CIN). Questions remain, however, concerning vaccine efficacy against HPV-related diseases other than cervical cancer, the duration of protection, vaccine acceptability and feasibility of vaccine delivery in the developing world. The goal of therapeutic vaccines is to prevent progression of HPV infection, induce regression of CIN or condylomata, or eradicate residual cervical cancer. Although therapeutic vaccines appear to induce both humoral and cell-mediated immunity, they have not consistently demonstrated clinical efficacy. SUMMARY: HPV vaccines in development have the potential to reduce the substantial morbidity and mortality associated with cervical cancer and other HPV-associated diseases. Large-scale efficacy studies that are planned or underway will provide additional information about vaccine tolerance and efficacy.     

Cervical cancer prevention: the impact of HPV vaccination

Cervical cancer remains a critical public health problem that is second only to breast cancer in overall disease burden for women throughout the world. In spite of the success of cervical cancer screening, Pap cytology screening is yet to be effectively implemented or has failed to reduce cervical cancer rates to an appreciable extent. Screening appears to benefit only a small fraction of women although a much larger percentage endures the inconvenience of the Pap test in order to avoid cervical cancer. The establishment of Human Papillomavirus (HPV) infection as the necessary cause of cervical precancers and cancers provides a tremendous opportunity for cervical cancer prevention through vaccination. HPV 16 and 18 which cause 70% of cervical cancers worldwide. Thus a prophylactic vaccine to prevent HPV related precancerous lesions and cancers would save lives, reduce the need for costly medical procedures and provide both women and communities throughout the world with substantial benefits. Based on the induction of neutralizing antibodies by non infectious Virus Like Particles (VLP) of L1 capside protein, prophylactic HPV vaccines have consistently induced high titter of neutralizing antibodies with minimal side effects and induce more than 90% protection from persistent HPV 16-18 infection and HPV 16 and 18 associated high-grade Cervical Intraepithelial Neoplasia (CIN) in proof of concept efficacy trials. HPV 16-18 vaccination will prevent HPV16-18 incident infection, and subsequently decrease in 90% the frequency of abnormal Pap attributable to these types and in about 50% overall abnormal Pap. HPV vaccination will reduce the number of women who require colposcopy, biopsy and cervical treatment for precancerous cervical lesions. The level of protection from death due to cervical cancer could exceed 95%. Three large phases prophylactic HPV VLP trials are now in progress and will form the basis for licensing of candidate vaccines in 2006. HPV vaccination targeting young female adolescents, aged 11 to 16 years, with a catch-up of those aged 17-25 years, would be a strategy to be addressed. Cervical cancer screening strategies, that will be cost-effective for the proper surveillance of women protected by HPV vaccination, are under analysis.     

Epidemiologic and mucosal immunologic aspects of HPV infection and HPV-related cervical neoplasia in the lower female genital tract: A review

Abstract. Tjiong MY, Out TA, ter Schegget J, Burger MPM, van der Vange N. Epidemiologic and mucosal immunologic aspects of HPV infection and HPV-related cervical neoplasia in the lower female genital tract: a review.
Human papillomavirus (HPV) infections are known to play an important role in the pathogenesis of cervical neoplasia. Considering the morbidity and mortality of cervical cancer, infection with HPV can be regarded as a worldwide problem, especially in developing countries. Currently, many studies focus on the development of both prophylactic and therapeutic HPV vaccines. Crucial for these vaccination protocols to be successful is that they will result in a long-lasting ability to generate an immune response that will eliminate the virus. HPV transmission and subsequent infection is a local event in the lower female genital tract and therefore the efficacy of vaccines against this locally transmitted infection can be best assessed by parameters of local immunity. In this review we describe both the epidemiology of HPV-related cervical neoplasia and the general aspects of mucosal immunity in the female genital tract while focusing on the local humoral immunity in HPV-related cervical neoplasia.     

