Cervical response to vaccination against HPV16 E7 in case of severe dysplasia

Effectiveness and Safety of Therapeutic Vaccines for Precancerous Cervical Lesions: A Systematic Review and Meta-Analysis

OBJECTIVE

This study systematically evaluated the effectiveness and safety of therapeutic vaccines for precancerous cervical lesions, providing evidence for future research.

METHODS

We systematically searched the literature in 10 databases from inception to February 18, 2021. Studies on the effectiveness and safety of therapeutic vaccines for precancerous cervical lesions were included. Then, we calculated the overall incidence rates of four outcomes, for which we used the risk ratio (RR) and 95% confidence interval (95% CI) to describe the effects of high-grade squamous intraepithelial lesions (HSILs) on recurrence.

RESULTS

A total of 39 studies were included, all reported in English, published from 1989 to 2021 in 16 countries. The studies covered 22,865 women aged 15-65 years, with a total of 5,794 vaccinated, and 21 vaccines were divided into six types. Meta-analysis showed that the overall incidence rate of HSIL regression in vaccine therapies was 62.48% [95% CI (42.80, 80.41)], with the highest rate being 72.32% for viral vector vaccines [95% CI (29.33, 99.51)]. Similarly, the overall incidence rates of HPV and HPV16/18 clearance by vaccines were 48.59% [95% CI (32.68, 64.64)] and 47.37% [95% CI (38.00, 56.81)], respectively, with the highest rates being 68.18% [95% CI (45.13, 86.14)] for bacterial vector vaccines and 55.14% [95% CI (42.31, 67.66)] for DNA-based vaccines. In addition, a comprehensive analysis indicated that virus-like particle vaccines after conization reduced the risk of HSIL recurrence with statistical significance compared to conization alone [RR = 0.46; 95% CI (0.29, 0.74)]. Regarding safety, only four studies reported a few severe adverse events, indicating that vaccines for precancerous cervical lesions are generally safe.

CONCLUSION

Virus-like particle vaccines as an adjuvant immunotherapy for conization can significantly reduce the risk of HSIL recurrence. Most therapeutic vaccines have direct therapeutic effects on precancerous lesions, and the effectiveness in HSIL regression, clearance of HPV, and clearance of HPV16/18 is great with good safety. That is, therapeutic vaccines have good development potential and are worthy of further research.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO https://www.crd.york.ac.uk/PROSPERO/, CRD42021275452.

Targeted immunotherapy of high-grade cervical intra-epithelial neoplasia: Expectations from clinical trials

Targeted immunotherapy of high-grade cervical intra-epithelial neoplasia (CIN) has been developed as an alternative to conization, to preserve future reproductive outcomes and avoid human papillomavirus (HPV) persistence. The objectives of the review are to present drugs according to their process of development and to examine their potential future use. A search for key words associated with CIN and targeted immunotherapy was carried out in the Cochrane library, Pubmed, Embase, and ClinicalTrials.gov from 1990 to 2016. Publications (randomized, prospective and retrospective studies) in any language were eligible for inclusion, as well as ongoing trials registered on the ClinicalTrials.gov website. Targeted immunotherapy includes peptide/protein-based vaccines, nucleic acid-based vaccines (DNA), and live vector-based vaccines (bacterial or viral). A total of 18 vaccines were identified for treatment of CIN at various stages of development, and the majority were well-tolerated. Adverse effects were primarily injection site reactions and flu-like symptoms under grade 2. The efficacy of vaccines defined by regression of CIN2/3 to no CIN or CIN1 ranged from 17 to 59% following a minimum of a 12-week follow-up. In the majority of studies, there was no association demonstrated between histological response and HPV clearance, or between histological or virological response and immune T cell response. Given that the spontaneous regression of CIN2/3 is 20-25% at 6 months, targeted immunotherapy occurs an additional value, which never reaches 50%, with one trial an exception to this. However, research and development on HPV eradication drugs needs to be encouraged, due to HPV-associated disease burden.

Efficacy of human papillomavirus vaccines: a systematic quantitative review

Human papillomavirus (HPV) types cause approximately 70% of cervical cancer worldwide. Two vaccines have been recently evaluated in randomized controlled trials: the bivalent vaccine for HPV 16 and 18 (Cervarix, GlaxoSmithKline Biologicals, Rixensart, Belgium) and the quadrivalent vaccine for HPV 6, 11, 16, and 18 (Gardasil, Merck and Co, Inc, Whitehouse Station, NJ). We have performed a systematic review of all randomized controlled trials in which vaccines against HPV were compared with placebo regarding efficacy, safety, and immunogenicity. Six studies met the inclusion criteria, which included 47,236 women. The first objective in this systematic review was to assess vaccine efficacy in the prevention of cytologically and/or histologically proven lesions. And the secondary objective was the evaluation of safety and vaccine immunogenicity. Bivalent and quadrivalent HPV vaccines significantly reduced the rate of lesions in the cervix, vulva, vagina, and anogenital region, with efficacy of 93% (95% confidence interval [CI], 87-96) and 62% (95% CI, 27-70), respectively, when compared with the control groups according to intention to treat. Regarding safety, we found more symptoms in the bivalent vaccine group (35%; 95% CI, 5-73) when compared with the control groups. In regard to vaccine immunogenicity, there was seroconversion in the group that received the vaccine when compared with the placebo group in the bivalent and quadrivalent vaccines. Prophylactic vaccination can prevent HPV infection in women aged 9 to 26 years not previously infected with the HPV subtypes covered by the vaccines. To evaluate cervical cancer incidence and mortality, a longer follow-up is necessary.

