Therapeutic vaccination with papillomavirus E6 and E7 long peptides results in the control of both established virus-induced lesions and latently infected sites in a pre-clinical cottontail rabbit papillomavirus model

Screening the B- and T-cell epitope map of TP0136 and exploring their effect in a Treponema pallidum rabbit model

The systemic immune response, including B- and T-cell reactions, plays a corresponding role in syphilis infections. The TP0136 protein is a target of the immune response in infected hosts and may mediate the immune response. Here, we developed a method that combining reverse vaccine approach with Pepscan/T-cell proliferation to screen and identify three B-cell and two T-cell epitopes of TP0136, and explore the role of the B- and T-cell epitopes in immunized-infected animals. The results showed that immunized with B-cell epitopes not only had no protective effect but also aggravated the syphilitic lesion development. While immunized with T-cell epitopes of TP0136 could induce a strong Th1-cellular immunity response, which could attenuate syphilitic lesion development to a certain extent. The variation in exacerbation or attenuation of skin lesions, induced by distinct B- and T-cell epitopes of Tp0136, within the host's defense against syphilis warrants in-depth exploration.

Targeting Biomolecular Condensation and Protein Aggregation against Cancer

Biomolecular condensates, membrane-less entities arising from liquid-liquid phase separation, hold dichotomous roles in health and disease. Alongside their physiological functions, these condensates can transition to a solid phase, producing amyloid-like structures implicated in degenerative diseases and cancer. This review thoroughly examines the dual nature of biomolecular condensates, spotlighting their role in cancer, particularly concerning the p53 tumor suppressor. Given that over half of the malignant tumors possess mutations in the TP53 gene, this topic carries profound implications for future cancer treatment strategies. Notably, p53 not only misfolds but also forms biomolecular condensates and aggregates analogous to other protein-based amyloids, thus significantly influencing cancer progression through loss-of-function, negative dominance, and gain-of-function pathways. The exact molecular mechanisms underpinning the gain-of-function in mutant p53 remain elusive. However, cofactors like nucleic acids and glycosaminoglycans are known to be critical players in this intersection between diseases. Importantly, we reveal that molecules capable of inhibiting mutant p53 aggregation can curtail tumor proliferation and migration. Hence, targeting phase transitions to solid-like amorphous and amyloid-like states of mutant p53 offers a promising direction for innovative cancer diagnostics and therapeutics.

First in man study: Bcl-Xl_42-CAF®09b vaccines in patients with locally advanced prostate cancer

Background

The B-cell lymphoma-extra-large (Bcl-XL) protein plays an important role in cancer cells’ resistance to apoptosis. Pre-clinical studies have shown that vaccination with Bcl-XL-derived peptides can induce tumor-specific T cell responses that may lead to the elimination of cancer cells. Furthermore, pre-clinical studies of the novel adjuvant CAF®09b have shown that intraperitoneal (IP) injections of this adjuvant can improve the activation of the immune system. In this study, patients with hormone-sensitive prostate cancer (PC) received a vaccine consisting of Bcl-XL-peptide with CAF®09b as an adjuvant. The primary aim was to evaluate the tolerability and safety of IP and intramuscular (IM) administration, determine the optimal route of administration, and characterize vaccine immunogenicity.

Patients and methods

Twenty patients were included. A total of six vaccinations were scheduled: in Group A (IM to IP injections), ten patients received three vaccines IM biweekly; after a three-week pause, patients then received three vaccines IP biweekly. In Group B (IP to IM injections), ten patients received IP vaccines first, followed by IM under a similar vaccination schedule. Safety was assessed by logging and evaluating adverse events (AE) according to Common Terminology Criteria for Adverse Events (CTCAE v. 4.0). Vaccines-induced immune responses were analyzed by Enzyme-Linked Immunospot and flow cytometry.

Results

No serious AEs were reported. Although an increase in T cell response against the Bcl-XL-peptide was found in all patients, a larger proportion of patients in group B demonstrated earlier and stronger immune responses to the vaccine compared to patients in group A. Further, we demonstrated vaccine-induced immunity towards patient-specific CD4, and CD8 T cell epitopes embedded in Bcl-XL-peptide and an increase in CD4 and CD8 T cell activation markers CD107a and CD137 following vaccination. At a median follow-up of 21 months, no patients had experienced clinically significant disease progression.

Conclusion

The Bcl-XL-peptide-CAF®09b vaccination was feasible and safe in patients with l hormone-sensitive PC. In addition, the vaccine was immunogenic and able to elicit CD4 and CD8 T cell responses with initial IP administration eliciting early and high levels of vaccine-specific responses in a higher number og patients.

Clinical trial registration

https://clinicaltrials.gov, identifier NCT03412786.

Modeling HPV-Associated Disease and Cancer Using the Cottontail Rabbit Papillomavirus

Approximately 5% of all human cancers are attributable to human papillomavirus (HPV) infections. HPV-associated diseases and cancers remain a substantial public health and economic burden worldwide despite the availability of prophylactic HPV vaccines. Current diagnosis and treatments for HPV-associated diseases and cancers are predominantly based on cell/tissue morphological examination and/or testing for the presence of high-risk HPV types. There is a lack of robust targets/markers to improve the accuracy of diagnosis and treatments. Several naturally occurring animal papillomavirus models have been established as surrogates to study HPV pathogenesis. Among them, the Cottontail rabbit papillomavirus (CRPV) model has become known as the gold standard. This model has played a pivotal role in the successful development of vaccines now available to prevent HPV infections. Over the past eighty years, the CRPV model has been widely applied to study HPV carcinogenesis. Taking advantage of a large panel of functional mutant CRPV genomes with distinct, reproducible, and predictable phenotypes, we have gained a deeper understanding of viral–host interaction during tumor progression. In recent years, the application of genome-wide RNA-seq analysis to the CRPV model has allowed us to learn and validate changes that parallel those reported in HPV-associated cancers. In addition, we have established a selection of gene-modified rabbit lines to facilitate mechanistic studies and the development of novel therapeutic strategies. In the current review, we summarize some significant findings that have advanced our understanding of HPV pathogenesis and highlight the implication of the development of novel gene-modified rabbits to future mechanistic studies.

Self-assembled flagella protein nanofibers induce enhanced mucosal immunity

Nanofibers are potential vaccines or adjuvants for vaccination at the mucosal interface. However, how their lengths affect the mucosal immunity is not well understood. Using length-tunable flagella (self-assembled from a protein termed flagellin) as model protein nanofibers, we studied the mechanisms of their interaction with mucosal interface to induce immune responses length-dependently. Briefly, through tuning flagellin assembly, length-controlled protein nanofibers were prepared. The shorter nanofibers exhibited more pronounced toll-like receptor 5 (TLR5) and inflammasomes activation accompanied by pyroptosis, as a result of cellular uptake, lysosomal damage, and mitochondrial reactive oxygen species generation. Accordingly, the shorter nanofibers elevated the IgA level in mucosal secretions and enhanced the serum IgG level in ovalbumin-based intranasal vaccinations. These mucosal and systematic antibody responses were correlated with the mucus penetration capacity of the nanofibers. Intranasal administration of vaccines (human papillomavirus type 16 peptides) adjuvanted with shorter nanofibers significantly elicited cytotoxic T lymphocyte responses, strongly inhibiting tumor growth and improving survival rates in a TC-1 cervical cancer model. This work suggests that length-dependent immune responses of nanofibers can be elucidated for designing nanofibrous vaccines and adjuvants for both infectious diseases and cancer.

