Unique potential of 4-1BB agonist antibody to promote durable regression of HPV+ tumors when combined with an E6/E7 peptide vaccine

Old concepts, new tricks: How peptide vaccines are reshaping cancer immunotherapy?

Over the past few decades, research on cancer immunotherapy has firmly established immune cells as key players in effective cancer treatment. Peptide vaccines directly targeting immune cells have demonstrated immense potential due to their specificity and applicability. However, developing peptide vaccines to generate tumor-reactive T cells remains challenging, primarily due to suboptimal immunogenicity and overcoming the immunosuppressive tumor microenvironment (TME). In this review, we discuss various elements of effective peptide vaccines, including antigen selection, peptide epitope optimization, vaccine adjuvants, and the combination of multiple immunotherapies, in addition to recent advances in tumor neoantigens as well as epitopes bound by non-classical human leukocyte antigen (HLA) molecules, to increase the understanding of cancer peptide vaccines and provide multiple references for the design of subsequent T cell-based peptide vaccines.

The multifaceted role of PCSK9 in cancer pathogenesis, tumor immunity, and immunotherapy

Proprotein convertase subtilisin/kexin type 9 (PCSK9), a well-known regulator of cholesterol metabolism and cardiovascular diseases, has recently garnered attention for its emerging involvement in cancer biology. The multifunctional nature of PCSK9 extends beyond lipid regulation and encompasses a wide range of cellular processes that can influence cancer progression. Studies have revealed that PCSK9 can modulate signaling pathways, such as PI3K/Akt, MAPK, and Wnt/β-catenin, thereby influencing cellular proliferation, survival, and angiogenesis. Additionally, the interplay between PCSK9 and cholesterol homeostasis may impact membrane dynamics and cellular migration, further influencing tumor aggressiveness. The central role of the immune system in monitoring and controlling cancer is increasingly recognized. Recent research has demonstrated the ability of PCSK9 to modulate immune responses through interactions with immune cells and components of the tumor microenvironment. This includes effects on dendritic cell maturation, T cell activation, and cytokine production, suggesting a role in shaping antitumor immune responses. Moreover, the potential influence of PCSK9 on immune checkpoints such as PD1/PD-L1 lends an additional layer of complexity to its immunomodulatory functions. The growing interest in cancer immunotherapy has prompted exploration into the potential of targeting PCSK9 for therapeutic benefits. Preclinical studies have demonstrated synergistic effects between PCSK9 inhibitors and established immunotherapies, offering a novel avenue for combination treatments. The strategic manipulation of PCSK9 to enhance tumor immunity and improve therapeutic outcomes presents an exciting area for further investigations. Understanding the mechanisms by which PCSK9 influences cancer biology and immunity holds promise for the development of novel immunotherapeutic approaches. This review aims to provide a comprehensive analysis of the intricate connections between PCSK9, cancer pathogenesis, tumor immunity, and the potential implications for immunotherapeutic interventions.

Preclinical evaluation of two phylogenetically distant arenavirus vectors for the development of novel immunotherapeutic combination strategies for cancer treatment

BACKGROUND

Engineered arenavirus vectors have recently been developed to leverage the body's immune system in the fight against chronic viral infections and cancer. Vectors based on Pichinde virus (artPICV) and lymphocytic choriomeningitis virus (artLCMV) encoding a non-oncogenic fusion protein of human papillomavirus (HPV)16 E6 and E7 are currently being tested in patients with HPV16+ cancer, showing a favorable safety and tolerability profile and unprecedented expansion of tumor-specific CD8+ T cells. Although the strong antigen-specific immune response elicited by artLCMV vectors has been demonstrated in several preclinical models, PICV-based vectors are much less characterized.

METHODS

To advance our understanding of the immunobiology of these two vectors, we analyzed and compared their individual properties in preclinical in vivo and in vitro systems. Immunogenicity and antitumor effect of intratumoral or intravenous administration of both vectors, as well as combination with NKG2A blockade, were evaluated in naïve or TC-1 mouse tumor models. Flow cytometry, Nanostring, and histology analysis were performed to characterize the tumor microenvironment (TME) and T-cell infiltrate following treatment.

RESULTS

Despite being phylogenetically distant, both vectors shared many properties, including preferential infection and activation of professional antigen-presenting cells, and induction of potent tumor-specific CD8+ T-cell responses. Systemic as well as localized treatment induced a proinflammatory shift in the TME, promoting the infiltration of inducible T cell costimulator (ICOS)+CD8+ T cells capable of mediating tumor regression and prolonging survival in a TC-1 mouse tumor model. Still, there was evidence of immunosuppression built-up over time, and increased expression of H2-T23 (ligand for NKG2A T cell inhibitory receptor) following treatment was identified as a potential contributing factor. NKG2A blockade improved the antitumor efficacy of artARENA vectors, suggesting a promising new combination approach. This demonstrates how detailed characterization of arenavirus vector-induced immune responses and TME modulation can inform novel combination therapies.

CONCLUSIONS

The artARENA platform represents a strong therapeutic vaccine approach for the treatment of cancer. The induced antitumor immune response builds the backbone for novel combination therapies, which warrant further investigation.

Genetic fusion of CCL11 to antigens enhances antigenicity in nucleic acid vaccines and eradicates tumor mass through optimizing T-cell response

Nucleic acid vaccines have shown promising potency and efficacy for cancer treatment with robust and specific T-cell responses. Improving the immunogenicity of delivered antigens helps to extend therapeutic efficacy and reduce dose-dependent toxicity. Here, we systematically evaluated chemokine-fused HPV16 E6/E7 antigen to improve the cellular and humoral immune responses induced by nucleotide vaccines in vivo. We found that fusion with different chemokines shifted the nature of the immune response against the antigens. Although a number of chemokines were able to amplify specific CD8 + T-cell or humoral response alone or simultaneously. CCL11 was identified as the most potent chemokine in improving immunogenicity, promoting specific CD8 + T-cell stemness and generating tumor rejection. Fusing CCL11 with E6/E7 antigen as a therapeutic DNA vaccine significantly improved treatment effectiveness and caused eradication of established large tumors in 92% tumor-bearing mice (n = 25). Fusion antigens with CCL11 expanded the TCR diversity of specific T cells and induced the infiltration of activated specific T cells, neutrophils, macrophages and dendritic cells (DCs) into the tumor, which created a comprehensive immune microenvironment lethal to tumor. Combination of the DNA vaccine with anti-CTLA4 treatment further enhanced the therapeutic effect. In addition, CCL11 could also be used for mRNA vaccine design. To summarize, CCL11 might be a potent T cell enhancer against cancer.

Immunity from NK Cell Subsets Is Important for Vaccine-Mediated Protection in HPV+ Cancers

High-risk human papillomaviruses (HPVs) are associated with genital and oral cancers, and the incidence of HPV+ head and neck squamous cell cancers is fast increasing in the USA and worldwide. Survival rates for patients with locally advanced disease are poor after standard-of-care chemoradiation treatment. Identifying the antitumor host immune mediators important for treatment response and designing strategies to promote them are essential. We reported earlier that in a syngeneic immunocompetent preclinical HPV tumor mouse model, intranasal immunization with an HPV peptide therapeutic vaccine containing the combination of aGalCer and CpG-ODN adjuvants (TVAC) promoted clearance of HPV vaginal tumors via induction of a strong cytotoxic T cell response. However, TVAC was insufficient in the clearance of HPV oral tumors. To overcome this deficiency, we tested substituting aGalCer with a clinically relevant adjuvant QS21 (TVQC) and observed sustained, complete regression of over 70% of oral and 80% of vaginal HPV tumors. The TVQC-mediated protection in the oral tumor model correlated with not only strong total and HPV-antigen-specific CD8 T cells, but also natural killer dendritic cells (NKDCs), a novel subset of NK cells expressing the DC marker CD11c. Notably, we observed induction of significantly higher overall innate NK effector responses by TVQC relative to TVAC. Furthermore, in mice treated with TVQC, the frequencies of total and functional CD11c+ NK cell populations were significantly higher than the CD11c- subset, highlighting the importance of the contributions of NKDCs to the vaccine response. These results emphasize the importance of NK-mediated innate immune effector responses in total antitumor immunity to treat HPV+ cancers.

