Human papillomavirus therapeutic vaccines: targeting viral antigens as immunotherapy for precancerous disease and cancer

Efficacy and safety of BVAC-C in HPV type 16- or 18-positive cervical carcinoma who failed 1st platinum-based chemotherapy: a phase I/IIa study

Background

BVAC-C, a B cell- and monocyte-based immunotherapeutic vaccine transfected with recombinant HPV E6/E7, was well tolerated in HPV-positive recurrent cervical carcinoma patients in a phase I study. This phase IIa study investigates the antitumor activity of BVAC-C in patients with HPV 16- or 18-positive cervical cancer who had experienced recurrence after a platinum-based combination chemotherapy.

Patients and methods

Patients were allocated to 3 arms; Arm 1, BVAC-C injection at 0, 4, 8 weeks; Arm 2, BVAC-C injection at 0, 4, 8, 12 weeks; Arm 3, BVAC-C injection at 0, 4, 8, 12 weeks with topotecan at 2, 6, 10, 14 weeks. Primary endpoints were safety and objective response rate (ORR) as assessed by an independent radiologist according to Response Evaluation Criteria in Solid Tumors version 1.1. Secondary endpoints included the disease control rate (DCR), duration of response (DOR), progression-free survival (PFS), and overall survival (OS).

Results

Of the 30 patients available for analysis, the ORR was 19.2% (Arm 1: 20.0% (3/15), Arm 2: 33.3% (2/6), Arm3: 0%) and the DCR was 53.8% (Arm 1: 57.1%, Arm 2: 28.6%, Arm3: 14.3%). The median DOR was 7.5 months (95% CI 7.1-not reported), the median PFS was 5.8 months (95% CI 4.2-10.3), and the median OS was 17.7 months (95% CI 12.0-not reported). All evaluated patients showed not only inflammatory cytokine responses (IFN-γ or TNF-α) but also potent E6/E7-specific T cell responses upon vaccinations. Immune responses of patients after vaccination were correlated with their clinical responses.

Conclusion

BVAC-C represents a promising treatment option and a manageable safety profile in the second-line setting for this patient population. Further studies are needed to identify potential biomarkers of response.

Clinical trial registration

ClinicalTrials.gov, identifier NCT02866006.

A Therapeutic DNA Vaccine Targeting HPV16 E7 in Combination with Anti-PD-1/PD-L1 Enhanced Tumor Regression and Cytotoxic Immune Responses

Persistent infection of high-risk human papillomavirus (HPV) and the expression of E6 and E7 oncoproteins are the main causes of cervical cancer. Several prophylactic HPV vaccines are used in the clinic, but these vaccines have limited efficacy in patients already infected with HPV. Since HPV E7 is vital for tumor-specific immunity, developing a vaccine against HPV E7 is an attractive strategy for cervical cancer treatment. Here, we constructed an HPV16 E7 mutant that loses the ability to bind pRb while still eliciting a robust immune response. In order to build a therapeutic DNA vaccine, the E7 mutant was packaged in an adenovirus vector (Ad-E7) for efficient expression and enhanced immunogenicity of the vaccine. Our results showed that the Ad-E7 vaccine effectively inhibited tumor growth and increased the proportion of interferon-gamma (IFN-γ)-secreting CD8+ T cells in the spleen, and tumor-infiltrating lymphocytes in a mouse cervical cancer model was achieved by injecting with HPV16-E6/E7-expressing TC-1 cells subcutaneously. Combining the Ad-E7 vaccine with the PD-1/PD-L1 antibody blockade significantly improved the control of TC-1 tumors. Combination therapy elicited stronger cytotoxic T lymphocyte (CTL) responses, and IFN-γ secretion downregulated the proportion of Tregs and MDSCs significantly. The expressions of cancer-promoting factors, such as TNF-α, were also significantly down-regulated in the case of combination therapy. In addition, combination therapy inhibited the number of capillaries in tumor tissues and increased the thickness of the tumor capsule. Thus, Ad-E7 vaccination, in combination with an immune checkpoint blockade, may benefit patients with HPV16-associated cervical cancer.

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.

An update on treatment of penile cancer

Penile cancer is a rare malignancy, particularly in industrialized nations. In the United States, rates are approximately less than 1 per 100,000 men per year with just over 2000 new cases per year. However, there is significantly increased prevalence in developing nations, with limited treatment expertise and reduced access to care, further driving an unmet clinical need. The most noteworthy risk factor for penile cancer is the association with human papillomavirus infection, which may be present in up to 50% of all penile carcinomas. In addition to local primary tumor approaches, multimodality treatment strategies are vital to patients with clinical regional nodal disease, locally advanced disease. Presence and degree of lymph node involvement remains the most important prognostic factor and patients may benefit from multiple treatment strategies. Interim analysis data from the first randomized clinical trial is expected to yield results in mid/late 2024–early 2025. These treatment approaches include neoadjuvant chemotherapy, adjuvant therapy, including chemotherapy and radiation. Systemic therapy for distant recurrent or metastatic disease is primarily a platinum-based chemotherapy, however with poor overall response. As poor outcomes remain high, particularly in indigent populations, there remains an unmet need for these patients, particularly for high level randomized trials and novel therapeutics. In this review, we will highlight treatment updates for penile cancer. In addition to standard of care, we will review novel lines of therapies including immunotherapies and targeted therapies as well as sequencing approaches.