The impact of anti HPV vaccination on cervical cancer incidence and HPV induced cervical lesions: consequences for clinical management

Cervical cancer is the second most common cause of cancer-related deaths in women worldwide. Screening for cervical cancer is accomplished utilizing a Pap smear and pelvic exam. While this technology is widely available and has reduced cervical cancer incidence in industrialized nations, it is not readily available in third world countries in which cervical cancer incidence and mortality is high. Development of cervical cancer is associated with infection with high risk types of human papillomavirus (HPV) creating a unique opportunity to prevent or treat cervical cancer through anti-viral vaccination strategies. Several strategies have been examined in clinical trials for both the prevention of HPV infection and the treatment of pre-existing HPV-related disease. Clinical trials utilizing prophylactic vaccines containing virus-like particles (VLPs) indicate good vaccine efficacy and it is predicted that a prophylactic vaccine may be available within the next five years. But, preclinical research in this area continues in order to deal with issues such as cost of vaccination in underserved third world populations. A majority of clinical trials using therapeutic agents which aim to prevent the progression of pre-existing HPV associated lesions or cancers have shown limited efficacy in eradicating established tumors in humans possibly due to examining patients with more advanced-stage cancer who tend to have decreased immune function. Future trends in clinical trials with therapeutic agents will examine patients with early stage cancers or pre-invasive lesions in order to prevent invasive cervical cancer. Meanwhile, preclinical studies in this field continue and include the further exploration of peptide or protein vaccination, and the delivery of HPV antigens in DNA-based vaccines or in viral vectors. Given that cervical cancers are caused by the human papillomavirus, the prospect of therapeutic vaccination to treat existing lesions and prophylactic vaccination to prevent persistent infection with the virus are high and may be implemented in the near future. The consequences for clinical management may include a significant reduction in the frequency of Pap smear screening in the case of prophylactic vaccines, and the availability of less invasive and disfiguring treatment options for women with pre-existing HPV associated lesions in the case of therapeutic vaccines. Implementation of both prophylactic and therapeutic vaccine regimens could result in a significant reduction of health care costs and reduction of worldwide cervical cancer incidence.     

Human papillomavirus update (including vaccination)

Human papillomavirus (HPV) is responsible for 99.7% of cervical cancer. Worldwide, cervical cancer causes more deaths than any other cancer, around one every two minutes. In the not so distant future cervical cancer may cause more deaths globally per year, (275,000 in 2008), than maternal deaths, (358,000 in 2008). Over 200 types of HPV have been identified. HPV is transmitted by skin-to-skin contact. Most HPV infections are cleared by the immune system; persistent infection may cause intraepithelial neoplasia and invasive disease.Prophylactic HPV vaccines prevent disease caused by the included HPV types and potentially prevent 70–75% cases of cervical cancer. The UK added HPV vaccination to the national immunization programme in 2008. The vaccines are safe and well tolerated. It is likely that the benefits will be seen over a 15–20 year period.Tests for HPV have been developed and are being evaluated as to their possible role in clinical practice.Research is ongoing regarding therapeutic HPV vaccination and second generation prophylactic vaccines to prevent more cases of cancer.     

Population-based HPV vaccination programmes are safe and effective: 2017 update and the impetus for achieving better global coverage

Persistent oncogenic human papillomavirus (HPV) is the cause of cervical cancer, as well as cancers of the anus, penis, vulva, vagina and oropharynx. There is good evidence that prophylactic HPV vaccines are immunogenic and effective against targeted-type HPV infections and type-specific genital lesions, including high-grade cervical intraepithelial neoplasia (CIN), when administered prior to HPV infection. There is good evidence that HPV vaccines are safe in population usage, with the most frequent adverse event being injection-site reactions. There is evidence to support some cross-protection against non-targeted types occurring following the administration of HPV vaccines. There is limited evidence suggesting that HPV vaccines may be beneficial in preventing future disease in women treated for high-grade CIN. This chapter focuses on the accumulated evidence regarding the global use of the three licensed HPV vaccines including safety, immunogenicity, duration of protection, effectiveness, coverage to date and barriers to higher coverage.     