Peritumoral administration of immunomodulatory antibodies as a triple combination suppresses skin tumor growth without systemic toxicity

BACKGROUND

Skin cancers, particularly keratinocyte cancers, are the most commonly diagnosed tumors. Although surgery is often effective in early-stage disease, skin tumors are not always easily accessible, can reoccur and have the ability to metastasize. More recently, immunotherapies, including intravenously administered checkpoint inhibitors, have been shown to control some skin cancers, but with off-target toxicities when used in combination. Our study investigated whether peritumoral administration of an antibody combination targeting PD-1, 4-1BB (CD137) and VISTA might control skin tumors and lead to circulating antitumor immunity without off-target toxicity.

METHODS

The efficacy of combination immunotherapy administered peritumorally or intravenously was tested using transplantable tumor models injected into mouse ears (primary tumors) or subcutaneously in flank skin (secondary tumors). Changes to the tumor microenvironment were tracked using flow cytometry while tumor-specific, CD8 T cells were identified through enzyme-linked immunospot (ELISPOT) assays. Off-target toxicity of the combination immunotherapy was assessed via serum alanine aminotransferase ELISA and histological analysis of liver sections.

RESULTS

The data showed that local administration of antibody therapy eliminated syngeneic murine tumors transplanted in the ear skin at a lower dose than required intravenously, and without measured hepatic toxicity. Tumor elimination was dependent on CD8 T cells and was associated with an increased percentage of CD8 T cells expressing granzyme B, KLRG1 and Eomes, and a decreased population of CD4 T cells including CD4+FoxP3+ cells in the treated tumor microenvironment. Importantly, untreated, distal tumors regressed following antibody treatment of a primary tumor, and immune memory prevented growth of subcutaneous flank tumors administered 50 days after regression of a primary tumor.

CONCLUSIONS

Together, these data suggest that peritumoral immunotherapy for skin tumors offers advantages over conventional intravenous delivery, allowing antibody dose sparing, improved safety and inducing long-term systemic memory. Future clinical trials of immunotherapy for primary skin cancer should focus on peritumoral delivery of combinations of immune checkpoint antibodies.

Cancer vaccines in the clinic

Vaccines are an important tool in the rapidly evolving repertoire of immunotherapies in oncology. Although cancer vaccines have been investigated for over 30 years, very few have achieved meaningful clinical success. However, recent advances in areas such antigen identification, formulation development and manufacturing, combination therapy regimens, and indication and patient selection hold promise to reinvigorate the field. Here, we provide a timely update on the clinical status of cancer vaccines. We identify and critically analyze 360 active trials of cancer vaccines according to delivery vehicle, antigen type, indication, and other metrics, as well as highlight eight globally approved products. Finally, we discuss current limitations and future applications for clinical translation of cancer vaccines.

HPV-associated head and neck cancer is characterized by distinct profiles of CD8+ T cells and myeloid-derived suppressor cells

Patients with HPV--localized head and neck cancer (HNC) show inferior outcomes after surgery and radiochemotherapy compared to HPV-associated cancers. The underlying mechanisms remain elusive, but differences in immune status and immune activity may be implicated. In this study, we analyzed immune profiles of CD8+ T cells and myeloid-derived suppressor cells (MDSC) in HPV+ versus HPV- disease.The overall frequency of CD8+ T cells was reduced in HNC versus healthy donors but substantially increased after curative therapy (surgery and/or radiochemotherapy). In HPV+ patients, this increase was associated with significant induction of peripheral blood CD8+/CD45RA-/CD62L- effector memory cells. The frequency of HPV-antigen-specific CD8+ cells was low even in patients with virally associated tumors and dropped to background levels after curative therapy. Pre-therapeutic counts of circulating monocytic MDSC, but not PMN-MDSC, were increased in patients with HPV- disease. This increase was accompanied by reduced fractions of terminally differentiated CD8+ effector cells. HPV- tumors showed reduced infiltrates of CD8+ and CD45RO+ immune cells compared with HPV+ tumors. Importantly, frequencies of tumor tissue-infiltrating PMN-MDSC were increased, while percentages of Granzyme B+ and Ki-67+ CD8 T cells were reduced in patients with HPV- disease.We report differences in frequencies and relative ratios of MDSC and effector T cells in HPV- HNC compared with more immunogenic HPV-associated disease. Our data provide new insight into the immunological profiles of these two tumor entities and may be utilized for more tailored immunotherapeutic approaches in the future.

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

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

Proinflammatory allogeneic dendritic cells enhance the therapeutic efficacy of systemic anti-4-1BB treatment

As an immune adjuvant, proinflammatory allogeneic dendritic cells (AlloDCs) have demonstrated promising immune-priming effects in several preclinical and clinical studies. The effector cells, including NK cells and T cells are widely acknowledged as pivotal factors in the effectiveness of cancer immunotherapy due to their ability to selectively identify and eradicate malignant cells. 4-1BB, as a costimulatory receptor, plays a significant role in the stimulation of effector cell activation. This study evaluated the anti-tumor effects when combining intratumoral administration of the immune-adjuvant AlloDCs with systemic α4-1BB treatment directly acting on effector cells. In both the CT-26 murine colon carcinoma model and B16 murine melanoma model, AlloDCs demonstrated a significant enhancement in the therapeutic efficacy of α4-1BB antibody. This enhancement was observed through the delayed growth of tumors and prolonged survival. Analysis of the tumor microenvironment (TME) in the combined-treatment group revealed an immune-inflamed TME characterized by increased infiltration of activated endogenous DCs and IFNγ+ CD8+ T cells, showing reduced signs of exhaustion. Furthermore, there was an augmented presence of tissue-resident memory (TRM) CD8+ T cells (CD103+CD49a+CD69+). The combination treatment also led to increased infiltration of CD39+CD103+ tumor-specific CD8+ T cells and neoantigen-specific T cells into the tumor. Additionally, the combined treatment resulted in a less immunosuppressive TME, indicated by decreased infiltration of myeloid-derived suppressor cells and Tregs. These findings suggest that the combination of intratumoral AlloDCs administration with systemic agonistic α4-1BB treatment can generate a synergistic anti-tumor response, thereby warranting further investigation through clinical studies.

Genome editing mRNA nanotherapies inhibit cervical cancer progression and regulate the immunosuppressive microenvironment for adoptive T-cell therapy

CRISPR/Cas9-based genome editing is promising for therapy of cervical cancer by precisely targeting human papillomavirus (HPV). To develop CRISPR/Cas9-based genome editing nanotherapies, a pH-responsive hybrid nonviral nanovector was constructed for co-delivering Cas9 mRNA and guide RNAs (gRNAs) targeting E6 or E7 oncogenes. The pH-responsive nanovector was fabricated using an acetalated cyclic oligosaccharide (ACD), in combination with low molecular weight polyethyleneimine. Thus obtained hybrid ACD nanoparticles (defined as ACD NP) showed efficient loading for both Cas9 mRNA and E6 or E7 gRNA, giving rise to two pH-responsive genome editing nanotherapies E6/ACD NP and E7/ACD NP, respectively. Cellularly, ACD NP exhibited high transfection but low cytotoxicity in HeLa cervical carcinoma cells. Also, efficient genome editing of target genes was achieved in HeLa cells, with minimal off-target effects. In mice bearing HeLa xenografts, treatment with E6/ACD NP or E7/ACD NP afforded effective editing of target oncogenes and considerable antitumor activities. More importantly, treatment with E6/ACD NP or E7/ACD NP notably promoted CD8+ T cell survival by reversing the immunosuppressive microenvironment, thereby leading to synergistic antitumor effects by combination therapy using the gene editing nanotherapies and adoptive T-cell transfer. Consequently, our pH-responsive genome editing nanotherapies deserve further development for the treatment of HPV-associated cervical cancer, and they can also serve as promising nanotherapies to improve efficacies of other immune therapies against different advanced cancers by regulating the immunosuppressive tumor microenvironment.

Targeting CD137 (4-1BB) towards improved safety and efficacy for cancer immunotherapy

T cells play a critical role in antitumor immunity, where T cell activation is regulated by both inhibitory and costimulatory receptor signaling that fine-tune T cell activity during different stages of T cell immune responses. Currently, cancer immunotherapy by targeting inhibitory receptors such as CTLA-4 and PD-1/L1, and their combination by antagonist antibodies, has been well established. However, developing agonist antibodies that target costimulatory receptors such as CD28 and CD137/4-1BB has faced considerable challenges, including highly publicized adverse events. Intracellular costimulatory domains of CD28 and/or CD137/4-1BB are essential for the clinical benefits of FDA-approved chimeric antigen receptor T cell (CAR-T) therapies. The major challenge is how to decouple efficacy from toxicity by systemic immune activation. This review focuses on anti-CD137 agonist monoclonal antibodies with different IgG isotypes in clinical development. It discusses CD137 biology in the context of anti-CD137 agonist drug discovery, including the binding epitope selected for anti-CD137 agonist antibody in competition or not with CD137 ligand (CD137L), the IgG isotype of antibodies selected with an impact on crosslinking by Fc gamma receptors, and the conditional activation of anti-CD137 antibodies for safe and potent engagement with CD137 in the tumor microenvironment (TME). We discuss and compare the potential mechanisms/effects of different CD137 targeting strategies and agents under development and how rational combinations could enhance antitumor activities without amplifying the toxicity of these agonist antibodies.

