Tailored immunotherapy for HPV positive head and neck squamous cell cancer

Is 2045 the best we can do? Mitigating the HPV-related oropharyngeal cancer epidemic

INTRODUCTION

Oropharyngeal cancer (OPC) will be among the most common cancers in men by 2045 due to a rapid rise in human papillomavirus (HPV)-related OPC. Those who survive their cancer often suffer life-long treatment effects and early death. HPV vaccination could prevent virtually all HPV-related cancers but is not an effective preventive strategy for those already exposed. Without a dramatic increase in vaccine uptake in the U.S., HPV vaccination will have a negligible effect on OPC incidence through 2045 and no substantial impact until 2060. Additionally, targeted screening for earlier diagnosis may soon be feasible for those inadequately protected by vaccination.

AREAS COVERED

PubMed search for English-language articles related to incidence, screening, and prevention of HPV-related malignancies, focused on OPC in the U.S.

EXPERT OPINION

HPV-related OPC incidence will continue to increase for the foreseeable future with prophylactic vaccination offering no substantial public health impact for decades. Consequently, we must rapidly increase vaccination rates and develop screening methods to identify high-risk individuals. Such individuals would be eligible for potential preventive treatments and screening to diagnose early-stage HPV-related OPC allowing less morbid treatments. These methods will bridge the population into an era of decreasing incidence after vaccination takes effect.

Immunotherapy for HPV Malignancies

Owing to the presence of known tumor-specific viral antigens, human papillomavirus (HPV)-associated cancers are well suited for treatment with immunotherapy designed to unleash, amplify or replace the T cell arm of the adaptive immune system. Immune checkpoint blockade designed to unleash existing T cell immunity is currently Food and Drug Administration approved for certain HPV-associated cancers. More specific immunotherapies such as therapeutic vaccines and T cell receptor-engineered cellular therapy are currently in clinical development. Such therapies may offer more specific immune activation against viral tumor antigens and decrease the risk of immune-related adverse events. Current and planned clinical study of these treatments will determine their utility in the treatment of patients with newly diagnosed advanced stage or relapsed HPV-associated cancer.

Immunotherapy for Head and Neck Cancer

Head and neck squamous cell carcinomas (HNSCC) remain an important cause of global cancer morbidity and mortality. Historically, outcomes for patients with recurrent or metastatic disease were poor with limited treatment options. In recent decades, the demographic profile of this disease has evolved with an increase in human papilloma virus-associated oropharyngeal carcinoma and a decrease in tobacco-related disease. The treatment paradigm for HNSCC has rapidly evolved with identification of novel, immune-directed, therapeutic strategies that take advantage of immune dysregulation commonly seen in HNSCC. This review summarizes recent developments in this field and discusses emerging strategies for future therapies.

Immunotherapeutic Strategies for Head and Neck Cancer

Immunotherapy has revolutionized the treatment of cancer, including head and neck squamous cell carcinoma (HNSCC). Most immune therapies consist of biologics, including monoclonal antibodies, vaccines, and cell therapy. This article reviews basic tumor immunology and provides an overview of immunotherapeutic strategies used for HNSCC. The current indications for use of programmed cell death protein 1 immune checkpoint inhibitors in recurrent/metastatic HNSCC are summarized. In addition, new immunotherapeutic biologics and combinations under investigation in early-phase clinical trials are highlighted.

Anti-tumor immunity induced by ectopic expression of viral antigens is transient and limited by immune escape

Immunotherapeutic treatments in head and neck cancer clinical trials include cancer vaccines targeting foreign viral antigens or mutational neoantigens derived from cancer-expressed proteins. Anti-tumor immune responses place cancer cells under selective pressure to lose or downregulate target antigens; therefore, vaccination against virus- or host- "driver" oncogenes are proposed as a strategy to overcome immune escape. Herein, we demonstrate the impact of immunogenic viral antigens on anti-tumor response and immune editing in MOC2-E6E7, a syngeneic murine oral cancer cell line expressing HPV-16 E6 and E7 oncoproteins. Using orthotopic syngeneic models, we observed in vivo tumor growth kinetics of MOC2-E6E7 is delayed in immunocompetent mice compared to parental MOC2 tumors. In contrast, tumor growth remained similar in Rag1^-/- mice lacking adaptive immunity. MOC2-E6E7 tumors demonstrated an "inflamed" or immune-activated tumor microenvironment and greater infiltration of CD8⁺ T cells compared to MOC2. By real-time PCR, we detected downregulation of E6 and E7 genes in MOC2-E6E7 tumors only in immunocompetent mice, suggesting the loss of ectopic viral antigen expression due to immune editing. We then assessed the efficacy of a biomaterials-based mesoporous silica rod (MSR) cancer vaccine targeting HPV-16 E7 in our model. Vaccination induced robust infiltration of antigen-specific CD8⁺ T cells, which led to tumor growth delay and modestly prolonged survival in MOC2-E6E7 tumors. Increased efficacy was seen in a separate head and neck cancer tumor model, mEER, which obligately expresses E7 antigen. Collectively, our data highlight the need for both immunogenicity and 'driver' status of target antigens to be considered in cancer vaccine design.