Design of a multi-epitope protein vaccine against herpes simplex virus, human papillomavirus and Chlamydia trachomatis as the main causes of sexually transmitted diseases

Sexually transmitted diseases (STDs) have a profound effect on reproductivity and sexual health worldwide. According to world health organization (WHO) 375 million new case of STD, including chlamydia trachomatis (chlamydia), Neisseria gonorrhoeae, HSV, HPV has been reported in 2016. More than 30 diverse pathogenesis have identified to be transmitted through sexual intercourse. Of these, viral infections (hepatitis B, herpes simplex virus (HSV or herpes), HIV, and human papillomavirus (HPV) are incurable. However, symptoms caused by the incurable viral infections can be alleviated through treatment. Antimicrobial resistance (AMR) of sexually transmitted infections (STIs) to antibiotics has increased recent years, in this regard, vaccination is proposed as an important strategy for prevention or treatment of STDs. Vaccine against HPV 16 and 18 suggests a new approach for controlling STDs but until now, there is no prophylactic or therapeutic vaccine have been approved for HSV-2 and Chlamydia trachomatis (CT); in this reason, developing an efficient vaccine is inevitable. Recently, different combinatorial forms of subunit vaccines against two or three type of bacteria have been designed. In this study, to design a combinatorial vaccine against HSV, CT, and HPV, the E7 and L2 from HPV, glycoprotein D from HSV-2 and ompA from CT were selected as final antigens. Afterward, the immunodominant helper T lymphocytes (HTLs) and cytolytic T lymphocytes (CTLs) epitopes were chosen from aforesaid antigens. P30 (tetanus toxoid epitope) as universal T-helper were also added to the vaccine. Moreover, flagellin D_1/D₀ as TLR5 agonist and the RS09 as a TLR4 ligand were incorporated to N and C-terminals of peptide vaccine, respectively. Finally, all selected parts were fused together by appropriate linkers to enhance vaccine efficiency. The physicochemical, structural, and immunological properties of the designed vaccine protein were assessed. To achieve the best 3D model of the protein vaccine, modeling, refinement, and validation of modeled structures were also done. Docking evaluation demonstrated suitable interaction between the vaccine and TLR5. Moreover, molecular dynamics (MD) studies showed an appropriate and stable structure of protein and TLR5. Based on immunoinformatic analysis, our vaccine candidate could potentially incite humoral and cellular immunities, which are critical for protection against HPV, HSV-2, and chlamydia trachomatis. It should be noted that, experimental studies are needed to confirm the efficacy of the designed vaccine.

Designing a therapeutic and prophylactic candidate vaccine against human papillomavirus through vaccinomics approaches

OBJECTIVE

Human papillomavirus (HPV) is the main cause of cervical cancer, the 4^th prominent cause of death in women globally. Previous vaccine development projects have led to several approved prophylactic vaccines available commercially, all of which are made using major capsid-based (L1). Administration of minor capsid protein (L2) gave rise to the second generation investigational prophylactic HPV vaccines, none of which are approved yet due to low immunogenicity provided by the L2 capsid protein. On the other hand, post-translation proteins, E6 and E7, have been utilized to develop experimental therapeutic vaccines. Here, in silico designing of a therapeutic and prophylactic vaccine against HPV16 is performed.

METHODS

In this study, several immunoinformatic and computational tools were administered to identify and design a vaccine construct with dual prophylactic and therapeutic applications consisting of several epitope regions on L2, E6, and E7 proteins of HPV16.

RESULTS

Immunodominant epitope regions (aa 12-23 and 78-78 of L2 protein, aa 11-27 of E6 protein, and aa 70-89 of E7 protein) were employed, which offered adequate immunogenicity to induce immune responses. Resuscitation-promoting factors (RpfB and RpfE) of Mycobacterium tuberculosis were integrated in two separate constructs as TLR4 agonists to act as vaccine adjuvants. Following physiochemical and structural evaluations carried out by various bioinformatics tools, the designed constructs were modeled and validated, resulting in two 3D structures. Molecular docking and molecular dynamic simulations suggested stable ligand-receptor interactions between the designed construct and TLR4.

CONCLUSION

Ultimately, this study led to suggest the designed construct as a potential vaccine candidate with both prophylactic and therapeutic applications against HPV by promoting Th1, Th2, CTL, and B cell immune responses, which should be further confirmed in experimental studies.

Pharmacotherapy for recurrent respiratory papillomatosis (RRP): a treatment update

Introduction: Recurrent respiratory papillomatosis is a rare human papillomavirus (HPV)-induced condition where warts grow within the airway and especially the larynx to effect voice and restrict breathing.Areas covered: A PubMed search using the following search terms was performed: respiratory papillomatosis and cidofovir, alpha-interferon, bevacizumab, PD1, and HPV vaccines. Surgery remains the mainstay of treatment. There has been a change in options available for adjuvant therapies with systemic bevacizumab and the potential benefits of prophylactic HPV vaccine. Despite efforts to identify a drug therapy to control RRP, no therapy yet remains which is predictable and effective in all. The current status of therapeutic vaccines and immunotherapy is discussed.Expert opinion: The current adjuvant therapies do offer a reasonable expectation of control but the effect for the individual is unpredictable despite the therapies being based on good science. The current therapies would allow an escalating treatment strategy to be formulated, however a single therapy is unlikely to be curative. Multi-center trials are required such that adequate numbers to show an effect are achieved.

Nanoparticle-based applications for cervical cancer treatment in drug delivery, gene editing, and therapeutic cancer vaccines

Cervical cancer is a leading cause of gynecological tumor related deaths worldwide. The applications of conventional approaches such as chemoradiotherapy and surgery are restricted due to their side effects and drug resistances. Although immune checkpoint inhibitors (ICIs) have emerged as novel choices, their clinical response rates are rather limited. To date there is a lack of effective treatment regimens for patients with metastatic or recurrent cervical cancer. Recently nanomaterials like liposomes, dendrimers, and polymers are considered as promising delivery carriers with advantages of tumor‐specific administration, reduced toxicity, and improved biocompatibility. Here, we review the applications of nanoparticles in the fields of drug delivery, CRISPR based genome‐editing and therapeutic vaccines in cervical cancer treatment.

This article is categorized under:

Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease

Identification of an immunogenic DKK1 long peptide for immunotherapy of human multiple myeloma

Dickkopf-1 (DKK1), broadly expressed by tumor cells from human multiple myeloma (MM) and other cancers but absent from most normal tissues, may be an ideal target for immunotherapy. Our previous studies have shown that DKK1 (peptide)-specific cytotoxic T lymphocytes can effectively lyse primary MM cells in vitro. To develop DKK1-based vaccines that can be easily and inexpensively made and used by all patients, we identified a DKK1 long peptide (LP), DKK13-76-LP, that contains 74 amino acids and epitopes that can potentially bind to all major MHC class I and II molecules. Using HLA-A*0201- and HLA-DR*4-transgenic mouse models, we found that DKK1-specific CD4+ and CD8+ T-cell responses, detected by DKK1 short peptide (P20 and P66v)-HLA-A*0201 tetramer staining and cytotoxic assay for CD8+ T cells or by carboxyfluorescein diacetate succinimidyl ester (CSFE) dilution and IFN-g secretion for CD4+ T cells, respectively, can be induced in vivo by immunizing mice with the DKK13-76-LP. In addition, DKK13-76-LP also induced anti-DKK1 humoral immunity in the transgenic mice and the DKK1 antibodies were functional. Finally, DKK13-76-LP stimulated human blood T cells ex vivo to generate DKK1-specific CD4+ and CD8+ T-cell responses from 8 out of 10 MM patients with different MHC backgrounds. The generated DKK1-specific CD8+ cells efficiently lysed autologous MM cells from these patients. Thus, these results confirm the immunogenicity of the DKK13-76-LP in eliciting DKK1-specific CD4+ and CD8+ T-cell responses in vitro and in vivo, and suggest that the DKK13-76-LP can be used for immunotherapy of MM and other cancers.