PCSK9 regulates the efficacy of immune checkpoint therapy in lung cancer

Proprotein convertase subtilisin/kexin type 9 (PCSK9) secreted by tumors was reported as a deleterious factor that led to the reduction of lymphocyte infiltration and the poorer efficacy of ICIs in vivo. This study aimed to explore whether PCSK9 expression in tumor tissue could predict the response of advanced non-small cell lung cancer (NSCLC) to anti-PD-1 immunotherapy and the synergistic antitumor effect of the combination of the PCSK9 inhibitor with the anti-CD137 agonist. One hundred fifteen advanced NSCLC patients who received anti-PD-1 immunotherapy were retrospectively studied with PCSK9 expression in baseline NSCLC tissues detected by immunohistochemistry (IHC). The mPFS of the PCSK9lo group was significantly longer than that of the PCSK9hi group [8.1 vs. 3.6 months, hazard ratio (HR): 3.450; 95% confidence interval (CI), 2.166-5.496]. A higher objective response rate (ORR) and a higher disease control rate (DCR) were observed in the PCSK9lo group than in the PCSK9hi group (54.4% vs. 34.5%, 94.7% vs. 65.5%). Reduction and marginal distribution of CD8+ T cells were observed in PCSK9hi NSCLC tissues. Tumor growth was retarded by the PCSK9 inhibitor and the anti-CD137 agonist alone in the Lewis lung carcinoma (LLC) mice model and further retarded by the PCSK9 inhibitor in combination with the CD137 agonist with long-term survival of the host mice with noticeable increases of CD8+ and GzmB+ CD8+ T cells and reduction of Tregs. Together, these results suggested that high PCSK9 expression in baseline tumor tissue was a deleterious factor for the efficacy of anti-PD-1 immunotherapy in advanced NSCLC patients. The PCSK9 inhibitor in combination with the anti-CD137 agonist could not only enhance the recruitment of CD8+ and GzmB+ CD8+ T cells but also deplete Tregs, which may be a novel therapeutic strategy for future research and clinical practice.

CD137 (4-1BB)-Based Cancer Immunotherapy on Its 25th Anniversary

Twenty-five years ago, we reported that agonist anti-CD137 monoclonal antibodies eradicated transplanted mouse tumors because of enhanced CD8+ T-cell antitumor immunity. Mouse models indicated that anti-CD137 agonist antibodies synergized with various other therapies. In the clinic, the agonist antibody urelumab showed evidence for single-agent activity against melanoma and non-Hodgkin lymphoma but caused severe liver inflammation in a fraction of the patients. CD137's signaling domain is included in approved chimeric antigen receptors conferring persistence and efficacy. A new wave of CD137 agonists targeting tumors, mainly based on bispecific constructs, are in early-phase trials and are showing promising safety and clinical activity.

SIGNIFICANCE

CD137 (4-1BB) is a costimulatory receptor of T and natural killer lymphocytes whose activity can be exploited in cancer immunotherapy strategies as discovered 25 years ago. Following initial attempts that met unacceptable toxicity, new waves of constructs acting agonistically on CD137 are being developed in patients, offering signs of clinical and pharmacodynamic activity with tolerable safety profiles.

A sugar modified amphiphilic cationic nano-adjuvant ceased tumor immune suppression and rejuvenated peptide vaccine induced antitumor immunity in cervical cancer

Human papilloma virus (HPV), one of the most common cancer-causing viruses, accounts for more than 90% of human anal and cervical cancers. Clinical studies have focused on adjuvant therapy with vaccines to improve therapeutic outcomes in patients with late-stage HPV-related cancers. In the present study, a mannose receptor (CD206) targeting a lithocholic acid-modified polyethylenimine (PEI) nano-adjuvant delivering the toll-like receptor 7/8 agonist, resiquimod (R848) (mLAPMi-R848), in a HPV E6- and E7-expressing TC-1 tumor murine model was developed. Peritumoral administration of mLAPMi resulted in enhanced accumulation in tumor/tumor-draining lymph nodes and significantly targeted antigen presenting cells like macrophage and dendritic cells. PEI-based nanocarriers can exploit the adjuvant potency of R848 and improve the antitumor immunity. Hence, co-administration of mLAPMi-R848 along with an E6E7 peptide in TC-1 tumor mice eradicated tumor burden and elicited splenocyte-induced cytotoxicity in TC-1 cancer cells. In a bilateral TC-1 tumor model, administration of mLAPMi-R848 and E6E7 peptide significantly suppressed both primary and secondary tumor burdens and improved the overall survival rate. Immune cell profiling revealed elevated levels of mature DCs and CD8+ T cells but reduced levels of tumor-associated immunosuppressive cells (TAICs) like myeloid derived suppressor cells (MDSCs) and regulatory T (Treg) cells in distal tumors. Overall, this study demonstrated that mLAPMi-R848 has improved the antitumor immunity of the peptide antigen against HPV-induced cancers by targeted immunodulation of antigen presenting cells (APCs) and reducing TAICs. Furthermore, this nano-adjuvant has the potential to offer a new treatment option for patients with cervical cancer and can be applied for the treatment of other HPV induced cancers.

Exposure of Immunogenic Tumor Antigens in Surrendered Immunity and the Significance of Autologous Tumor Cell-Based Vaccination in Precision Medicine

The mechanisms by which immune systems identify and destroy tumors, known as immunosurveillance, have been discussed for decades. However, several factors that lead to tumor persistence and escape from the attack of immune cells in a normal immune system have been found. In the process known as immunoediting, tumors decrease their immunogenicity and evade immunosurveillance. Furthermore, tumors exploit factors such as regulatory T cells, myeloid-derived suppressive cells, and inhibitory cytokines that avoid cytotoxic T cell (CTL) recognition. Current immunotherapies targeting tumors and their surroundings have been proposed. One such immunotherapy is autologous cancer vaccines (ACVs), which are characterized by enriched tumor antigens that can escalate specific CTL responses. Unfortunately, ACVs usually fail to activate desirable therapeutic effects, and the low immunogenicity of ACVs still needs to be elucidated. This difficulty highlights the significance of immunogenic antigens in antitumor therapies. Previous studies have shown that defective host immunity triggers tumor development by reprogramming tumor antigenic expressions. This phenomenon sheds new light on ACVs and provides a potential cue to improve the effectiveness of ACVs. Furthermore, synergistically with the ACV treatment, combinational therapy, which can reverse the suppressive tumor microenvironments, has also been widely proposed. Thus, in this review, we focus on tumor immunogenicity sculpted by the immune systems and discuss the significance and application of restructuring tumor antigens in precision medicine.

Role of TNFSF9 bidirectional signal transduction in antitumor immunotherapy

The complex structure of the tumor microenvironment leads to the poor efficacy of tumor immunotherapy. The therapeutic adjuvant designed to enhance the effect of T cells by acting on the costimulatory molecule tumor necrosis factor superfamily member 9 (TNFSF9) has achieved good results. However, because some tumors are characterized by reduced T-cell infiltration, adjuvants acting on T cells alone may have limitations. On the other hand, the blockade of TNFSF9 reverse signalling can have an antitumor effect by reshaping the tumor microenvironment. Therefore, this paper mainly discusses the current status and potential of TNFSF9 bidirectional signalling in antitumor immunotherapy to provide new ideas for tumor immunotherapy.

Immunotherapeutic approaches for HPV-caused cervical cancer

Cervical cancer, the fourth most frequent women cancer worldwide, is mostly (about 99%) associated with human papillomavirus (HPV). Despite availability of three effective prophylactic vaccines for more than one decade and some other preventive measures, it is still the fourth cause of cancer death among women globally. Thus, development of therapeutic vaccines seems essential, which has been vastly studied using different vaccine platforms. Even with very wide efforts during the past years, no therapeutic vaccine has been approved yet, which might be partly due to the complex events and interactions taken place in the tumor microenvironment. On the other hand, immunotherapy has opened its way into the management plans of some cancers. The recent approval of pembrolizumab for the treatment of metastatic/recurrent cervical cancer brings new hopes to the management of this disease, while some other immunotherapeutic approaches are also under investigation either alone or in combination with vaccines. Here, following a summary about HPV and its pathogenesis, cervical cancer therapeutic vaccines would be reviewed. Cell-based vaccines as well as immunomodulation and other modalities used along with vaccines would be also discussed.

