Intravaginal TLR agonists increase local vaccine-specific CD8 T cells and human papillomavirus-associated genital-tumor regression in mice

Toll-like receptor agonists as cancer vaccine adjuvants

Cancer immunotherapy has emerged as a promising strategy to treat cancer patients. Among the wide range of immunological approaches, cancer vaccines have been investigated to activate and expand tumor-reactive T cells. However, most cancer vaccines have not shown significant clinical benefit as monotherapies. This is likely due to the antigen targets of vaccines, "self" proteins to which there is tolerance, as well as to the immunosuppressive tumor microenvironment. To help circumvent immune tolerance and generate effective immune responses, adjuvants for cancer vaccines are necessary. One representative adjuvant family is Toll-Like receptor (TLR) agonists, synthetic molecules that stimulate TLRs. TLRs are the largest family of pattern recognition receptors (PRRs) that serve as the sensors of pathogens or cellular damage. They recognize conserved foreign molecules from pathogens or internal molecules from cellular damage and propel innate immune responses. When used with vaccines, activation of TLRs signals an innate damage response that can facilitate the development of a strong adaptive immune response against the target antigen. The ability of TLR agonists to modulate innate immune responses has positioned them to serve as adjuvants for vaccines targeting infectious diseases and cancers. This review provides a summary of various TLRs, including their expression patterns, their functions in the immune system, as well as their ligands and synthetic molecules developed as TLR agonists. In addition, it presents a comprehensive overview of recent strategies employing different TLR agonists as adjuvants in cancer vaccine development, both in pre-clinical models and ongoing clinical trials.

Combining toll-like receptor agonists with immune checkpoint blockade affects antitumor vaccine efficacy

BACKGROUND

T cell checkpoint receptors are expressed when T cells are activated, and modulation of the expression or signaling of these receptors can alter the function of T cells and their antitumor efficacy. We previously found that T cells activated with cognate antigen had increases in the expression of PD-1, and this was attenuated in the presence of multiple toll-like receptor (TLR) agonists, notably TLR3 plus TLR9. In the current report, we sought to investigate whether combining TLR agonists with immune checkpoint blockade can further augment vaccine-mediated T cell antitumor immunity in murine tumor models.

METHODS

TLR agonists (TLR3 plus TLR9) and immune checkpoint inhibitors (antibodies targeting PD-1, CTLA-4, LAG-3, TIM-3 or VISTA) were combined and delivered with vaccines or vaccine-activated CD8+T cells to E.G7-OVA or MyC-CaP tumor-bearing mice. Tumors were assessed for growth and then collected and analyzed by flow cytometry.

RESULTS

Immunization of E.G7-OVA tumor-bearing mice with SIINFEKL peptide vaccine, coadministered with TLR agonists and αCTLA-4, demonstrated greater antitumor efficacy than immunization with TLR agonists or αCTLA-4 alone. Conversely, the antitumor efficacy was abrogated when vaccine and TLR agonists were combined with αPD-1. TLR agonists suppressed PD-1 expression on regulatory T cells (Tregs) and activated this population. Depletion of Tregs in tumor-bearing mice led to greater antitumor efficacy of this combination therapy, even in the presence of αPD-1. Combining vaccination with TLR agonists and αCTLA-4 or αLAG-3 showed greater antitumor than with combinations with αTIM-3 or αVISTA.

CONCLUSION

The combination of TLR agonists and αCTLA-4 or αLAG-3 can further improve the efficacy of a cancer vaccine, an effect not observed using αPD-1 due to activation of Tregs when αPD-1 was combined with TLR3 and TLR9 agonists. These data suggest that optimal combinations of TLR agonists and immune checkpoint blockade may improve the efficacy of human anticancer vaccines.

Innate sensing and cellular metabolism: role in fine tuning antiviral immune responses

Several studies over the last decade have identified intimate links between cellular metabolism and macrophage function. Metabolism has been shown to both drive and regulate macrophage function by producing bioenergetic and biosynthetic precursors as well as metabolites (and other bioactive molecules) that regulate gene expression and signal transduction. Many studies have focused on lipopolysaccharide-induced reprogramming, assuming that it is representative of most inflammatory responses. However, emerging evidence suggests that diverse pathogen-associated molecular patterns (PAMPs) are associated with unique metabolic profiles, which may drive pathogen specific immune responses. Further, these metabolic pathways and processes may act as a rheostat to regulate the magnitude of an inflammatory response based on the biochemical features of the local microenvironment. In this review, we will discuss recent work examining the relationship between cellular metabolism and macrophage responses to viral PAMPs and describe how these processes differ from lipopolysaccharide-associated responses. We will also discuss how an improved understanding of the specificity of these processes may offer new insights to fine-tune macrophage function during viral infections or when using viral PAMPs as therapeutics.

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.

Towards the future exploration of mucosal mRNA vaccines against emerging viral diseases; lessons from existing next-generation mucosal vaccine strategies

The mRNA vaccine platform has offered the greatest potential in fighting the COVID-19 pandemic owing to rapid development, effectiveness, and scalability to meet the global demand. There are many other mRNA vaccines currently being developed against different emerging viral diseases. As with the current COVID-19 vaccines, these mRNA-based vaccine candidates are being developed for parenteral administration via injections. However, most of the emerging viruses colonize the mucosal surfaces prior to systemic infection making it very crucial to target mucosal immunity. Although parenterally administered vaccines would induce a robust systemic immunity, they often provoke a weak mucosal immunity which may not be effective in preventing mucosal infection. In contrast, mucosal administration potentially offers the dual benefit of inducing potent mucosal and systemic immunity which would be more effective in offering protection against mucosal viral infection. There are however many challenges posed by the mucosal environment which impede successful mucosal vaccination. The development of an effective delivery system remains a major challenge to the successful exploitation of mucosal mRNA vaccination. Nonetheless, a number of delivery vehicles have been experimentally harnessed with different degrees of success in the mucosal delivery of mRNA vaccines. In this review, we provide a comprehensive overview of mRNA vaccines and summarise their application in the fight against emerging viral diseases with particular emphasis on COVID-19 mRNA platforms. Furthermore, we discuss the prospects and challenges of mucosal administration of mRNA-based vaccines, and we explore the existing experimental studies on mucosal mRNA vaccine delivery.

TLR9 in the Human Papilloma Virus Infections: Friend or Foe?

Immune system plays dual roles during human papilloma virus (HPV) infections, from defense against the virus to induction or stimulation of the HPV-related cancers. It appears that various differences within the immune-related genes and the functions of the immunological parameters of the patients are the main factors responsible for the roles played by immune system during HPV infections. Toll-like receptors (TLRs) play key roles in the recognition of viruses and activation of immune responses. The molecules also can alter the target cell intracellular signaling and may participate in the transformation of the infected cells. TLR9 is the unique intracellular member of TLRs that recognize foreign DNA, including viral DNA. Thus, TLR9 may play significant roles in the defense against HPV and its related cancers. This review article discusses TLR9 antiviral and pathological roles during HPV infection.