HPV-Associated Tumor Eradication by Vaccination with Synthetic Short Peptides and Particle-Forming Liposomes

Human papilloma virus (HPV)-16 is associated with cervical cancers and induces expression of the E6 and E7 oncogenes. Using a murine cell line that expresses these, the genes are sequenced, and six predicted major histocompatibility complex (MHC) class I (MHC-I) epitopes are identified. A liposomal vaccine adjuvant based on cobalt-porphyrin-phospholipid (CoPoP) is admixed with synthetic 9-mer epitopes appended with three histidine residues, resulting in rapid formation of peptide-liposome particles. Immunization with multivalent peptides leads to protection from tumor challenge. Of the peptides screened, only the previously identified E749-57 epitope is functional. The peptide-liposome particles that form upon mixing E7HHH49-57 with CoPoP liposomes are stable in serum and are avidly taken up by immune cells in vitro. Immunization results in robust protection from tumor challenge and re-challenge. A 100 ng peptide dose protects mice in a therapeutic tumor challenge when admixed with CoPoP liposomes, whereas 200-fold higher peptide doses are ineffective with the polyinosinic-polycytidylic (poly(I:C)) adjuvant. CoPoP induces a strong infiltrating CD8+ T-cell response within the tumor microenvironment with an improved functional profile. Vaccine monotherapy using nanogram dosing of the E7HHH49-57 peptide admixed with CoPoP reverses the growth of large established tumors, eradicating subcutaneous tumors upwards of 100 mm3 . Immunization also eradicates lung tumors in a metastasis model.

Employing ATP as a New Adjuvant Promotes the Induction of Robust Antitumor Cellular Immunity by a PLGA Nanoparticle Vaccine

Tumor vaccines based on synthetic human papillomavirus (HPV) oncoprotein E7 and/or E6 peptides have shown encouraging results in preclinical model studies and human clinical trials. However, the clinical efficacy may be limited by the disadvantages of vulnerability to enzymatic degradation and low immunogenicity of peptides. To further improve the potency of vaccine, we developed a poly(lactide-co-glycolide)-acid (PLGA) nanoparticle, which encapsulated the antigenic peptide HPV16 E7_44-62, and used adenosine triphosphate (ATP), one of the most important intracellular metabolites and an endogenous extracellular danger signal for the immune system, as a new adjuvant component. The results showed that PLGA nanoparticles increased the in vivo stability, lymph node accumulation, and dendritic cell (DC) uptake of the E7 peptide; in addition, ATP further increased the migration, nanoparticle uptake, and maturation of DCs. Preventive immunization with ATP-adjuvanted nanoparticles completely abolished the growth of TC-1 tumors in mice and produced long-lasting immunity against tumor rechallenge. When tumors were fully established, therapeutic immunization with ATP-adjuvanted nanoparticles still significantly inhibited tumor progression. Mechanistically, ATP-adjuvanted nanoparticles significantly improved the systemic generation of antitumor effector cells, boosted the local functional status of these cells in tumors, and suppressed the generation and tumor infiltration of immunosuppressive Treg cells and myeloid-derived suppressor cells. These findings indicate that ATP is an effective vaccine adjuvant and that nanoparticles adjuvanted with ATP were able to elicit robust antitumor cellular immunity, which may provide a promising therapeutic vaccine candidate for the treatment of clinical malignancies, such as cervical cancer.

Orf Virus-Based Therapeutic Vaccine for Treatment of Papillomavirus-Induced Tumors

Orf virus (ORFV) represents a suitable vector for the generation of efficient, prophylactic antiviral vaccines against different pathogens. The present study investigated for the first time the therapeutic application of ORFV vector-based vaccines against tumors induced by cottontail rabbit papillomavirus (CRPV). ORFV-CRPV recombinants were constructed expressing the early CRPV gene E1, E2, E7, or LE6. In two independent experiments we used in total 23 rabbits which were immunized with a mixture of the four ORFV-CRPV recombinants or empty ORFV vector as a control 5 weeks after the appearance of skin tumors. For the determination of the therapeutic efficacy, the subsequent growth of the tumors was recorded. In the first experiment, we could demonstrate that three immunizations of rabbits with high tumor burden with the combined four ORFV-CRPV recombinants resulted in significant growth retardation of the tumors compared to the control. A second experiment was performed to test the therapeutic effect of 5 doses of the combined vaccine in rabbits with a lower tumor burden than in nonimmunized rabbits. Tumor growth was significantly reduced after immunization, and one vaccinated rabbit even displayed complete tumor regression until the end of the observation period at 26 weeks. Results of delayed-type hypersensitivity (DTH) skin tests suggest the induction of a cellular immune response mediated by the ORFV-CRPV vaccine. The data presented show for the first time a therapeutic potential of the ORFV vector platform and encourage further studies for the development of a therapeutic vaccine against virus-induced tumors.IMPORTANCE Viral vectors are widely used for the development of therapeutic vaccines for the treatment of tumors. In our study we have used Orf virus (ORFV) strain D1701-V for the generation of recombinant vaccines expressing cottontail rabbit papillomavirus (CRPV) early proteins E1, E2, LE6, and E7. The therapeutic efficacy of the ORFV-CRPV vaccines was evaluated in two independent experiments using the outbred CRPV rabbit model. In both experiments the immunization achieved significant suppression of tumor growth. In total, 84.6% of all outbred animals benefited from the ORFV-CRPV vaccination, showing reduction in tumor size and significant tumor growth inhibition, including one animal with complete tumor regression without recurrence.

HPV16-E7 Protein T Cell Epitope Prediction and Global Therapeutic Peptide Vaccine Design Based on Human Leukocyte Antigen Frequency: An In-Silico Study

Cervical cancer is the second most common leading cause of women's death due to cancer worldwide, about 528,000 patients’ cases and 266,000 deaths per year, related to human papillomavirus (HPV). Peptide-based vaccines being safe, stable, and easy to produce have demonstrated great potential to develop therapeutic HPV vaccine. In this study, the major histocompatibility complex (MHC) class I, class II T cell epitopes of HPV16-E7 were predicted. Therefore, we designed a plan to find the most effective peptides to prompt appropriate immune responses. For this purpose, retrieving protein sequences, conserved region identification, phylogenic tree construction, T cell epitope prediction, epitope-predicted population coverage calculation, and molecular docking were performed consecutively and most effective immune response prompting peptides were selected. Based on different tools index, six CD8+ T cells and six CD4+ epitopes were chosen. This combination of 12 epitopes created a putative global vaccine with a 95.06% population coverage. These identified peptides can be employed further for peptide analysis and can be used as a peptide or poly-epitope candidates for therapeutic vaccine studies to treat HPV-associated cancers.

The rabbit papillomavirus model: a valuable tool to study viral-host interactions

Cottontail rabbit papillomavirus (CRPV) was the first DNA virus shown to be tumorigenic. The virus has since been renamed and is officially known as Sylvilagus floridanus papillomavirus 1 (SfPV1). Since its inception as a surrogate preclinical model for high-risk human papillomavirus (HPV) infections, the SfPV1/rabbit model has been widely used to study viral-host interactions and has played a pivotal role in the successful development of three prophylactic virus-like particle vaccines. In this review, we will focus on the use of the model to gain a better understanding of viral pathogenesis, gene function and host immune responses to viral infections. We will discuss the application of the model in HPV-associated vaccine testing, in therapeutic vaccine development (using our novel HLA-A2.1 transgenic rabbits) and in the development and validation of novel anti-viral and anti-tumour compounds. Our goal is to demonstrate the role the SfPV1/rabbit model has played, and continues to play, in helping to unravel the intricacies of papillomavirus infections and to develop tools to thwart the disease. This article is part of the theme issue 'Silent cancer agents: multi-disciplinary modelling of human DNA oncoviruses'.