Cancer Vaccines: Antigen Selection Strategy

Unlike traditional cancer therapies, cancer vaccines (CVs) harness a high specificity of the host’s immunity to kill tumor cells. CVs can train and bolster the patient’s immune system to recognize and eliminate malignant cells by enhancing immune cells’ identification of antigens expressed on cancer cells. Various features of antigens like immunogenicity and avidity influence the efficacy of CVs. Therefore, the choice and application of antigens play a critical role in establishing and developing CVs. Tumor-associated antigens (TAAs), a group of proteins expressed at elevated levels in tumor cells but lower levels in healthy normal cells, have been well-studied and developed in CVs. However, immunological tolerance, HLA restriction, and adverse events are major obstacles that threaten TAA-based CVs’ efficacy due to the “self-protein” characteristic of TAAs. As “abnormal proteins” that are completely absent from normal cells, tumor-specific antigens (TSAs) can trigger a robust immune response against tumor cells with high specificity and without going through central tolerance, contributing to cancer vaccine development feasibility. In this review, we focus on the unique features of TAAs and TSAs and their application in vaccines, summarizing their performance in preclinical and clinical trials.

Progress in Neoantigen Targeted Cancer Immunotherapies

Immunotherapies that harness the immune system to kill cancer cells have showed significant therapeutic efficacy in many human malignancies. A growing number of studies have highlighted the relevance of neoantigens in recognizing cancer cells by intrinsic T cells. Cancer neoantigens are a direct consequence of somatic mutations presenting on the surface of individual cancer cells. Neoantigens are fully cancer-specific and exempt from central tolerance. In addition, neoantigens are important targets for checkpoint blockade therapy. Recently, technological innovations have made neoantigen discovery possible in a variety of malignancies, thus providing an impetus to develop novel immunotherapies that selectively enhance T cell reactivity for the destruction of cancer cells while leaving normal tissues unharmed. In this review, we aim to introduce the methods of the identification of neoantigens, the mutational patterns of human cancers, related clinical trials, neoantigen burden and sensitivity to immune checkpoint blockade. Moreover, we focus on relevant challenges of targeting neoantigens for cancer treatment.

Development of multiepitope therapeutic vaccines against the most prevalent high-risk human papillomaviruses

Aim: Our goal was the development of DNA- or peptide-based multiepitope vaccines targeting HPV E7, E6 and E5 oncoproteins in tumor mouse model. Materials & methods: After designing the multiepitope E7, E6 and E5 constructs from four types of high risk HPVs (16, 18, 31 & 45) using bioinformatics tools, mice vaccination was performed by different homologous and heterologous modalities in a prophylactic setting. Then, anti-tumor effects of the best prophylactic strategies were studied in a therapeutic setting. Results: In both prophylactic and therapeutic experiments, groups receiving homologous E7+E6+E5 polypeptide, and heterologous E7+E6+E5 DNA prime/polypeptide boost were successful in complete rejection of tumors. Conclusion: The designed multiepitope constructs can be considered as promising candidates to develop effective therapeutic HPV vaccines.

Phase I Study of a B Cell-Based and Monocyte-Based Immunotherapeutic Vaccine, BVAC-C in Human Papillomavirus Type 16- or 18-Positive Recurrent Cervical Cancer

BVAC-C is a B cell-based and monocyte-based immuno-therapeutic vaccine transfected with a recombinant human papillomavirus (HPV) 16/18 E6/E7 gene and loaded with alpha-galactosyl ceramide, which is a natural killer T cell ligand. This phase I study sought to determine the tolerability and immunogenicity of BVAC-C in platinum-resistant recurrent cervical cancer patients. Patients with HPV 16-positive or 18-positive recurrent or persistent cervical cancer who had received at least one prior platinum-based combination chemotherapy were enrolled. BVAC-C was injected intravenously three times every four weeks, and dose escalation was planned in a three-patient cohort design at doses of 1 × 10⁷, 4 × 10⁷, or 1 × 10⁸ cells/dose. Eleven patients were enrolled, and six (55%) patients had received two or more lines of platinum-based chemotherapy prior to enrollment. Treatment-related adverse events (TRAEs) were observed in 21 cycles. Most TRAEs were mild fever (n = 6.55%) or myalgia (n = 4.36%). No dose-limiting toxicities occurred. The overall response rate was 11% among nine patients evaluable, and the duration of response was 10 months. Five patients (56%) achieved a stable disease for 4.2–11 months as their best overall response. The median progression-free survival in all patients was 6.8 months (95% CI, 3.2 to infinite months), and the overall survival rate at 6 and 12 months was 89% (95% CI, 71 to 100%) and 65% (95% CI, 39 to 100%), respectively. BVAC-C induced the activation of natural killer T cells, natural killer cells, and HPV 16/18 E6/E7-specific T cells upon vaccination in all patients evaluated. BVAC-C was well tolerated and demonstrated a durable anti-tumor activity with an immune response in HPV 16-positive or 18-positive recurrent cervical carcinoma patients. A Phase 2 efficacy trial is currently underway.