Toll-like receptor agonist combinations augment mouse T-cell anti-tumor immunity via IL-12- and interferon ß-mediated suppression of immune checkpoint receptor expression

We previously found that activated CD8+ T-cells increase expression of PD-1, which can be attenuated in the presence of specific Toll-like receptor (TLR) agonists, mediated by IL-12 secreted by professional antigen-presenting cells. While these CD8+ T-cells had greater anti-tumor activity, T-cells stimulated by different TLR had different gene expression profiles. Consequently, we sought to determine whether combinations of TLR agonists might further affect the expression of T-cell checkpoint receptors and improve T-cell anti-tumor immunity. Activation of CD8+ T-cells in the presence of specific TLR ligands resulted in decreased expression of PD-1, LAG-3, and CD160, notably with combinations of TLR1/2, TLR3, and TLR9 agonists. Immunization of E.G7-OVA or TRAMP-C1 tumor-bearing mice with peptide or DNA vaccines, co-administered with combination of TLR3 and TLR9 agonists, showed greater suppression of tumor growth. The anti-tumor effect of TLR1/2 and/or TLR9, but not TLR3, was abrogated in IL-12KO mice. RNA sequencing of TLR-conditioned CD8+ T-cells revealed IL-12 pathway activation, and type 1 IFN pathway activation following TLR3 stimulation. Our results provide a mechanistic rationale for the choice of optimal combinations of TLR ligands to use as adjuvants to improve the efficacy of anti-tumor vaccines.

Peptide-Based Nanovaccines in the Treatment of Cervical Cancer: A Review of Recent Advances

Persistent infection with high-risk human papillomaviruses (HPVs), such as HPV-16 and HPV-18, can induce cervical cancer in humans. The disease carries high morbidity and mortality among females worldwide. Inoculation with prophylactic HPV vaccines, such as Gardasil^® or Cervarix^®, is the predominant method of preventing cervical cancer in females 6 to 26 years of age. However, despite the availability of commercial prophylactic HPV vaccines, no therapeutic HPV vaccines to eliminate existing HPV infections have been approved. Peptide-based vaccines, which form one of the most potent vaccine platforms, have been broadly investigated to overcome this shortcoming. Peptide-based vaccines are especially effective in inducing cellular immune responses and eradicating tumor cells when combined with nanoscale adjuvant particles and delivery systems. This review summarizes progress in the development of peptide-based nanovaccines against HPV infection.

Nucleic acid nanoparticles (NANPs) as molecular tools to direct desirable and avoid undesirable immunological effects

Nucleic acid nanoparticles (NANPs) represent a highly versatile molecular platform for the targeted delivery of various therapeutics. However, despite their promise, further clinical translation of this innovative technology can be hindered by immunological off-target effects. All human cells are equipped with an arsenal of receptors that recognize molecular patterns specific to foreign nucleic acids and understanding the rules that guide this recognition offer the key rationale for the development of therapeutic NANPs with tunable immune stimulation. Numerous recent studies have provided increasing evidence that in addition to NANPs' physicochemical properties and therapeutic effects, their interactions with cells of the immune system can be regulated through multiple independently programmable architectural parameters. The results further suggest that defined immunomodulation by NANPs can either support their immunoquiescent delivery or be used for conditional stimulation of beneficial immunological responses.

Integrative Systems Biology Approaches to Identify Potential Biomarkers and Pathways of Cervical Cancer

Nowadays, cervical cancer (CC) is treated as the leading cancer among women throughout the world. Despite effective vaccination and improved surgery and treatment, CC retains its fatality rate of about half of the infected population globally. The major screening biomarkers and therapeutic target identification have now become a global concern. In the present study, we have employed systems biology approaches to retrieve the potential biomarkers and pathways from transcriptomic profiling. Initially, we have identified 76 of each up-regulated and down-regulated gene from a total of 4643 differentially expressed genes. The up-regulatory genes mainly concentrate on immune-inflammatory responses, and the down-regulatory genes are on receptor binding and gamma-glutamyltransferase. The involved pathways associated with these genes were also assessed through pathway enrichment, and we mainly focused on different cancer pathways, immunoresponse, and cell cycle pathways. After the subsequent enrichment of these genes, we have identified 12 hub genes, which play a crucial role in CC and are verified by expression profile analysis. From our study, we have found that genes LILRB2 and CYBB play crucial roles in CC, as reported here for the first time. Furthermore, the survivability of the hub genes was also assessed, and among them, finally, CXCR4 has been identified as one of the most potential differentially expressed genes that might play a vital role in the survival of CC patients. Thus, CXCR4 could be used as a prognostic and/or diagnostic biomarker and a drug target for CC.

Roles of Toll-Like Receptor 3 in Human Tumors

Toll-like receptor 3 (TLR3) is an important member of the TLR family, which is an important group of pathogen-associated molecular patterns. TLR3 can recognize double-stranded RNA and induce activation of NF-κB and the production of type I interferons. In addition to its immune-associated role, TLR3 has also been detected in some tumors. However TLR3 can play protumor or antitumor roles in different tumors or cell lines. Here, we review the basic signaling associated with TLR3 and the pro- or antitumor roles of TLR3 in different types of tumors and discuss the possible reasons for the opposing roles of TLR3 in tumors.

Bivalent therapeutic vaccine against HPV16/18 genotypes consisting of a fusion protein between the extra domain A from human fibronectin and HPV16/18 E7 viral antigens

Background

In vivo targeting of human papillomavirus (HPV) derived antigens to dendritic cells might constitute an efficient immunotherapeutic strategy against cervical cancer. In previous works, we have shown that the extra domain A from murine fibronectin (mEDA) can be used to target antigens to toll-like receptor 4 (TLR4) expressing dendritic cells and induce strong antigen-specific immune responses. In the present study, we have produced a bivalent therapeutic vaccine candidate consisting of the human EDA (hEDA) fused to E7 proteins from HPV16 and HPV18 (hEDA-HPVE7-16/18) and evaluate its potential as a therapeutic vaccine against cervical cancer.

Materials and methods

Recombinant fusion proteins containing HPV E7 proteins from HPV16 and HPV18 virus subtypes fused to hEDA were produced and tested in vitro on their capacity to bind TLR4 and induce the production of tumor necrosis factor-α or interleukin (IL)-12 by human monocytes and dendritic cells. The immunogenicity and potential therapeutic activity of the vaccine in combination with cisplatin or with the TLR3 agonist molecules polyinosinic‐polycytidylic acid (Poly IC) or Poly ICLC was evaluated in mice bearing subcutaneous or genital orthotopic HPV16 TC-1 tumors.

Results

hEDA-HPVE7-16/18 prototype vaccine binds human TLR4 and stimulate TLR4-dependent signaling pathways and IL-12 production by human monocyte-derived dendritic cell. Vaccination with hEDA-HPVE7-16/18 induced strong HPVE7-specific Cytotoxic T lymphocyte (CTL) responses and eliminated established tumors in the TC-1-based tumor model. The antitumor efficacy was significantly improved by combining the fusion protein with cisplatin or with the TLR-3 ligand Poly IC and especially with the stabilized analog Poly ICLC. Moreover, hEDA-HPVE7-16/18+Poly ICLC induced full tumor regression in 100% of mice bearing orthotopic genital HPV tumors.

Conclusion

Our results suggest that this therapeutic vaccine formulation may be an effective treatment for cervical tumors that do not respond to current therapies.

Preclinical safety assessment of a therapeutic human papillomavirus DNA vaccine combined with intravaginal interleukin-7 fused with hybrid Fc in female rats

This study was conducted to establish the toxicological profile of combination treatment with therapeutic HPV DNA vaccines (GX-188E) and the long-acting form of recombinant human interleukin-7 fused with hybrid Fc (IL-7hyFc). GX-188E was administered intramuscularly by electroporation with or without IL-7hyFc intravaginally once per 2 weeks for 8 weeks (five times) in female Sprague-Dawley rats. Because up-regulation of immune responses and migration of antigen-specific T cells in cervicoviginal tissue were predicted as therapeutic effects, we distinguished adverse effects from therapeutic effects based on the severity of the systemic immune response, reversibility of lymphoid tissue changes, target tissue damage, and off-target immune responses. We observed that the number of neutrophils was increased, and the number of lymphocytes was decreased in the blood. Further, myofiber degeneration, necrosis, fibroplasia, and cell infiltration were observed at the GX-188E administration site. These changes were fully or partially recovered over a 4-week period. Analysis of lymphocytes in spleen revealed that CD4+ T cells and total T cells decreased in rats treated with GX-188E in combination with a high dose of IL-7hyFc (1.25 mg/animal). However, these changes were not considered adverse because they were transient and may have been related to electroporation-mediated DNA delivery or the local migration of lymphocytes induced by IL-7. Therefore, the potential toxicity of the combination of GX-188E and IL-7hyFc treatment was comparable to that of GX-188E treatment alone, and the no observed adverse effect level for GX-188E with IL-7hyFc was considered as 320 μg/animal for GX-188E and 1.25 mg/animal for IL-7hyFc.