New Developments in Therapeutic HPV Vaccines

Human papillomavirus (HPV) infection is the central causal factor in cervical cancer. For years efforts were undertaken to control HPV-associated disease by the development of HPV vaccines. While prophylactic HPV vaccination represents a major public health breakthrough, it is limited to new infection by certain HPV types and does not have therapeutic effects or prevent progression of pre-existing HPV infections to malignancy. Thus, there is an urgent need for therapeutic HPV vaccines. Therapeutic vaccines aim to induce cytotoxic T cells, facilitating clearance of HPV high-grade lesions and cancers. HPV E6 and E7 oncogenes represent ideal antigens for therapeutic HPV vaccination because of their constitutive expression in HPV-containing carcinomas and their critical role in the induction and maintenance of HPV-associated disease. This review discusses the most recent advances in HPV therapeutic vaccines and summarizes effects of new basic immunology findings and vaccine delivery technologies.     

Prophylactic HPV vaccines

Infection with human papillomavirus (HPV), in particular HPV 16 and HPV 18, is the main cause of cervical cancer. Two prophylactic vaccines against types 6, 11, 16 and 18 have shown great promise in clinical trials, with recent results demonstrating 100% efficacy against persistent HPV infection and development of CIN up to five years of follow-up. One of these (Gardasil, recently licensed) contains all four HPV types, offering protection against genital warts (types 6 and 11) as well as cervical cancer. The other (Cervarix) contains types 16 and 18, targeting cervical cancer alone. Recent data suggest a degree of cross-protection, against types 31 and 45; this could significantly increase the level of protection afforded by the vaccines. It is envisaged that girls between 11 and 12 will be the target, and this is what has been recommended in the United States. There is still debate about the issue of vaccinating boys. A fundamental issue is the lack of education of both the public and health professionals about HPV. In theory, an HPV vaccine could prevent almost all cervical cancer, eventually removing the need for cervical smears. However, there is at least one whole generation of women for whom the vaccine will come too late, and who will continue to require screening.     

Human papillomavirus (including vaccination)

Human papillomavirus (HPV) is responsible for 99.7% of cervical cancer. Worldwide, cervical cancer causes more deaths than any other cancer, almost two per minute. Over 200 types of HPV have been identified. HPV is transmitted by skin-to-skin contact. Most HPV infections are cleared by the immune system; persisting infections can cause intra-epithelial neoplasia and invasive disease. Prophylactic HPV vaccines have been developed and prevent disease caused by the included HPV types. Current vaccines could prevent 70–75% cases of cervical cancer. The UK, in 2008 added HPV vaccination to the national immunization programme. The vaccines are safe and well tolerated. It is likely that the benefits will be seen over a 15–20 year period. Tests for HPV have been developed and are being evaluated as to their possible role in clinical practice. Research is ongoing regarding therapeutic HPV vaccination and improving prophylactic vaccines to prevent more cases of cancer.     

Prevention of cervical cancer in Africa: a daunting task?

Africa has a high estimated incidence of cervical cancer, thus requiring the development of an effective prevention strategy. Cytology-based screening is beyond the capacity of many African countries, hence the need for alternatives. Visual inspection of the cervix after application of 3-5% acetic acid (VIA) is a promising screening test, with similar sensitivity to that of cytology but lower specificity. The same accounts for other VIA methods using magnification devices, visual inspection after the application of Lugol's iodine, or human papilloma virus (HPV) DNA testing, all proposed alternatives to cervical cancer prevention screening tests. Vaccination against HPV is the most promising strategy for the prevention of cervical cancer, but a wider variety of HPV types than currently being investigated must be considered for the development of the multivalent vaccine preparations required in Africa. Other considerations in developing an effective prevention programme include full public sector investment and achieving acceptability of a vaccine against a sexually transmitted infection targeted for adolescents. Unfortunately, however, if HPV vaccines are developed the initial impact of prophylactic vaccines will be delayed for many years. Alternative strategies should, therefore, be promoted in parallel. There are several approaches to cervical cancer prevention and their evaluation should be comprehensive and coordinated to achieve short and long-term public health benefits in different programme settings.     

