PD-1 blockade synergizes with intratumoral vaccination of a therapeutic HPV protein vaccine and elicits regression of tumor in a preclinical model

Combined IL6 and CCR2 blockade potentiates antitumor activity of NK cells in HPV-negative head and neck cancer

BACKGROUND

While T cell-activating immunotherapies against recurrent head and neck squamous cell carcinoma (HNSCC) have shown impressive results in clinical trials, they are often ineffective in the majority of patients. NK cells are potential targets for immunotherapeutic intervention; however, the setback in monalizumab-based therapy in HNSCC highlights the need for an alternative treatment to enhance their antitumor activity.

METHODS

Single-cell RNA sequencing (scRNA-seq) and TCGA HNSCC datasets were used to identify key molecular alterations in NK cells. Representative HPV-positive ( +) and HPV-negative ( -) HNSCC cell lines and orthotopic mouse models were used to validate the bioinformatic findings. Changes in immune cells were examined by flow cytometry and immunofluorescence.

RESULTS

Through integration of scRNA-seq data with TCGA data, we found that the impact of IL6/IL6R and CCL2/CCR2 signaling pathways on evasion of immune attack by NK cells is more pronounced in the HPV - HNSCC cohort compared to the HPV + HNSCC cohort. In orthotopic mouse models, blocking IL6 with a neutralizing antibody suppressed HPV - but not HPV + tumors, which was accompanied by increased tumor infiltration and proliferation of CD161+ NK cells. Notably, combining the CCR2 chemokine receptor antagonist RS504393 with IL6 blockade resulted in a more pronounced antitumor effect that was associated with more activated intratumoral NK cells in HPV - HNSCC compared to either agent alone.

CONCLUSIONS

These findings demonstrate that dual blockade of IL6 and CCR2 pathways effectively enhances the antitumor activity of NK cells in HPV-negative HNSCC, providing a novel strategy for treating this type of cancer.

METTL3-mediated HPV vaccine enhances the effect of anti PD-1 immunotherapy to alleviate the development of cutaneous squamous cell carcinoma

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) develops from epithelial keratinocytes by dysregulation of self-renewal and differentiation. Recent studies have found that the size and number of cSCC tumors gradually decrease or even disappear after HPV vaccination. However, the role of the HPV vaccine in the cSCC mechanism is poorly understood.

OBJECTIVE

The aim of this study is to investigate the effect and mechanism of the HPV vaccine in cSCC.

METHODS

Immunofluorescence was used to study the immune infiltrating cells in the tumor tissues of patients with cSCC. The effects of the HPV vaccine on cSCC cells and tissues were studied by Cell Culture, Real-time PCR, Western Blot, Cytotoxicity Assay, Enzyme-linked Immunosorbent Assay, m6A Blotting, CCK-8 Assay, m6A Ribonucleic acid Methylation Quantification and tumor transplantation.

RESULTS

The HPV vaccine enhanced the toxic effect of CD8+T cells on cSCC cells and promoted the secretion of multiple cytokines by CD8+T cells. In addition, HPV vaccines can increase tumor sensitivity to anti-PD-1 therapy by downregulating METTL3 in tumor tissue, with the combination of HPV vaccine and PD-1 monoclonal antibodies producing enhanced immune cell infiltration compared to PD-1 blockade alone.

STUDY LIMITATIONS

It is important to note the limitations of this study, including the small sample size, the construction of the mouse model, and the choice of HPV vaccine and PD-1 monoclonal antibody, which may limit the generalization of our findings to a wider population.

CONCLUSIONS

It is hoped that this research will contribute to a deeper understanding of the role of the HPV vaccine in the treatment of cSCC. HPV vaccine is expected to become an important approach to alleviate the development of cSCC.

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.

Advances, opportunities and challenges in developing therapeutic cancer vaccines

Therapeutic cancer vaccines have shown promising efficacy in helping immunotherapy for cancer patients, but the systematic characterization of the clinical application and the method for improving efficacy is lacking. Here, we mainly summarize the classification of therapeutic cancer vaccines, including protein vaccines, nucleic acid vaccines, cellular vaccines and anti-idiotypic antibody vaccines, and subdivide the above vaccines according to different types and delivery forms. Additionally, we outline the clinical efficacy and safety of vaccines, as well as the combination strategies of therapeutic cancer vaccines with other therapies. This review will provide a detailed overview and rationale for the future clinical application and development of therapeutic cancer vaccines.