Identification of prognosis-related genes in the cervical cancer immune microenvironment

BACKGROUND

Cervical cancer is the fourth most commonly diagnosed cancer in women worldwide. The metastasis and invasion of this type of cancer are closely related to the tumor microenvironment. Immune cells and stromal cells dominate the tumor microenvironment in cervical cancer. Therefore, we should further investigate the complex interplay between the tumor progression with immune cells or stromal cells.

METHODS

We downloaded the gene expression profiles and clinical data of 307 patients with cervical cancers based on the TCGA database. Subsequently, the Estimation of Stromal and Immune cells in Malignant Tumours using Expression data (ESTIMATE) algorithm was used to calculate the scores of stromal cells and immune cells in order to uncover differential expressed genes, and we analyzed the correlation between their scores and patient survival. Then the Cell type Identification By Estimating Relative Subsets Of known RNA Transcripts (CIBERSORT) deconvolution algorithm was applied to quantify the fraction and infiltration of 22 types of immune cells in cervical cancer. Moreover, we also used R language packs and network tools to analyze GO term, gene enrichment pathway, and protein-protein relationship to trace down genes related to inflammation and immune regulation.

RESULTS

The gene expression profiles and corresponding clinical data of 307 patients were obtained from TCGA database. The results showed that the scores were statistically significant between the high immunescore group and the low immunescore group. And the low immunescore group had shorter survival period than the high scores group (P = 0.035). Among the 22 types of immune cells, only T cells and mast cells were significantly related to the survival rate of cervical cancer patients. Moreover, PPI network analysis revealed that CCR5 and CXCL9, -10, -11/CXCR3 axis might be a new target for cervical cancer treatment. Finally, Kaplan-Meier survival curves found outnine representative genes significantly related to survival rate including BTNL8, CCR7, CD1E, CD6, CD27, CD79A, GRAP2, SP1B, LY9.

CONCLUSIONS

These genes can be used as markers for the prognosis and diagnosis of cervical cancer and also might be used as treatment targets.

TLRs as a Promise Target Along With Immune Checkpoint Against Gastric Cancer

Gastric cancer (GC) is one of the most common cancers in the world, and the incidence of gastric cancer in Asia appears to increase in recent years. Although there is a lot of improvement in treatment approaches, the prognosis of GC is poor. So it is urgent to search for a novel and more effective treatment to improve the survival rate of patients. Both innate immunity and adaptive immunity are important in cancer. In the innate immune system, pattern recognition receptors (PRRs) activate immune responses by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Toll-like receptors (TLRs) are a class of pattern recognition receptors (PRRs). Many studies have reported that TLRs are involved in the occurrence, development, and treatment of GC. Therefore, TLRs are potential targets for immunotherapy to gastric cancer. However, gastric cancer is a heterogeneous disorder, and TLRs function in GC is complex. TLRs agonists can be potentially used not only as therapeutic agents to treat gastric cancer but also as adjuvants in conjunction with other immunotherapies. They might provide a promising new target for GC treatment. In the review, we sort out the mechanism of TLRs involved in tumor immunity and summarize the current progress in TLRs-based therapeutic approaches and other immunotherapies in the treatment of GC.

Lymph-directed immunotherapy - Harnessing endogenous lymphatic distribution pathways for enhanced therapeutic outcomes in cancer

The advent of immunotherapy has revolutionised the treatment of some cancers. Harnessing the immune system to improve tumour cell killing is now standard clinical practice and immunotherapy is the first line of defence for many cancers that historically, were difficult to treat. A unifying concept in cancer immunotherapy is the activation of the immune system to mount an attack on malignant cells, allowing the body to recognise, and in some cases, eliminate cancer. However, in spite of a significant proportion of patients that respond well to treatment, there remains a subset who are non-responders and a number of cancers that cannot be treated with these therapies. These limitations highlight the need for targeted delivery of immunomodulators to both tumours and the effector cells of the immune system, the latter being highly concentrated in the lymphatic system. In this context, macromolecular therapies may provide a significant advantage. Macromolecules are too large to easily access blood capillaries and instead typically exhibit preferential uptake via the lymphatic system. In contexts where immune cells are the therapeutic target, particularly in cancer therapy, this may be advantageous. In this review, we examine in brief the current immunotherapy approaches in cancer and how macromolecular and nanomedicine strategies may improve the therapeutic profiles of these drugs. We subsequently discuss how therapeutics directed either by parenteral or mucosal administration, can be taken up by the lymphatics thereby accessing a larger proportion of the body's immune cells. Finally, we detail drug delivery strategies that have been successfully employed to target the lymphatics.

Treatment Combinations with DNA Vaccines for the Treatment of Metastatic Castration-Resistant Prostate Cancer (mCRPC)

Simple Summary

The only vaccine approved by FDA as a treatment for cancer is sipuleucel-T, a therapy for patients with metastatic castration-resistant prostate cancer (mCRPC). Most investigators studying anti-tumor vaccines believe they will be most effective as parts of combination therapies, rather than used alone. Unfortunately, the cost and complexity of sipuleucel-T makes it difficult to feasibly be used in combination with many other agents. In this review article we discuss the use of DNA vaccines as a simpler vaccine approach that has demonstrated efficacy in several animal species. We discuss the use of DNA vaccines in combination with traditional treatments for mCRPC, and other immune-modulating treatments, in preclinical and early clinical trials for patients with mCRPC.

Abstract

Metastatic castration-resistant prostate cancer (mCRPC) is a challenging disease to treat, with poor outcomes for patients. One antitumor vaccine, sipuleucel-T, has been approved as a treatment for mCRPC. DNA vaccines are another form of immunotherapy under investigation. DNA immunizations elicit antigen-specific T cells that cause tumor cell lysis, which should translate to meaningful clinical responses. They are easily amenable to design alterations, scalable for large-scale manufacturing, and thermo-stable for easy transport and distribution. Hence, they offer advantages over other vaccine formulations. However, clinical trials with DNA vaccines as a monotherapy have shown only modest clinical effects against tumors. Standard therapies for CRPC including androgen-targeted therapies, radiation therapy and chemotherapy all have immunomodulatory effects, which combined with immunotherapies such as DNA vaccines, could potentially improve treatment. In addition, many investigational drugs are being developed which can augment antitumor immunity, and together with DNA vaccines can further enhance antitumor responses in preclinical models. We reviewed the literature available prior to July 2020 exploring the use of DNA vaccines in the treatment of prostate cancer. We also examined various approved and experimental therapies that could be combined with DNA vaccines to potentially improve their antitumor efficacy as treatments for mCRPC.