Recent Advances on Prediction of Human Papillomaviruses Risk Types

BACKGROUND

Some studies have shown that Human Papillomavirus (HPV) is strongly associated with cervical cancer. As we all know, cervical cancer still remains the fourth most common cancer, affecting women worldwide. Thus, it is both challenging and essential to detect risk types of human papillomaviruses.

METHODS

In order to discriminate whether HPV type is highly risky or not, many epidemiological and experimental methods have been proposed recently. For HPV risk type prediction, there also have been a few computational studies which are all based on Machine Learning (ML) techniques, but adopt different feature extraction methods. Therefore, we conclude and discuss several classical approaches which have got a better result for the risk type prediction of HPV.

RESULTS

This review summarizes the common methods to detect human papillomavirus. The main methods are sequence- derived features, text-based classification, gap-kernel method, ensemble SVM, Word statistical model, position- specific statistical model and mismatch kernel method (SVM). Among these methods, position-specific statistical model get a relatively high accuracy rate (accuracy=97.18%). Word statistical model is also a novel approach, which extracted the information of HPV from the protein "sequence space" with word statistical model to predict high-risk types of HPVs (accuracy=95.59%). These methods could potentially be used to improve prediction of highrisk types of HPVs.

CONCLUSION

From the prediction accuracy, we get that the classification results are more accurate by establishing mathematical models. Thus, adopting mathematical methods to predict risk type of HPV will be the main goal of research in the future.

The Journey of in vivo Virus Engineered Dendritic Cells From Bench to Bedside: A Bumpy Road

Dendritic cells (DCs) are recognized as highly potent antigen-presenting cells that are able to stimulate cytotoxic T lymphocyte (CTL) responses with antitumor activity. Consequently, DCs have been explored as cellular vaccines in cancer immunotherapy. To that end, DCs are modified with tumor antigens to enable presentation of antigen-derived peptides to CTLs. In this review we discuss the use of viral vectors for in situ modification of DCs, focusing on their clinical applications as anticancer vaccines. Among the viral vectors discussed are those derived from viruses belonging to the families of the Poxviridae, Adenoviridae, Retroviridae, Togaviridae, Paramyxoviridae, and Rhabdoviridae. We will further shed light on how the combination of viral vector-based vaccination with T-cell supporting strategies will bring this strategy to the next level.

Combined immunization against TGF-β1 enhances HPV16 E7-specific vaccine-elicited antitumour immunity in mice with grafted TC-1 tumours

Therapeutic vaccine appears to be a potential approach for the treatment of human papillomavirus (HPV)-associated tumours, but its efficacy can be dampened by immunosuppressive factors such as transforming growth factor (TGF)-β1. We sought to investigate whether active immunity against TGF-β1 enhances the anti-tumour immunity elicited by an HPV16 E7-specific vaccine that we developed previously. In this study, virus-like particles of hepatitis B virus core antigen were used as vaccine carriers to deliver either TGF-β1 B cell epitopes or E7 cytotoxic T-lymphocyte epitope. The combination of preventive immunization against TGF-β1 and therapeutic immunization with the E7 vaccine significantly reduced the growth of grafted TC-1 tumours in C57 mice, showing better efficacy than immunization with only one of the vaccines. The improved efficacy of combined immunization is evidenced by elevated IFN-γ and decreased IL-4 and TGF-β1 levels in cultured splenocytes, increased E7-specific IFN-γ-expressing splenocytes, and increased numbers of CD4⁺IFN-γ⁺ and CD8⁺IFN-γ⁺ cells and decreased numbers of Treg (CD4⁺Foxp3⁺) cells in the spleen and tumours. The results strongly indicate that targeting TGF-β1 through active immunization might be a potent approach to enhancing antigen-specific therapeutic vaccine-induced anti-tumour immune efficacy and providing a combined strategy for effective cancer immunotherapy.

Therapeutic vaccines for high-risk HPV-associated diseases

Cancer is the second leading cause of death worldwide, and it is estimated that Human papillomavirus (HPV) related cancers account for 5% of all human cancers. Current HPV vaccines are extremely effective at preventing infection and neoplastic disease; however, they are prophylactic and do not clear established infections. Therapeutic vaccines which trigger cell-mediated immune responses for the treatment of established infections and malignancies are therefore required. The E6 and E7 early genes are ideal targets for vaccine therapy due to their role in disruption of the cell cycle and their constitutive expression in premalignant and malignant tissues. Several strategies have been investigated for the development of therapeutic vaccines, including live-vector, nucleic acid, peptide, protein-based and cell-based vaccines as well as combinatorial approaches, with several vaccine candidates progressing to clinical trials. With the current understanding of the HPV life cycle, molecular mechanisms of infection, carcinogenesis, tumour biology, the tumour microenvironment and immune response mechanisms, an approved HPV therapeutic vaccine seems to be a goal not far from being achieved. In this article, the status of therapeutic HPV vaccines in clinical trials are reviewed, and the potential for plant-based vaccine production platforms described.