Design of Peptide-Based Nanovaccines Targeting Leading Antigens From Gynecological Cancers to Induce HLA-A2.1 Restricted CD8+ T Cell Responses

Gynecological cancers are a leading cause of mortality in women. CD8⁺ T cell immunity largely correlates with enhanced survival, whereas inflammation is associated with poor prognosis. Previous studies have shown polystyrene nanoparticles (PSNPs) are biocompatible, do not induce inflammation and when used as vaccine carriers for model peptides induce CD8⁺ T cell responses. Herein we test the immunogenicity of 24 different peptides, from three leading vaccine target proteins in gynecological cancers: the E7 protein of human papilloma virus (HPV); Wilms Tumor antigen 1 (WT1) and survivin (SV), in PSNP conjugate vaccines. Of relevance to vaccine development was the finding that a minimal CD8⁺ T cell peptide epitope from HPV was not able to induce HLA-A2.1 specific CD8⁺ T cell responses in transgenic humanized mice using conventional adjuvants such as CpG, but was nevertheless able to generate strong immunity when delivered as part of a specific longer peptide conjugated to PSNPs vaccines. Conversely, in most cases, when the minimal CD8⁺ T cell epitopes were able to induce immune responses (with WT1 or SV super agonists) in CpG, they also induced responses when conjugated to PSNPs. In this case, extending the sequence around the CD8⁺ T cell epitope, using the natural protein context, or engineering linker sequences proposed to enhance antigen processing, had minimal effects in enhancing or changing the cross-reactivity pattern induced by the super agonists. Nanoparticle approaches, such as PSNPs, therefore may offer an alternative vaccination strategy when conventional adjuvants are unable to elicit the desired CD8⁺ T cell specificity. The findings herein also offer sequence specific insights into peptide vaccine design for nanoparticle-based vaccine carriers.

A comprehensive in silico analysis for identification of therapeutic epitopes in HPV16, 18, 31 and 45 oncoproteins

Human papillomaviruses (HPVs) are a group of circular double-stranded DNA viruses, showing severe tropism to mucosal tissues. A subset of HPVs, especially HPV16 and 18, are the primary etiological cause for several epithelial cell malignancies, causing about 5.2% of all cancers worldwide. Due to the high prevalence and mortality, HPV-associated cancers have remained as a significant health problem in human society, making an urgent need to develop an effective therapeutic vaccine against them. Achieving this goal is primarily dependent on the identification of efficient tumor-associated epitopes, inducing a robust cell-mediated immune response. Previous information has shown that E5, E6, and E7 early proteins are responsible for the induction and maintenance of HPV-associated cancers. Therefore, the prediction of major histocompatibility complex (MHC) class I T cell epitopes of HPV16, 18, 31 and 45 oncoproteins was targeted in this study. For this purpose, a two-step plan was designed to identify the most probable CD8+ T cell epitopes. In the first step, MHC-I and II binding, MHC-I processing, MHC-I population coverage and MHC-I immunogenicity prediction analyses, and in the second step, MHC-I and II protein-peptide docking, epitope conservation, and cross-reactivity with host antigens’ analyses were carried out successively by different tools. Finally, we introduced five probable CD8+ T cell epitopes for each oncoprotein of the HPV genotypes (60 epitopes in total), which obtained better scores by an integrated approach. These predicted epitopes are valuable candidates for in vitro or in vivo therapeutic vaccine studies against the HPV-associated cancers. Additionally, this two-step plan that each step includes several analyses to find appropriate epitopes provides a rational basis for DNA- or peptide-based vaccine development.

Recent advances in preclinical model systems for papillomaviruses

Preclinical model systems to study multiple features of the papillomavirus life cycle have greatly aided our understanding of Human Papillomavirus (HPV) biology, disease progression and treatments. The challenge to studying HPV in hosts is that HPV along with most PVs are both species and tissue restricted. Thus, fundamental properties of HPV viral proteins can be assessed in specialized cell culture systems but host responses that involve innate immunity and host restriction factors requires preclinical surrogate models. Fortunately, there are several well-characterized and new animal models of papillomavirus infections that are available to the PV research community. Old models that continue to have value include canine, bovine and rabbit PV models and new rodent models are in place to better assess host-virus interactions. Questions arise as to the strengths and weaknesses of animal PV models for HPV disease and how accurately these preclinical models predict malignant progression, vaccine efficacy and therapeutic control of HPV-associated disease. In this review, we examine current preclinical models and highlight the strengths and weaknesses of the various models as well as provide an update on new opportunities to study the numerous unknowns that persist in the HPV research field.

Designing of Epitope-Focused Vaccine by Targeting E6 and E7 Conserved Protein Sequences: An Immuno-Informatics Approach in Human Papillomavirus 58 Isolates

Human papillomavirus (HPV) is a DNA virus that belongs to the papillomavirus family and is capable of infecting humans. Currently, few vaccines are available to prevent infection by HPV. However, they are not so much effective and provide little benefit to women who have already been infected with HPV. The aim of this study was to design epitope-based vaccines of HPV58 by targeting E6 and E7 proteins of HPV58. Proteomic sequences were retrieved from different isolates at different time periods and later analyzed by performing alignment of these sequences. To ensure the capacity of humoral and cell-mediated immunity, both B cell and T cell immunity were checked for the peptides. For E6 protein, the peptide sequence from 48 to 54 amino acids and one 9-m epitope ETSVHEIEL were the most potential B cell and T cell epitopes, respectively. This peptide could interact with as many as eight MHC-1 alleles and showed high population coverage up to 90.31 %. On the other hand, the peptide region for the E7 protein ranged from 27 to 33 amino acids and two 9-m epitopes QAQPATANY, SSDEDEIGL were found as the most potential B cell and T cell epitopes, respectively. The peptide sequences could interact with as many as seven MHC-1 alleles and showed population coverage up to 90.31 %. Furthermore, conservancy analysis was also performed using in silico tools and showed a conservancy of 100 % for all the selected epitopes. In addition to this, the allergenicity of the epitopes was also evaluated. Although the study requires further in vitro and in vivo screening, this epitope-focused peptide vaccine designing opens up a new skyline that holds a prospective future in HPV research.

Targeting immune response with therapeutic vaccines in premalignant lesions and cervical cancer: hope or reality from clinical studies

Human papillomavirus (HPV) is widely known as a cause of cervical cancer (CC) and cervical intraepithelial neoplasia (CIN). HPVs related to cancer express two main oncogenes, i.e. E6 and E7, considered as tumorigenic genes; their integration into the host genome results in the abnormal regulation of cell cycle control. Due to their peculiarities, these oncogenes represent an excellent target for cancer immunotherapy. In this work the authors highlight the potential use of therapeutic vaccines as safe and effective pharmacological tools in cervical disease, focusing on vaccines that have reached the clinical trial phase. Many therapeutic HPV vaccines have been tested in clinical trials with promising results. Adoptive T-cell therapy showed clinical activity in a phase II trial involving advanced CC patients. A phase II randomized trial showed clinical activity of a nucleic acid-based vaccine in HPV16 or HPV18 positive CIN. Several trials involving peptide-protein-based vaccines and live-vector based vaccines demonstrated that these approaches are effective in CIN as well as in advanced CC patients. HPV therapeutic vaccines must be regarded as a therapeutic option in cervical disease. The synergic combination of HPV therapeutic vaccines with radiotherapy, chemotherapy, immunomodulators or immune checkpoint inhibitors opens a new and interesting scenario in this disease.

Long-Peptide Cross-Presentation by Human Dendritic Cells Occurs in Vacuoles by Peptide Exchange on Nascent MHC Class I Molecules

Cross-presentation enables dendritic cells to present on their MHC class I molecules antigenic peptides derived from exogenous material, through a mechanism that remains partly unclear. It is particularly efficient with long peptides, which are used in cancer vaccines. We studied the mechanism of long-peptide cross-presentation using human dendritic cells and specific CTL clones against melanoma Ags gp100 and Melan-A/MART1. We found that cross-presentation of those long peptides does not depend on the proteasome or the transporter associated with Ag processing, and therefore follows a vacuolar pathway. We also observed that it makes use of newly synthesized MHC class I molecules, through peptide exchange in vesicles distinct from the endoplasmic reticulum and classical secretory pathway, in an SEC22b- and CD74-independent manner. Our results indicate a nonclassical secretion pathway followed by nascent HLA-I molecules that are used for cross-presentation of those long melanoma peptides in the vacuolar pathway. Our results may have implications for the development of vaccines based on long peptides.

