The current state of therapeutic and T cell-based vaccines against human papillomaviruses

Vaccine process technology-A decade of progress

In the past decade, new approaches to the discovery and development of vaccines have transformed the field. Advances during the COVID-19 pandemic allowed the production of billions of vaccine doses per year using novel platforms such as messenger RNA and viral vectors. Improvements in the analytical toolbox, equipment, and bioprocess technology have made it possible to achieve both unprecedented speed in vaccine development and scale of vaccine manufacturing. Macromolecular structure-function characterization technologies, combined with improved modeling and data analysis, enable quantitative evaluation of vaccine formulations at single-particle resolution and guided design of vaccine drug substances and drug products. These advances play a major role in precise assessment of critical quality attributes of vaccines delivered by newer platforms. Innovations in label-free and immunoassay technologies aid in the characterization of antigenic sites and the development of robust in vitro potency assays. These methods, along with molecular techniques such as next-generation sequencing, will accelerate characterization and release of vaccines delivered by all platforms. Process analytical technologies for real-time monitoring and optimization of process steps enable the implementation of quality-by-design principles and faster release of vaccine products. In the next decade, the field of vaccine discovery and development will continue to advance, bringing together new technologies, methods, and platforms to improve human health.

The use of proteins and peptides-based therapy in managing and preventing pathogenic viruses

Therapeutic proteins have been employed for centuries and reached approximately 50 % of all drugs investigated. By 2023, they represented one of the top 10 largest-selling pharma products ($387.03 billion) and are anticipated to reach around $653.35 billion by 2030. Growth hormones, insulin, and interferon (IFN α, γ, and β) are among the leading applied therapeutic proteins with a higher market share. Protein-based therapies have opened new opportunities to control various diseases, including metabolic disorders, tumors, and viral outbreaks. Advanced recombinant DNA biotechnology has offered the production of therapeutic proteins and peptides for vaccination, drugs, and diagnostic tools. Prokaryotic and eukaryotic expression host systems, including bacterial, fungal, animal, mammalian, and plant cells usually applied for recombinant therapeutic proteins large-scale production. However, several limitations face therapeutic protein production and applications at the commercial level, including immunogenicity, integrity concerns, protein stability, and protein degradation under different circumstances. In this regard, protein-engineering strategies such as PEGylation, glycol-engineering, Fc-fusion, albumin conjugation, and fusion, assist in increasing targeting, product purity, production yield, functionality, and the half-life of therapeutic protein circulation. Therefore, a comprehensive insight into therapeutic protein research and findings pave the way for their successful implementation, which will be discussed in the current review.

Delayed vaccine-induced CD8+ T cell expansion by topoisomerase I inhibition mediates enhanced CD70-dependent tumor eradication

BACKGROUND

The survival of patients with cervical cancer who are treated with cisplatin in conjunction with the topoisomerase I inhibitor topotecan is enhanced when compared with patients treated with only one of these chemotherapeutics. Moreover, cisplatin-based and T cell-based immunotherapy have been shown to synergize, resulting in stronger antitumor responses. Here, we interrogated whether topotecan could further enhance the synergy of cisplatin with T cell-based cancer immunotherapy.

METHODS

Mice bearing human papilloma virus 16 (HPV16) E6/E7-expressing TC-1 tumors were vaccinated with HPV16 E7 long peptides and additionally received chemotherapy consisting of cisplatin and topotecan. We performed an in-depth study of this combinatorial chemoimmunotherapy on the effector function and expansion/contraction kinetics of vaccine-induced CD8+ T cells in the peripheral blood and tumor microenvironment (TME). In addition, we interrogated the particular role of chemotherapy-induced upregulation of costimulatory ligands by tumor-infiltrated myeloid cells on T cell proliferation and survival.

RESULTS

We show that E7 long peptide vaccination combined with cisplatin and topotecan, results in CD8+ T cell-dependent durable rejection of established tumors and 94% long-term survival. Although topotecan initially repressed the expansion of vaccine-induced CD8+ T cells, these cells eventually expanded vigorously, which was followed by delayed contraction. These effects associated with the induction of the proliferation marker Ki-67 and the antiapoptosis molecule Bcl-2 by intratumoral tumor-specific CD8+ T cells, which was regulated by topotecan-mediated upregulation of the costimulatory ligand CD70 on myeloid cells in the TME.

CONCLUSIONS

Taken together, our data show that although treatment with cisplatin, topotecan and vaccination initially delays T cell expansion, this combinatorial therapy results eventually in a more robust T cell-mediated tumor eradication due to enhancement of costimulatory molecules in the TME.

Immune responses, therapeutic anti-tumor effects, and tolerability upon therapeutic HPV16/18 E6/E7 DNA vaccination via needle-free biojector

IMPORTANCE

Respectively, HPV16 and HPV18 cause 50% and 20% of cervical cancer cases globally. Viral proteins E6 and E7 are obligate drivers of oncogenic transformation. We recently developed a candidate therapeutic DNA vaccine, pBI-11, that targets HPV16 and HPV18 E6 and E7. Single-site intramuscular delivery of pBI-11 via a needle elicited therapeutic anti-tumor effects in mice and is now being tested in high-risk human papillomavirus+ head and neck cancer patients (NCT05799144). Needle-free biojectors such as the Tropis device show promise due to ease of administration, high patient acceptability, and the possibility of improved delivery. For example, vaccination of patients with the ZyCoV-D DNA vaccine using the Tropis device is effective against COVID19, well tolerated, and licensed. Here we show that split-dose, multi-site administration and intradermal delivery via the Tropis biojector increase the delivery of pBI-11 DNA vaccine, enhance HPV antigen-specific CD8+ T-cell responses, and improve anti-tumor therapeutic effects, suggesting its translational potential to treat HPV16/18 infection and disease.

Methods behind oncolytic virus-based DC vaccines in cancer: Toward a multiphase combined treatment strategy for Glioblastoma (GBM) patients

Glioblastoma (GBM) remains an orphan cancer disease with poor outcome. Novel treatment strategies are needed. Immunotherapy has several modes of action. The addition of active specific immunotherapy with dendritic cell vaccines resulted in improved overall survival of patients. Integration of DC vaccination within the first-line combined treatment became a challenge, and immunogenic cell death immunotherapy during chemotherapy was introduced. We used a retrospective analysis using real world data to evaluate the complex combined treatment, which included individualized multimodal immunotherapy during and after standard of care, and which required adaptations during treatment, and found a further improvement of overall survival. We also discuss the use of real world data as evidence. Novel strategies to move the field of individualized multimodal immunotherapy forward for GBM patients are reviewed.

The significance of nonsurgical therapies for cervical infection of high-risk human papilloma virus: A systematic review and meta-analysis

OBJECTIVE

To assess whether nonsurgical therapies were related with clearance of cervical infection of high-risk human papilloma virus (hr-HPV) or regression of mild abnormal cytology related with hr-HPV.

METHODS

Until March 2023, we identified a total of 10 424 women with cervical infection of hr-HPV and 1966 women with mild abnormal cytology related with hr-HPV from 44 studies that met the inclusion criteria.