HPV16E7-Induced Hyperplasia Promotes CXCL9/10 Expression and Induces CXCR3+ T-Cell Migration to Skin

Chemokines regulate tissue immunity by recruiting specific subsets of immune cells. Mice expressing the E7 protein of human papilloma virus 16 as a transgene from a keratin 14 promoter (K14.E7) show increased epidermal and dermal lymphocytic infiltrates, epidermal hyperplasia, and suppressed local immunity. Here, we show that CXCL9 and CXCL10 are overexpressed in non-hematopoietic cells in skin of K14.E7 mice when compared with non-transgenic animals, and recruit CXCR3⁺ lymphocytes to the hyperplastic skin. Overexpression of CXCL9 and CXCL10 is not observed in E7 transgenic mice with mutated Rb gene whose protein product cannot interact with E7 (K14.E7xRb^ΔL/ΔL) and in consequence lack hyperplastic epithelium. CXCR3⁺ T cells are preferentially recruited by CXCL9 and CXCL10 in supernatants of K14.E7 but not K14.E7xRb^ΔL/ΔL skin cultures in vitro. CXCR3 signalling promotes infiltration of a subset of effector T lymphocytes that enables donor lymphocyte deficient, E7-expressing skin graft rejection. Taken together, this suggests that recruitment of CXCR3⁺ T cells can be an important factor in the rejection of precancerous skin epithelium providing they can overcome local immunosuppressive mechanisms driven by skin-resident lymphocytes.

Expression optimization of a cell membrane-penetrating human papillomavirus type 16 therapeutic vaccine candidate in Nicotiana benthamiana

High-risk human papillomaviruses (hr-HPVs) cause cervical cancer, the fourth most common cancer in women worldwide. A HPV-16 candidate therapeutic vaccine, LALF32-51-E7, was developed by fusing a modified E7 protein to a bacterial cell-penetrating peptide (LALF): this elicited both tumour protection and regression in pre-clinical immunization studies. In the current study, we investigated the potential for producing LALF32-51-E7 in a plant expression system by evaluating the effect of subcellular localization and usage of different expression vectors and gene silencing suppressors. The highest expression levels of LALF32-51-E7 were obtained by using a self-replicating plant expression vector and chloroplast targeting, which increased its accumulation by 27-fold compared to cytoplasmic localization. The production and extraction of LALF32-51-E7 was scaled-up and purification optimized by affinity chromatography. If further developed, this platform could potentially allow for the production of a more affordable therapeutic vaccine for HPV-16. This would be extremely relevant in the context of developing countries, where cervical cancer and other HPV-related malignancies are most prevalent, and where the population have limited or no access to preventative vaccines due to their typical high costs.

Characterizing neoantigens for personalized cancer immunotherapy

Somatic mutations can generate neoantigens that are presented on MHC molecules and drive effective T cells responses against cancer. Mutation load in cancer patients predicts response to immune checkpoint blockade therapy. Additionally, vaccination targeting neoantigens controls established tumor growth in preclinical models. These recent findings led to a renewed interest in the field of cancer vaccines and the development of antigen-targeted cancer immunotherapies. However, targeting neoantigens is challenging, as most mutations are unique to each cancer patient. In addition, only a small fraction of the mutations are immunogenic and therefore their accurate prediction is critical. In this review, we discuss the properties of neoantigens that influence their immunogenicity, along with questions that remain to be addressed in order to improve prediction algorithms.

GTL001, a bivalent therapeutic vaccine against human papillomavirus 16 and 18, induces antigen-specific CD8+ T cell responses leading to tumor regression

BACKGROUND

Prophylactic vaccines are available for women and girls not yet infected with HPV, but women already infected with HPV need a treatment to prevent progression to high-grade cervical lesions and cancer. GTL001 is a bivalent therapeutic vaccine for eradicating HPV-infected cells that contains HPV16 E7 and HPV18 E7 both fused to detoxified adenylate cyclase from Bordetella pertussis, which binds specifically to CD11b+ antigen-presenting cells. This study examined the ability of therapeutic vaccination with GTL001 adjuvanted with topical imiquimod cream to induce functional HPV16 E7- and HPV18 E7-specific CD8+ T cell responses.

METHODS

Binding of GTL001 to human CD11b was assessed by a cell-based competition binding assay. Cellular immunogenicity of intradermal vaccination with GTL001 was assessed in C57BL/6 mice by enzyme-linked immunospot assay and in vivo killing assays. In vivo efficacy of GTL001 vaccination was investigated in the TC-1 murine HPV16 E7-expressing tumor model.