Immunotherapy and targeted therapy for cervical cancer: an update

The prognosis of patients with metastatic cervical cancer is poor with a median survival of 8-13 months. Despite the potency of chemotherapeutic drugs, this treatment is rarely curative and should be considered palliative only. In the last few years, a better understanding of Human papillomavirus tumor-host immune system interactions and the development of new therapeutics targeting immune check points have renewed interest in the use of immunotherapy in cervical cancer patients. Moreover, next generation sequencing has emerged as an attractive option for the identification of actionable driver mutations and other markers. In this review, we provide background information on the molecular biology of cervical cancer and summarize immunotherapy studies, targeted therapies, including those with angiogenesis inhibitors and tyrosine kinase inhibitors recently completed or currently on-going in cervical cancer patients.

Blocking IL-10 signalling at the time of immunization renders the tumour more accessible to T cell infiltration in mice

We recently reported that blockade of IL-10 signalling at the time of a human papillomavirus (HPV) long E7 peptide/LPS immunization leads to the regression of established HPV-16 immortalized tumours in mice similar to that induced by long E7 peptide/incomplete Freund's adjuvant (IFA)-based vaccination. In this paper, we demonstrated that blockade of IL-10 signalling at the time of long E7 peptide/LPS could elicit stronger T cells responses and render the tumour more accessible for immune cell infiltration than vaccination with long E7 peptide/IFA. Furthermore, priming with long E7 peptide/LPS and IL10 signalling blockade then boosting with long E7 peptide/IFA elicits stronger CD8+ T cell responses than long E7 peptide/IFA immunization. The results suggest that priming with long E7 peptide/LPS and IL10 signalling inhibitor, then boosting with long E7 peptide/IFA elicits may lead to better HPV infection related tumour regression in clinic.

Improving Multi-Epitope Long Peptide Vaccine Potency by Using a Strategy that Enhances CD4+ T Help in BALB/c Mice

Peptide-based vaccines are attractive approaches for cancer immunotherapy; but the success of these vaccines in clinical trials have been limited. Our goal is to improve immune responses and anti-tumor effects against a synthetic, multi-epitope, long peptide from rat Her2/neu (rHer2/neu) using the help of CD4+ T cells and appropriate adjuvant in a mouse tumor model. Female BALB/c mice were vaccinated with P₅₊₄₃₅ multi-epitope long peptide that presents epitopes for cytotoxic T lymphocytes (CTL) in combination with a universal Pan DR epitope (PADRE) or CpG-oligodeoxynucleotides (CpG-ODNs) as a Toll-like receptor agonist adjuvant. The results show that vaccination with the multi-epitope long peptide in combination with the PADRE peptide and CpG-ODN induced expansion of subpopulations of CD4+ and CD8+ cells producing IFN-γ, the average tumor size in the vaccinated mice was less than that of the other groups, and tumor growth was inhibited in 40% of the mice in the vaccinated group. The mean survival time was 82.6 ± 1.25 days in mice vaccinated with P₅₊₄₃₅ + CpG+ PADRE. Our results demonstrate that inclusion of PADRE and CpG with the peptide vaccine enhanced significant tumor specific-immune responses in vaccinated mice.

Design, Immune Responses and Anti-Tumor Potential of an HPV16 E6E7 Multi-Epitope Vaccine

Cervical cancer is a common type of cancer among women worldwide and infection with high-risk human papillomavirus (HPVs) types represents the major risk factor for the etiopathogenesis of the disease. HPV-16 is the most frequently identified HPV type in cervical lesions and expression of E6 and E7 oncoproteins is required for the uncontrolled cellular proliferation. In the present study we report the design and experimental testing of a recombinant multi-epitope protein containing immunogenic epitopes of HPV-16 E6 and E7. Tumor preventive assays, based on the engraftment of TC-1 cells in mice, showed that the E6E7 multi-epitope protein induced a full preventive anti-tumor protection in wild-type mice, as well as in mice deficient in expression of CD4+ T cells and TLR4 receptor. Nonetheless, no anti-tumor protection was observed in mice deficient in CD8+ T cells. Also, the vaccine promoted high activation of E6/E7-specific T cells and in a therapeutic-approach, E6E7 protein conferred full anti-tumor protection in mice. These results show a potential use of this E6E7 multi-epitope antigen as a new and promising antigen for the development of a therapeutic vaccine against tumors induced by HPV.

Interest of Tumor-Specific CD4 T Helper 1 Cells for Therapeutic Anticancer Vaccine

Nowadays, immunotherapy represents one promising approach for cancer treatment. Recently, spectacular results of cancer immunotherapy clinical trials have confirmed the crucial role of immune system in cancer regression. Therapeutic cancer vaccine represents one widely used immunotherapy strategy to stimulate tumor specific T cell responses but clinical impact remains disappointing in targeting CD8 T cells. Although CD8 T cells have been initially considered to be the main protagonists, it is now clear that CD4 T cells also play a critical role in antitumor response. In this article, we discuss the role of tumor antigen-specific CD4 T cell responses and how we can target these cells to improve cancer vaccines.

Humoral responses to HIVconsv induced by heterologous vaccine modalities in rhesus macaques

Vaccines delivering T cell immunogen HIVconsv vectored by plasmid DNA, non-replicating simian adenovirus and non-replicating modified vaccinia virus Ankara (MVA) are under clinical evaluation in phase I/IIa trials in UK, Europe, and Africa. While these vaccines aim to induce effector T cell responses specific for HIV-1, we here characterized the humoral responses induced by HIVconsv administration to macaques using six different vaccine modalities: plasmid DNA, human adenovirus serotype 5, simian adenovirus serotype 63, MVA, Semliki Forest virus replicons, and adjuvanted overlapping synthetic long peptides (SLP). We found that only the SLP formulation, but none of the genetic vaccine platforms induced antibodies recognizing linear HIVconsv epitopes, median 32/46 SLP.HIVconsv peptides. These antibodies bound to 15-mer and SLP peptides, recombinant gp120 and trimeric gp140 of HIV-1 Bal, YU2, JRFL, and UG037, but failed to react with HIV-1 Bal and IIIB virions and HIV-1 Bal- and IIIB-infected human cells, and consequently failed to induce neutralizing antibodies. The HIVconsv immunogen contains conserved regions derived from Gag, Pol, Vif, and Env proteins of HIV-1, and antibodies induced by the SLP.HIVconsv vaccination resulted in positive signals in routine HIV-1 tests. Thus, only HIVconsv delivered by SLP resulted in seroconversion, an observation that provides important guidance for recruiting volunteers into future clinical trials. Furthermore, our data confirms that vaccine delivery by SLP induces humoral as well as cellular immune responses and could be considered for inclusion in future vaccine regimens where this is required.