RESULTS

After systematically retrieving literature, we identified 2317 citations and 44 randomized controlled studies (RCT) were enrolled. Cumulative results suggested women with cervical infection of hr-HPV might benefit from nonsurgical therapies. Both the clearance of hr-HPV (OR: 3.83, I2  = 99%, p < 0.00001) and regression of mild abnormal cytology related with hr-HPV (OR: 3.12, I2  = 63%, p < 0.00001) were significantly higher than control group. Subgroup analysis stratified by systematic therapy, topical therapy, traditional Chinese medicines (TCMs), and presistent hr-HPV got consistent results. There was substantial heterogeneity between trials (I2  = 87% for clearance of hr-HPV and 63% for regression of cytology), sensitivity analysis was performed by excluding single study one by one, and found the cumulative results were stable and dependable. Both the funnel plots for clearance of hr-HPV and regression of abnormal cytology were asymmetrical, significant publication bias might exist.

CONCLUSION

Nonsurgical therapies might benefit women who had a cervical infection of hr-HPV with/without mild abnormal cytology related with hr-HPV. Both the clearance of hr-HPV and regression of abnormal cytology were significantly higher than control group. More studies with less heterogeneity were needed urgently to draw concrete conclusion.

ADCY7 mRNA Is a Novel Biomarker in HPV Infection and Cervical High-Grade Squamous Lesions or Higher

The effect of cervical cancer immunotherapy is limited. Combination therapy will be a new direction for cervical cancer. Thus, it is essential to discover a novel and available predictive biomarker to stratify patients who may benefit from immunotherapy for cervical cancer. In this study, 563 participants were enrolled. Adenylate cyclase 7 (ADCY7) mRNA was detected by real-time quantitative PCR (qPCR) with cervical cytology specimens. The relationship between ADCY7 and cervical intraepithelial neoplasia in grade 2 and higher (CIN2+) was analyzed, and the optimal cut-off values of the relative expression of ADCY7 mRNA to predict CIN2+ were calculated. In addition, the clinical significance of ADCY7 in cervical cancer was determined by the Kaplan–Meier Cox regression based on the TCGA database. The mean ADCY7 mRNA expression increased significantly with cervical lesion development, especially compared with CIN2+ (p < 0.05). Moreover, the expression of ADCY7 increased significantly in high-risk human papillomavirus (HR-HPV) infection but not in HPV-A5/6 species. The area under the receiver operating characteristic curve (AUC) of ADCY7 was 0.897, and an optimal cut-off was 0.435. Furthermore, ADCY7 had the highest OR (OR= 8.589; 95% CI (2.281–22.339)) for detecting CIN 2+, followed by HPV genotyping, TCT, and age (OR = 4.487, OR = 2.071, and OR = 1.345; 95% CI (1.156–10.518), (0.370–8.137), and (0.171–4.694), respectively). Moreover, this study indicated that higher ADCY7 levels could be a suitable predictor for poor prognosis in cervical cancer due to immune cell infiltration. A new auxiliary predictor of CIN2+ in cervical cytology specimens is ADCY7 ≥ 0.435. Furthermore, it may be a promising prognosis predictor and potential immunotherapy target for the combined treatment of cervical cancer and possibly further block HR-HPV persistent infection.

Development of therapeutic vaccines for the treatment of diseases

Vaccines are one of the most effective medical interventions to combat newly emerging and re-emerging diseases. Prophylactic vaccines against rabies, measles, etc., have excellent effectiveness in preventing viral infection and associated diseases. However, the host immune response is unable to inhibit virus replication or eradicate established diseases in most infected people. Therapeutic vaccines, expressing specific endogenous or exogenous antigens, mainly induce or boost cell-mediated immunity via provoking cytotoxic T cells or elicit humoral immunity via activating B cells to produce specific antibodies. The ultimate aim of a therapeutic vaccine is to reshape the host immunity for eradicating a disease and establishing lasting memory. Therefore, therapeutic vaccines have been developed for the treatment of some infectious diseases and chronic noncommunicable diseases. Various technological strategies have been implemented for the development of therapeutic vaccines, including molecular-based vaccines (peptide/protein, DNA and mRNA vaccines), vector-based vaccines (bacterial vector vaccines, viral vector vaccines and yeast-based vaccines) and cell-based vaccines (dendritic cell vaccines and genetically modified cell vaccines) as well as combinatorial approaches. This review mainly summarizes therapeutic vaccine-induced immunity and describes the development and status of multiple types of therapeutic vaccines against infectious diseases, such as those caused by HPV, HBV, HIV, HCV, and SARS-CoV-2, and chronic noncommunicable diseases, including cancer, hypertension, Alzheimer's disease, amyotrophic lateral sclerosis, diabetes, and dyslipidemia, that have been evaluated in recent preclinical and clinical studies.

Implications and Emerging Therapeutic Avenues of Inflammatory Response in HPV+ Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinomas (HNSCC) are a heterogeneous group of malignancies which have shown exponential incidence in the last two decades especially due to human papillomavirus (HPV) infection. The HPV family comprises more than 100 types of viruses with HPV16 and HPV18 being the most prevalent strains in HNSCC. Literature data reveal that the mutation profile as well as the response to chemotherapy and radiotherapy are distinct among HPV+ versus HPV-negative tumors. Furthermore, the presence of the virus induces activation of an immune response, in particular the recruitment of specific antiviral T lymphocytes to tumor sites. These T cells when activated produce soluble factors including cytokines and chemokines capable of modifying the local immune tumor microenvironment and impact on tumor response to the treatment. In this comprehensive review we investigated current knowledge on how the presence of an HPV can modify the inflammatory response systemically and within the tumor microenvironment's immunological responses, thereby impacting on disease prognosis and survival. We highlighted the research gaps and emerging approaches necessary to discover novel immunotherapeutic targets for HPV-associated HNSCC.

Immunotherapy in Head and Neck Cancer When, How, and Why?

Head and neck cancer (HNC) is one of the most common cancers worldwide. Alcohol and tobacco consumption, besides viral infections, are the main risk factors associated with this cancer. When diagnosed in advanced stages, HNC patients present a higher probability of recurrence or metastasising. The complexity of therapeutic options and post-treatment surveillance is associated with poor prognosis and reduced overall survival (OS). This review aims to explore immunotherapy (immune checkpoint inhibitors (ICI), therapeutic vaccines, and oncolytic viruses) in HNC patients’ treatment, and to explore when, how, and why patients can benefit from it. The monotherapy with ICI or in combination with chemotherapy (QT) shows the most promising results. Compared to standard therapy, ICI are able to increase OS and patients’ quality of life. QT in combination with ICI demonstrates significant response rates and considerable long-term clinical benefits. However, the toxicity associated with this approach is still a hurdle to overcome. In parallel, the therapeutic vaccines directed to the Human Papilloma Virus are also efficient in increasing the antitumour response, inducing cellular and humoral immunity. Although these results demonstrate clinical benefits compared to standard therapy, it is also important to unravel the resistance mechanisms in order to predict the clinical benefit of immunotherapy.