Human Biofield Therapy Modulates Tumor Microenvironment and Cancer Stemness in Mouse Lung Carcinoma

Studies have demonstrated that purported biofield therapy emitted from humans can inhibit the proliferation of cancer cells and suppress tumor growth in various cancers. We explored the effects of biofield therapy on tumor growth in the Lewis lung carcinoma and expanded mechanistic outcomes. We found biofield therapy did not inhibit tumor growth. However, the experimental (Ex) condition exposed tumors had a significantly higher percentage of necrosis (24.4 ± 6.8%) compared with that of the Control condition (6.5 ± 2.7%; P < .02) and cleaved caspase-3 positive cells were almost 2.3-fold higher (P < .05). Similarly, tumor-infiltrating lymphocytes profiling showed that CD8+/CD45+ immune cell population was significantly increased by 2.7-fold in Ex condition (P < .01) whereas the number of intratumoral FoxP3+/CD4+ (T-reg cells) was 30.4% lower than that of the Control group (P = .01), leading to a significant 3.1-fold increase in the ratio of CD8+/T-reg cells (P < .01). Additionally, there was a 51% lower level of strongly stained CD68+ cells (P < .01), 57.9% lower level of F4/80high/CD206+ (M2 macrophages; P < .02) and a significant 1.8-fold increase of the ratio of M1/M2 macrophages (P < .02). Furthermore, Ex exposure resulted in a 15% reduction of stem cell marker CD44 and a significant 33% reduction of SOX2 compared with that of the Controls (P < .02). The Ex group also engaged in almost 50% less movement throughout the session than the Controls. These findings suggest that exposure to purported biofields from a human is capable of enhancing cancer cell death, in part mediated through modification of the tumor microenvironment and stemness of tumor cells in mouse Lewis lung carcinoma model. Future research should focus on defining the optimal treatment duration, replication with different biofield therapists, and exploring the mechanisms of action.

CD40 Agonist Targeted to Fibroblast Activation Protein α Synergizes with Radiotherapy in Murine HPV-Positive Head and Neck Tumors

PURPOSE

The incidence of human papillomavirus-associated head and neck squamous cell carcinoma (HPV⁺-HNSCC) is rising worldwide and although current therapeutic modalities are efficient in the majority of patients, there is a high rate of treatment failures. Thus, novel combination approaches are urgently needed to achieve better disease control in patients with HPV⁺-HNSCC. We investigated the safety and therapeutic efficacy of a novel fibroblast activation protein (FAP)-targeted CD40 agonist (FAP-CD40) in combination with local hypofractionated radiation in a syngeneic HPV⁺-HNSCC model.

EXPERIMENTAL DESIGN

Using an established orthotopic model, we treated tumor-bearing mice with local hypofractionated radiotherapy (2 × 6 Gy) alone or in combination with a systemic administration of the FAP-CD40 antibody. Following up the mice, we evaluated the changes in the tumor microenvironment (TME) by immunofluorescence, FACS, and NanoString RNA analysis.

RESULTS

The suboptimal radiotherapy regimen chosen failed to control tumors in the treated mice. The FAP-CD40 administered in monotherapy transiently controlled tumor growth, whereas the combined therapy induced durable complete responses in more than 80% of the tumor-bearing mice. This notable efficacy relied on the radiotherapy-induced remodeling of the TME and activation of the CD8⁺ T-cell-cDC1 axis and was devoid of the systemic toxicity frequently associated with CD40-targeted therapy. Moreover, the robust immunologic memory developed effectively prevented tumor relapses, a common feature in patients with HNSCC.

CONCLUSIONS

Our study provides proof of concept, as well as mechanistic insights of the therapeutic efficacy of a bispecific FAP-CD40 combined with local radiotherapy in a FAP⁺-HNSCC model increasing overall survival and inducing long-term antitumor immunity.

PLGA Nanoparticles Co-encapsulating NY-ESO-1 Peptides and IMM60 Induce Robust CD8 and CD4 T Cell and B Cell Responses

Tumor-specific neoantigens can be highly immunogenic, but their identification for each patient and the production of personalized cancer vaccines can be time-consuming and prohibitively expensive. In contrast, tumor-associated antigens are widely expressed and suitable as an off the shelf immunotherapy. Here, we developed a PLGA-based nanoparticle vaccine that contains both the immunogenic cancer germline antigen NY-ESO-1 and an α-GalCer analog IMM60, as a novel iNKT cell agonist and dendritic cell transactivator. Three peptide sequences (85-111, 117-143, and 157-165) derived from immunodominant regions of NY-ESO-1 were selected. These peptides have a wide HLA coverage and were efficiently processed and presented by dendritic cells via various HLA subtypes. Co-delivery of IMM60 enhanced CD4 and CD8 T cell responses and antibody levels against NY-ESO-1 in vivo. Moreover, the nanoparticles have negligible systemic toxicity in high doses, and they could be produced according to GMP guidelines. Together, we demonstrated the feasibility of producing a PLGA-based nanovaccine containing immunogenic peptides and an iNKT cell agonist, that is activating DCs to induce antigen-specific T cell responses.

Cancer Vaccines: Adjuvant Potency, Importance of Age, Lifestyle, and Treatments

Although the discovery and characterization of multiple tumor antigens have sparked the development of many antigen/derived cancer vaccines, many are poorly immunogenic and thus, lack clinical efficacy. Adjuvants are therefore incorporated into vaccine formulations to trigger strong and long-lasting immune responses. Adjuvants have generally been classified into two categories: those that ‘depot’ antigens (e.g. mineral salts such as aluminum hydroxide, emulsions, liposomes) and those that act as immunostimulants (Toll Like Receptor agonists, saponins, cytokines). In addition, several novel technologies using vector-based delivery of antigens have been used. Unfortunately, the immune system declines with age, a phenomenon known as immunosenescence, and this is characterized by functional changes in both innate and adaptive cellular immunity systems as well as in lymph node architecture. While many of the immune functions decline over time, others paradoxically increase. Indeed, aging is known to be associated with a low level of chronic inflammation—inflamm-aging. Given that the median age of cancer diagnosis is 66 years and that immunotherapeutic interventions such as cancer vaccines are currently given in combination with or after other forms of treatments which themselves have immune-modulating potential such as surgery, chemotherapy and radiotherapy, the choice of adjuvants requires careful consideration in order to achieve the maximum immune response in a compromised environment. In addition, more clinical trials need to be performed to carefully assess how less conventional form of immune adjuvants, such as exercise, diet and psychological care which have all be shown to influence immune responses can be incorporated to improve the efficacy of cancer vaccines. In this review, adjuvants will be discussed with respect to the above-mentioned important elements.

Combination Therapies for HPV-Associated Malignancies

Human papillomavirus (HPV)-associated malignancies cause almost all cases of cervical cancer in women, and a significant percentage of head and neck cancer, together totaling almost 5% of the global cancer burden, and representing an important public health issue. The approval and use of two prophylactic HPV vaccines, Gardasil® and Cervarix®, have significantly decreased infections with HPV, but unfortunately, prophylactic vaccination does not treat established infections or malignancies resulting from HPV. Therefore, therapies for HPV-associated malignancies are necessary to improve the quality of life and survival in patients with these diseases. This review will detail new combinations of therapies in clinical development for HPV-associated malignancies.

Peptidic vaccines: The new cure for heart diseases?

Cardiovascular disease continues to be the most common cause of death worldwide. The global burden is so high that numerous organizations are providing counseling recommendations and annual revisions of current pharmacological and non-pharmacological treatments as well as risk prediction for disease prevention and further progression. Although primary preventive interventions targeting risk factors such as obesity, hypertension, smoking, and sedentarism have led to a global decline in hospitalization rates, the aging population has overwhelmed these efforts on a global scale. This review focuses on peptidic vaccines, with the known and not well-known autoantigens in atheroma formation or acquired cardiac diseases, as novel potential immunotherapy approaches to counteract harmful heart disease continuance. We summarize how cancer immunomodulatory strategies started novel approaches to modulate the innate and adaptive immune responses, and how they can be targeted for therapeutic purposes in the cardiovascular system. Brief descriptions focused on the processes that start as either immunologic or non-immunologic, and the ultimate loss of cardiac muscle cell contractility as the outcome, are discussed. We conclude debating how novel strategies with nanoparticles and nanovaccines open a promising therapeutic option to reduce or prevent cardiovascular diseases.