Inducing Immunity Where It Matters: Orthotopic HPV Tumor Models and Therapeutic Vaccinations

Anogenital and oropharyngeal cancers caused by human papillomavirus (HPV) infections account for 4.5% of all cancer cases worldwide. So far, only the initial infection with selected high-risk types can be prevented by prophylactic vaccination. Already existing persistent HPV infections, however, can currently only be treated by surgical removal of resulting lesions. Therapeutic HPV vaccination, promoting cell-based anti-HPV immunity, would be ideal to eliminate and protect against HPV-induced lesions and tumors. A multitude of vaccination approaches has been tested to date, many of which led to high amounts of HPV-specific T cells in vivo. However, growing evidence suggests that not the induction of systemic but of local immunity is paramount for tackling mucosal infections and tumors. Therefore, recent therapeutic vaccination studies have focused on how to induce tissue-resident T cells in the anogenital and oropharyngeal mucosa. These approaches include direct mucosal vaccinations and influencing the migration of systemic T cells toward the mucosa. The efficacy of these new vaccination approaches is best tested in vivo by utilizing orthotopic tumor models, i.e. HPV-positive tumors being located in the animal's mucosa. In line with this, we here review existing HPV tumor models and describe two novel tumorigenic cell lines for the MHC-humanized mouse model A2.DR1. These were used for the establishment of an HPV16 E6/E7-positive vaginal tumor model, suitable for testing therapeutic vaccines containing HLA-A2-restricted HPV16-derived epitopes. The newly developed MHC-humanized orthotopic HPV16-positive tumor model is likely to improve the translatability of in vivo findings to the clinical setting.

Robust anti-tumor T cell response with efficient intratumoral infiltration by nanodisc cancer immunotherapy

Potent anti-tumor T cell response and efficient intratumoral T cell infiltration are the major challenges for therapeutic cancer vaccines. To address these issues, a nano-vaccine system has been designed to promote anti-tumor T cell responses, and intratumoral infiltration was examined in various murine tumor models. Subcutaneous vaccination with nanodiscs carrying human papillomavirus (HPV)-16 E7 antigen elicits as high as ~32% E7-specific CD8 α + T cell responses in circulation, representing a 29-fold improvement over the soluble peptide vaccination. Importantly, nanodisc vaccination also promotes robust intratumoral T cell infiltration and eliminates HPV16 E6/E7-expressing TC-1 tumors at mucosal sites, including lungs, inner lip, and intravaginal tissues. In a benchmark study with a live Listeria vaccine combined with anti-PD-1 IgG, nanodiscs plus anti-PD-1 immune checkpoint blockade elicits comparable levels of T cell responses with anti-tumor efficacy. Furthermore, compared with Complete Freund's Adjuvant combined with tetanus toxoid, nanodisc vaccination in HLA-A02 mice generates >200-fold stronger IFN-γ+ T cell responses against a neoantigen from an HLA-A02 melanoma patient. Overall, these results show that the nanodisc system is a promising cancer vaccine platform for inducing anti-tumor T cell responses.

Local mucosal immunization of self-assembled nanofibers elicits robust antitumor effects in an orthotopic model of mouse genital tumors

Human papillomavirus (HPV) is the identified causative agent of cervical cancer. Current therapeutic HPV vaccine candidates lack significant clinical efficacy, which can be attributed to insufficient activation of effector cells, lack of effective modification of the immunosuppressive tumor microenvironment, and the limitations of applied tumor models for preclinical vaccine evaluation. Here, a mouse model of orthotopic genital tumors was used to assess the effect of self-assembled nanofibers on eliciting a robust antitumor response via local mucosal immunization. A candidate vaccine was obtained by fusing HPV16 E7_44-62 to the self-assembling peptide Q11, which was assembled into nanofibers in a salt solution. Mice bearing an established genital TC-1 tumor were immunized with nanofibers through the intravaginal, intranasal, or subcutaneous route. Mucosal vaccination, especially via the intravaginal route, was more effective for suppressing tumor growth than subcutaneous immunization. The potential underlying mechanisms include promoting the systemic generation and tumor accumulation of antigen-specific cytotoxic T lymphocytes expressing high levels of interferon (IFN)-γ or granzyme-B, and reducing the tumor infiltration of immunosuppressive regulatory T cells and myeloid-derived suppressor cells. The levels of IFN-γ, the chemokines CXCL9 and CXCL10, and CXCR3⁺CD8⁺ T cells were significantly increased in tumor tissues, which may account for the improved recruitment of effector T cells into the tumor. Local mucosal immunization of nanofibers via the intravaginal route represents a new and promising vaccination strategy for the treatment of genital tumor lesions such as cervical cancer.

IL-6 expression promoted by Poly(I:C) in cervical cancer cells regulates cytokine expression and recruitment of macrophages

Poly(I:C) is a promising adjuvant for cancer treatment vaccines to enhance the host anti‐tumour immune response. However, the roles of poly(I:C) in the cervical cancer microenvironment and local immune reactions are not well understood. In this study, we investigated the roles of poly(I:C) in the cervical cancer. We analysed the cytokine transcription and secretion of cervical cancer cell lines and THP‐1–derived macrophages after poly(I:C) treatment, respectively. These results revealed that IL‐6 was significantly up‐regulated, and this up‐regulation was partly dose dependent. poly(I:C)‐stimulated supernatant of cervical cancer cells promoted M1‐type cytokine IL‐1β and IL‐6 expression of THP‐1–derived macrophages, but inhibited the expression of M2‐type cytokine, IL‐10 and CCL22. The recruitment of THP‐1–derived macrophages by poly(I:C)‐stimulated cervical cancer cell supernatant was also enhanced. Inhibition of IL‐6 expression in cervical cancer cells by siRNA transfection almost completely reversed the effects of poly(I:C) treatment. Finally, we found that phosphorylation of the NF‐κB signalling pathway in cervical cancer cells occurred quickly after poly(I:C) treatment. Moreover, the NF‐κB signalling pathway inhibitor PDTC significantly inhibited poly(I:C)‐induced IL‐6 expression. Taken together, these results suggest that poly(I:C) might regulate the effects of cervical cancer cells on tumour‐infiltrated macrophages, and subsequently promote a pro‐inflammatory tumour microenvironment.

Different types of adjuvants in prophylactic and therapeutic human papillomavirus vaccines in laboratory animals: a systematic review

Human papillomavirus (HPV) causes cervical carcinoma, which and is the third most common cancer, accounting for 275,000 deaths annually worldwide. Adjuvants have a key role in promotion of vaccine efficacy; therefore, using prophylactic and therapeutic vaccines combined with adjuvant could be of great benefit in prevention and treatment of cervical cancer. There are different types of adjuvants, including MF59^TM adjuvants, RNA-based, JY (interleukin2/chitosan), cholera toxin (CT), heat-labile enterotoxin (LT), Freund's adjuvant, alum, SA-4-1BBL, λ-carrageenan (λ-CGN), heat shock proteins (HSPs), juzen-taiho-to (JTT) and hochu-ekki-to (HET), ISCOM and ISCOMATRIX™, very small size proteoliposomes (VSSPs), granulocyte macrophage colony-stimulating factor (GM-CSF), and Toll-like receptors (TLRs). Adjuvants have various functions, especially in therapeutic vaccines, and they lead to an increase in cytotoxic T lymphocytes (CTLs), so they are important in the design of vaccines. Here, we review the currently used adjuvants and their combinations with HPV protein vaccines in order to introduce an appropriate adjuvant for HPV vaccines.

Papillomavirus Immune Evasion Strategies Target the Infected Cell and the Local Immune System

Persistent infection with human papillomavirus (HPV) initiates ~5% of all human cancers, and particularly cervical and oropharyngeal cancers. HPV vaccines prevent HPV infection, but do not eliminate existing HPV infections. Papillomaviruses induce hyperproliferation of epithelial cells. In this review we discuss how hyperproliferation renders epithelial cells less sensitive to immune attack, and impacts upon the efficiency of the local immune system. These observations have significance for the design of therapeutic HPV cancer immunotherapies.