Role of tumor microenvironment in cancer progression and therapeutic strategy

Cancer is now considered a tumor microenvironment (TME) disease, although it was originally thought to be a cell and gene expression disorder. Over the past 20 years, significant advances have been made in understanding the complexity of the TME and its impact on responses to various anticancer therapies, including immunotherapies. Cancer immunotherapy can recognize and kill cancer cells by regulating the body's immune system. It has achieved good therapeutic effects in various solid tumors and hematological malignancies. Recently, blocking of programmed death-1 (PD-1), programmed death-1 ligand-1 (PD-L1), and programmed death Ligand-2 (PD-L2), the construction of antigen chimeric T cells (CAR-T) and tumor vaccines have become popular immunotherapies Tumorigenesis, progression, and metastasis are closely related to TME. Therefore, we review the characteristics of various cells and molecules in the TME, the interaction between PD-1 and TME, and promising cancer immunotherapy therapeutics.

Liposomal Formulations of a Polyleucine-Antigen Conjugate as Therapeutic Vaccines against Cervical Cancer

Human papilloma virus (HPV) is responsible for all cases of cervical cancer. While prophylactic vaccines are available, the development of peptide-based vaccines as a therapeutic strategy is still under investigation. In comparison with the traditional and currently used treatment strategies of chemotherapy and surgery, vaccination against HPV is a promising therapeutic option with fewer side effects. A peptide derived from the HPV-16 E7 protein, called 8Qm, in combination with adjuvants showed promise as a therapeutic vaccine. Here, the ability of polymerized natural amino acids to act as a self-adjuvating delivery system as a therapeutic vaccine was investigated for the first time. Thus, 8Qm was conjugated to polyleucine by standard solid-phase peptide synthesis and self-assembled into nanoparticles or incorporated in liposomes. The liposome bearing the 8Qm conjugate significantly increased mice survival and decreased tumor growth after a single immunization. Further, these liposomes eradicated seven-day-old well-established tumors in mice. Dendritic cell (DC)-targeting moieties were introduced to further enhance vaccine efficacy, and the newly designed liposomal vaccine was tested in mice bearing 11-day-old tumors. Interestingly, these DCs-targeting moieties did not significantly improve vaccine efficacy, whereas the simple liposomal formulation of 8Qm-polyleucine conjugate was still effective in tumor eradication. In summary, a peptide-based anticancer vaccine was developed that stimulated strong cellular immune responses without the help of a classical adjuvant.

Statin drugs enhance responses to immune checkpoint blockade in head and neck cancer models

BACKGROUND

Anti-PD-1 immune checkpoint blockade is approved for first-line treatment of recurrent/metastatic head and neck squamous cell carcinoma (HNSCC), but few patients respond. Statin drugs (HMG-CoA reductase inhibitors) are associated with superior survival in several cancer types, including HNSCC. Emerging data suggest that manipulation of cholesterol may enhance some aspects of antitumor immunity.

METHODS

We used syngeneic murine models (mouse oral cancer, MOC1 and TC-1) to investigate our hypothesis that a subset of statin drugs would enhance antitumor immunity and delay tumor growth.

RESULTS

Using an ex vivo coculture assay of murine cancer cells and tumor infiltrating lymphocytes, we discovered that all seven statin drugs inhibited tumor cell proliferation. Simvastatin and lovastatin also enhanced T-cell killing of tumor cells. In mice, daily oral simvastatin or lovastatin enhanced tumor control and extended survival when combined with PD-1 blockade, with rejection of MOC1 tumors in 30% of mice treated with lovastatin plus anti-PD-1. Results from flow cytometry of tumors and tumor-draining lymph nodes suggested T cell activation and shifts from M2 to M1 macrophage predominance as potential mechanisms of combination therapy.

CONCLUSIONS

These results suggest that statins deserve further study as well-tolerated, inexpensive drugs that may enhance responses to PD-1 checkpoint blockade and other immunotherapies for HNSCC.