Therapeutic vaccines against human papillomavirus and cervical cancer

Cervical cancer and its precursor intra-epithelial lesions are linked to infection by a subset of so-called "highrisk" human papillomavirus types, which are estimated to infect nearly four hundred million women worldwide. Two prophylactic vaccines have been commercialized recently targeting HPV16 and 18, the most prevalent viral types found in cervical cancer, which operate through induction of capsid-specific neutralizing antibodies. However, in patients with persistent infection these vaccines have not been found to protect against progression to neoplasia. Attempts are being made to develop therapeutic vaccines targeting nonstructural early viral proteins. Among these, E6 and E7 are the preferred targets, since they are essential for induction and maintenance of the malignant phenotype and are constitutively expressed by the transformed epithelial cells. Here are reviewed the most relevant potential vaccines based on HPV early antigens that have shown efficacy in preclinical models and that are being tested in clinical studies, which should determine their therapeutic capacity for eradicating HPV-induced premalignant and malignant lesions and cure cervical cancer.

COX-2 overexpression as a biomarker of early cervical carcinogenesis: a pilot study

BACKGROUND

Recent studies have demonstrated that cyclooxygenase-2 (COX-2) expression is up-regulated in a number of cancers. Selective inhibition of COX-2 offers a potential pharmacological strategy for cancer prevention. The COX-2 isoform is induced in response to inflammatory factors and is expressed in premalignant lesions, including cervical tissues. Few studies have investigated COX-2 expression as a biomarker for early cervical carcinogenesis. In this preliminary study, we assessed the variability of COX-2 overexpression in cervical premalignant lesions.

METHODS

Fifty-two patients were recruited and consented. Paired abnormal and control (normal) cervical biopsies were obtained and evaluated for high-risk human papillomavirus (HPV), inflammation, histopathological diagnosis, and COX-2 protein concentration by ELISA. Paired Student's t-test and general linear regression models were used to compare mean COX-2 protein concentrations among biopsy samples and selected risk variables.

RESULTS

Forty-seven of fifty-two paired biopsies were evaluated. COX-2 protein concentrations were 4.9-fold greater in abnormal biopsies (CIN 1 and CIN 2) than normal biopsies. COX-2 was also significantly increased in inflammation-positive biopsies. No significant association was found between COX-2 levels and HPV high-risk positivity, age, parity, STI history, or hormonal contraceptive use, but the sample size was small.

CONCLUSIONS

These results suggest that COX-2 induction begins in the premalignant phase of cervical carcinogenesis and is correlated with inflammation. A trial using a much larger number of specimens will allow further development of our understanding of COX-2 as a biomarker for use in chemoprevention trials.

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.

Progress in vaccines for sexually transmitted diseases

The development pipeline for vaccines to control sexually transmitted infections holds greater promise than ever before. Preclinical studies are encouraging in the development of chlamydia and gonococcal vaccines, and for the first time, recent clinical trials have shown the feasibility of creating vaccines to control genital herpes and cervical human papillomavirus infections. Behavioral research suggests that these vaccines will likely find acceptance among health care providers and consumers.

Vaccination strategies for the treatment and prevention of cervical cancer

PURPOSE OF REVIEW

Immunotherapy of HPV-induced premalignant anogenital lesions and cervical cancer has made impressive progress. HPV as causative agent is targeted by prophylactic and therapeutic vaccination strategies. Preclinical and clinical studies have shown induction of natural and/or vaccine-induced immune responses. This review will summarize the status of vaccine development and clinical testing published since March 2003.

RECENT FINDINGS

For prophylactic vaccines there is first clinical evidence of effectivity (ie, 100% protection from HPV infection and dysplasia by virus-like particle (VLP) vaccine-induced neutralizing antibodies). Also, therapeutic vaccines have entered clinical evaluation. While prophylactic VLP vaccines are immunogenic per se, therapeutic vaccines will need further adjuvants to guide T cell differentiation, expansion, survival, and homing to tumor sites. To enhance clinical outcome of successful T cell induction in patients, the susceptibility of the tumor cells for lysis must be addressed in the future, since tumor immune evasion is a severe problem in cervical cancer.

SUMMARY

While successful prophylactic HPV vaccines have entered large clinical trials, therapeutic HPV vaccines, in spite of T cell induction, lack clinical responses due to the problem of tumor immune evasion. Adjuvants for systemic and local immune modulation will be mandatory for effective therapy.