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

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

A Comparison of Plasmid DNA and mRNA as Vaccine Technologies

This review provides a comparison of the theoretical issues and experimental findings for plasmid DNA and mRNA vaccine technologies. While both have been under development since the 1990s, in recent years, significant excitement has turned to mRNA despite the licensure of several veterinary DNA vaccines. Both have required efforts to increase their potency either via manipulating the plasmid DNA and the mRNA directly or through the addition of adjuvants or immunomodulators as well as delivery systems and formulations. The greater inherent inflammatory nature of the mRNA vaccines is discussed for both its potential immunological utility for vaccines and for the potential toxicity. The status of the clinical trials of mRNA vaccines is described along with a comparison to DNA vaccines, specifically the immunogenicity of both licensed veterinary DNA vaccines and select DNA vaccine candidates in human clinical trials.

Therapeutic potential of toll-like receptors in treatment of gynecological cancers

Toll-like receptors (TLRs) play an important role in the innate and adaptive immune system. They are expressed in various regions of the female reproductive tract, and their regulation may be involved in the pathogenesis of gynecological lesions. There is growing evidence that ligands for several TLRs are potentially anticancer agents, some of which have already been approved by the FDA, and these compounds are now undergoing clinical evaluation. There is a rationale for using these ligands as adjuvants in the treatment or prevention of gynecological cancer. Some TLR agonists that are of potential interest in the treatment of gynecological lesions include imiquimod, motolimod, cervarix, and CpG-oligodeoxynucleotides (ODNs). In this review, we outline the different functions of TLRs in gynecological cancer with particular emphasis on the value of TLR agonists as a potential therapeutic target in the treatment of gynecological cancer. © 2019 IUBMB Life, 71(5):549-564, 2019.

The role of TLR9 on Leishmania amazonensis infection and its influence on intranasal LaAg vaccine efficacy

Leishmania (L.) amazonensis is one of the etiological agents of cutaneous leishmaniasis (CL) in Brazil. Currently, there is no vaccine approved for human use against leishmaniasis, although several vaccine preparations are in experimental stages. One of them is Leishvacin, or LaAg, a first-generation vaccine composed of total L. amazonensis antigens that has consistently shown an increase of mouse resistance against CL when administered intranasally (i.n.). Since Toll-like receptor 9 (TLR9) is highly expressed in the nasal mucosa and LaAg is composed of TLR9-binding DNA CpG motifs, in this study we proposed to investigate the role of TLR9 in both L. amazonensis infection and in LaAg vaccine efficacy in C57BL/6 (WT) mice and TLR9-/- mice. First, we evaluated, the infection of macrophages by L. amazonensis in vitro, showing no significant difference between macrophages from WT and TLR9-/- mice in terms of both infection percentage and total number of intracellular amastigotes, as well as NO production. In addition, neutrophils from WT and TLR9-/- mice had similar capacity to produce neutrophil extracellular traps (NETs) in response to L. amazonensis. L. amazonensis did not activate dendritic cells from WT and TLR9-/- mice, analysed by MHCII and CD86 expression. However, in vivo, TLR9-/- mice were slightly more susceptible to L. amazonensis infection than WT mice, presenting a larger lesion and an increased parasite load at the peak of infection and in the chronic phase. The increased TLR9-/- mice susceptibility was accompanied by an increased IgG and IgG1 production; a decrease of IFN-γ in infected tissue, but not IL-4 and IL-10; and a decreased number of IFN-γ producing CD8+ T cells, but not CD4+ T cells in the lesion-draining lymph nodes. Also, TLR9-/- mice could not control parasite growth following i.n. LaAg vaccination unlike the WT mice. This protection failure was associated with a reduction of the hypersensitivity response induced by immunization. The TLR9-/- vaccinated mice failed to respond to antigen stimulation and to produce IFN-γ by lymph node cells. Together, these results suggest that TLR9 contributes to C57BL/6 mouse resistance against L. amazonensis, and that the TLR9-binding LaAg comprising CpG motifs may be important for intranasal vaccine efficacy against CL.

A Prime-Pull-Amplify Vaccination Strategy To Maximize Induction of Circulating and Genital-Resident Intraepithelial CD8+ Memory T Cells

Recent insight into the mechanisms of induction of tissue-resident memory (T_RM) CD8⁺ T cells (CD8⁺ T_RM) enables the development of novel vaccine strategies against sexually transmitted infections. To maximize both systemic and genital intraepithelial CD8⁺ T cells against vaccine Ags, we assessed combinations of i.m. and intravaginal routes in heterologous prime-boost immunization regimens with unrelated viral vectors. Only i.m. prime followed by intravaginal boost induced concomitant strong systemic and intraepithelial genital-resident CD8⁺ T cell responses. Intravaginal boost with vectors expressing vaccine Ags was far superior to intravaginal instillation of CXCR3 chemokine receptor ligands or TLR 3, 7, and 9 agonists to recruit and increase the pool of cervicovaginal CD8⁺ T_RM Transient Ag presentation increased trafficking of cognate and bystander circulating activated, but not naive, CD8⁺ T cells into the genital tract and induced in situ proliferation and differentiation of cognate CD8⁺ T_RM Secondary genital CD8⁺ T_RM were induced in the absence of CD4⁺ T cell help and shared a similar TCR repertoire with systemic CD8⁺ T cells. This prime-pull-amplify approach elicited systemic and genital CD8⁺ T cell responses against high-risk human papillomavirus type 16 E7 oncoprotein and conferred CD8-mediated protection to a vaccinia virus genital challenge. These results underscore the importance of the delivery route of nonreplicating vectors in prime-boost immunization to shape the tissue distribution of CD8⁺ T cell responses. In this context, the importance of local Ag presentation to elicit genital CD8⁺ T_RM provides a rationale to develop novel vaccines against sexually transmitted infections and to treat human papillomavirus neoplasia.

Novel TLR2-binding adjuvant induces enhanced T cell responses and tumor eradication

Background

Ligands for the Toll-like receptor (TLR) family can induce activation of cells of the innate immune system and are widely studied for their potential to enhance adaptive immunity. Conjugation of TLR2-ligand Pam3CSK4 to synthetic long peptides (SLPs) was shown to strongly enhance the induction of antitumor immunity. To further improve cancer vaccination, we have previously shown that the novel TLR2-L Amplivant (AV), a modified Pam3CSK4, potentiates the maturation effects on murine DCs. In the current study, we further assessed the immunological properties of AV.

Methods

Naïve mice were vaccinated with a conjugate of either Pam3CSK4 or AV and an SLP to assess specific T cell priming efficiency in vivo. The potency of AV and Pam3CSK4, either as free compounds or conjugated to different SLPs, to mature murine DCs was compared by stimulating murine dendritic cells overnight followed by ELISA and flow cytometry analysis. Murine tumor experiments were carried out by vaccinating mice carrying established HPV16 E6 and E7-expressing tumors and subsequently analyzing myeloid and lymphoid cells infiltrating the tumor microenvironment. Furthermore, tumor outgrowth after vaccination was monitored to enable comparison of the efficiency to induce antitumor immunity by Pam3CSK-SLP and AV-SLP conjugates. To enhance therapeutic efficacy, AV-SLP conjugate vaccination was combined with ablative therapies to assess whether synergism between such therapies would occur.

Results

SLPs conjugated to AV induce stronger DC maturation, in vivo T cell priming and antitumor immunity compared to conjugates with Pam3CSK4. Interestingly, AV-SLP conjugates modulate the macrophage populations in the tumor microenvironment, correlating with a therapeutic effect in an aggressive murine tumor model. The potency of AV-SLP conjugates in cancer vaccination operates optimally in combination with chemotherapy or photodynamic therapy.

Conclusion

These data allow further optimization of vaccination-based immunotherapy of cancer by use of the improved TLR2-ligand Amplivant.