RESULTS

GTL001 bound specifically to the human CD11b/CD18 receptor. GTL001 adjuvanted with topical 5% imiquimod cream induced HPV16 E7 and HPV18 E7-specific CD8+ T cell responses. This CD8+ T-cell response mediated in vivo killing of HPV E7-expressing cells. In the HPV16 E7-expressing tumor model, GTL001 adjuvanted with imiquimod but not imiquimod alone or a combination of unconjugated HPV16 E7 and HPV18 E7 caused complete tumor regression.

CONCLUSIONS

GTL001 adjuvanted with topical 5% imiquimod is immunogenic and induces HPV16 E7 and HPV18 E7-specific CD8+ T cell responses that can kill HPV E7-expressing cells and eliminate HPV E7-expressing tumors.

A Platform for Designing Genome-Based Personalized Immunotherapy or Vaccine against Cancer

Due to advancement in sequencing technology, genomes of thousands of cancer tissues or cell-lines have been sequenced. Identification of cancer-specific epitopes or neoepitopes from cancer genomes is one of the major challenges in the field of immunotherapy or vaccine development. This paper describes a platform Cancertope, developed for designing genome-based immunotherapy or vaccine against a cancer cell. Broadly, the integrated resources on this platform are apportioned into three precise sections. First section explains a cancer-specific database of neoepitopes generated from genome of 905 cancer cell lines. This database harbors wide range of epitopes (e.g., B-cell, CD8+ T-cell, HLA class I, HLA class II) against 60 cancer-specific vaccine antigens. Second section describes a partially personalized module developed for predicting potential neoepitopes against a user-specific cancer genome. Finally, we describe a fully personalized module developed for identification of neoepitopes from genomes of cancerous and healthy cells of a cancer-patient. In order to assist the scientific community, wide range of tools are incorporated in this platform that includes screening of epitopes against human reference proteome (http://www.imtech.res.in/raghava/cancertope/).

The Impact of HPV as an Etiological Factor in Gynecological and Oropharyngeal Cancer

The human papilloma virus (HPV) is one of several viral pathogens linked to human cancer. This article reviews the current worldwide cancer burden related to this pathogen. The article also examines the role of HPV in oropharyngeal and gynecological malignancies, current treatment implications, and future directions in the treatment and prevention of HPV-related disease.

GTL001, A Therapeutic Vaccine for Women Infected with Human Papillomavirus 16 or 18 and Normal Cervical Cytology: Results of a Phase I Clinical Trial

PURPOSE

Women infected with human papillomavirus (HPV) with normal cytology to mild abnormalities currently have no treatment options other than watchful waiting or surgery if high-grade cervical lesions or cancer develop. A therapeutic vaccine would offer the possibility of preventing high-grade lesions in HPV-infected women. GTL001 is a therapeutic vaccine composed of recombinant HPV16 and HPV18 E7 proteins fused to catalytically inactive Bordetella pertussis CyaA. This study examined the tolerability and immunogenicity of GTL001 in women infected with HPV16 or HPV18 with normal cytology.

EXPERIMENTAL DESIGN

This was a phase I trial (EudraCT No. 2010-018629-21). In an open-label part, subjects received two intradermal vaccinations 6 weeks apart of 100 or 600 μg GTL001 + topical 5% imiquimod cream at the injection site. In a double-blind part, subjects were randomized 2:1:1 to two vaccinations 6 weeks apart of 600 μg GTL001 + imiquimod, 600 μg GTL001 + placebo cream, or placebo + imiquimod.

RESULTS

Forty-seven women were included. No dropouts, treatment-related serious adverse events, or dose-limiting toxicities occurred. Local reactions were transient and mostly mild or moderate. HPV16/18 viral load decreased the most in the 600 μg GTL001 + imiquimod group. In post hoc analyses, the 600 μg GTL001 + imiquimod group had the highest rates of initial and sustained HPV16/18 clearance. Imiquimod increased antigen-specific T-cell response rates but not rates of solicited reactions. All subjects seroconverted to CyaA.

CONCLUSIONS

For women infected with HPV16 or HPV18 with normal cervical cytology, GTL001 was immunogenic and had acceptable safety profile. Clin Cancer Res; 22(13); 3238-48. ©2016 AACR.

The Human Papillomavirus Vaccine: Current Perspective and Future Role in Prevention and Treatment of Anal Intraepithelial Neoplasia and Anal Cancer

The incidences of human papillomavirus (HPV)-related anal cancer and its precursor lesion, anal intraepithelial neoplasia, are rising in the U.S. and globally. Five-year survival rates with current modalities of treatment for anal cancer are generally favorable for localized and regional disease. For metastatic disease, the relative survival rate is poor. Major contributing factors for the increase in anal cancer incidence include increasing receptive anal intercourse (hetero- and homosexual), increasing HPV infections, and longer life expectancy of treated people who are seropositive for human immunodeficiency virus. Because treatment outcomes with systemic therapy in patients with advanced disease are so poor, prevention may be the best approach for reducing disease burden. The association of a major causative agent with anal cancer provides an excellent opportunity for prevention and treatment. The advent of the HPV vaccine for anal cancer prevention and treatment is a significant milestone and has the potential to greatly impact these cancers. The data regarding potential use of the HPV vaccine in anal cancer prevention and treatment are reviewed.