Sequential cisplatin therapy and vaccination with HPV16 E6E7L2 fusion protein in saponin adjuvant GPI-0100 for the treatment of a model HPV16+ cancer

Clinical studies suggest that responses to HPV16 E6E7L2 fusion protein (TA-CIN) vaccination alone are modest, and GPI-0100 is a well-tolerated, potent adjuvant. Here we sought to optimize both the immunogenicity of TA-CIN via formulation with GPI-0100 and treatment of HPV16+ cancer by vaccination after cisplatin chemotherapy. HPV16 neutralizing serum antibody titers, CD4+ T cell proliferative and E6/E7-specific CD8+ T cell responses were significantly enhanced when mice were vaccinated subcutaneously (s.c.) or intramuscularly (i.m.) with TA-CIN formulated with GPI-0100. Vaccination was tested for therapy of mice bearing syngeneic HPV16 E6/E7+ tumors (TC-1) either in the lung or subcutaneously. Mice treated with TA-CIN/GPI-0100 vaccination exhibited robust E7-specific CD8+ T cell responses, which were associated with reduced tumor burden in the lung, whereas mice receiving either component alone were similar to controls. Since vaccination alone was not sufficient for cure, mice bearing s.c. TC-1 tumor were first treated with two doses of cisplatin and then vaccinated. Vaccination with TA-CIN/GPI-0100 i.m. substantially retarded tumor growth and extended survival after cisplatin therapy. Injection of TA-CIN alone, but not GPI-0100, into the tumor (i.t.) was similarly efficacious after cisplatin therapy, but the mice eventually succumbed. However, tumor regression and extended remission was observed in 80% of the mice treated with cisplatin and then intra-tumoral TA-CIN/GPI-0100 vaccination. These mice also exhibited robust E7-specific CD8+ T cell and HPV16 neutralizing antibody responses. Thus formulation of TA-CIN with GPI-0100 and intra-tumoral delivery after cisplatin treatment elicits potent therapeutic responses in a murine model of HPV16+ cancer.

Origin and immunoescape of uterine cervical cancer

Human papillomavirus associated uterine cervical cancer is an important public health problem since it is classified as the fourth most common cancer in women worldwide with more than 500,000 recorded cases. This review is focused on where and why HPV infection induces cervical cancers and how this virus avoids the host immune response. Immunological therapeutic approaches are also addressed.

A synthetic chimeric peptide harboring human papillomavirus 16 cytotoxic T lymphocyte epitopes shows therapeutic potential in a murine model of cervical cancer

Infection with human papillomavirus (HPV) such as HPV16 is known to be associated with cervical cancer. The E6 and E7 oncoproteins of this virus are attractive targets for T-cell-based immunotherapy to cervical cancer. In our study, software predicted, multiple H-2D(b) restricted HPV16 cytotoxic T lymphocytes (CTL) epitopes on a synthetic chimeric peptide, was used along with different immunopotentiating adjuvants such as alum, heat-killed Mycobacterium w (Mw) cells, and poly D,L-lactic-co-glycolide (PLGA) microspheres. We have shown that subcutaneous immunization with H-2D(b)-restricted HPV16 peptide was able to generate CTL-mediated cytolysis of HPV16 E6- and E7-expressing TC-1 tumor cells in vitro, as well as protect against in vivo challenge with TC-1 cells in C57BL/6 mice. In vitro, this chimeric peptide showed best efficacy with PLGA microspheres, moderate with alum, and least with Mw as adjuvant. This approach may thus provide a potential peptide-based therapeutic candidate vaccine for the control of HPV infection and hence cervical cancer.

Therapeutic Vaccine Strategies against Human Papillomavirus

High-risk types of human papillomavirus (HPV) cause over 500,000 cervical, anogenital and oropharyngeal cancer cases per year. The transforming potential of HPVs is mediated by viral oncoproteins. These are essential for the induction and maintenance of the malignant phenotype. Thus, HPV-mediated malignancies pose the unique opportunity in cancer vaccination to target immunologically foreign epitopes. Therapeutic HPV vaccination is therefore an ideal scenario for proof-of-concept studies of cancer immunotherapy. This is reflected by the fact that a multitude of approaches has been utilized in therapeutic HPV vaccination design: protein and peptide vaccination, DNA vaccination, nanoparticle- and cell-based vaccines, and live viral and bacterial vectors. This review provides a comprehensive overview of completed and ongoing clinical trials in therapeutic HPV vaccination (summarized in tables), and also highlights selected promising preclinical studies. Special emphasis is given to adjuvant science and the potential impact of novel developments in vaccinology research, such as combination therapies to overcome tumor immune suppression, the use of novel materials and mouse models, as well as systems vaccinology and immunogenetics approaches.

HPV vaccination in head and neck HPV-related pathologies

Recent data demonstrate that human papilloma virus (HPV) plays a role in pathologies other than ano-genital cancers, specifically head and neck malignancies, and non-cancerous conditions such as recurrent respiratory papillomatosis (RRP). High-risk HPV16 and 18, and low risk HPV6 and 11 play the main role in HPV-related pathologies. As more and more information about the role of HPV infection in non-cervical diseases is amassed, additional questions about whether prophylactic HPV vaccines will effectively prevent these conditions are raised. HPV vaccination programs for the cervical pathology are being implemented worldwide. In the United States, the US Food and Drug Administration (FDA) approved the quadrivalent HPV vaccine for girls in 2006 and for boys in 2011. These vaccination programs were aimed at the genital, HPV-related lesions, and there was not much recognition at that time of how HPV vaccination programs might affect oral HPV infection, which is a risk factor for the development of HPV-related head and neck cancers. Vaccination has proved to be a successful policy, and an extant recommendation is aimed at preventing HPV and associated cervical and other anogenital cancers with the routine use of HPV vaccines for males and females. However, HPV vaccines are presently not recommended for preventing oropharyngeal cancer (OPC), although they have been shown to be highly effective against the HPV strains that are most commonly found in the oropharynx. This review is aimed at presenting the evidence-based knowledge concerning HPV vaccination and highlighting the trials and strategies for vaccine administration in HPV-dependent head and neck pathologies.

Long-peptide therapeutic vaccination against CRPV-induced papillomas in HLA-A2.1 transgenic rabbits

Long peptide immunization is a promising strategy to clear established tumors. In the current study, we investigated the therapeutic effect of a naturally existing long peptide that contained two HLA-A2.1 restricted epitopes (CRPVE1/149-157 and CRPVE1/161-169) from cottontail rabbit papillomavirus (CRPV) E1 using our CRPV/HLA-A2.1 transgenic rabbit model. A universal Tetanus Toxin helper motif (TT helper) was tagged at either the N-terminus or the carboxyl-terminus of this long peptide and designated as TT-E1 peptide and E1 peptide-TT respectively. Four groups of HLA-A2.1 transgenic rabbits were infected with wild type CRPV DNA. Three weeks post-infection, the rabbits were immunized four times with TT-E1 peptide, E1peptide only, E1 peptide -TT or TT-control peptide with two-week intervals between immunizations. Tumor outgrowth was monitored and recorded weekly. After the third booster immunization, tumors on two of the four E1 peptide-TT immunized rabbits began to shrink. One animal from this group was free of tumors at the termination of the study. The mean papilloma size of E1 peptide-TT immunized rabbits was significantly smaller when compared with that of the three other groups (P<0.05, one way ANOVA analysis). It is interesting that E1 peptide-TT vaccination not only stimulated stronger T cell mediate immune responses but also stronger antibody generations. We conclude that the location of a TT helper motif tagged at the long peptide vaccine is critical for the outcome of therapeutic responses to persistent tumors in our HLA-A2.1 transgenic rabbit model.

Intranasal immunization with a flagellin-adjuvanted peptide anticancer vaccine prevents tumor development by enhancing specific cytotoxic T lymphocyte response in a mouse model

PURPOSE

Human papillomavirus (HPV) is a significant cause of cervical cancer-related deaths worldwide. Because HPV is a sexually transmitted mucosal pathogen, enhancement of antigen-specific mucosal immune response likely serves good strategy for vaccination. However, mucosal vaccines generally do not induce strong enough immune responses. Previously we proved that a bacterial flagellin, Vibrio vulnificus FlaB, induce strong antigen-specific immune responses by stimulating the Toll-like receptor 5. In this study, we tested whether FlaB could serve as an effective mucosal adjuvant for a peptide-based HPV preventive cancer vaccine.

MATERIALS AND METHODS

Mice were intranasally administered with a mixture of FlaB and E6/E7 protective peptides in 5-day interval for a total of two times. Five-days after the last vaccination, cellular immune responses of the vaccinated mice were analyzed. Tumor growth was also observed after a subcutaneous implantation of TC-1 cells bearing E6/E7 antigens.