Electronic supplementary material

The online version of this article (10.1186/s40425-018-0455-2) contains supplementary material, which is available to authorized users.

Tumor Resident Memory T Cells: New Players in Immune Surveillance and Therapy

Tissue resident memory T cells (Trm) are a subset of memory T cells mainly described in inflammation and infection settings. Their location in peripheral tissues, such as lungs, gut, or skin, makes them the earliest T cell population to respond upon antigen recognition or under inflammatory conditions. The study of Trm cells in the field of cancer, and particularly in cancer immunotherapy, has recently gained considerable momentum. Different reports have shown that the vaccination route is critical to promote Trm generation in preclinical cancer models. Cancer vaccines administered directly at the mucosa, frequently result in enhanced Trm formation in mucosal cancers compared to vaccinations via intramuscular or subcutaneous routes. Moreover, the intratumoral presence of T cells expressing the integrin CD103 has been reported to strongly correlate with a favorable prognosis for cancer patients. In spite of recent progress, the full spectrum of Trm anti-tumoral functions still needs to be fully established, particularly in cancer patients, in different clinical contexts. In this mini-review we focus on the recent vaccination strategies aimed at generating Trm cells, as well as evidence supporting their association with patient survival in different cancer types. We believe that collectively, this information provides a strong rationale to target Trm for cancer immunotherapy.

Nanoparticle Conjugation of Human Papillomavirus 16 E7-long Peptides Enhances Therapeutic Vaccine Efficacy against Solid Tumors in Mice

Treatment of patients bearing human papillomavirus (HPV)-related cancers with synthetic long-peptide (SLP) therapeutic vaccines has shown promising results in clinical trials against premalignant lesions, whereas responses against later stage carcinomas have remained elusive. We show that conjugation of a well-documented HPV-E7 SLP to ultra-small polymeric nanoparticles (NP) enhances the antitumor efficacy of therapeutic vaccination in different mouse models of HPV⁺ cancers. Immunization of TC-1 tumor-bearing mice with a single dose of NP-conjugated E7LP (NP-E7LP) generated a larger pool of E7-specific CD8⁺ T cells with increased effector functions than unconjugated free E7LP. At the tumor site, NP-E7LP prompted a robust infiltration of CD8⁺ T cells that was not accompanied by concomitant accumulation of regulatory T cells (Tregs), resulting in a higher CD8⁺ T-cell to Treg ratio. Consequently, the amplified immune response elicited by the NP-E7LP formulation led to increased regression of large, well-established tumors, resulting in a significant percentage of complete responses that were not achievable by immunizing with the non-NP-conjugated long-peptide. The partial responses were characterized by distinct phases of regression, stable disease, and relapse to progressive growth, establishing a platform to investigate adaptive resistance mechanisms. The efficacy of NP-E7LP could be further improved by therapeutic activation of the costimulatory receptor 4-1BB. This NP-E7LP formulation illustrates a "solid-phase" antigen delivery strategy that is more effective than a conventional free-peptide ("liquid") vaccine, further highlighting the potential of using such formulations for therapeutic vaccination against solid tumors. Cancer Immunol Res; 6(11); 1301-13. ©2018 AACR.

Targeting Resident Memory T Cells for Cancer Immunotherapy

A novel population of memory CD8⁺ T cells called resident memory T cells (T_RM) has been identified based on their phenotype (CD103, CD69) and on their local tissue residency without recirculating in the blood. These cells have been implicated in protective immune response against pathogens in both animal models and humans. Their role in cancer is just emerging as a key player in tumor immunosurveillance. Many properties of these cells suggest that they could control tumor growth: (i) they respond much faster to reexposure to cognate antigen than circulating memory cells, (ii) they express high levels of cytotoxic molecules, and (iii) they are enriched in tumor-specific T cells in close contact with tumor cells. T_RM are present in many human cancers and are associated with a good clinical outcome independently of the infiltration of CD8⁺ T cells. It has been recently shown that the efficacy of cancer vaccines depends on their ability to elicit T_RM. In adoptive cell therapy, the transfer of cells with the ability to establish T_RM at the tumor site correlates with the potency of this approach. Interestingly, T_RM express immune checkpoint molecules and preliminary data showed that they could expand early during anti-PD-1 treatment, and thus be considered as a surrogate marker of response to immunotherapy. Some cues to better expand these cells in vivo and improve the success of cancer immunotherapy include using mucosal routes of immunization, targeting subpopulations of dendritic cells as well as local signal at the mucosal site to recruit them in mucosal tissue.

Viral Modulation of TLRs and Cytokines and the Related Immunotherapies for HPV-Associated Cancers

The modulation of the host innate immune system is a well-established carcinogenesis feature of several tumors, including human papillomavirus- (HPV-) related cancers. This virus is able to interrupt the initial events of the immune response, including the expression of Toll-like receptors (TLRs), cytokines, and inflammation. Both TLRs and cytokines play a central role in HPV recognition, cell maturation and differentiation as well as immune signalling. Therefore, the imbalance of this sensitive control of the immune response is a key factor for developing immunotherapies, which strengthen the host immune system to accomplish an efficient defence against HPV and HPV-infected cells. Based on this, the review is aimed at exposing the HPV immune evasion mechanisms involving TLRs and cytokines and at discussing existing and potential immunotherapeutic TLR- and cytokine-related tools.

Synergy effects of Polyinosinic-polycytidylic acid, CpG oligodeoxynucleotide, and cationic peptides to adjuvant HPV E7 epitope vaccine through preventive and therapeutic immunization in a TC-1 grafted mouse model

Cross-talk by pattern recognition receptors may facilitate the maturation of dendritic cells and fine tune the immune response. Thus, the inclusion of ligands agonistic to multiple receptors in a vaccine formula may be an effective strategy to elicit robust antitumor cellular immunity. We tested the adjuvant effects and possible synergy of CpG (CpG oligodeoxynucleotide), Poly I:C (polyinosinic-polycytidylic acid) and the cationic peptide Cramp (cathelicidin-related antimicrobial peptide) formulated in a DOTAP (1,2-dioleoyl-3-trimethylammonium-propane) liposomal HPV E7 epitope vaccine on a TC-1 grafted mouse model. The vaccine formulations were administered both preventively and therapeutically. Based on our results, both CpG and Poly I:C-adjuvanted vaccines abolished tumor development in a preventive trial and significantly suppressed tumor growth in a therapeutic trial. Increased interferon (IFN)-γ expression and potent memory T cells in splenocytes as well as elevated CD8+IFN-γ+ cells in both spleen and tumor tissue indicated an elevated E7_44-62-specific cellular immune response. Although synergistic effects were detected between CpG and Poly I:C, their adjuvant effects were not enhanced further when combined with Cramp. Because the enhancement of tumor antigen-specific cellular immune responses is vital for the clearance of infected and cancerous cells, our results contribute a potential adjuvant combination for cancer vaccines.

Expression of Toll-like receptor 9 increases with progression of cervical neoplasia in Tunisian women--a comparative analysis of condyloma, cervical intraepithelial neoplasia and invasive carcinoma

Toll-like receptors (TLRs) are expressed in immune and tumor cells and recognize pathogen-associated molecular patterns. Cervical cancer (CC) is directly linked to a persistent infection with high risk human papillomaviruses (HR-HPVs) and could be associated with alteration of TLRs expression. TLR9 plays a key role in the recognition of DNA viruses and better understanding of this signaling pathway in CC could lead to the development of novel immunotherapeutic approaches. The present study was undertaken to determine the level of TLR9 expression in cervical neoplasias from Tunisian women with 53 formalin-fixed and paraffin-embedded specimens, including 22 samples of invasive cervical carcinoma (ICC), 18 of cervical intraepithelial neoplasia (CIN), 7 of condyloma and 6 normal cervical tissues as control cases. Quantification of TLR9 expression was based on scoring four degrees of extent and intensity of immunostaining in squamous epithelial cells. TLR9 expression gradually increased from CIN1 (80% weak intensity) to CIN2 (83.3% moderate), CIN3 (57.1% strong) and ICC (100% very strong). It was absent in normal cervical tissue and weak in 71.4% of condyloma. The mean scores of TLR9 expression were compared using the Kruskall-Wallis test and there was a statistical significance between normal tissue and condyloma as well as between condyloma, CINs and ICC. These results suggest that TLR9 may play a role in progression of cervical neoplasia in Tunisian patients and could represent a useful biomarker for malignant transformation of cervical squamous cells.