IMPLICATIONS FOR PRACTICE

The incidences of human papillomavirus (HPV)-related anal cancer and its precursor lesion, anal intraepithelial neoplasia, are on the rise in the U.S. and globally. Based on recent studies, the HPV vaccine is approved for prevention of the infection and development of HPV-related anal cancer. In addition, several small studies have shown that the vaccine may be useful as adjuvant therapy for anal cancer. There is a need for public health strategies aimed at education of both patients and practitioners to improve the use of the vaccine for prevention of HPV-related anal cancer. The development of a therapeutic vaccine is a work in progress.

Flagellin is a strong vaginal adjuvant of a therapeutic vaccine for genital cancer

Cervical cancer is a high-incidence female cancer most commonly caused by human papilloma virus (HPV) infection of the genital mucosa. Immunotherapy targeting HPV-derived tumor antigens (TAs) has been widely studied in animal models and in patients. Because the female genital tract is a portal for the entry of HPV and a highly compartmentalized system, the development of topical vaginal immunotherapy in an orthotopic cancer model would provide an ideal therapeutic. Thus, we examined whether flagellin, a potent mucosal immunomodulator, could be used as an adjuvant for a topical therapeutic vaccine for female genital cancer. Intravaginal (IVAG) co-administration of the E6/E7 peptides with flagellin resulted in tumor suppression and long-term survival of tumor-bearing mice. In contrast to IVAG vaccination, intranasal (IN) or subcutaneous (SC) immunization did not induce significant tumor suppression in the same model. The vaginal adjuvant effect of the flagellin was completely abolished in Toll-like receptor-5 (TLR5) knock-out mice. IVAG immunization with the E6/E7 peptides plus flagellin induced the accumulation of CD4⁺ and CD8⁺ cells and the expression of T cell activation-related genes in the draining genital lymph nodes (gLNs). The co-administered flagellin elicited antigen-specific IFNγ production in the gLNs and spleen. The intravaginally administered flagellin was found in association with CD11c⁺ cells in the gLNs. Moreover, after immunization with a flagellin and the E6/E7 peptides, the TLR5 expression in gLN cells was significantly upregulated. These results suggest that flagellin serves as a potent vaginal adjuvant for a therapeutic peptide cancer vaccine through the activation of TLR5 signaling.

Ubiquitin-like Molecule ISG15 Acts as an Immune Adjuvant to Enhance Antigen-specific CD8 T-cell Tumor Immunity

ISG15 is an ubiquitin-like protein induced by type I interferon associated with antiviral activity. ISG15 is also secreted and known to function as an immunomodulatory molecule. However, ISG15's role in influencing the adaptive CD8 T-cell responses has not been studied. Here, we demonstrate the efficacy of ISG15 as a vaccine adjuvant, inducing human papilloma virus (HPV) E7-specific IFNγ responses as well as the percentage of polyfunctional, cytolytic, and effector CD8 T-cell responses. Vaccination with ISG15 conferred remarkable control and/or regression of established HPV-associated tumor-bearing mice. T-cell depletion coupled with adoptive transfer experiments revealed that ISG15 protective efficacy was CD8 T-cell mediated. Importantly, we demonstrate that ISG15 vaccine-induced responses could be generated independent of ISGylation, suggesting that responses were mostly influenced by free ISG15. Our results provide more insight into the immunomodulatory properties of ISG15 and its potential to serve as an effective immune adjuvant in a therapeutic tumor or infectious disease setting.

Tapping the Potential of DNA Delivery with Electroporation for Cancer Immunotherapy

Cancer is a worldwide leading cause of death, and current conventional therapies are limited. The search for alternative preventive or therapeutic solutions is critical if we are going to improve outcomes for patients. The potential for DNA vaccines in the treatment and prevention of cancer has gained great momentum since initial findings almost 2 decades ago that revealed that genetically engineered DNA can elicit an immune response. The combination of adjuvants and an effective delivery method such as electroporation is overcoming past setbacks for naked plasmid DNA (pDNA) as a potential preventive or therapeutic approach to cancer in large animals and humans. In this chapter, we aim to focus on the novel advances in recent years for DNA cancer vaccines, current preclinical data, and the importance of adjuvants and electroporation with emphasis on prostate, melanoma, and cervical cancer.

Human papillomavirus vaccination: where are we now?