The Interaction of Human Papillomavirus Infection and Prostaglandin E2 Signaling in Carcinogenesis: A Focus on Cervical Cancer Therapeutics

Chronic infection by high-risk human papillomaviruses (HPV) and chronic inflammation are factors associated with the onset and progression of several neoplasias, including cervical cancer. Oncogenic proteins E5, E6, and E7 from HPV are the main drivers of cervical carcinogenesis. In the present article, we review the general mechanisms of HPV-driven cervical carcinogenesis, as well as the involvement of cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) and downstream effectors in this pathology. We also review the evidence on the crosstalk between chronic HPV infection and PGE2 signaling, leading to immune response weakening and cervical cancer development. Finally, the last section updates the current therapeutic and preventive options targeting PGE2-derived inflammation and HPV infection in cervical cancer. These treatments include nonsteroidal anti-inflammatory drugs, prophylactic and therapeutical vaccines, immunomodulators, antivirals, and nanotechnology. Inflammatory signaling pathways are closely related to the carcinogenic nature of the virus, highlighting inflammation as a co-factor for HPV-dependent carcinogenesis. Therefore, blocking inflammatory signaling pathways, modulating immune response against HPV, and targeting the virus represent excellent options for anti-tumoral therapies in cervical cancer.

Emerging Trends in the Pathological Research of Human Papillomavirus-positive Oropharyngeal Squamous Cell Carcinoma

Oropharyngeal squamous cell carcinomas (OPSCCs) have shown an alarming rate of increase in incidence over the past several decades, markedly in men. In the United States, transcriptionally-active human papillomavirus (HPV), particularly HPV 16, has become the highest contributive agent of OPSCCs, affecting approximately 16,000 people a year. Compared to patients with HPV-negative OPSCCs, patients with HPV-positive OPSCCs exhibit better health responses to chemoradiotherapy and an overall increase in long-term survival. Despite promising treatment options, many OPSCCs are discovered at an advanced stage, and ~20% of cases will recur after definitive treatment. Therefore, extensive research is ongoing to identify new targets for precision treatment and to stratify tumor prognosis. The aim of this review is to capture the most updated research on HPV-positive OPSCCs, emphasizing their relevance as potential new targets for precision medicine and survival prognosis.

Vaccine-Based Immunotherapy for Head and Neck Cancers

Simple Summary

Therapeutic vaccines are given to patients with cancer, as opposed to prophylactic vaccines given to a healthy population. The challenge for therapeutic oncological vaccines is to stimulate an immune T cell response against endogenous (or derived) antigens that is sufficiently potent to induce cytotoxic activity and broad enough to take tumor heterogeneity into account. The purpose of this article is to provide an updated review of the prophylactic and therapeutic vaccines that target viral or non-viral antigens, particularly in head and neck cancers.

Abstract

In 2019, the FDA approved pembrolizumab, a monoclonal antibody targeting PD-1, for the first-line treatment of recurrent or metastatic head and neck cancers, despite only a limited number of patients benefiting from the treatment. Promising effects of therapeutic vaccination led the FDA to approve the use of the first therapeutic vaccine in prostate cancer in 2010. Research in the field of therapeutic vaccination, including possible synergistic effects with anti-PD(L)1 treatments, is evolving each year, and many vaccines are in pre-clinical and clinical studies. The aim of this review article is to discuss vaccines as a new therapeutic strategy, particularly in the field of head and neck cancers. Different vaccination technologies are discussed, as well as the results of the first clinical trials in HPV-positive, HPV-negative, and EBV-induced head and neck cancers.

Physiopathology and effectiveness of therapeutic vaccines against human papillomavirus

Human papillomavirus (HPV) is a well-known sexually transmitted disorder globally. Human papillomavirus (HPV) is the 3rd most common cancer that causes cervical carcinoma, and globally it accounts for 275,000 deaths every year. The load of HPV-associated abrasions can be lessened through vaccination. At present, three forms of prophylactic vaccines, Cervarix, Gadrasil, and Gardasil 9, are commercially accessible but all these prophylactic vaccines have not the ability to manage and control developed abrasions or infections. Therefore, a considerable amount of the population is not secured from HPV infectivity. Consequently, the development of therapeutic HPV vaccines is a crucial requirement of this era, for the treatment of persisting infections, and to stop the progression of HPV-associated cancers. Therapeutic vaccines are a developing trial approach. Because of the constitutive expression of E6 and E7 early genes in cancerous and pre-cancerous tissues, and their involvement in disturbance of the cell cycle, these are best targets for this therapeutic vaccine treatment. For the synthesis and development of therapeutic vaccines, various approaches have been examined comprising cell-based vaccines, peptide/protein-based vaccines, nucleic acid-based vaccines, and live-vector vaccines all proceeding towards clinical trials. This review emphasizes the development, progress, current status, and future perspective of several vaccines for the cure of HPV-related abrasions and cancers. This review also provides an insight to assess the effectiveness, safety, efficacy, and immunogenicity of therapeutic vaccines in the cure of patients infected with HPV-associated cervical cancer.

Development of a Novel Mouse Model of Spontaneous High-Risk HPVE6/E7-Expressing Carcinoma in the Cervicovaginal Tract

Current preclinical models for cervical cancer lack important clinical and pathologic features. To improve upon these models, we aimed to develop a novel, spontaneous HPV16-expressing carcinoma model that captures major aspects of HPV-associated cancer in the female genital tract. This novel preclinical model features (i) expression of HPV oncogenes E6 and E7 in the tumors in female reproductive tract of mice, (ii) spontaneous progression through high-grade squamous intraepithelial lesion (HSIL) to carcinoma, and (iii) flexibility to model cancers from different high-risk HPV genotypes. This was accomplished by injecting plasmids expressing HPV16 E6/E7-luciferase, AKT, c-myc, and Sleeping Beauty transposase into the cervicovaginal tract of C57BL/6 mice followed by electroporation. Cell lines derived from these tumors expressed HPV16 E6/E7 oncogenes, formed tumors in immunocompetent mice, and displayed carcinoma morphology. In all, this novel HPV-associated cervicogenital carcinoma model and HPV16E6/E7-expressing tumor cell line improves upon current HPV16-E6/E7-expressing tumor models. These tumor models may serve as important preclinical models for the development of therapeutic HPV vaccines or novel therapeutic interventions against HPV E6/E7-expressing tumors. SIGNIFICANCE: This study describes the development of a clinically relevant mouse model of cervicovaginal carcinoma that progresses from high-grade lesions and recapitulates key features of human HPV⁺ cervical cancer.