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.

Effect of Antibiotics on Gut and Vaginal Microbiomes Associated with Cervical Cancer Development in Mice

Antibiotics affect microbial diversity in the gut, leading to dysbiosis and impaired immunity. However, the impact of antibiotics on microbial communities at other sites, such as vagina is less understood. It is also not clear whether changes induced by antibiotics in both microbiomes affect the development of cervical cancer. In this study, we utilized the murine model to evaluate these questions. We show that oral application of broad-spectrum antibiotics in mice changed not only diversity, but composition and sharing of gut and vaginal microbiomes in mice and influenced cervical cancer development in an orthotopic tumor model. Antibiotics decreased richness and diversity indexes in the gut but increased them in the vagina. Some beneficial taxa, such as Bacteroides, Ruminococcaceae, and Lachnospiraceae increased their abundance in the vagina while other pathogenic species, such as Proteobacteria, were decreased. As a result of the changes, mice with greater richness and diversity of the vaginal microbiome after antibiotics exposure were less likely developed tumors. No association between richness and diversity of the gut microbiome and tumor development was identified.

The Potential of Immune Checkpoint Blockade in Cervical Cancer: Can Combinatorial Regimens Maximize Response? A Review of the Literature

OPINION STATEMENT

Cervical cancer (CC) is most often caused by the human papillomavirus (HPV). In principle, these ties to the virus should make HPV tumors a relatively easy target for clearance by the immune system. However, these HPV-associated tumors have evolved strategies to escape immune attack. Checkpoint inhibition immunotherapy, which has had remarkable success in cancer treatment, has the potential to overcome the immune escape in CC by harnessing the patient's own immune system and priming it to recognize and kill tumors. Recent work involving PD-1/PD-L1 inhibitors in CC lends credence to this belief, as pembrolizumab has shown evidence of clinical efficacy and consequently been granted accelerated approval by the FDA. That being said, the oncologic outcomes following monotherapy with these biologics have mostly been modest and variable, and this can be attributed to alternative resistance mechanisms to tumor response. The use of therapies that stimulate immune responses via checkpoint-independent activation will therefore augment release of T cell inhibition by checkpoint inhibitors for stronger and more sustained clinical responses. Such a combinatorial approach holds promise for weak- or non-responders to checkpoint therapies as supported by evidence from various, recent pre-clinical, and preliminary clinical studies.

Melanoma Evolves Complete Immunotherapy Resistance through the Acquisition of a Hypermetabolic Phenotype

Despite the clinical success of T-cell checkpoint blockade, most patients with cancer still fail to have durable responses to immunotherapy. The molecular mechanisms driving checkpoint blockade resistance, whether preexisting or evolved, remain unclear. To address this critical knowledge gap, we treated B16 melanoma with the combination of CTLA-4, PD-1, and PD-L1 blockade and a Flt3 ligand vaccine (≥75% curative), isolated tumors resistant to therapy, and serially passaged them in vivo with the same treatment regimen until they developed complete resistance. Using gene expression analysis and immunogenomics, we determined the adaptations associated with this resistance phenotype. Checkpoint resistance coincided with acquisition of a "hypermetabolic" phenotype characterized by coordinated upregulation of the glycolytic, oxidoreductase, and mitochondrial oxidative phosphorylation pathways. These resistant tumors flourished under hypoxic conditions, whereas metabolically starved T cells lost glycolytic potential, effector function, and the ability to expand in response to immunotherapy. Furthermore, we found that checkpoint-resistant versus -sensitive tumors could be separated by noninvasive MRI imaging based solely on their metabolic state. In a cohort of patients with melanoma resistant to both CTLA-4 and PD-1 blockade, we observed upregulation of pathways indicative of a similar hypermetabolic state. Together, these data indicated that melanoma can evade T-cell checkpoint blockade immunotherapy by adapting a hypermetabolic phenotype.

Combined prophylactic and therapeutic immune responses against human papillomaviruses induced by a thioredoxin-based L2-E7 nanoparticle vaccine

Global burden of cervical cancer, the most common cause of mortality caused by human papillomavirus (HPV), is expected to increase during the next decade, mainly because current alternatives for HPV vaccination and cervical cancer screening programs are costly to be established in low-and-middle income countries. Recently, we described the development of the broadly protective, thermostable vaccine antigen Trx-8mer-OVX313 based on the insertion of eight different minor capsid protein L2 neutralization epitopes into a thioredoxin scaffold from the hyperthermophilic archaeon Pyrococcus furiosus and conversion of the resulting antigen into a nanoparticle format (median radius ~9 nm) upon fusion with the heptamerizing OVX313 module. Here we evaluated whether the engineered thioredoxin scaffold, in addition to humoral immune responses, can induce CD8⁺ T-cell responses upon incorporation of MHC-I-restricted epitopes. By systematically examining the contribution of individual antigen modules, we demonstrated that B-cell and T-cell epitopes can be combined into a single antigen construct without compromising either immunogenicity. While CD8⁺ T-cell epitopes had no influence on B-cell responses, the L2 polytope (8mer) and OVX313-mediated heptamerization of the final antigen significantly increased CD8⁺ T-cell responses. In a proof-of-concept experiment, we found that vaccinated mice remained tumor-free even after two consecutive tumor challenges, while unvaccinated mice developed tumors. A cost-effective, broadly protective vaccine with both prophylactic and therapeutic properties represents a promising option to overcome the challenges associated with prevention and treatment of HPV-caused diseases.

Currently, there are three licensed prophylactic vaccines available against HPV, but none of them shows a therapeutic effect on pre-existing infections. Thus, a prophylactic vaccine also endowed with a therapeutic activity presents application potentials to individuals regardless of their HPV-infection status. Such a dual-purpose vaccine would be particularly valuable for post-exposure prophylaxis and shields population from recurrent HPV infections. Here, we constructed a combined vaccine relying on L2- and E7-specific epitopes grafted onto the surface of a hyper-stable thioredoxin scaffold. The resulting antigen was converted into a nanoparticle format with the use of a heptamerization domain. Our data document that the modular design of the antigen allows combination of B-cell and T-cell epitopes in one antigen without compromising either’s immunogenicity. The antigen retains its ability to provide broad protection against different HPV types but also presents strong therapeutic effects in a mouse tumor model. Therefore, the vaccine is potentially capable of resolving productive infection as well as HPV-related malignancies, and thus benefitting both uninfected and already infected individuals. Moreover, our vaccine utilizes E. coli as protein producer and distribution does not require cold-chain, which reduces costs making it applicable to less-affluent countries.

A 2020 update of anal cancer: the increasing problem in women and expanding treatment landscape

INTRODUCTION

Anal cancer is a rare malignancy with increasing incidence, notably in women. This disease is highly associated with HPV infection and its incidence and mortality are currently rising. Most patients present with localized disease which has a high survival after definitive treatment with chemoradiation. For patients who develop metastatic disease or present with this de novo, survival is poor.

AREAS COVERED

This review provides a summary of current literature on anal cancer. With a focus on women, this includes current epidemiological trends, role of HPV, and the current and future treatment landscape, including HPV vaccination and immunotherapy. Screening currently focusses on HIV-positive men, missing most female cases. In curative disease, trials are investigating treatment de-intensification in good prognostic groups. Immunotherapy is showing early promise in the advanced disease setting.

EXPERT OPINION

Similar to cervical cancer, anal cancer is strongly associated with HPV, and therefore, broader implementation of screening programs may reduce its incidence. HPV vaccination is expected to reduce the development of (pre)malignant anal lesions. The emergence of biomarkers will assist patient treatment selection, allowing optimal balance of treatment efficacy and morbidity. It is hoped that new treatment approaches, including immunotherapy, will improve outcomes. International collaboration is needed.