The development of efficacious prophylactic human papillomavirus vaccines provided an opportunity for the primary prevention of related infections and diseases. Certain oncogenic human papillomaviruses that preferentially infect the genital epithelium cause cervical cancer and a substantial proportion of anal, penile, vaginal, vulvar and oropharyngeal cancers. Following extensive clinical trials demonstrating their efficacy and safety, two vaccines have been in global use for over 6 years. This review summarises the accumulated evidence regarding their high level of efficacy, safety in population usage, reductions in genital warts, infections and cervical disease following their adoption, and facilitators and barriers to achieving high vaccination coverage. The review also discusses practical issues and frequently asked questions regarding duration of effect, vaccination of women treated for cervical disease and alternate vaccination schedules, as well as the need to review cervical screening strategies in the post- vaccination environment.

Identification of novel epitopes from human papillomavirus type 18 E7 that can sensitize PBMCs of multiple HLA class I against human cervical cancer

Background

To identify the novel epitopes from the human papillomavirus type 18 E7 which can sensitize PBMCs of four different major HLA class I A allele.

Methods

Twenty-four synthetic overlapping 15-amino acid peptides were screened by measuring the frequency of CD8⁺ cytotoxic T lymphocytes (CTLs)-producing interferon-γ (IFN-γ) by using flow cytometry and ELISpot assays and selected peptides were validated for cytolytic activity by using the ⁵¹Cr release assay. Truncated peptides in the selected epitopes were tested to determine the important residues using ELISpot and ⁵¹Cr release assay.

Results

Among 24 peptides, E7_81-95DDLRAFQQLFLNTLS (#21) and E7_89-103LFLNTLSFVCPWCAS (#23) induced significantly higher Th 1 response including IFN-γ production and in vitro cytotoxicity of PBMCs of four different HLA-A alleles against cervical cancer cells than that of other peptides and the negative control (no peptide sensitization). In E7_81–95 (#21), amino acid position 81, 82 (N-terminus) and 92, 94, 95 (C-terminus) for HLA-A*02:02 and 24:02, and 81, 82 (N-terminus) and 92, 95 (C-terminus) for HLA-A*11:01 and 33:03 were important to elicit Th1 response of PBMCS. In E7_89–103 (#23), residue 100 and103 (C-terminus) were important to elicit the CD8⁺ CTL response in HLA-A*02:01, 11:01 and 33:03 and 100, 101, and 103 (C-terminus) were important to elicit the CD8⁺ CTL response in HLA-A*24:02.

Conclusions

E7_81–95 (#21) and E7_89–103 (#23) were identified as novel epitopes from HPV18 E7 which could sensitized PBMCs of four different HLA class I (HLA-A*02:01, 24:02, 11:01 and 33:03). These epitopes could be useful for immune monitoring and immunotherapy for HPV 18+ cervical cancer.

Antitumor effect of therapeutic HPV DNA vaccines with chitosan-based nanodelivery systems

Background

Cervical cancer is the second-most-common cause of malignancies in women worldwide, and the oncogenic activity of the human papilloma virus types (HPV) E7 protein has a crucial role in anogenital tumors. In this study, we have designed a therapeutic vaccine based on chitosan nanodelivery systems to deliver HPV-16 E7 DNA vaccine, considered as a tumor specific antigen for immunotherapy of HPV-associated cervical cancer. We have developed a Nano-chitosan (NCS) as a carrier system for intramuscular administration using a recombinant DNA vaccine expressing HPV-16 E7 (NCS-DNA E7 vaccine). NCS were characterized in vitro for their gene transfection ability.

Results

The transfection of CS-pEGFP NPs was efficient in CHO cells and the expression of green fluorescent proteins was well observed. In addition, NCS-DNA E7 vaccine induced the strongest E7-specific CD8+ T cell and interferon γ responses in C57BL/6 mice. Mice vaccinated with NCS-DNA E7 vaccine were able to generate potent protective and therapeutic antitumor effects against challenge with E7-expressing tumor cell line, TC-1.

Conclusions

The strong therapeutic effect induced by the Chitosan-based nanodelivery suggest that nanoparticles may be an efficient carrier to improve the immunogenicity of DNA vaccination upon intramuscular administration and the platform could be further exploited as a potential cancer vaccine candidate in humans.

DNA vaccine encoding HPV-16 E7 with mutation in L-Y-C-Y-E pRb-binding motif induces potent anti-tumor responses in mice

Cervical cancer is the second most common cancer among women worldwide and remains a clinical problem despite improvements in early detection and therapy. The human papillomavirus (HPV) type 16 (HPV16) E7 oncoprotein expressed in cervical carcinoma cells are considered as attractive tumor-specific antigen targets for immunotherapy. Since the transformation potential of the oncogenes, vaccination based of these oncogenes is not safe. In present study, DNA vaccine expressing the modified variant with mutation in pRb-binding motif of the HPV-16 E7 oncoprotein was generated. A novel modified E7 gene with mutation in LYCYE motif was designed and constructed and the immunogenicity and antitumor effect of therapeutic DNA vaccines encoding the mutant and wild type of E7 gene were investigated. The L-Y-C-Y-E pRb-binding motif of E7 proteins has been involved in the immortalization and transformation of the host cell. The results showed that the mutant and wild type HPV-16 E7 vectors expressed the desired protein. Furthermore, the immunological mechanism behind mutant E7 DNA vaccine can be attributed at least partially to increased cytotoxic T lymphocyte, accompanied by the up-regulation of Th1-cytokine IFN-γ and TNF-β and down-regulation of Th3-cytokine TGF-β. Immunized mice with mutant plasmid demonstrated significantly stronger cell immune responses and higher levels of tumor protection than wild-type E7 DNA vaccine. The results exhibit that modified E7 DNA vaccine may be a promising candidate for development of therapeutic vaccine against HPV-16 cancers.