RESULTS

Intranasal administration of the E6/E7 peptide mixture with FlaB elicited a strong antigen-specific cytotoxic T lymphocyte activity and antigen-specific interferon-γ production from splenocytes and cervical lymph node cells. Furthermore, FlaB, as a mucosal adjuvant, conferred an excellent protection against TC-1 tumor challenge with high survival rates in E6/E7 immunized animals.

CONCLUSION

These results indicate that FlaB can be a promising mucosal adjuvant for nasal HPV vaccine development.

HPV16 synthetic long peptide (HPV16-SLP) vaccination therapy of patients with advanced or recurrent HPV16-induced gynecological carcinoma, a phase II trial

Background

Human papilloma virus type 16 (HPV16)-induced gynecological cancers, in particular cervical cancers, are found in many women worldwide. The HPV16 encoded oncoproteins E6 and E7 are tumor-specific targets for the adaptive immune system permitting the development of an HPV16-synthetic long peptide (SLP) vaccine with an excellent treatment profile in animal models. Here, we determined the toxicity, safety, immunogenicity and efficacy of the HPV16 SLP vaccine in patients with advanced or recurrent HPV16-induced gynecological carcinoma.

Methods

Patients with HPV16-positive advanced or recurrent gynecological carcinoma (n = 20) were subcutaneously vaccinated with an HPV16-SLP vaccine consisting of a mix of 13 HPV16 E6 and HPV16 E7 overlapping long peptides in Montanide ISA-51 adjuvant. The primary endpoints were safety, toxicity and tumor regression as determined by RECIST. In addition, the vaccine-induced T-cell response was assessed by proliferation and associated cytokine production as well as IFNγ-ELISPOT.

Results

No systemic toxicity beyond CTCAE grade II was observed. In a few patients transient flu-like symptoms were observed. In 9 out of 16 tested patients vaccine-induced HPV16-specific proliferative responses were detected which were associated with the production of IFNγ, TNFα, IL-5 and/or IL-10. ELISPOT analysis revealed a vaccine-induced immune response in 11 of the 13 tested patients. The capacity to respond to the vaccine was positively correlated to the patient’s immune status as reflected by their response to common recall antigens at the start of the trial. Median survival was 12.6 ± 9.1 months. No regression of tumors was observed among the 12 evaluable patients. Nineteen patients died of progressive disease.

Conclusions

The HPV16-SLP vaccine was well tolerated and induced a broad IFNγ-associated T-cell response in patients with advanced or recurrent HPV16-induced gynecological carcinoma but neither induced tumor regression nor prevented progressive disease. We, therefore, plan to use this vaccine in combination with chemotherapy and immunomodulation.

Targeted treatments for cervical cancer: a review

Cervical cancer is the second most common cause of cancer death in women worldwide and the development of new diagnosis, prognostic, and treatment strategies merits special attention. Although surgery and chemoradiotherapy can cure 80%–95% of women with early stage cancer, the recurrent and metastatic disease remains a major cause of cancer death. Many efforts have been made to design new drugs and develop gene therapies to treat cervical cancer. In recent decades, research on treatment strategies has proposed several options, including the role of HPV E6 and E7 oncogenes, which are retained and expressed in most cervical cancers and whose respective oncoproteins are critical to the induction and maintenance of the malignant phenotype. Other efforts have been focused on antitumor immunotherapy strategies. It is known that during the development of cervical cancer, a cascade of abnormal events is induced, including disruption of cellular cycle control, perturbation of antitumor immune response, alteration of gene expression, and deregulation of microRNA expression. Thus, in this review article we discuss potential targets for the treatment of cervical cancer associated with HPV infection, with special attention to immunotherapy approaches, clinical trials, siRNA molecules, and their implications as gene therapy strategies against cervical cancer development.

TLR ligand-peptide conjugate vaccines: toward clinical application

Approaches to treat cancer with therapeutic vaccination have made significant progress. In order to induce efficient antitumor immunity, a vaccine should target and activate antigen-presenting cells, such as the dendritic cell, while delivering the tumor-derived antigen of choice. Conjugates of synthetic peptides and ligands of pattern-recognition receptors (PRRs) combine these features and, given their synthetic nature, can be produced under GMP conditions. Therefore, conjugation of antigenic peptides to potent PRR ligands is a promising vaccination approach for the treatment of cancer. This review focuses on the different PRR families that can be exploited for the design of conjugates and explores the results obtained so far with PRR ligands conjugated to antigen. The uptake and processing of Toll-like receptor ligand-peptide conjugates are discussed in more detail, as well as future directions that may further enhance the immunogenicity of conjugates.

Synthetic vaccine for the treatment of lesions caused by high risk human papilloma virus

Until recently, therapeutic cancer vaccines only sporadically led to long-term clinical responses. We here report on a novel vaccine modality, characterized by the administration of long (23-45 amino acids) synthetic peptides in incomplete Freund adjuvant (mineral oil-based, Montanide ISA-51), delivered subcutaneously. Such vaccines were first demonstrated to be much more potent in preclinical T-cell response induction and tumor therapy experiments than short major histocompatibility complex class I-binding peptides that have been used extensively in the clinic. A long-peptide vaccine consisting of 13 overlapping peptides, together covering the entire length of the 2 oncogenic proteins E6 and E7 of high-risk human papilloma virus type 16 (HPV16), caused complete regression of all lesions and eradication of virus in 9 of 20 women with high-grade vulvar intraepithelial neoplasia. The nature and strength of the vaccine-induced T-cell response were significantly correlated with the clinical response. This vaccine promises to be of use, not only in patients with premalignant lesions caused by high-risk HPV16, but also in patients with malignant tumors caused by this virus, including HPV16-positive cervical cancer, anal cancer, and head and neck cancer.

Peptide Based Vaccine Approaches for Cancer-A Novel Approach Using a WT-1 Synthetic Long Peptide and the IRX-2 Immunomodulatory Regimen

Therapeutic cancer vaccines have the potential to generate a long lasting immune response that will destroy tumor cells with specificity and safety, in contrast to many other current cancer therapies. Clinical success to date has been limited by a number of factors including choice of immunogenic cancer rejection antigens, optimization of vaccine platforms and immune adjuvants to effectively polarize the immune response, and incorporation of strategies to reverse cancer mediated immune suppression by utilization of effective adjuvant/immune modulators. WT-1 (Wilms' tumor gene 1) is a cancer antigen that is required for tumorigenesis, expressed in a high percentage of tumor cells and rarely expressed in adult normal cells. Moreover spontaneous immunity to WT-1 is seen in cancer patients and can be augmented with various therapeutic vaccine approaches. IRX-2 is an immune modulator with demonstrated preclinical and clinical pleiotropic immune activities including enhancement of the immune response to potential tumor antigens. This paper presents the rationale and preclinical data for utilizing the WT-1 tumor antigen in a novel vaccine platform consisting of a synthetic long peptide containing multiple class I and class II epitopes in combination with the IRX-2 immunomodulatory regimen to overcome immuno-suppressive pathways and enhance the anti-tumor response.