Chronic Myelocytic Leukemia (CML) Patient-Derived Dendritic Cells Transfected with Autologous Total RNA Induces CML-Specific Cytotoxicity

The oncogenic bcr/abl1 fusion gene is a chronic myelogenous leukemia (CML)-specific antigen which is absent in normal tissues. This makes bcr/abl1 a perfect target for developing CML vaccines that elicit specific immune responses against minimal residual disease while sparing normal tissue. The aim of this study was to use different methods to induce dendritic cells (DCs) derived from patients with CML (CML-DCs) and analyze them for CML-specific tumor cytotoxicity for immune therapy. Bone marrow-derived mononuclear cells from ten CML patients were studied to induce CML-DC differentiation in the presence of recombinant human interleukin-4, rh-granulocyte-macrophage-colony stimulating factor, and tumor necrosis factor-alpha with either a total RNA-lipofectamine complex, total RNA or CML tumor lysate (freeze-thawed). CML-DC maturation, confirmed by expression of CD1α, CD40, CD80, CD83, CD86 and by real-time polymerase chain reaction, validated the CML-origin of these DC cells. CML-DCs stimulated cytotoxic T-cell (CTL) apoptosis, high levels of IL-12 secretion, and had significant inhibitory effect on K562 tumorigenicity in nude mice. CML-DCs pulsed with total RNA by lipofectamine transfection produced the strongest effect in tumor-specific CTL functions. These results indicate that CML-DCs transfected with total RNA by lipofectamine induce the strongest CTL cytotoxicity and have the greatest potential for CML immune therapy. This study holds promise for a DC-based strategy for inducing anti-leukemia responses and establishes a foundation for developing RNA vaccination against CML.

Intravesical Bacillus Calmette Guerin Combined with a Cancer Vaccine Increases Local T-Cell Responses in Non-muscle-Invasive Bladder Cancer Patients

PURPOSE

Treatments with cancer vaccines may be delivered as combination therapies for better efficacy. Addition of intravesical immunostimulation with bacteria promotes vaccine-specific T cells in the bladder and tumor-regression in murine bladder cancer models. Here, we determined whether an adjuvanted cancer vaccine can be safely administered with concomitant standard intravesical Bacillus-Calmette-Guérin (BCG) therapy and how vaccine-specific immune responses may be modulated in patients with non-muscle-invasive bladder cancer (NMIBC).

EXPERIMENTAL DESIGN

In a nonrandomized phase I open-label exploratory study, 24 NMIBC patients, apportioned in three groups, received 5 injections of a subunit cancer vaccine (recMAGE-A3 protein+AS15) alone or in two combinations of intravesical BCG-instillations. Safety profiles were compared between the three treatment groups, considering single vaccine injections or BCG instillations and concomitant interventions. Immune responses in blood and urine were compared between treatment groups and upon BCG instillations.

RESULTS

The mild adverse events (AE) experienced by all the patients were similar to AE previously reported for this vaccine and standard BCG treatment. AEs were not increased by the double interventions, suggesting that BCG did not exacerbate the AE caused by the MAGE-A3 vaccine and vice-versa. All patients seroconverted after MAGE-A3 vaccination. In half of the patients, vaccine-specific T cells were induced in blood, irrespective of BCG treatment. Interestingly, such T cells were only detected in urine upon BCG-induced T-cell infiltration.

CONCLUSIONS

Cancer vaccines, including strong adjuvants, can be safely combined with intravesical BCG therapy. The increase of vaccine-specific T cells in the bladder upon BCG provides proof-of-principle evidence that cancer vaccines with local immunostimulation may be beneficial. Clin Cancer Res; 23(3); 717-25. ©2016 AACR.

Immunogenic Human Papillomavirus Pseudovirus-Mediated Suicide-Gene Therapy for Bladder Cancer

Bladder cancer is the second most common urological malignancy in the world. In 70% of cases it is initially diagnosed as non-muscle-invasive bladder cancer (NMIBC) and it is amenable to local treatments, with intravesical (IVES) Bacillus-Calmette-Guerin (BCG) immunotherapy being routinely used after transurethral resection of the lesion. However, this treatment is associated with significant side-effects and treatment failures, highlighting the necessity of novel strategies. One potent approach is the suicide-gene mediated therapy/prodrug combination, provided tumor-specificity can be ensured and anti-tumor immune responses induced. Using the mouse syngeneic orthotopic MB49-bladder tumor model, here we show that IVES human papillomavirus non-replicative pseudovirions (PsV) can pseudoinfect tumors with a ten-fold higher efficacy than normal bladders. In addition, PsV carrying the suicide-gene herpes-simplex virus thymidine kinase (PsV-TK) combined to Ganciclovir (GCV) led to immunogenic cell-death of tumor cells in vitro and to MB49-specific CD8 T-cells in vivo. This was associated with reduction in bladder-tumor growth and increased mice survival. Altogether, our data show that IVES PsV-TK/GCV may be a promising alternative or combinatory treatment for NMIBC.

Intravaginal Administration of Fc-Fused IL7 Suppresses the Cervicovaginal Tumor by Recruiting HPV DNA Vaccine-Induced CD8 T Cells

PURPOSE

The induction of tissue-localized virus-specific CD8 T-cell response is essential for the development of an effective therapeutic vaccine against genital diseases, such as cervical cancer and genital herpes. Here, we aimed to elucidate the immunologic role of IL7 in the induction of mucosal cellular immunity.

EXPERIMENTAL DESIGN

IL7 was engineered through Fc fusion to enhance mucosal delivery across the genital epithelial barrier. The immunomodulatory role of IL7 was evaluated by monitoring the kinetics of various immune cells and measuring the expression of chemokines and cytokines after intravaginal administration of Fc-fused IL7 (IL7-Fc). The antitumor effects of intramuscular human papillomavirus (HPV) DNA vaccine or topical IL7-Fc alone or in a combinational regimen on mice survival were compared using a orthotopic cervical cancer model.

RESULTS

Intravaginal treatment of IL7-Fc, but not native IL7, induces upregulation of chemokines (CXCL10, CCL3, CCL4, and CCL5), cytokines (IFNγ, TNFα, IL6, and IL1β), and an adhesion molecule (VCAM-1) in the genital tract, leading to the recruitment of several leukocytes, including CD4, CD8, γδ T cells, and dendritic cells. Importantly, in this murine cervical cancer model, topical administration of IL7-Fc after intramuscular HPV DNA vaccination increases the number of HPV-specific CD8 T cells in the genital mucosa, but not in the spleen, leading to stronger antitumor activity than the HPV DNA vaccine alone.

CONCLUSIONS

Our findings provide an important insight into the immunomodulatory role of IL7-Fc via topical application and the design of therapeutic vaccine regimen that induces effective genital-mucosal CD8 T-cell responses. Clin Cancer Res; 22(23); 5898-908. ©2016 AACR.