Combination immunotherapy with two attenuated Listeria strains carrying shuffled HPV-16 E6E7 protein causes tumor regression in a mouse tumor model

Cervical cancer continues to impose a heavy burden worldwide, and human papilloma virus (HPV) infection, especially persistent infection with type 16 (HPV-16), is known to be the primary etiological factor. Therapeutic vaccines are urgently needed because prophylactic vaccines are ineffective at clearing pre-existing HPV infection. Here, two recombinant Listeria strains (LMΔ-E6E7 & LIΔ-E6E7) with deletions of the actA and plcB genes, expressing the shuffled HPV-16 E6E7 protein were constructed. The strains were delivered into the spleen and liver by intravenous inoculation, induced antigen-specific cellular immunity and were eliminated completely from the internal organs several days later. Intravenously treating with single strain for three times, or with both strains alternately for three times significantly reduced the tumor size and prolonged the survival time of model mice. Combination immunotherapy with two strains seemed more effective than immunotherapy with single strain in that it enhanced the survival of the mice, and the LMΔ-E6E7-prime-LIΔ-E6E7-boost strategy showed significant stronger efficacy than single treatment with the LIΔ-E6E7 strain. The antitumor effect of this treatment might due to its ability to increase the proportion of CD8⁺ T cells and reduce the proportion of T regulatory cells (Tregs) in the intratumoral milieu. This is the first report regarding Listeria ivanovii-based therapeutic vaccine candidate against cervical cancer. Most importantly we are the first to confirm that combination therapy with two different recombinant Listeria strains has a more satisfactory antitumor effect than administration of a single strain. Thus, we propose a novel prime-boost treatment strategy.

Design of a multi-epitope vaccine against cervical cancer using immunoinformatics approaches

Cervical cancer, caused by human papillomavirus (HPV), is the fourth most common type of cancer among women worldwide. While HPV prophylactic vaccines are available, they have no therapeutic effects and do not clear up existing infections. This study aims to design a therapeutic vaccine against cervical cancer using reverse vaccinology. In this study, the E6 and E7 oncoproteins from HPV16 were chosen as the target antigens for epitope prediction. Cytotoxic T lymphocytes (CTL) and helper T lymphocytes (HTL) epitopes were predicted, and the best epitopes were selected based on antigenicity, allergenicity, and toxicity. The final vaccine construct was composed of the selected epitopes, along with the appropriate adjuvant and linkers. The multi-epitope vaccine was evaluated in terms of physicochemical properties, antigenicity, and allergenicity. The tertiary structure of the vaccine construct was predicted. Furthermore, several analyses were also carried out, including molecular docking, molecular dynamics (MD) simulation, and in silico cloning of the vaccine construct. The results showed that the final proposed vaccine could be considered an effective therapeutic vaccine for HPV; however, in vitro and in vivo experiments are required to validate the efficacy of this vaccine candidate.

PD-L1 Expression Correlates With Young Age and CD8+ TIL Density in Poorly Differentiated Cervical Squamous Cell Carcinoma

Management options are limited in advanced or recurrent cervical carcinoma. The Food and Drug Administration has recently approved programed cell death-1 (PD-1)/PD-ligand-1 (PD-L1) inhibitors for the treatment of advanced PD-L1 positive cervical cancer. We studied PD-L1 expression in cervical squamous cell carcinoma (CSCC) samples initially on a The tissue microarray and then in full-tissue sections from poorly differentiated (grade 3) cancers. Tissue microarray was composed of 45 grade 3 and 2 (moderately differentiated) tumors. PD-L1 expression was evaluated as categorical data and by obtaining combined positive score of neoplastic and mononuclear inflammatory cells. In tissue microarray samples PD-L1 expression was higher in poorly differentiated cancers compared with grade 2 tumors by immunohistochemistry. Full-tissue sections from grade 3 CSCC (n=22) were stained with PD-L1, CD8, and VEGF antibodies. Poorly differentiated CSCC samples had diffuse (≥50%) and focal/patchy staining patterns. The latter pattern showed localized tumor-stroma interface staining in 5 samples with low combined positive score. Importantly, younger patients (median=36) had tumors with higher expression. PD-L1 expression was associated with larger tumor size and absent lymphovascular invasion. In addition, CD8 tumor-infiltrating lymphocyte density within the neoplastic tissue matched with PD-L1 levels. The overall survival rates did not correlate with PD-L1 expression. However, in early-stage disease high CD8 tumor-infiltrating lymphocyte density within the peritumoral stroma was associated with better survival outcomes in multivariate analysis. PD-L1 expression and CD8 tumor-infiltrating lymphocyte density may be useful to define a subgroup of patients with relatively better prognosis in poorly differentiated CSCC. It is warranted to validate our results in a larger sample size.

Cervical Cancer Immunotherapy: Facts and Hopes

It is a sad fact that despite being almost completely preventable through human papillomavirus (HPV) vaccination and screening, cervical cancer remains the fourth most common cancer to affect women worldwide. Persistent high-risk HPV (hrHPV) infection is the primary etiologic factor for cervical cancer. Upward of 70% of cases are driven by HPV types 16 and 18, with a dozen other hrHPVs associated with the remainder of cases. Current standard-of-care treatments include radiotherapy, chemotherapy, and/or surgical resection. However, they have significant side effects and limited efficacy against advanced disease. There are a few treatment options for recurrent or metastatic cases. Immunotherapy offers new hope, as demonstrated by the recent approval of programmed cell death protein 1-blocking antibody for recurrent or metastatic disease. This might be augmented by combination with antigen-specific immunotherapy approaches, such as vaccines or adoptive cell transfer, to enhance the host cellular immune response targeting HPV-positive cancer cells. As cervical cancer progresses, it can foster an immunosuppressive microenvironment and counteract host anticancer immunity. Thus, approaches to reverse suppressive immune environments and bolster effector T-cell functioning are likely to enhance the success of such cervical cancer immunotherapy. The success of nonspecific immunostimulants like imiquimod against genital warts also suggest the possibility of utilizing these immunotherapeutic strategies in cervical cancer prevention to treat precursor lesions (cervical intraepithelial neoplasia) and persistent hrHPV infections against which the licensed prophylactic HPV vaccines have no efficacy. Here, we review the progress and challenges in the development of immunotherapeutic approaches for the prevention and treatment of cervical cancer.

Harnessing immunity for therapy in human papillomavirus driven cancers

In persistent high-risk HPV infection, viral gene expression can trigger some important early changes to immune capabilities which act to protect the lesion from immune attack and subsequently promote its growth and ability for sustained immune escape. This includes immune checkpoint-inhibitor ligand expression (e.g. PD-L1) by tumour or associated immune cells that can block any anti-tumour T-cell effectors. While there are encouraging signs of efficacy for cancer immunotherapies including with immune checkpoint inhibitors, therapeutic vaccines and adoptive cell therapies, overall response and survival rates remain relatively low. HPV oncogene vaccination has shown some useful efficacy in treatment of patients with high-grade lesions but was unable to control later stage cancers. To maximally exploit anti-tumour immune responses, the suppressive factors associated with HPV carcinogenesis must be countered. Importantly, a combination of chemotherapy, reducing immunosuppressive myeloid cells, with therapeutic HPV vaccination significantly improves impact on cancer treatment. Many clinical trials are investigating checkpoint inhibitor treatments in HPV associated cancers but response rates are limited; combination with vaccination is being tested. Further investigation of how chemo- and/or radio-therapy can influence the recovery of effective anti-tumour immunity is warranted. Understanding how to optimally deploy and sequence conventional and immunotherapies is the challenge.