Colposcopy and cervical intraepithelial neoplasia

Cervical cancer is both preventable and curable. It has a long natural history with a prolonged pre-cancerous phase that is easily detectable and treatable. Exfoliative cytology has been the mainstay for screening of cervical intra-epithelial neoplasia (CIN). Assessment of women presenting with abnormal cervical cytology and the selection of those requiring treatment relied mainly on colposcopic impressions of the cervical transformation zone and the histological appraisal of directed punch biopsies. The need to maximise clinical resources, achieve quicker and more effective management of patients, limit postoperative complications and preserve reproductive function has led to the popularity of local excisional methods for cervical premalignancy. Although the cure rates for all local ablative and excisional methods are more than 90% after one treatment, the excisional methods provide a more reliable histopathological diagnosis and the patient can be treated at the initial visit. The recognition that persistent infection with oncogenic human papillomavirus (HPV) causes cervical cancer has led to the development of new HPV tests/biomarkers and prophylactic vaccines against HPV. The HPV DNA test that targets the viral DNA has been introduced as a test of cure after CIN treatment and as a triage tool in women presenting with borderline or low-grade findings at cytology. HPV DNA test will be introduced in primary screening in the future. The national HPV immunisation programme was initiated in the NHS in September 2008. The vaccines are safe, well tolerated and highly efficacious in HPV naive women.     

Prophylactic and therapeutic vaccine therapy in papillomavirus infections

HPV types are carcinogenic in cervical cancer. This view is supported by epidemiological and biological evidence. Knowledges of HPV gene expression, of natural history of cervical HPV infection and neoplasia and of tumoral antigenic expression have lead to develop two strategies for vaccine development: 1-Prophylactic vaccines of HPV infections. 2-Therapeutic vaccines aimed to control the tumor growth and even to cure the patient. After an update of natural history of cervical HPV infection, the different target of vaccine strategies. The first published trials will be presented.     

Cervical cancer vaccines: progress and prospects

Cervical cancer remains a leading cause of cancer-related mortality in women, particularly in developing countries. The causal association between genital human papillomavirus (HPV) infection and cervical cancer has been firmly established and the oncogenic potential of certain HPV types has been clearly demonstrated. In recognition of the causal association of cervical cancer with this sexually transmitted viral infection, substantial interest has arisen to develop effective prophylactic and therapeutic vaccines. Prophylactic strategies currently under investigation focus on the induction of effective humoral and cellular immune responses that are potentially protective against subsequent HPV infection. Papillomavirus-like particles have been synthesized to induce neutralizing antibody responses, and impressive immunoprophylactic effects have been demonstrated in both animals and humans. For the treatment of existing HPV infection, techniques to augment cellular immunity by enhancing viral antigen recognition are under investigation. Vaccines targeting the oncogenic proteins E6 and E7 of HPV-16 and -18 are the focus of current clinical trials for cervical cancer patients. It is hoped that the development of successful HPV-specific vaccines will diminish the costs of existing cervical cancer screening programs and reduce the morbidity and mortality associated with the treatment of cervical neoplasias.     

Vacunas contra el virus del papiloma humano

Persistent infection by human papilloma virus (HPV) is considered to be the main cause of cervical cancer and other ano-genital cancers. Of more than 30 genotypes able to infect the anogenital tract, it is estimated that, worldwide, HPV 16 and 18 cause 70% of cervical cancers and that HPV 6 and 11 cause more than 90% of genital warts. In the last few years, the morbidity and mortality and health costs associated with cervical cancer and its precursor lesions have stimulated intense research activity to achieve primary prevention of this disease through prophylactic vaccines.     