Alarmin IL-33 acts as an immunoadjuvant to enhance antigen-specific tumor immunity

Studies of interleukin (IL)-33 reveal a number of pleiotropic properties. Here, we report that IL-33 has immunoadjuvant effects in a human papilloma virus (HPV)-associated model for cancer immunotherapy where cell-mediated immunity is critical for protection. Two biologically active isoforms of IL-33 exist that are full-length or mature, but the ability of either isoform to function as a vaccine adjuvant that influences CD4 T helper 1 or CD8 T-cell immune responses is not defined. We showed that both IL-33 isoforms are capable of enhancing potent antigen-specific effector and memory T-cell immunity in vivo in a DNA vaccine setting. In addition, although both IL-33 isoforms drove robust IFN-γ responses, neither elevated secretion of IL-4 or immunoglobulin E levels. Further, both isoforms augmented vaccine-induced antigen-specific polyfunctional CD4(+) and CD8(+) T-cell responses, with a large proportion of CD8(+) T cells undergoing plurifunctional cytolytic degranulation. Therapeutic studies indicated that vaccination with either IL-33 isoform in conjunction with an HPV DNA vaccine caused rapid and complete regressions in vivo. Moreover, IL-33 could expand the magnitude of antigen-specific CD8(+) T-cell responses and elicit effector-memory CD8(+) T cells. Taken together, our results support the development of these IL-33 isoforms as immunoadjuvants in vaccinations against pathogens, including in the context of antitumor immunotherapy.

A personalized view on cancer immunotherapy

Recent progress in cancer immunotherapy has resulted in complete responses in patients refractory to current standard cancer therapies. However, due to tumor heterogeneity and inter-individual variations in anti-tumor immunity, only subsets of patients experience clinical benefit. This review highlights the implementation of a personalized approach to enhance treatment efficacy and reduce side effects, including the identification of tumor-specific antigens for cancer vaccination and adoptive T cell therapies. Furthermore, together with the current advances and promising clinical outcomes of combination cancer (immuno-)therapies, the screening for predictive biomarkers in a patient-specific manner is emphasized.

Targeted therapies for squamous cell carcinoma of the head and neck: current knowledge and future directions

Despite progress in the therapeutic management of patients with squamous cell carcinoma of the head and neck (SCCHN), the mortality rate of patients presenting with advanced disease remains high. One approach to improve treatment efficacy is to add novel molecular targeted agents to the classical treatment regimens. Monoclonal antibodies targeting the epidermal growth factor receptor (EGFR) have shown clinical benefits in palliative and curative settings. However, only a minority of patients presenting with recurrent or metastatic (R/M) SCCHN have meaningful tumor regression with these agents and virtually all who do develop acquired tumor resistance after a few months of treatment. For these reasons, other inhibitors of EGFR or molecules that interfere with known molecular pathways activated in SCCHN are of considerable interest, either as single agents or in combination with other treatment modalities. In this review, we discuss the different molecular therapeutic approaches explored in SCCHN. We also briefly outline new trial designs that could be used to accelerate the investigation of emerging therapeutic agents in this disease.

Human papillomaviruses and cancer

Human papillomaviruses (HPV) are small oncogenic DNA viruses of which more than 200 types have been identified to date. A small subset of these is etiologically linked to the development of anogenital malignancies such as cervical cancer. In addition, recent studies established a causative relationship between these high-risk HPV types and tonsillar and oropharyngeal cancer. Clinical management of cervical cancer and head and neck squamous cell carcinomas (HNSCCs) is largely standardized and involves surgical removal of the tumor tissue as well as adjuvant chemoradiation therapy. Notably, the response to therapeutic intervention of HPV-positive HNSCCs has been found to be better as compared to HPV-negative tumors. Although the existing HPV vaccine is solely licensed for the prevention of cervical cancer, it might also have prophylactic potential for the development of high-risk HPV-associated HNSCCs. Another group of viruses, which belongs to the beta-HPV subgroup, has been implicated in nonmelanoma skin cancer, however, the etiology remains to be established. Treatment of HPV-induced nonmelanoma skin cancer is based on local excision. However, topically applied immune-modulating substances represent non-surgical alternatives for the management of smaller cutaneous tumors. In this review we present the current knowledge of the role of HPV in cancer development and discuss clinical management options as well as targets for the development of future intervention therapies.