Modulation of Determinant Factors to Improve Therapeutic Combinations with Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICPi) have shown their superiority over conventional therapies to treat some cancers. ICPi are effective against immunogenic tumors. However, patients with tumors poorly infiltrated with immune cells do not respond to ICPi. Combining ICPi with other anticancer therapies such as chemotherapy, radiation, or vaccines, which can stimulate the immune system and recruit antitumor T cells into the tumor bed, may be a relevant strategy to increase the proportion of responding patients. Such an approach still raises the following questions: What are the immunological features modulated by immunogenic therapies that can be critical to ensure not only immediate but also long-lasting tumor protection? How must the combined treatments be administered to the patients to harness their full potential while limiting adverse immunological events? Here, we address these points by reviewing how immunogenic anticancer therapies can provide novel therapeutic opportunities upon combination with ICPi. We discuss their ability to create a permissive tumor microenvironment through the generation of inflamed tumors and stimulation of memory T cells such as resident (T_RM) and stem-cell like (T_SCM) cells. We eventually underscore the importance of sequence, dose, and duration of the combined anticancer therapies to design optimal and successful cancer immunotherapy strategies.

Intranasal Therapeutic Peptide Vaccine Promotes Efficient Induction and Trafficking of Cytotoxic T Cell Response for the Clearance of HPV Vaginal Tumors

Human papillomavirus (HPV)-induced cancers continue to affect millions of women around the world, and the five year survival rate under the current standard of care for these cancers is less than 60% in some demographics. Therefore there is still an unmet need to develop an effective therapy that can be easily administered to treat established HPV cervical cancer lesions. We sought to investigate the potential of an intranasal HPV peptide therapeutic vaccine incorporating the combination of α-Galactosylceramide (α-GalCer) and CpG-ODN adjuvants (TVAC) against established HPV genital tumors in a syngeneic C57BL/6J mouse model. We obtained evidence to show that TVAC, delivered by the mucosal intranasal route, induced high frequencies of antigen-specific CD8 T cells concurrent with significant reduction in the immunosuppressive regulatory T cells and myeloid derived suppressor cells in the tumor microenvironment (TME), correlating with sustained elimination of established HPV genital tumors in over 85% of mice. Inclusion of both the adjuvants in the vaccine was necessary for significant increase of antigen-specific CD8 T cells to the tumor and antitumor efficacy because vaccination incorporating either adjuvant alone was inefficient. These results strongly support the utility of the TVAC administered by needle-free intranasal route as a safe and effective strategy for the treatment of established genital HPV tumors.

Nanovaccine administration route is critical to obtain pertinent iNKt cell help for robust anti-tumor T and B cell responses

Nanovaccines, co-delivering antigen and invariant natural killer T (iNKT) cell agonists, proved to be very effective in inducing anti-tumor T cell responses due to their exceptional helper function. However, it is known that iNKT cells are not equally present in all lymphoid organs and nanoparticles do not get evenly distributed to all immune compartments. In this study, we evaluated the effect of the vaccination route on iNKT cell help to T and B cell responses for the first time in an antigen and agonist co-delivery setting. Intravenous administration of PLGA nanoparticles was mainly targeting liver and spleen where iNKT1 cells are abundant and induced the highest serum IFN-y levels, T cell cytotoxicity, and Th-1 type antibody responses. In comparison, after subcutaneous or intranodal injections, nanoparticles mostly drained or remained in regional lymph nodes where iNKT17 cells were abundant. After subcutaneous and intranodal injections, antigen-specific IgG2 c production was hampered and IFN-y production, as well as cytotoxic T cell responses, depended on sporadic systemic drainage. Therapeutic anti-tumor experiments also demonstrated a clear advantage of intravenous injection over intranodal or subcutaneous vaccinations. Moreover, tumor control could be further improved by PD-1 immune checkpoint blockade after intravenous vaccination, but not by intranodal vaccination. Anti PD-1 antibody combination mainly exerts its effect by prolonging the cytotoxicity of T cells. Nanovaccines also demonstrated synergism with anti-4-1BB agonistic antibody treatment in controlling tumor growth. We conclude that nanovaccines containing iNKT cell agonists shall be preferentially administered intravenously, to optimally reach cellular partners for inducing effective anti-tumor immune responses.

Therapeutic Vaccines for HPV-Associated Malignancies

Human papillomavirus (HPV)-related malignancies are responsible for almost all cases of cervical cancer in women, and over 50% of all cases of head and neck carcinoma. Worldwide, HPV-positive malignancies account for 4.5% of the global cancer burden, or over 600,000 cases per year. HPV infection is a pressing public health issue, as more than 80% of all individuals have been exposed to HPV by age 50, representing an important target for vaccine development to reduce the incidence of cancer and the economic cost of HPV-related health issues. The approval of Gardasil^® as a prophylactic vaccine for high-risk HPV 16 and 18 and low-risk HPV6 and 11 for people aged 11-26 in 2006, and of Cervarix^® in 2009, revolutionized the field and has since reduced HPV infection in young populations. Unfortunately, prophylactic vaccination does not induce immunity in those with established HPV infections or HPV-induced neoplasms, and there are currently no therapeutic HPV vaccines approved by the US Food and Drug Administration. This comprehensive review will detail the progress made in the development of therapeutic vaccines against high-risk HPV types, and potential combinations with other immunotherapeutic agents for more efficient and rational designs of combination treatments for HPV-associated malignancies.

Personalized Neo-Epitope Vaccines for Cancer Treatment

After more than a century of efforts to establish cancer immunotherapy in clinical practice, the advent of checkpoint inhibition (CPI) therapy was a critical breakthrough toward this direction (Hodi et al. in Cell Rep 13(2):412-424, 2010; Wolchok et al. in N Engl J Med 369(2):122-133, 2013; Herbst et al. in Nature 515(7528):563-567, 2014; Tumeh et al. in Nature 515(7528):568-571, 2014). Further, CPIs shifted the focus from long studied shared tumor-associated antigens to mutated ones. As cancer is caused by mutations in somatic cells, the concept to utilize these correlates of 'foreignness' to enable recognition and lysis of the cancer cell by T cell immunity seems an obvious thing to do.

Human Biofield Therapy and the Growth of Mouse Lung Carcinoma

Biofield therapies have gained popularity and are being explored as possible treatments for cancer. In some cases, devices have been developed that mimic the electromagnetic fields that are emitted from people delivering biofield therapies. However, there is limited research examining if humans could potentially inhibit the proliferation of cancer cells and suppress tumor growth through modification of inflammation and the immune system. We found that human NSCLC A549 lung cancer cells exposed to Sean L. Harribance, a purported healer, showed reduced viability and downregulation of pAkt. We further observed that the experimental exposure slowed growth of mouse Lewis lung carcinoma evidenced by significantly smaller tumor volume in the experimental mice (274.3 ± 188.9 mm³) than that of control mice (740.5 ± 460.2 mm³; P < .05). Exposure to the experimental condition markedly reduced tumoral expression of pS6, a cytosolic marker of cell proliferation, by 45% compared with that of the control group. Results of reversed phase proteomic array suggested that the experimental exposure downregulated the PD-L1 expression in the tumor tissues. Similarly, the serum levels of cytokines, especially MCP-1, were significantly reduced in the experimental group (P < .05). Furthermore, TILs profiling showed that CD8⁺/CD4⁻ immune cell population was increased by almost 2-fold in the experimental condition whereas the number of intratumoral CD25⁺/CD4⁺ (T-reg cells) and CD68⁺ macrophages were 84% and 33%, respectively, lower than that of the control group. Together, these findings suggest that exposure to purported biofields from a human is capable of suppressing tumor growth, which might be in part mediated through modification of the tumor microenvironment, immune function, and anti-inflammatory activity in our mouse lung tumor model.

Quxie Capsule Inhibits Colon Tumor Growth Partially Through Foxo1-Mediated Apoptosis and Immune Modulation

Quxie capsule (QX), a herbal remedy used in traditional Chinese medicine, is routinely used in advanced colorectal cancer treatment in Xiyuan Hospital in Beijing, China. However, the mechanism(s) underlying the effect of QX in colorectal cancer remain unclear, which hampers the optimal use of QX for the treatment of the disease. The transcription factor forkhead box O1 (Foxo1) plays important roles in regulation of cell cycle, apoptosis, and immune response in various cancers. In this study, we examined the antitumor efficacy of QX in a mouse model of colorectal cancer and further investigated the mechanism by which QX regulated Foxo1 protein-mediated pathways. QX administered via gavage daily for 2 weeks in mice carrying CT26 mouse colon tumors resulted in significantly lower mean tumor weight (0.93 ± 0.32 g) compared with that in vehicle control-treated mice (1.57 ± 0.57 g, P <.05). Foxo1 protein expression in tumors was also higher in the QX group than that in the vehicle control group. Furthermore, QX treatment upregulated apoptotic proteins such as Fas, Bim, and cleaved caspase-3 in tumor tissue compared with those in the vehicle control group. Intriguingly, the ratios of Th1/Th2 and Th17/Treg cells and levels of T-bet protein (the key regulator of Th1 and Th2 cells) were higher while the level of Foxp3 (the key regulator of Treg cells) was lower in QX-treated mice compared to vehicle control mice, revealing that Foxo1 upregulated T-bet and downregulated Foxp3 and induced a shift in immune balance. This shift could be critical in the antitumor efficacy of QX. Furthermore, knocking down Foxo1 in human colon cancer HCT116 cells partially blocked the effect of QX-elicited antiproliferative activity. Together, these results suggest that QX exerts antitumor activity in CT26 mouse colon cancer model partially mediated by Foxo1-induced apoptosis and antitumor immune response.