Human papilloma virus: diagnostic, treatment and preventive issues

Human Papilloma Virus (HPV), a sexually transmitted virus, is usually found in the genital tract and causes various lesions at the mucosae of both men and women. It is considered as a causative factor of cervical cancer even if all women infected by HPV will not develop the disease. This article reviews diagnostic aspects and therapeutic alternatives for the treatment of HPV infected females, as well as aspects concerning the prophylactic HPV vaccines.     

HPV infection and cervical carcinoma--epidemiology, detection and immunology

Certain molecularly defined types of human papillomaviruses (HPV) induce, by interaction with additional cofactors, cervical cancer. In comparison to infection with HPV, all risk factors identified to date are less important. In addition to HPV a not yet classified genetic predisposition is important. Identification of HPV in cervical smears is done by detection of viral DNA. PCR based methods have the highest specificity. Currently, first vaccination studies with therapeutic vaccines are performed and phase I/II trials for prophylactic vaccination show promising results.     

Vaccination against HPV: indications for women and the impact on the cervical screening programme

A novel approach for primary prevention of cervical cancer has become available by the discovery of efficient prophylactic human papillomavirus (HPV) vaccines based on virus-like particles. This review elaborates on the progress in the field of prophylactic HPV vaccination achieved in the past decade, provides indications for prophylactic HPV vaccination, and discusses the impact on public health and the current secondary prevention system. In summary, with current vaccines, effective prevention and control of cervical cancer within the next decades requires an integrated vaccination-screening approach, including routine prophylactic vaccination to young women and adapted cervical screening for older women (≥30 years).     

A study of women's knowledge regarding human papillomavirus infection, cervical cancer and human papillomavirus vaccines

AIMS: Human papillomavirus (HPV) infection is a common sexually transmitted viral infection and is associated with the development of cervical cancer. HPV vaccines are now undergoing phase 3 clinical trials in Australia. It is likely that an HPV vaccine will become licensed for use in the near future. METHODS: Ninety women aged 18-30 years from three different groups (those attending a dysplasia clinic, a local university health service and participants currently involved in a phase 3 HPV vaccine trial) completed a questionnaire assessing their knowledge base regarding HPV infection, cervical cancer, Pap tests and HPV vaccines. RESULTS: Respondents demonstrated good understanding of the Pap test and interpretation of an abnormal result. Most respondents (89%) had heard of HPV and attributed a number of different clinical symptoms to infection. For women who had not heard of an HPV vaccine, 79% of respondents stated that the most common resource they would use to obtain further information is their general practitioner. DISCUSSION: Many women do not understand the risk factors for HPV infection, the clinical problems it may cause and the potential long-term complications of infection. Few women have heard of a HPV vaccine, but most women surveyed would approach their general practitioner for more information if one became available. CONCLUSION: This study highlights the need for further education regarding HPV infection and the potential long-term complications such as cervical cancer. It also demonstrates that education of general practitioners regarding an HPV vaccine is essential, as this is the most likely resource women will use to obtain further information in the future.     

Strategies for the prevention of cervical cancer by human papillomavirus vaccination

As cervical cancer is causally associated with 14 high-risk types of human papillomavirus (HPV), a successful HPV vaccine will have a major impact on this disease. Although some persistent HPV infections progress to cervical cancer, host immunity is generally able to clear most HPV infections. Both cell-mediated and antibody responses have been implicated in influencing the susceptibility, persistence or clearance of genital HPV infection. There have been two clinical trials that show that vaccines based on virus-like particles (VLPs) made from the major capsid protein, L1, are able to type specifically protect against cervical intra-epithelial neoplasia and infection. However, there is no evidence that even a mixed VLP vaccine will protect against types not included in the vaccine, and a major challenge that remains is how to engineer protection across a broader spectrum of viruses. Strategies for production of HPV vaccines using different vaccine vectors and different production systems are also reviewed.