Development of DNA Vaccine Targeting E6 and E7 Proteins of Human Papillomavirus 16 (HPV16) and HPV18 for Immunotherapy in Combination with Recombinant Vaccinia Boost and PD-1 Antibody

Immunotherapy for cervical cancer should target high-risk human papillomavirus types 16 and 18, which cause 50% and 20% of cervical cancers, respectively. Here, we describe the construction and characterization of the pBI-11 DNA vaccine via the addition of codon-optimized human papillomavirus 18 (HPV18) E7 and HPV16 and 18 E6 genes to the HPV16 E7-targeted DNA vaccine pNGVL4a-SigE7(detox)HSP70 (DNA vaccine pBI-1). Codon optimization of the HPV16/18 E6/E7 genes in pBI-11 improved fusion protein expression compared to that in DNA vaccine pBI-10.1 that utilized the native viral sequences fused 3' to a signal sequence and 5' to the HSP70 gene of Mycobacterium tuberculosis Intramuscular vaccination of mice with pBI-11 DNA better induced HPV antigen-specific CD8+ T cell immune responses than pBI-10.1 DNA. Furthermore, intramuscular vaccination with pBI-11 DNA generated stronger therapeutic responses for C57BL/6 mice bearing HPV16 E6/E7-expressing TC-1 tumors. The HPV16/18 antigen-specific T cell-mediated immune responses generated by pBI-11 DNA vaccination were further enhanced by boosting with tissue-antigen HPV vaccine (TA-HPV). Combination of the pBI-11 DNA and TA-HPV boost vaccination with PD-1 antibody blockade significantly improved the control of TC-1 tumors and extended the survival of the mice. Finally, repeat vaccination with clinical-grade pBI-11 with or without clinical-grade TA-HPV was well tolerated in vaccinated mice. These preclinical studies suggest that the pBI-11 DNA vaccine may be used with TA-HPV in a heterologous prime-boost strategy to enhance HPV 16/18 E6/E7-specific CD8+ T cell responses, either alone or in combination with immune checkpoint blockade, to control HPV16/18-associated tumors. Our data serve as an important foundation for future clinical translation.IMPORTANCE Persistent expression of high-risk human papillomavirus (HPV) E6 and E7 is an obligate driver for several human malignancies, including cervical cancer, wherein HPV16 and HPV18 are the most common types. PD-1 antibody immunotherapy helps a subset of cervical cancer patients, and its efficacy might be improved by combination with active vaccination against E6 and/or E7. For patients with HPV16+ cervical intraepithelial neoplasia grade 2/3 (CIN2/3), the precursor of cervical cancer, intramuscular vaccination with a DNA vaccine targeting HPV16 E7 and then a recombinant vaccinia virus expressing HPV16/18 E6-E7 fusion proteins (TA-HPV) was safe, and half of the patients cleared their lesions in a small study (NCT00788164). Here, we sought to improve upon this therapeutic approach by developing a new DNA vaccine that targets E6 and E7 of HPV16 and HPV18 for administration prior to a TA-HPV booster vaccination and for application against cervical cancer in combination with a PD-1-blocking antibody.

Immunodiagnosis and Immunotherapeutics Based on Human Papillomavirus for HPV-Induced Cancers

Infection with human papillomavirus (HPV) is one of the main causes of malignant neoplasms, especially cervical, anogenital, and oropharyngeal cancers. Although we have developed preventive vaccines that can protect from HPV infection, there are still many new cases of HPV-related cancers worldwide. Early diagnosis and therapy are therefore important for the treatment of these diseases. As HPVs are the major contributors to these cancers, it is reasonable to develop reagents, kits, or devices to detect and eliminate HPVs for early diagnosis and therapeutics. Immunological methods are precise strategies that are promising for the accurate detection and blockade of HPVs. During the last decades, the mechanism of how HPVs induce neoplasms has been extensively elucidated, and several oncogenic HPV early proteins, including E5, E6, and E7, have been shown to be positively related to the oncogenesis and malignancy of HPV-induced cancers. These oncoproteins are promising biomarkers for diagnosis and as targets for the therapeutics of HPV-related cancers. Importantly, many specific monoclonal antibodies (mAbs), or newly designed antibody mimics, as well as new immunological kits, devices, and reagents have been developed for both the immunodiagnosis and immunotherapeutics of HPV-induced cancers. In the current review, we summarize the research progress in the immunodiagnosis and immunotherapeutics based on HPV for HPV-induced cancers. In particular, we depict the most promising serological methods for the detection of HPV infection and several therapeutical immunotherapeutics based on HPV, using immunological tools, including native mAbs, radio-labelled mAbs, affitoxins (affibody-linked toxins), intracellular single-chain antibodies (scFvs), nanobodies, therapeutical vaccines, and T-cell-based therapies. Our review aims to provide new clues for researchers to develop novel strategies and methods for the diagnosis and treatment of HPV-induced tumors.

Vaccination Strategies for the Control and Treatment of HPV Infection and HPV-Associated Cancer

Human papillomavirus (HPV) is the most common sexually transmitted infection, currently affecting close to 80 million Americans. Importantly, HPV infection is recognized as the etiologic factor for numerous cancers, including cervical, vulval, vaginal, penile, anal, and a subset of oropharyngeal cancers. The prevalence of HPV infection and its associated diseases are a significant problem, affecting millions of individuals worldwide. Likewise, the incidence of HPV infection poses a significant burden on individuals and the broader healthcare system. Between 2011 and 2015, there were an estimated 42,700 new cases of HPV-associated cancers each year in the United States alone. Similarly, the global burden of HPV is high, with around 630,000 new cases of HPV-associated cancer occurring each year. In the last decade, a total of three preventive major capsid protein (L1) virus-like particle-based HPV vaccines have been licensed and brought to market as a means to prevent the spread of HPV infection. These prophylactic vaccines have been demonstrated to be safe and efficacious in preventing HPV infection. The most recent iteration of the preventive HPV vaccine, a nanovalent, L1-VLP vaccine, protects against a total of nine HPV types (seven high-risk and two low-risk HPV types), including the high-risk types HPV16 and HPV18, which are responsible for causing the majority of HPV-associated cancers. Although current prophylactic HPV vaccines have demonstrated huge success in preventing infection, existing barriers to vaccine acquisition have limited their widespread use, especially in low- and middle-income countries, where the burden of HPV-associated diseases is highest. Prophylactic vaccines are unable to provide protection to individuals with existing HPV infections or HPV-associated diseases. Instead, therapeutic HPV vaccines capable of generating T cell-mediated immunity against HPV infection and associated diseases are needed to ameliorate the burden of disease in individuals with existing HPV infection. To generate a cell-mediated immune response against HPV, most therapeutic vaccines target HPV oncoproteins E6 and E7. Several types of therapeutic HPV vaccine candidates have been developed including live-vector, protein, peptide, dendritic cell, and DNA-based vaccines. This chapter will review the commercially available prophylactic HPV vaccines and discuss the recent progress in the development of therapeutic HPV vaccines.

Immunotherapy in gynecological cancers: where are we?

PURPOSE OF REVIEW

This manuscript discusses the clinical evidence on immunotherapy for ovarian, endometrial, and cervical cancer. We report here the results of the clinical trials and present the ongoing trial in this area.