Evaluation of Diagnostic Utility of a High-Risk Human Papillomavirus PCR Test on Formalin-Fixed, Paraffin-Embedded Head and Neck Tumor Tissues

The increasing prevalence of high-risk human papillomavirus (HR-HPV)-associated head and neck squamous cell carcinoma (HNSCC) has prompted strong clinical demands for detecting HR-HPV directly in the tumor. Although p16 immunohistochemistry (IHC) has been the standard testing method, it has limitations including false positivity, lack of sensitivity in low tumor cell samples such as fine-needle aspirate (FNA), and its subjectivity. We developed a modified method based on a commercial automated HR-HPV PCR assay and evaluated the performance characteristics and the diagnostic utility of this assay for direct HR-HPV detection in the HNSCC samples. HNSCC formalin-fixed, paraffin-embedded blocks were retrieved from archives including 44 excisions, 63 biopsies, and 16 FNAs. Tissue slices were trimmed from the blocks, deparaffinized, lysed, and loaded on the commercial automated platform for HR-HPV PCR. All specimens had a concurrent p16 IHC performed. The PCR assay showed high concordance with the p16 IHC (96%; 99/103) and excellent positive agreement (91.5%) and negative agreement (100%). In addition, the PCR assay provided more conclusive results in samples with equivocal p16 IHC results. The modified commercial automated HR-HPV PCR test is a labor-efficient, quick, reliable, sensitive, and specific method for detecting HR-HPV in formalin-fixed, paraffin-embedded samples. This assay also showed excellent diagnostic utility in samples with equivocal p16 IHC results, including FNA cell blocks.

Neoantigens in immunotherapy and personalized vaccines: Implications for head and neck squamous cell carcinoma

The recent success of immunotherapies has demonstrated the potency of tumor-specific immune cells in mediating tumor rejection and generating durable tumor immunity. Our understanding of the scientific basis of these responses results from the confluence of a better comprehension of the cancer immunoediting process and the revolution in next generation sequencing of cancer genomes. Recent evidence suggests that T cell specificity for cancer cell expressed mutant proteins - termed neoantigens - is an important component of immune mediated tumor rejection. Improved neoantigen prediction algorithms have made it possible to predict and monitor immune responses to checkpoint inhibitors and adoptively transferred autologous lymphocytes and have enabled the development of tumor-specific therapeutic vaccines. Herein, we review the current research on cancer neoantigens in immunotherapies and its implications for the future of head and neck cancer management.

The emerging role of immunotherapy in head and neck squamous cell carcinoma (HNSCC): anti-tumor immunity and clinical applications

Head and neck squamous cell carcinoma (HNSCC) carries a poor prognosis, with low survival rates for advanced stage tumors and minimal improvement in survival trends through the past decades. It is becoming increasingly clear that HNSCC oncogenesis and evolution is characterized by profound immune defects, as cancer cells evade immunosurveillance due to accumulation of genetic mutations and tumor heterogeneity. Improved understanding of the role of the immune system in cancer has led to the identification of novel therapeutic targets, which are being investigated for their potential to provide durable responses. In this review, we will summarize the role of the immune system in HNSCC, the rationale behind immunotherapy strategies and their clinical applications.

Immunotherapy for Head and Neck Squamous Cell Carcinoma

Although head and neck squamous cell carcinoma has traditionally been considered to be a very immunosuppressive, or at least nonimmunogenic, tumor type, recent results from clinical studies of immune checkpoint blockade strategies have led to resurgence in the enthusiasm for immunotherapeutic approaches. Additional strategies for immunotherapy that are under active investigation include enhancement of cetuximab-mediated antibody-dependent cell-mediated cytotoxicity, tumor vaccines, and engineered T cells for adoptive therapy. All of these studies have early-phase clinical trials under way, and the next several years will be exciting as the results of these studies are reported.

HPV-Associated Head and Neck Cancer: Unique Features of Epidemiology and Clinical Management

Human papillomavirus (HPV) is a recently identified causative agent for a subset of head and neck cancers, primarily in the oropharynx, and is largely responsible for the rising worldwide incidence of oropharyngeal cancer (OPC). Patients with HPV-positive OPC have distinct risk factor profiles and generally have a better prognosis than patients with traditional, HPV-negative, head and neck cancer. Concurrent chemotherapy and radiation is a widely accepted primary treatment modality for many patients with HPV-positive OPC. However, recent advances in surgical modalities, including transoral laser and robotic surgery, have led to the reemergence of primary surgical treatment for HPV-positive patients. Clinical trials are under way to determine optimal treatment strategies for the growing subset of patients with HPV-positive OPC. Similarly, identifying those patients with HPV-positive cancer who are at risk for recurrence and poor survival is critical in order to tailor individual treatment regimens and avoid potential undertreatment.