Papillomavirus-specific CD4+ T cells exhibit reduced STAT-5 signaling and altered cytokine profiles in patients with recurrent respiratory papillomatosis

Recurrent respiratory papillomatosis (RRP) is caused by human papillomavirus type 6 (HPV-6) or HPV-11. Specific HLA-DR haplotypes DRB1*01:02 and DRB1*03:01 are associated with the development of RRP, disease severity, and Th2-like responses to HPV early proteins. Th1-like responses to HPV proteins have been shown to be protective in animal models. Therefore, we investigated the hypothesis that RRP patients have dysfunctional Th1-like, HPV-specific T cell responses. Using MHC class II tetramers, we identified immunogenic peptides within HPV-11 early proteins. Two distinct peptides (E6(113-132) and E2(1-20)) contained DRB1*01:02- or DRB1*03:01-restricted epitopes, respectively. An additional peptide (E2(281-300)) contained an epitope presented by both alleles. Peptide binding, tetramer, and proliferation assays identified minimal epitopes within these peptides. These epitopes elicited E2/E6-specific CD4(+) T cell responses in RRP patients and healthy control subjects, allowing the isolation of HPV-specific T cell lines using tetramers. The cytokine profiles and STAT signaling of these tetramer-positive T cells were measured to compare the polarization and responsiveness of HPV-specific T cells from patients with RRP and healthy subjects. HPV-specific IFN-γ secretion was substantially lower in T cells from RRP patients. HPV-specific IL-13 secretion was seen at modest levels in T cells from RRP patients and was absent in T cells from healthy control subjects. HPV-specific T cells from RRP patients exhibited reduced STAT-5 phosphorylation and reduced IL-2 secretion, suggesting anergy. Levels of STAT-5 phosphorylation and IFN-γ secretion could be improved through addition of IL-2 to HPV-specific T cell lines from RRP patients. Therapeutic vaccination or interventions aimed at restoring Th1-like cytokine responses to HPV proteins and reversing anergy could improve clinical outcomes for RRP patients.

Control of cervicovaginal HPV-16 E7-expressing tumors by the combination of therapeutic HPV vaccination and vascular disrupting agents

Abstract Antigen-specific immunotherapy and vascular disrupting agents, such as 5,6-dimethylxanthenone-4-acetic acid (DMXAA), have emerged as attractive approaches for the treatment of cancers. In the current study, we tested the combination of DMXAA treatment with therapeutic human papillomavirus type 16 (HPV-16) E7 peptide-based vaccination for their ability to generate E7-specific CD8+ T-cell immune responses, as well as their ability to control E7-expressing tumors in a subcutaneous and a cervicovaginal tumor model. We found that the combination of DMXAA treatment with E7 long peptide (amino acids 43-62) vaccination mixed with polyriboinosinic:polyribocytidylic generated significantly stronger E7-specific CD8+ T-cell immune responses and antitumor effects compared with treatment with DMXAA alone or HPV peptide vaccination alone in the subcutaneous model. Additionally, we found that the DMXAA-mediated enhancement of E7-specific CD8+ T-cell immune responses generated by the therapeutic HPV peptide-based vaccine was dependent on the timing of administration of DMXAA. Treatment with DMXAA in tumor-bearing mice was also shown to lead to increased dendritic cell maturation and increased production of inflammatory cytokines in the tumor. Furthermore, we observed that the combination of DMXAA with HPV-16 E7 peptide vaccination generated a significant enhancement in the antitumor effects in the cervicovaginal TC-1 tumor growth model, which closely resembles the tumor microenvironment of cervical cancer. Taken together, our data demonstrated that administration of the vascular disrupting agent, DMXAA, enhances therapeutic HPV vaccine-induced cytotoxic T-lymphocyte responses and antitumor effects against E7-expressing tumors in two different locations. Our study has significant implications for future clinical translation.

Improving therapeutic HPV peptide-based vaccine potency by enhancing CD4+ T help and dendritic cell activation

Background

Effective vaccination against human papillomavirus (HPV) represents an opportunity to control cervical cancer. Peptide-based vaccines targeting HPV E6 and/or E7 antigens while safe, will most likely require additional strategies to enhance the vaccine potency.

Methods

We tested the HPV-16 E7 peptide-based vaccine in combination with a strategy to enhance CD4+ T help using a Pan HLA-DR epitope (PADRE) peptide and a strategy to enhance dendritic cell activation using the toll-like receptor 3 ligand, poly(I:C).

Results

We observed that mice vaccinated with E7 peptide-based vaccine in combination with PADRE peptide and poly(I:C) generated better E7-specific CD8⁺ T cell immune responses as well as significantly improved therapeutic anti-tumor effects against TC-1 tumors compared to E7 peptide-based vaccine with either PADRE peptide or poly(I:C) alone. Furthermore, we found that intratumoral vaccination with the E7 peptide in conjunction with PADRE peptide and poly(I:C) generates a significantly higher frequency of E7-specific CD8⁺ T cells as well as better survival compared to subcutaneous vaccination with the same regimen in treated mice.

Conclusions

The combination of PADRE peptide and poly(I:C) with antigenic peptide is capable of generating potent antigen-specific CD8+ T cell immune responses and antitumor effects in vaccinated mice. Our study has significant clinical implications for peptide-based vaccination.

NCI First International Workshop on The Biology, Prevention and Treatment of Relapse after Allogeneic Hematopoietic Cell Transplantation: report from the committee on prevention of relapse following allogeneic cell transplantation for hematologic malignancies

Prevention of relapse after allogeneic hematopoietic stem cell transplantation is the most likely approach to improve survival of patients treated for hematologic malignancies. Herein we review the limits of currently available transplant therapies and the innovative strategies being developed to overcome resistance to therapy or to fill therapeutic modalities not currently available. These novel strategies include nonimmunologic therapies, such as targeted preparative regimens and posttransplant drug therapy, as well as immunologic interventions, including graft engineering, donor lymphocyte infusions, T cell engineering, vaccination, and dendritic cell-based approaches. Several aspects of the biology of the malignant cells as well as the host have been identified that obviate success of even these newer strategies. To maximize the potential for success, we recommend pursuing research to develop additional targeted therapies to be used in the preparative regimen or as maintenance posttransplant, better characterize the T cell and dendritic cells subsets involved in graft-versus-host disease and the graft-versus-leukemia/tumor effect, identify strategies for timing immunologic or nonimmunologic therapies to eliminate the noncycling cancer stem cell, identify more targets for immunotherapies, develop new vaccines that will not be limited by HLA, and develop methods to identify populations at very high risk for relapse to accelerate clinical development and avoid toxicity in patients not at risk for relapse.

Immunotherapy for cervical cancer: Research status and clinical potential

The high-risk types of human papillomavirus (HPV) have been found to be associated with most cervical cancers and play an essential role in the pathogenesis of the disease. Despite recent advances in preventive HPV vaccine development, such preventive vaccines are unlikely to reduce the prevalence of HPV infections within the next few years, due to their cost and limited availability in developing countries. Furthermore, preventive HPV vaccines may not be capable of treating established HPV infections and HPV-associated lesions, which account for high morbidity and mortality worldwide. Thus, it is important to develop therapeutic HPV vaccines for the control of existing HPV infection and associated malignancies. Therapeutic vaccines are quite different from preventive vaccines in that they require the generation of cell-mediated immunity, particularly T cell-mediated immunity, instead of the generation of neutralizing antibodies. The HPV-encoded early proteins, the E6 and E7 oncoproteins, form ideal targets for therapeutic HPV vaccines, since they are consistently expressed in HPV-associated cervical cancer and its precursor lesions and thus play crucial roles in the generation and maintenance of HPV-associated disease. Our review covers the various therapeutic HPV vaccines for cervical cancer, including live vector-based, peptide or protein-based, nucleic acid-based, and cell-based vaccines targeting the HPV E6 and/or E7 antigens. Furthermore, we review the studies using therapeutic HPV vaccines in combination with other therapeutic modalities and review the latest clinical trials on therapeutic HPV vaccines.

Perspectives for preventive and therapeutic HPV vaccines

Human Papillomavirus (HPV) has been associated with several human cancers, including cervical cancer, vulvar cancer, vaginal and anal cancer, and a subset of head and neck cancers. Thus effective vaccination against HPV provides an opportunity to reduce the morbidity and mortality associated with HPV. The Food and Drug Administration of the United States has approved two preventive vaccines to limit the spread of HPV. However, these are unlikely to impact upon HPV prevalence and cervical cancer rates for many years. Furthermore, preventive vaccines do not exert therapeutic effects on pre-existing HPV infections and HPV-associated lesions. In order to further impact upon the burden of HPV infections worldwide, therapeutic vaccines are being developed. These vaccines aim to generate a cell-mediated immune response to infected cells. This review discusses current preventive and therapeutic HPV vaccines and their future directions.