Viral delivery of a peptide-based immunomodulator enhances T cell priming during vaccination

Modern, subunit-based vaccines have so far failed to induce significant T cell responses, contributing to ineffective vaccination against many pathogens. Importantly, while today's adjuvants are designed to trigger innate and non-specific immune responses, they fail to directly stimulate the adaptive immune compartment. Programmed cell death 1 (PD-1) partly regulates naïve-to-antigen-specific effector T cell transition and differentiation by suppressing the magnitude of activation. Indeed, we previously reported on a microbial-derived, peptide-based PD-1 checkpoint inhibitor, LD01, which showed potent T cell-stimulating activity when combined with a vaccine. Here we sought to improve the potency of LD01 by designing and testing new LD01 derivatives. Accordingly, we found that a modified version of an 18-amino acid metabolite of LD01, LD10da, improved T cell activation capability in a malaria vaccine model. Specifically, LD10da demonstrates improved antigen-specific CD8⁺ T cell expansion when combined prophylactically with an adenovirus-based malaria vaccine. A single dose of LD10da at the time of vaccination is sufficient to increase antigen-specific CD8⁺ T cell expansion in wild-type mice. Further, we show that LD10 can be encoded and delivered by a Modified Vaccinia Ankara viral vector and can enhance antigen-specific CD8⁺ T cell expansion comparable to that of synthetic peptide administration. Therefore, LD10da represents a promising biologic-based immunomodulator that can be genetically encoded and delivered, along with the antigen, by viral or other nucleic acid vectors to improve the efficacy and delivery of vaccines for ineradicable and emerging infectious diseases.

Cervical cancer heterogeneity: a constant battle against viruses and drugs

Cervical cancer is the first identified human papillomavirus (HPV) associated cancer and the most promising malignancy to be eliminated. However, the ever-changing virus subtypes and acquired multiple drug resistance continue to induce failure of tumor prevention and treatment. The exploration of cervical cancer heterogeneity is the crucial way to achieve effective prevention and precise treatment. Tumor heterogeneity exists in various aspects including the immune clearance of viruses, tumorigenesis, neoplasm recurrence, metastasis and drug resistance. Tumor development and drug resistance are often driven by potential gene amplification and deletion, not only somatic genomic alterations, but also copy number amplifications, histone modification and DNA methylation. Genomic rearrangements may occur by selection effects from chemotherapy or radiotherapy which exhibits genetic intra-tumor heterogeneity in advanced cervical cancers. The combined application of cervical cancer therapeutic vaccine and immune checkpoint inhibitors has become an effective strategy to address the heterogeneity of treatment. In this review, we will integrate classic and recently updated epidemiological data on vaccination rates, screening rates, incidence and mortality of cervical cancer patients worldwide aiming to understand the current situation of disease prevention and control and identify the direction of urgent efforts. Additionally, we will focus on the tumor environment to summarize the conditions of immune clearance and gene integration after different HPV infections and to explore the genomic factors of tumor heterogeneity. Finally, we will make a thorough inquiry into completed and ongoing phase III clinical trials in cervical cancer and summarize molecular mechanisms of drug resistance among chemotherapy, radiotherapy, biotherapy, and immunotherapy.

Effectiveness of combination therapy with ISA101 vaccine for the treatment of human papillomavirus-induced cervical cancer

Cervical cancer is one of the women-associated tumors that affects numerous people yearly. It is the fourth most common malignancy in women worldwide. Following early diagnosis, this cancer can be cured mainly by traditional methods such as surgery, tumor resection, and chemotherapy; nonetheless, it becomes more challenging to treat in advanced and metastatic stages. With the advent of novel treatments such as angiogenesis inhibitors or immuno-checkpoint blockers in recent years, the survival rate of patients with advanced cervical cancer has significantly increased. However, it has not yet reached a satisfactory level. It has been revealed that human papillomavirus (HPV) infection is responsible for more than 90% of cervical cancer cases. However, evidence revealed that monotherapy with anti-HPV vaccines such as ISA101 could not affect tumor growth and progression in patients with HPV-induced cervical cancer. Therefore, combining ISA101 and immune checkpoint blockers or other immunotherapeutic approaches may be more robust and effective than monotherapy with ISA101 or immune checkpoint blockers for treating cervical cancer. This review summarizes the ISA101 properties, advantages and disadvantages. Furthermore, various conducted combination therapies with ISA101 and the effectiveness and challenges of this treatment have been discussed.