Nonviral oncogenic antigens and the inflammatory signals driving early cancer development as targets for cancer immunoprevention

Cancer immunoprevention is an emerging field that holds much promise. Within the past 20 years, prophylactic vaccines have been implemented on the population level for the immunoprevention of carcinomas induced by viruses, specifically hepatitis B virus (HBV) and human papillomavirus (HPV) infection. Armed with the success of prophylactic vaccines that prevent viral-induced tumors, the field must overcome its next hurdle: to develop robust prophylactic vaccines that prevent the remaining >80% of human cancers not induced by viral infection. In this review, we discuss some of the most promising non-virus-associated prophylactic vaccines that target endogenous neoantigens, including the earliest oncogene products, altered mucin 1 (MUC1) and α-enolase (ENO1), all of which produce new targets in the earliest stages of nonviral-induced tumorigenesis. We also highlight a novel attenuated Listeria monocytogenes-based vaccine expressing mutant oncogene Kras(G12D) (LM-Kras) effective in a pancreatic cancer model. A novel chimeric human/rat HER-2 plasmid vaccine (HuRT-DNA vaccine) effective in a breast cancer model is also discussed. In addition to prophylactic vaccine developments, this review highlights the potential use of classic drugs, such as aspirin and metformin, as chemopreventive agents that can potentially be used as adjuvants to enhance the anticancer immunogenicity and efficacy of noninfectious prophylactic vaccines by modulating the inflammatory pathways within the early tumor microenvironment (TME) that propels tumorigenesis. Finally, timing of prophylactic vaccine administration is critical to its immunopreventive efficacy, providing a necessary role of current and emerging biomarkers for cancer screening and early cancer detection.

Emerging biomarkers in head and neck cancer in the era of genomics

Head and neck cancer (HNC) broadly includes carcinomas arising from the mucosal epithelia of the head and neck region as well as various cell types of salivary glands and the thyroid. As reflected by the multiple sites and histologies of HNC, the molecular characteristics and clinical outcomes of this disease vary widely. In this Review, we focus on established and emerging biomarkers that are most relevant to nasopharyngeal carcinoma and head and neck squamous-cell carcinoma (HNSCC), which includes primary sites in the oral cavity, oropharynx, hypopharynx and larynx. Applications and limitations of currently established biomarkers are discussed along with examples of successful biomarker development. For emerging biomarkers, preclinical or retrospective data are also described in the context of recently completed comprehensive molecular analyses of HNSCC, which provide a broad genetic landscape and molecular classification beyond histology and clinical characteristics. We will highlight the ongoing effort that will see a shift from prognostic to predictive biomarker development in HNC with the goal of delivering individualized cancer therapy.

Translational genomics and head and neck cancer: toward precision medicine

Head and neck squamous cell carcinoma (HNSCC) comprise a wide spectrum of neoplasms with different tumor biologies, prognosis and response to therapies. Current tumor classification and traditional diagnostic methods (e.g. clinical assessment, histopathology) are limited in their capacity to determine prognosis and clinical decision-making. Despite recent improvements in treatment, the outcome for patients with HNSCC remains poor. Similar to most tumors, several patient-related factors, (e.g. genetics and environment) and disease-related factors (e.g. tumor location, TMN staging) play a significant role on survival. Thus, the problem in defining the prognosis is that the clinical course and response to treatment differ considerably among patients. Such interindividual variability is related to the heterogeneity of the tumor, genetic and epigenetic variations, thus reflecting the interaction of multiple biological components that result in a unique phenotype. Integrative genomics are developed to identify the molecular pathways leading to cancer at the individual level and find novel prognostic markers for HNSCC, hence tailoring a treatment accordingly. Such genetic-based personalized diagnosis allows tumor stratification and implementation of targeted therapy. Modern medicine includes new drugs that disrupt the implicated molecules and their signaling pathways. Here, we summarize the current state of knowledge that elucidates the translation of genetic data into clinical benefit.

Regulation of interleukin-6 in head and neck squamous cell carcinoma is related to papillomavirus infection

The prevalence of head and neck squamous cell carcinoma (HNSCC) related to human papillomavirus (HPV) is increasing, unlike tobacco- and alcohol-associated cancers. To gain a clearer understanding of the molecular mechanisms implicated in HNSCC, depending on the presence or not of a viral sequence, we investigated the expression of proteins detected in the tumor regions of HNSCC patients. Twenty-two untreated HNSCC patients were selected according to the presence of HPV-16. For six patients, tumor and controlateral healthy tissues were tested for viral detection before quantitative proteomic analysis. After confirmation by Western blot, proteins were connected into a network, leading to investigate interleukin-6 (IL-6) by immunocytochemistry and ELISA. 41 ± 5% of proteins quantified by proteomics were differentially expressed in tumor compared with healthy regions. Among them, 36 proteins were retained as modulated in HPV-16 positive or negative tumors, including cytokeratins, tubulins, annexin A1, and serpin B1. Network analysis suggested a central role of IL-6, confirmed by overexpression of IL-6 in tumor tissues as in sera of HPV-negative HNSCC compared with HPV-16-positive tumors. This modulation may contribute to the survival and proliferation of cancer cells, although it was not related to tumor stage or to the level of HPV-16 DNA.