RECENT FINDINGS

Immunotherapy has become a pillar of cancer treatment improving the prognosis of many patients with a broad variety of solid malignancies. Unfortunately, until recently the progress achieved in some other tumors has not been seen in the majority of patients with gynecological cancer. Except for some subgroups of endometrial cancers the immune checkpoint inhibitors in monotherapy have shown unsatisfactory results. However, several combinations of immunotherapy with other drugs are under investigation and are very promising. It is essential, to develop tools to select the patients who will response best to immunotherapy.

SUMMARY

Combined immune checkpoint inhibitors with targeted therapies are awaited in gynecological cancers and could provide additional benefit.

HPV post-infection microenvironment and cervical cancer

Human papillomavirus (HPV) is the most common sexually transmitted virus worldwide. More than 99% of cervical cancer cases are associated with certain types of HPVs, termed high-risk types. In addition to the well-known transformative properties, HPVs-infected cells actively instruct the local milieu and create a supportive post-infection microenvironment (PIM), which is becoming recognized as a key factor for the viral persistence, propagation, and malignant progression. The PIM is initiated and established via a complex interplay among virus-infected cells, immune cells, and host stroma, as well as their derived components including chemokines, cytokines, extracellular vesicles, and metabolites. In this review, we summarize the current understanding of these key components, characteristics, and effects of the PIM, and highlights the prospect of targeting the PIM as a potential strategy to improve therapeutic outcomes for cervical cancer.

Arsenic exposure associated T cell proliferation, smoking, and vitamin D in Bangladeshi men and women

There are limited data examining the consequences of environmental exposure to arsenic on the immune system in adults, particularly among smokers. Smoking has been shown to exacerbate or contribute to impaired immune function in men chronically exposed to arsenic. In contrast, vitamin D (VitD) is known to have a positive influence on innate and adaptive immune responses. The effect of circulating VitD on arsenic-associated immune dysfunction is not known. Here we examine the relationship of arsenic exposure and T cell proliferation (TCP), a measure of immune responsiveness, and circulating VitD among adult men and women in Bangladesh. Arsenic exposure was assessed using total urinary arsenic as well as urinary arsenic metabolites all adjusted for urinary creatinine. TCP was measured ex vivo in cryopreserved peripheral blood mononuclear cells from 614 adult participants enrolled in the Bangladesh Health Effects of Arsenic Longitudinal Study; serum VitD was also evaluated. The influence of cigarette smoking on arsenic-induced TCP modulation was assessed only in males as there was an inadequate number of female smokers. These studies show that arsenic suppressed TCP in males. The association was significantly strong in male smokers and to a lesser extent in male non-smokers. Interestingly, we found a strong protective effect of high/sufficient serum VitD levels on TCP among non-smoking males. Furthermore, among male smokers with low serum VitD (⊔20 ng/ml), we found a strong suppression of TCP by arsenic. On the other hand, high VitD (>20 ng/ml) was found to attenuate effects of arsenic on TCP among male-smokers. Overall, we found a strong protective effect of VitD, when serum levels were >20 ng/ml, on arsenic-induced inhibition of TCP in men, irrespective of smoking status. To our knowledge this is the first large study of immune function in healthy adult males and females with a history of chronic arsenic exposure.

Development of a β-HPV vaccine: Updates on an emerging frontier of skin cancer prevention

Human papillomaviruses (HPVs) are small, non-enveloped, doublestranded DNA viruses. Over 200 subtypes of HPV have been identified, organized into five major genera. β-HPVs are a group of approximately 50 HPV subtypes that preferentially infect cutaneous sites. While α-HPVs are primarily responsible for genital lesions and mucosal cancers, growing evidence has established an association between β-HPVs and the development of cutaneous squamous cell carcinomas. Given this association, the development of a vaccine against β-HPVs has become an important topic of research; however, currently licensed vaccines only provide coverage for genital HPVs, leaving β-HPV infections and their associated skin cancers unaddressed. In this review, we summarize the current advances in β-HPV vaccine development, including progress made in preclinical testing and limited clinical data. We also discuss novel findings in the viral pathomechanisms involved in β-HPV cutaneous tumorigenesis that may play a large role in future vaccine development. We hope that synthesizing the available data and advances surrounding β- HPV vaccine development will not only lead to increased dedication to vaccine development, but also heightened awareness of a future vaccine among clinicians and the public.

A Current Update on Human Papillomavirus-Associated Head and Neck Cancers

Human papillomavirus (HPV) infection is the cause of a growing percentage of head and neck cancers (HNC); primarily, a subset of oral squamous cell carcinoma, oropharyngeal squamous cell carcinoma, and laryngeal squamous cell carcinoma. The majority of HPV-associated head and neck cancers (HPV + HNC) are caused by HPV16; additionally, co-factors such as smoking and immunosuppression contribute to the progression of HPV + HNC by interfering with tumor suppressor miRNA and impairing mediators of the immune system. This review summarizes current studies on HPV + HNC, ranging from potential modes of oral transmission of HPV (sexual, self-inoculation, vertical and horizontal transmissions), discrepancy in the distribution of HPV + HNC between anatomical sites in the head and neck region, and to studies showing that HPV vaccines have the potential to protect against oral HPV infection (especially against the HPV types included in the vaccines). The review concludes with a discussion of major challenges in the field and prospects for the future: challenges in diagnosing HPV + HNC at early stages of the disease, measures to reduce discrepancy in the prevalence of HPV + HNC cases between anatomical sites, and suggestions to assess whether fomites/breast milk can transmit HPV to the oral cavity.

Acquired resistance to cancer immunotherapy: Role of tumor-mediated immunosuppression

In the tumor microenvironment (TME), tumor cells are constantly evolving to reduce neoantigen generation and the mutational burden to escape the anti-tumor response. This will lower tumor reactivity to the adaptive immune response and give rise to tumor intrinsic factors, such as altered expression of immune regulatory molecules on tumor cells. Tumor-extrinsic factors, such as immunosuppressive cells, soluble suppressive molecules or inhibitory receptors expressed by immune cells will alter the composition and activity of tumor-infiltrating lymphocytes (TILs) (by increasing T regulatory cells:T effector cells ratio and inhibiting T effector cell function) and promote tumor growth and metastasis. Together, these factors limit the response rates and clinical outcomes to a particular cancer therapy. Within the TME, the cross-talks between immune and non-immune cells result in the generation of positive feedback loops, which augment immunosuppression and support tumor growth and survival (termed as tumor-mediated immunosuppression). Cancer immunotherapies, such as immune checkpoint inhibitors (ICIs) and adoptive cell transfer (ACT), have shown therapeutic efficacy in hematologic cancers and different types of solid tumors. However, achieving durable response rates in some cancer patients remains a challenge as a result of acquired resistance and tumor immune evasion. This could be driven by the cellular and molecular suppressive network within the TME or due to the loss of tumor antigens. In this review, we describe the contribution of the immunosuppressive cellular and molecular tumor network to the development of acquired resistance against cancer immunotherapies. We also discuss potential combined therapeutic strategies which could help to overcome such resistance against cancer immunotherapies, and to enhance anti-tumor immune responses and improve clinical outcomes in patients.