Limited Cross-Linking of 4-1BB by 4-1BB Ligand and the Agonist Monoclonal Antibody Utomilumab

Monoclonal antibodies (mAbs) targeting the co-stimulatory molecule 4-1BB are of interest for tumor immunotherapy. We determined the complex structures of human 4-1BB with 4-1BB ligand (4-1BBL) or utomilumab to elucidate the structural basis of 4-1BB activation. The 4-1BB/4-1BBL complex displays a typical TNF/TNFR family binding mode. The structure of utomilumab/4-1BB complex shows that utomilumab binds to dimeric 4-1BB with a distinct but partially overlapping binding area with 4-1BBL. Competitive binding analysis demonstrates that utomilumab blocks the 4-1BB/4-1BBL interaction, indicating the interruption of ligand-mediated signaling. The binding profiles of 4-1BBL and utomilumab to monomeric or dimeric 4-1BB indicate limited cross-linking of 4-1BB molecules. These findings provide mechanistic insight into the binding of 4-1BB with its ligand and its agonist mAb, which may facilitate the future development of anti-4-1BB biologics for tumor immunotherapy.

Targeting interferon signaling and CTLA-4 enhance the therapeutic efficacy of anti-PD-1 immunotherapy in preclinical model of HPV+ oral cancer

Background

The US is experiencing an epidemic of HPV⁺ oropharyngeal cancers (OPC), the rates and burden of which now exceed that for cervical cancer. Immunotherapy targeting programmed death 1 (PD-1) on tumor-infiltrating lymphocytes and/or its ligand PD-L1 on tumor cells, which was effective in several cancers has however, showed efficacy in only less than 15% of patients.

Methods

We used a preclinical HPV⁺ oral tumor model, mEER, consisting of mouse tonsil derived epithelial cells expressing HPV-16 E6 and E7 genes, along with the H-ras oncogene to test strategies for enhancing the efficacy of anti-PD-1 therapy.

Results

Monotherapy with PD-1 blocking antibody was ineffective against flank-implanted tumors, but induced regression in 54% of mice bearing orthotopic tongue tumors that correlated with higher CD8 T cell responses. Since the CD8⁺ T cells derived from tongue tumors also showed high levels of the immune checkpoint inhibitory receptor CTLA-4, we tested combination immunotherapy targeting both CTLA-4 and PD-1 together and observed 93.3% survival of mice bearing tumors in the tongue for the duration of our 100-day study. Protective immunity correlated with a significant decrease in immunosuppressive lymphoid and myeloid populations within the tumor microenvironment. Consistent with the reported capacity of interferon-driven PD-L1/PD-1 pathway induction to serve as a biomarker of response to PD-1 blockade, we observed elevated interferon signaling and significantly higher levels of PD-1/PD-L1 in tongue-implanted mEER tumors compared to those growing on the flank correlating with their preferential responsiveness to PD-1 blockade. More importantly, in a pseudometastasic mouse model bearing both flank and tongue tumors to represent metastatic disease, delivery of Stimulator of Interferon Induced Genes (STING) agonist into the flank tumors combined with systemic treatment with α-PD-1 and α-CTLA-4 antibodies resulted in sustained tumor regression in 71% of mice. In this case, productive abscopal anti-tumor immunity was associated with robust increases in the ratios of cytotoxic CD8⁺ T cells (CTL) versus regulatory T cells (Treg) and versus functional myeloid-derived suppressor cells (MDSC).

Conclusions

These results support combining α-PD-1 therapy with induction of IFN-α/β signaling via provision of STING agonist and/or through CTLA-4 blockade as potential treatment option for HNSCC patients, especially, those not responding to α-PD-1 monotherapy.

The Double-Edged Sword-How Human Papillomaviruses Interact With Immunity in Head and Neck Cancer

Patients with human papilloma virus (HPV)-associated head and neck squamous cell carcinoma (HNSCC) have remarkably better prognosis, which differs from HPV-negative oropharyngeal squamous cell carcinoma (OPSCC) with respect to clinical, genomic, molecular, and immunological aspects, especially having the characteristics of high levels of immune cell infiltration and high degrees of immunosuppression. This review will summarize immune evasion mechanisms in HPV-positive HNSCC, analyze the host various immune responses to HPV and abundant numbers of infiltrating immune cell, and discuss the differences between HPV-positive HNSCC with cervical cancer. A deeper understanding of the immune landscape will help new concepts to emerge in immune-checkpoint oncology, which might be a valuable add-on to established concepts.

Transcriptional Profiles of California Sea Lion Peripheral NK and CD+8 T Cells Reflect Ecological Regionalization and Infection by Oncogenic Viruses

The California sea lion is one of the few wild mammals prone to develop cancer, particularly urogenital carcinoma (UGC), whose prevalence is currently estimated at 25% of dead adult sea lions stranded along the California coastline. Genetic factors, viruses and organochlorines have been identified as factors that increase the risk of occurrence of this pathology. Given that no cases of UGC have as yet been reported for the species along its distribution in Mexican waters, the potential relevance of contaminants for the development of urogenital carcinoma is highlighted even more as blubber levels of organochlorines are more than two orders of magnitude lower in the Gulf of California and Mexican Pacific than in California. In vitro studies have shown that organochlorines can modulate anti-viral and tumor-surveillance activities of NK and cytotoxic T-cells of marine mammals, but little is known about the activity of these effectors in live, free-living sea lions. Here, we examine leukocyte transcriptional profiles of free-ranging adult California sea lions for eight genes (Eomes, Granzyme B, Perforin, Ly49, STAT1, Tbx21, GATA3, and FoxP3) selected for their key role in anti-viral and tumor-surveillance, and investigate patterns of transcription that could be indicative of differences in ecological variables and exposure to two oncogenic viruses: sea lion type one gammaherpesvirus (OtHV-1) and sea lion papillomavirus type 1 (ZcPV-1) and systemic inflammation. We observed regional differences in the expression of genes related to Th1 responses and immune modulation, and detected clear patterns of differential regulation of gene expression in sea lions infected by genital papillomavirus compared to those infected by genital gammaherpesvirus or for simultaneous infections, similar to what is known about herpesvirus and papillomavirus infections in humans. Our study is a first approach to profile the transcriptional patterns of key immune effectors of free-ranging California sea lions and their association with ecological regions and oncogenic viruses. The observed results add insight to our understanding of immune competence of marine mammals, and may help elucidate the marked difference in the number of cases of urogenital carcinoma in sea lions from US waters and other areas of their distribution.

New Hope for Therapeutic Cancer Vaccines in the Era of Immune Checkpoint Modulation

The driver and passenger mutations accumulated in the process of malignant transformation offer an adequate spectrum of immune visible alterations to the cellular proteome and resulting peptidome to render these cancers targetable-and, in theory, rejectable-by the host T cell immune response. In addition, cancers often overexpress tissue-specific and developmental antigens to which immune tolerance is incomplete. Sometimes, virally transferred oncogenes drive malignant transformation and remain expressed throughout the cancer. Despite this state of antigenic sufficiency, cancer grows progressively and overcomes all efforts of the host immune system to contain it. While therapeutic cancer vaccination can mobilize high frequencies of tumor-specific T cells, these responses remain subject to intratumoral attenuation. Antibody modulation of T cell function through checkpoint blockade or costimulatory activation can restore survival, proliferation, and effector function to these tumor-infiltrating T cells and convert otherwise subtherapeutic vaccines into potentially curative cancer immunotherapeutics.