A Phase II Study Evaluating the Interest to Combine UCPVax, a Telomerase CD4 TH1-Inducer Cancer Vaccine, and Atezolizumab for the Treatment of HPV Positive Cancers: VolATIL Study

Background

There is a strong rational of using anti–programmed cell death protein-1 and its ligand (anti–PD-1/L1) antibodies in human papillomavirus (HPV)–induced cancers. However, anti–PD-1/L1 as monotherapy induces a limited number of objective responses. The development of novel combinations in order to improve the clinical efficacy of an anti–PD-1/L1 is therefore of interest. Combining anti–PD-1/L1 therapy with an antitumor vaccine seems promising in HPV-positive (+) cancers. UCPVax is a therapeutic cancer vaccine composed of two separate peptides derived from telomerase (hTERT, human telomerase reverse transcriptase). UCPVax is being evaluated in a multicenter phase I/II study in NSCLC (non–small cell lung cancer) and has demonstrated to be safe and immunogenic. The aim of the VolATIL study is to evaluate the combination of atezolizumab (an anti-PD-L1) and UCPVax vaccine in a multicenter phase II study in patients with HPV⁺ cancers.

Methods

Patients with HPV⁺ cancer (anal canal, head and neck, and cervical or vulvar), at locally advanced or metastatic stage, and refractory to at least one line of systemic chemotherapy are eligible. The primary end point is the objective response rate (ORR) at 4 months. Patients will receive atezolizumab every 3 weeks at a fixed dose of 1,200 mg in combination with the UCPVax vaccine at 1 mg subcutaneously.

Discussion

Anti-cancer vaccines can restore cancer-immunity via the expansion and activation of tumor-specific T cells in patients lacking pre-existing anti-tumor responses. Moreover, preclinical data showed that specific T_H1 CD4 T cells sustain the quality and homing of an antigen-specific CD8⁺ T-cell immunity. In previous clinical studies, the induction of anti-hTERT immunity was significantly correlated to survival in patients with advanced squamous anal cell carcinoma. Thus, there is a strong rational to combine an anti-cancer hTERT vaccine and an immune checkpoint inhibitor to activate and promote antitumor T-cell immunity. This pivotal proof of concept study will evaluate the efficacy and safety of the combination of a telomerase-based T_H1 inducing vaccine (UCPVax) and an anti–PD-L1 (atezolizumab) immunotherapy in HPV⁺ cancers, as well as confirming their synergic mechanism, and settling the basis for a new combination for future clinical trials.

Clinical Trial Registration

https://www.clinicaltrials.gov/, identifier NCT03946358.

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.

Intratumoral Injection of a Human Papillomavirus Therapeutic Vaccine-Induced Strong Anti-TC-1-Grafted Tumor Activity in Mice

Purpose

The route of administration of a therapeutic tumor vaccine is a critical factor in inducing antitumor activity. In this study, we explored the effects of three vaccination routes (subcutaneous, peritumoral, and intratumoral injection) on antitumor activity induced by a human papillomavirus (HPV) therapeutic vaccine containing HPV16 E7 peptide combined with the adjuvant CpG ODN in established TC-1 grafted tumors.

Methods

We used flow cytometry to evaluate splenic and tumor-infiltrating immune cells. We also assessed transcriptional changes in a sequence of immune-related genes in tumors of different treatment groups using quantitative real-time polymerase chain reaction. Immunohistochemistry was used to determine the expression of molecules related to tumor infiltrating immune cells, angiogenesis, and cancer-associated fibroblasts in tumor tissues.

Results

Our results suggested that intratumoral and peritumoral vaccination generated enhanced antitumor activity compared to subcutaneous delivery. In particular, intratumoral vaccination elicited a stronger antitumor effect, with two of the six treated mice being nearly tumor-free at day 28. Three vaccination routes induced increases in splenic CD4+ and/or CD8+ T lymphocytes, and marked decreases in immunosuppressive cells. Peritumoral vaccination increased the tumor-infiltrating CD8+T cells in tumors, while intratumoral vaccination enhanced the tumor-infiltrating CD4+ and CD8+ T lymphocytes, as well as decreased the tumor-infiltrating of immunosuppressive cells, which may result in stronger inhibition of tumor growth and prolonged survival in mice bearing tumors. Furthermore, compared to the subcutaneous route, intratumoral vaccination led to a significant increase in antitumor cytokines and chemokines. In addition, our data showed marked downregulation of MMP-2, MMP-9, VEGF, CD31, and α-SMA in the intratumoral vaccination group, which might contribute to the suppression of tumor invasion, angiogenesis, and metastasis.

Conclusion

Overall, intratumoral vaccination is superior to subcutaneous delivery and has the potential to inhibit tumor growth by improving the tumor microenvironment.

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

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