Intratumoral delivery of an HPV vaccine elicits a broad anti-tumor immune response that translates into a potent anti-tumor effect in a preclinical murine HPV model

Therapeutic cancer vaccines have met limited clinical success. In the setting of cancer, the immune system is either tolerized and/or has a limited tumor-specific T cell repertoire. In this study, we explore whether intratumoral (IT) vaccination with an HPV vaccine can elicit quantitative and qualitative differences in immune response as compared to intramuscular (IM) vaccination to overcome immune resistance in established tumors. We report that IT administration of an HPV-16 E7 peptide vaccine formulated with polyinosinic-polycytidylic acid [poly(I:C)] generated an enhanced antitumor effect relative to IM delivery. The elicited anti-tumor effect with IT vaccination was consistent among the vaccinated groups and across various C57BL/6 substrains. IT vaccination resulted in an increased frequency of PD-1^hi TILs, which represented both vaccine-targeted and non-vaccine-targeted tumor-specific CD8⁺ T cells. Overall, the CD8⁺/Treg ratio was increased within the tumor microenvironment using IT vaccination. We also assessed transcriptional changes in several immune-related genes in the tumor microenvironment of the various treated groups, and our data suggest that IT vaccination leads to upregulation of a broad complement of immunomodulatory genes, including upregulation of interferon gamma (IFNγ) and antigen presentation and processing machine (APM) components. IT vaccine delivery is superior to traditional IM vaccination routes with the potential to improve tumor immunogenicity, which has potential clinical application in the setting of accessible lesions such as head and neck squamous cell carcinomas (HNSCCs).

Carboplatin/paclitaxel, E7-vaccination and intravaginal CpG as tri-therapy towards efficient regression of genital HPV16 tumors

High-risk human papillomavirus (HPV) are responsible for genital and oral cancers associated with the expression of the E6/E7 HPV oncogenes. Therapeutic vaccines targeting those oncogenes can only partially control tumor progression, highlighting the necessity to investigate different treatment strategies. Using the genital orthotopic HPV16 TC-1 model, herein we sequentially investigated in progressively more stringent settings the effects of systemic administration of carboplatin/paclitaxel (C + P) chemotherapy combined with HPV16-E7 synthetic long peptide (E7LP) vaccination, followed by intravaginal immunostimulation with the synthetic toll-like-receptor-9 agonist CpG. Our data show that systemic delivery of C + P prior to E7LP vaccination significantly increased mice survival. This survival benefit was associated with both reduced genital tumor growth at the time of vaccination, and a decreased infiltration of Ly6G myeloid cells and tumor-associated macrophages. Adding intravaginal CpG, which results in increased E7-specific CD8 T cells locally, to E7LP vaccination and the chemotherapy formed a tri-therapy, which significantly increased mice survival as compared to any of the dual treatments. When the tri-therapy was further refined by using a recently optimized nanoparticle-conjugated E7LP vaccine, even larger end-stage genital-TC-1 tumors responded, with 90% of mice showing a survival benefit as compared to 30% of mice with the tri-therapy involving the traditional E7LP ‘liquid’ vaccine. C + P is commonly used to treat cervical cancer patients and its combination with E7/E6 vaccination is currently being tested in a phase I/II trial (NCT02128126). Our data suggests that new vaccine formulations combined with local immunostimulation and standard-of-care chemotherapy have promise to further benefit patients with HPV-associated cancer.

Natural history of human papillomavirus and vaccinations in men: A literature review

BACKGROUND AND AIMS

Infection with high-risk (HR) genotypes of the human papillomavirus (HPV) is necessary for and causative of almost all cervical cancers and their precursor condition, cervical intraepithelial neoplasia. These conditions have been sharply reduced by cervical cytology screening, and a further decrease is expected because of the recent introduction of prophylactic HPV vaccinations. While significant attention has been given to gynecologic HPV disease, men can be affected by HPV-related cancers of the anus, penis, and oropharynx. This literature review aims to address disparities in HPV-related disease in men, and certain HR male subpopulations, compared with women.

DISCUSSION

Overall, immunocompetent men are far less likely than women to develop anogenital HPV-related cancers, despite harboring HR HPV infections at anogenital sites. On the other hand, men who have sex with men and men living with human immunodeficiency virus infection are at considerably higher risk of HPV-related disease. Historic rates of prophylactic HPV vaccination in males have trailed those of females due to numerous multilevel factors, although, in recent years, this sex gap in vaccination coverage has been closing. In the absence of routine HPV screening in males, therapeutic vaccinations have emerged as a potential treatment modality for preinvasive neoplasia and are in various phases of clinical testing.

CONCLUSION

Successful reductions in HPV disease morbidity at the population level must acknowledge and target HPV infections in men.

Opportunities to improve immune-based prevention of HPV-associated cancers

Immunization of adolescent girls with VLP vaccines, made of L1 proteins from the most medically significant high risk HPV types, is a major strategy for prevention of cervical cancer plus other HPV-associated cancers. Maximal population impact, including through herd immunity, requires high vaccination coverage. However, protection of unvaccinated women requires secondary prevention through cytology screening. Unfortunately in countries with the highest incidence/mortality due to cervical cancer HPV vaccination (or cytology screening) is not sufficiently available. Vaccination programme costs and a lack of accessibility of the populations for immunization remain significant hurdles. Several approaches could increase effective implementation of HPV vaccination. 1) Use of a single immunization of the current VLP vaccines. 2) Vaccination bundled with other paediatric vaccines with lower dosage to facilitate delivery, improve coverage and reduce costs through established logistics. 3) Local manufacture with lower cost systems (e.g. bacteria) for VLP or capsomer based vaccine production and utilization of additional protective epitopes (e.g L2) for increasing breadth of protection. However, all the latter need appropriate clinical validation. Gender neutral vaccination and extending routine vaccination strategies to women up to age 30 years in combination with at least one HPV screening test can also hasten impact on cancer incidence.

From HPV Infection to Lesion Progression: The Role of HLA Alleles and Host Immunity

Persistent high-risk human papillomavirus (HPV) infection has been associated with increased risk for cervical precancerous lesions and cancer. The host's genetic variability is known to play a role in the development of cervical cancer. The human leukocyte antigen (HLA) genes are highly polymorphic and have shown to be important risk determinants of HPV infection persistence and disease progression. HLA class I and II cell surface molecules regulate the host's immune system by presenting HPV-derived peptides to T-cells. The activation of T-cell response may vary depending on the HLA allele polymorphism. The engagement of the T-cell receptor with the HPV peptide-HLA complex to create an active costimulatory signal is essential for the activation of the T-cell response. Functional peptide presentation by both HLA class I and II molecules is needed to activate efficient helper and effector T-cell responses in HPV infection recognition and clearance. Some of these HLA risk alleles could also be used as preventive tools in the detection of HPV-induced cervical lesions and cancer. These HLA alleles, together with HPV vaccines, could potentially offer possible solutions for reducing HPV-induced cervical cancer as well as other HPV-related cancers.