The TNF-TNFR Family of Co-signal Molecules

Costimulatory signals initiated by the interaction between the tumor necrosis factor (TNF) ligand and cognate TNF receptor (TNFR) superfamilies promote clonal expansion, differentiation, and survival of antigen-primed CD4⁺ and CD8⁺ T cells and have a pivotal role in T-cell-mediated adaptive immunity and diseases. Accumulating evidence in recent years indicates that costimulatory signals via the subset of the TNFR superfamily molecules, OX40 (TNFRSF4), 4-1BB (TNFRSF9), CD27, DR3 (TNFRSF25), CD30 (TNFRSF8), GITR (TNFRSF18), TNFR2 (TNFRSF1B), and HVEM (TNFRSF14), which are constitutive or inducible on T cells, play important roles in protective immunity, inflammatory and autoimmune diseases, and tumor immunotherapy. In this chapter, we will summarize the findings of recent studies on these TNFR family of co-signaling molecules regarding their function at various stages of the T-cell response in the context of infection, inflammation, and cancer. We will also discuss how these TNFR co-signals are critical for immune regulation and have therapeutic potential for the treatment of T-cell-mediated diseases.

Liposomal formulation of polyacrylate-peptide conjugate as a new vaccine candidate against cervical cancer

Peptide-based vaccines have been proposed as a therapeutic strategy for many infectious diseases, including human papilloma virus (HPV)-related cervical cancer. Peptide-based vaccines are a better treatment option than traditional chemotherapeutic agents and surgery, as they rely on the use of the body’s immune system to fight cancer cells, resulting in minimal risk of side effects. However, to increase the efficacy of peptide-based vaccines, the application of potent adjuvant and a suitable delivery system is essential. In this study, we developed a self-adjuvanting delivery system based on a combination of polymer and liposomes, for a therapeutic vaccine against cervical cancer. Peptide epitope (8Qm) derived from HPV-16 E7 protein was conjugated to dendritic poly(tert-butyl acrylate) as a primary delivery system and incorporated into cationic liposomes, which served as a secondary delivery system. Our vaccine candidate was able to kill established HPV-16 E7-positive tumor (TC-1) cells in mice following a single immunization. The immunized mice had 80% survival rate after two months. In contrast, both polymer-8Qm conjugate and liposomes bearing 8Qm failed to eradicate TC-1 tumors. The survival rate of mice was only 20% when immunized with 8Qm formulated with standard incomplete Freund’s adjuvant.

The application of nanotechnology in immune checkpoint blockade for cancer treatment

Cancer immunotherapy, which could utilize the host's immune system to kill tumor cells, has great potential in long-term inhibition of tumor growth and recurrence compared to chemotherapy and radiotherapy. As we know, tumors exhibit powerful adaption to escape the destruction of immune system at the late stage of diseases due to overactivation of immune checkpoint pathways which function as natural "brakes" for immune responses. The newly emerging immune checkpoint inhibitors are regarded as the breakthrough for cancer immunotherapy as they can re-boost the host's immune system by restoring T cells function and promoting cytotoxic T lymphocytes (CTLs) responses. However, there is still scope for improvement in enhancing the clinical efficacy and reducing side effects of these immune modulators. In this review, we mainly introduce the basic mechanisms of the immune checkpoint pathways and outline the recent successes of immune checkpoint blockade (ICB) therapy in combination with nanoparticle delivery system. Furthermore, the underexplored potential in application of nanotechnology to enhance the efficacy of immune checkpoint therapy and overcome the limits of immune checkpoint inhibitors is also discussed.

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.

Mucosal HPV E6/E7 Peptide Vaccination in Combination with Immune Checkpoint Modulation Induces Regression of HPV+ Oral Cancers

High-risk human papillomavirus (HPV)-associated squamous cell carcinomas of the oropharynx (SCCOP) are among the fastest growing cancers. After standard-of-care treatment, however, patients with HPV⁺ SCCOP have better overall and disease-specific survival than patients with HPV^- SCCOP, suggesting the importance of HPV-specific immunity. We reasoned that therapeutic vaccination targeting the HPV-16 E6 and E7 oncogenes could elicit high-affinity, high-frequency tumor antigen-specific T-cell responses, which could then be augmented and shielded from suppression in the tumor microenvironment by immune checkpoint modulation. In this study, we used a preclinical syngeneic mouse model of oral cancer comprised of mouse tonsil-derived epithelial cells stably expressing HPV-16 E6 and E7 genes along with H-ras oncogene (mEER) to identify combinations of vaccination and checkpoint antibodies capable of promoting tumor regression. Intranasal HPV E6/E7 peptide vaccination and single checkpoint antibodies failed to elicit responses in more than half of animals; however, 4-1BB agonist antibody along with either CD40 agonist antibody or CTLA-4 blockade eliminated the majority of established mEER tumors. The combination of intranasal HPV peptide vaccine and α4-1BB and αCTLA-4 antibodies produced curative efficacy and a better safety profile against orally implanted mEER tumors. Correlates of protective immunity included enhanced intratumoral levels of CD8 T cells relative to immunosuppressive regulatory T cells and myeloid-derived suppressor cells. Overall, our results demonstrate combination vaccine-immunotherapy modalities as novel treatment options for HPV⁺ SCCOP.Significance: Combinations of vaccine and checkpoint modulation are effective and safe treatment options for HPV⁺ oral cancers. Cancer Res; 78(18); 5327-39. ©2018 AACR.

Therapeutic cancer vaccine: building the future from lessons of the past

Anti-cancer vaccines have raised many hopes from the start of immunotherapy but have not yet been clinically successful. The few positive results of anti-cancer vaccines have been observed in clinical situations of low tumor burden or preneoplastic lesions. Several new concepts and new results reposition this therapeutic approach in the field of immunotherapy. Indeed, cancers that respond to anti-PD-1/PD-L1 (20-30%) are those that are infiltrated by anti-tumor T cells with an inflammatory infiltrate. However, 70% of cancers do not appear to have an anti-tumor immune reaction in the tumor microenvironment. To induce this anti-tumor immunity, therapeutic combinations between vaccines and anti-PD-1/PD-L1 are being evaluated. In addition, the identification of neoepitopes against which the immune system is less tolerated is giving rise to a new enthusiasm by the first clinical results of the vaccine including these neoepitopes in humans. The ability of anti-cancer vaccines to induce a population of anti-tumor T cells called memory resident T cells that play an important role in immunosurveillance is also a new criterion to consider in the design of therapeutic vaccines.

A facile approach to enhance antigen response for personalized cancer vaccination

Existing strategies to enhance peptide immunogenicity for cancer vaccination generally require direct peptide alteration, which, beyond practical issues, may impact peptide presentation and result in vaccine variability. Here, we report a simple adsorption approach using polyethyleneimine (PEI) in a mesoporous silica microrod (MSR) vaccine to enhance antigen immunogenicity. The MSR-PEI vaccine significantly enhanced host dendritic cell activation and T-cell response over the existing MSR vaccine and bolus vaccine formulations. Impressively, a single injection of the MSR-PEI vaccine using an E7 peptide completely eradicated large, established TC-1 tumours in about 80% of mice and generated immunological memory. When immunized with a pool of B16F10 or CT26 neoantigens, the MSR-PEI vaccine eradicated established lung metastases, controlled tumour growth and synergized with anti-CTLA4 therapy. Our findings from three independent tumour models suggest that the MSR-PEI vaccine approach may serve as a facile and powerful multi-antigen platform to enable robust personalized cancer vaccination.

Synthetic vaccine particles for durable cytolytic T lymphocyte responses and anti-tumor immunotherapy

We previously reported that synthetic vaccine particles (SVP) encapsulating antigens and TLR agonists resulted in augmentation of immune responses with minimal production of systemic inflammatory cytokines. Here we evaluated two different polymer formulations of SVP-encapsulated antigens and tested their ability to induce cytolytic T lymphocytes (CTL) in combination with SVP-encapsulated adjuvants. One formulation led to efficient antigen processing and cross-presentation, rapid and sustained CTL activity, and expansion of CD8⁺ T cell effector memory cells locally and centrally, which persisted for at least 1–2 years after a single immunization. SVP therapeutic dosing resulted in suppression of tumor growth and a substantial delay in mortality in several syngeneic mouse cancer models. Treatment with checkpoint inhibitors and/or cytotoxic drugs, while suboptimal on their own, showed considerable synergy with SVP immunization. SVP encapsulation of endosomal TLR agonists provided superior CTL induction, therapeutic benefit and/or improved safety profile compared to free adjuvants. SVP vaccines encapsulating mutated HPV-16 E7 and E6/E7 recombinant proteins led to induction of broad CTL activity and strong inhibition of TC-1 tumor growth, even when administered therapeutically 13–14 days after tumor inoculation in animals bearing palpable tumors. A pilot study in non-human primates showed that SVP-encapsulated E7/E6 adjuvanted with SVP-encapsulated poly(I:C) led to robust induction of antigen-specific T and B cell responses.