Moving forward with human papillomavirus immunotherapies

Persistent human papillomavirus (HPV) is the primary etiologic agent of cervical cancer and causes a significant number of vulvar, penile, anal and oropharyngeal cancers. The development of highly effective HPV therapeutic vaccines is a reasonable goal given the recent advances in basic and applied immunology. A number of vaccine strategies designed to induce systemic T cell responses have been tested in clinical trials against high grade cervical or vulvar high grade neoplasia and cancers, but with limited success. In line with the emerging trend to focus more on the epithelial context of HPV infection and premalignant disease, it might be advantageous to develop vaccination strategies that promote trafficking of HPV-specific T cells into lesions and overcome the local immunosuppressive environment. The development of more biologically relevant animal models would improve the preclinical evaluation of therapeutic vaccine candidates. Finally, persistent infection and low grade lesions may prove to be easier targets for therapeutic vaccines, and these vaccines would likely be commercially viable in high income countries and valuable components in screen and treat programs in low resource settings.

The role of Toll-like receptor 9 in gynecologic cancer

Toll-like receptor 9 (TLR9) plays a major role in the fight against DNA viruses infections. Despite its antitumor properties, inappropriate activation of TLR9 during chronic inflammation may cause the activation of transcription factors inducing pro-cancerous activities. Thus, the relationship between TLR9 and cancer remains highly confrontational especially in gynecological cancers and cervical cancer induced by viruses. In this review, we focus on the beneficial and detrimental role of TLR9 in gynecological carcinogenesis. TLR9 contributes to tumor regression by inducing cytotoxic T cell response (CTL), reducing the numbers of myeloid-derived suppressor cells (MDSCs), the tumor-associated macrophages (TAMs) and the regulatory T cells (T regs). It can however, also promote tumor progression and invasiveness of cervical tissue. Therefore, the dichotomous role of TLR9 needs to be carefully investigated in the setting of neoplastic disease.

Current therapeutic vaccination and immunotherapy strategies for HPV-related diseases

Carcinomas of the anogenital tract, in particular cervical cancer, remains one of the most common cancers in women, and represent the most frequent gynecological malignancies and the fourth leading cause of cancer death in women worldwide. Human papillomavirus (HPV)-induced lesions are immunologically distinct in that they express viral antigens, which are necessary to maintain the cancerous phenotype. The causal relationship between HPV infection and anogenital cancer has prompted substantial interest in the development of therapeutic vaccines against high-risk HPV types targeting the viral oncoproteins E6 and E7. This review will focus on the most recent clinical trials for immunotherapies for mucosal HPV-induced lesions as well as emerging therapeutic strategies that have been tested in pre-clinical models for HPV-induced diseases. Progress in peptide- and protein-based vaccines, DNA-based vaccines, viral/bacterial vector-based vaccines, immune checkpoint inhibition, immune response modifiers, and adoptive cell therapy for HPV will be discussed.

Human papillomavirus-exposed Langerhans cells are activated by stabilized Poly-I:C

Human papillomaviruses (HPV) establish persistent infections because of evolved immune evasion mechanisms, particularly HPV-mediated suppression of the immune functions of Langerhans cells (LC), the antigen presenting cells of the epithelium. Polyinosinic-polycytidilic acid (Poly-I:C) is broadly immunostimulatory with the ability to enhance APC expression of costimulatory molecules and inflammatory cytokines resulting in T cell activation. Here we investigated the activation of primary human LC derived from peripheral blood monocytes after exposure to HPV16 virus like particles followed by treatment with stabilized Poly-I:C compounds (s-Poly-I:C), and their subsequent induction of HPV16-specific T cells. Our results indicate that HPV16 particles alone were incapable of inducing LC activation as demonstrated by the lack of costimulatory molecules, inflammatory cytokines, chemokine-directed migration, and HPV16-specific CD8⁺ T cells in vitro. Conversely, s-Poly-I:C caused significant upregulation of costimulatory molecules and induction of chemokine-directed migration of LC that were pre-exposed to HPV16. In HLA-A*0201-positive donors, s-Poly-I:C treatment was able to induce CD8⁺ T cell immune responses against HPV16-derived peptides. Thus, s-Poly-I:C compounds are attractive for translation into therapeutics in which they could potentially mediate clearance of persistent HPV infection.

Recent progress in vaccination against human papillomavirus-mediated cervical cancer

It has been more than 7 years since the commercial introduction of highly successful vaccines protecting against high-risk human papillomavirus (HPV) subtypes and the development of cervical cancer. From an immune standpoint, the dependence of cervical cancer on viral infection has meant that HPV proteins can be targeted as strong tumour antigens leading to clearance of the infection and the subsequent protection from cancer. Commercially available vaccines consisting of the L1 capsid protein assembled as virus-like particles (VLPs) induce neutralising antibodies that deny access of the virus to cervical epithelial cells. While greater than 90% efficacy has been demonstrated at the completion of large phase III trials in young women, vaccine developers are now addressing broader issues such as efficacy in boys, longevity of the protection and inducing cross-reactive antibody for oncogenic, non-vaccine HPV strains. For women with existing HPV infection, the prophylactic vaccines provide little protection, and consequently, the need for therapeutic vaccines will continue into the future. Therapeutic vaccines targeting HPVE6 and E7 proteins are actively being pursued with new adjuvants and delivery vectors, combined with an improved knowledge of the tumour microenvironment, showing great promise. This review will focus on recent progress in prophylactic and therapeutic vaccine development and implementation since the publication of end of study data from phase III clinical trials between 2010 and 2012.

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.

Mucosal vaccines: novel strategies and applications for the control of pathogens and tumors at mucosal sites

The mucosal immune system displays several adaptations reflecting the exposure to the external environment. The efficient induction of mucosal immune responses also requires specific approaches, such as the use of appropriate administration routes and specific adjuvants and/or delivery systems. In contrast to vaccines delivered via parenteral routes, experimental, and clinical evidences demonstrated that mucosal vaccines can efficiently induce local immune responses to pathogens or tumors located at mucosal sites as well as systemic response. At least in part, such features can be explained by the compartmentalization of mucosal B and T cell populations that play important roles in the modulation of local immune responses. In the present review, we discuss molecular and cellular features of the mucosal immune system as well as novel immunization approaches that may lead to the development of innovative and efficient vaccines targeting pathogens and tumors at different mucosal sites.

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.

Local Salmonella immunostimulation recruits vaccine-specific CD8 T cells and increases regression of bladder tumor

The efficacy of antitumoral responses can be increased using combinatorial vaccine strategies. We recently showed that vaccination could be optimized by local administration of diverse molecular or bacterial agents to target and augment antitumoral CD8 T cells in the genital mucosa (GM) and increase regression of cervical cancer in an animal model. Non muscle-invasive bladder cancer is another disease that is easily amenable to local therapies. In contrast to data obtained in the GM, in this study we show that intravesical (IVES) instillation of synthetic toll-like receptor (TLR) agonists only modestly induced recruitment of CD8 T cells to the bladder. However, IVES administration of Ty21a, a live bacterial vaccine against typhoid fever, was much more effective and increased the number of total and vaccine-specific CD8 T cells in the bladder approximately 10 fold. Comparison of chemokines induced in the bladder by either CpG (a TLR-9 agonist) or Ty21a highlighted the preferential increase in complement component 5a, CXCL5, CXCL2, CCL8, and CCL5 by Ty21a, suggesting their involvement in the attraction of T cells to the bladder. IVES treatment with Ty21a after vaccination also significantly increased tumor regression compared to vaccination alone, resulting in 90% survival in an orthotopic murine model of bladder cancer expressing a prototype tumor antigen. Our data demonstrate that combining vaccination with local immunostimulation may be an effective treatment strategy for different types of cancer and also highlight the great potential of the Ty21a vaccine, which is routinely used worldwide, in such combinatorial therapies.