Advances in Designing and Developing Vaccines, Drugs and Therapeutic Approaches to Counter Human Papilloma Virus

Human papillomavirus (HPV) is a viral infection with skin-to-skin based transmission mode. HPV annually caused over 500,000 cancer cases including cervical, anogenital and oropharyngeal cancer among others. HPV vaccination has become a public-health concern, worldwide, to prevent the cases of HPV infections including precancerous lesions, cervical cancers, and genital warts especially in adolescent female and male population by launching national programs with international alliances. Currently, available prophylactic and therapeutic vaccines are expensive to be used in developing countries for vaccination programs. The recent progress in immunotherapy, biotechnology, recombinant DNA technology and molecular biology along with alternative and complementary medicinal systems have paved novel ways and valuable opportunities to design and develop effective prophylactic and therapeutic vaccines, drugs and treatment approach to counter HPV effectively. Exploration and more researches on such advances could result in the gradual reduction in the incidences of HPV cases across the world. The present review presents a current global scenario and futuristic prospects of the advanced prophylactic and therapeutic approaches against HPV along with recent patents coverage of the progress and advances in drugs, vaccines and therapeutic regimens to effectively combat HPV infections and its cancerous conditions.

PD-1/PD-L1 immune checkpoint inhibitors in advanced cervical cancer

Programmed cell death-1 and programmed cell death ligand-1 (PD-1/PD-L1) blockage has become an important treatment modality after approval of pembrolizumab and nivolumab by Food and Drug Administration in advanced cancers. Patients with metastatic and recurrent cervical cancer have limited treatment options and usually receive palliative platinum-based chemotherapy without significant survival benefit. Recent studies provided support for usage of immune checkpoint inhibitors in advanced cervical cancer. Around 35% of cervical squamous cell carcinoma (C-SCC) and 17% of adenocarcinomas expressed PD-L1. Human Papilloma Virus status was also correlated with PD-L1 expression. PD-1/PD-L1 expression in tumor infiltrating inflammatory cells was higher in cervical cancer in comparison to endometrial and ovarian adenocarcinomas. In C-SCC diffuse PD-L1 expression as compared to marginal PD-L1 expression on the interface between tumor and stroma was a risk factor for poor disease-free and disease-specific survival rates. Higher numbers of infiltrating regulatory T cells in PD-L1 positive tumors was associated with better prognosis. The studies performed on other cancer types revealed PD-L1 tumor heterogeneity and transient marker expression. Drug-resistance to immune checkpoint inhibitors is also a potential problem. Currently Phase I/II clinical trials evaluating effects of PD-1 therapy are in progress for cervical carcinoma. Additional studies are required to develop novel biomarkers and for standard evaluation of PD-L1 testing in order to predict response to immune checkpoint inhibitors in all cancer types including cervical carcinoma.

Therapeutic DNA Vaccines for Human Papillomavirus and Associated Diseases

Human papillomavirus (HPV) has long been recognized as the causative agent of cervical cancer. High-risk HPV types 16 and 18 alone are responsible for over 70% of all cases of cervical cancers. More recently, HPV has been identified as an etiological factor for several other forms of cancers, including oropharyngeal, anogenital, and skin. Thus, the association of HPV with these malignancies creates an opportunity to control these HPV lesions and HPV-associated malignancies through immunization. Strategies to prevent or to therapeutically treat HPV infections have been developed and are still pushing innovative boundaries. Currently, commercial prophylactic HPV vaccines are widely available, but they are not able to control established infections or lesions. As a result, there is an urgent need for the development of therapeutic HPV vaccines, to treat existing infections, and to prevent the development of HPV-associated cancers. In particular, DNA vaccination has emerged as a promising form of therapeutic HPV vaccine. DNA vaccines have great potential for the treatment of HPV infections and HPV-associated cancers due to their safety, stability, simplicity of manufacturability, and ability to induce antigen-specific immunity. This review focuses on the current state of therapeutic HPV DNA vaccines, including results from recent and ongoing clinical trials, and outlines different strategies that have been employed to improve their potencies. The continued progress and improvements made in therapeutic HPV DNA vaccine development holds great potential for innovative ways to effectively treat HPV infections and HPV-associated diseases.

Eradicating HPV-Associated Cancer Through Immunization: A Glass Half Full…

The human papillomavirus (HPV) is an important causal agent of premalignant cervical epithelial changes and cervical cancers. These cancers account for ∼5% of all cancers globally and kill more than a quarter million women annually. HPV infections also associate with certain anogenital and oropharyngeal cancers. Events leading to the development of HPV vaccines to prevent associated cancers are described, with a further discussion of goals that must be met to achieve full virus eradication.

Current status and future prospects for human papillomavirus vaccines

Cervical cancer is the fourth most frequent cancer among women worldwide. Human papillomaviruses (HPVs) cause almost all cervical cancers in low-income countries. Three prophylactic HPV virus-like particle-based vaccines have been licensed to date, and they have all shown high efficacy and reliable safety profiles. However, isolated safety issues have resulted in a reluctance to use these vaccinations. In addition, the high prices of the vaccinations have caused the inequitable distribution of the vaccine: the prices are unaffordable for low-income countries. Meanwhile, great effort has been put into the development of therapeutic HPV vaccines, including protein/peptide-, live vector-, DNA- and cell-based vaccines. These new vaccines have considerable therapeutic potential but limited practical use. The development of immune checkpoint inhibitors and personalized immunotherapy remain challenges for future study. In this article, the current status of the licensed vaccines, therapeutic HPV vaccines and biosimilars, and new platforms for HPV vaccines, are reviewed, and safety issues related to the licensed vaccines are discussed. In addition, the prospects for HPV vaccines are considered.

Characterization of HPV18 E6-specific T cell responses and establishment of HPV18 E6-expressing tumor model

Human papillomavirus (HPV) has been identified as the primary etiologic factor of cervical cancer, and subsets of anogenital and oropharyngeal cancers. HPV18 is the second most prevalent high-risk HPV type after HPV16. Furthermore, HPV18 is responsible for approximately 12% of cervical squamous cell carcinoma and 37% of cervical adenocarcinoma cases worldwide. In this study, we aimed to characterize the HPV18-E6-specific epitope and establish an HPV18 animal tumor model to evaluate the E6-specific immune response induced by our DNA vaccine. We vaccinated naïve C57BL/6 mice with a prototype DNA vaccine, pcDNA3-HPV18-E6, via intramuscular injection followed by electroporation, and analyzed the E6-specific CD8+ T cell responses by flow cytometry using a reported T cell epitope. We then characterized the MHC restriction element for the characterized HPV18-E6 epitope. Additionally, we generated an HPV18-E6-expressing tumor cell line to study the antitumor effect mediated by E6-specific immunity. We observed a robust HPV18-E6aa67-75 peptide-specific CD8+ T cell response after vaccination with pcDNA3-HPV18-E6. Further characterization demonstrated that this epitope was mainly restricted by H-2K^b, but was also weakly presented by HLA-A^∗0201, as previously reported. We observed that vaccination with pcDNA3-HPV18-E6 significantly inhibited the growth of HPV18-E6-expressing tumor cells, TC-1/HPV18-E6, in mice. An antibody depletion study demonstrated that both CD4+ and CD8+ T cells are necessary for the observed antitumor immunity. The characterization of HPV18-E6-specific T cell responses and the establishment of HPV18-E6-expressing tumor cell line provide infrastructures for further development of HPV18-E6 targeted immunotherapy.