The role of antagonists of the PD-1:PD-L1/PD-L2 axis in head and neck cancer treatment

Ferroptosis and oral squamous cell carcinoma: connecting the dots to move forward

Oral squamous cell carcinoma (OSCC) is an aggressive disease whose incomplete biological comprehension contributes to the inappropriate clinical management and poor prognosis. Thus, the identification of new promising molecular targets to treat OSCC is of paramount importance. Ferroptosis is a regulated cell death caused by the iron-dependent accumulation of reactive oxygen species and the consequent oxidative damage of lipid membranes. Over the last five years, a growing number of studies has reported that OSCC is sensitive to ferroptosis induction and that ferroptosis inducers exert a remarkable antitumor effect in OSCC, even in those displaying low response to common approaches, such as chemotherapy and radiotherapy. In addition, as ferroptosis is considered an immunogenic cell death, it may modulate the immune response against OSCC. In this review, we summarize the so far identified ferroptosis regulatory mechanisms and prognostic models based on ferroptosis-related genes in OSCC. In addition, we discuss the perspective of inducing ferroptosis as a novel strategy to directly treat OSCC or, alternatively, to improve sensitivity to other approaches. Finally, we integrate data emerging from the research studies, reviewed here, through in silico analysis and we provide a novel personal perspective on the potential interconnection between ferroptosis and autophagy in OSCC.

Increased tumor-infiltrating plasmacytoid dendritic cells express high levels of PD-L2 and affect CD8+ T lymphocyte infiltration in human laryngeal squamous cell carcinoma

The infiltration and prognostic significance of tumor-infiltrating plasmacytoid dendritic cells (TI-pDC) have been elucidated in various human solid cancers. However, the infiltrating patterns and functional importance of TI-pDC in laryngeal squamous cell carcinoma (LSCC) remain unknown. In this study, flow cytometric analyses were conducted to characterize the infiltration of dendritic cells and T lymphocytes, along with their respective subgroups in tumor tissues (TT), para-carcinoma tissues (PT), and peripheral blood (PB) from LSCC patients. Immunohistochemical staining for CD4 and CD8, as well as immunofluorescence staining for CD123, were performed on serial tissue sections to investigate the co-localization of TI-pDC and tumor-infiltrating T lymphocytes (TIL) within the tumor microenvironment (TME). Our results demonstrated significantly lower percentages of all three DC subsets in PB compared to TT and PT. Notably, the pDC percentage was markedly higher in TT than in PT. Moreover, TI-pDC percentage was significantly elevated in N+ stage patients compared to those with N0 stage. The results of survival analysis consistently demonstrated that high levels of TI-pDC infiltration were indicative of a poor prognosis. Further investigation revealed a significant negative correlation between TI-pDC and CD8+ TILs; notably, pDCs expressed an inhibitory surface molecule PD-L2 rather than PD-L1 within PT. Collectively, our findings suggest that increased TI-pDC is associated with adverse outcomes in LSCC patients while exhibiting an inhibitory phenotype that may play a crucial role in suppressing CD8+ TILs within LSCC tumors. These results highlight the potential therapeutic strategy targeting PD-L2+ pDCs for immunotherapies against LSCC.

MYO5A overexpression promotes invasion and correlates with low lymphocyte infiltration in head and neck squamous carcinoma

Head and neck squamous carcinoma (HNSC) poses a significant public health challenge due to its substantial morbidity. Nevertheless, despite advances in current treatments, the prognosis for HNSC remains unsatisfactory. To address this, single-cell RNA sequencing (RNA-seq) and bulk RNA-seq data combined with in vitro studies were conducted to examine the role of MYO5A (Myosin VA) in HNSC. Our investigation revealed an overexpression of MYO5A in HNSC that promotes HNSC migration in vitro. Remarkably, knockdown of MYO5A suppressed vimentin expression. Furthermore, analyzing the TCGA database evidenced that MYO5A is a risk factor for human papillomavirus positive (HPV+) HNSC (HR = 0.81, P < 0.001). In high MYO5A expression HNSC, there was a low count of tumor infiltrating lymphocytes (TIL), including activated CD4+ T cells, CD8+ T cells, and B cells. Of note, CD4+ T cells and B cells were positively associated with improved HPV+ HNSC outcomes. Correlation analysis demonstrated a decreased level of immunostimulators in high MYO5A-expressing HNSC. Collectively, these findings suggest that MYO5A may promote HNSC migration through vimentin and involve itself in the process of immune infiltration in HNSC, advancing the understanding of the mechanisms and treatment of HNSC.

Immuno-oncologic signature of malignant transformation in oral squamous cell carcinoma

OBJECTIVE

The purpose of this study is to identify the immuno-oncologic (IO) signature at the surgical tumor margin (TM) of oral squamous cell carcinoma (OSCC) that is involved in the process of malignant transformation.

STUDY DESIGN

Under institutional review board approval, TM of 73 OSCC were investigated using immunohistochemistry for the immune biomarker, programmed death ligand-1 (PD-L1). NanoString 770 IO-focused gene set was analyzed in 5 pairs of TM and invasive tumor (T). PD-L1 regulation in response to interferon-gamma (IFN-γ) was investigated in an oral potentially malignant cell line (OPMC).

RESULTS

Programmed death ligand-1 expression in the epithelial margin directly correlated with its expression in the underlying immune cells (P = .0082). Differential gene expression showed downregulation of PD-L1 and IFN-γ 6 gene signature in the TM relative to T pair.CD8 and macrophages were higher in TM. CNTFR, LYZ, C7, RORC, and FGF13 downregulation in T relative to TM. TDO2, ADAM12, MMP1, LAMC2, MB21D1, TYMP, OASL, COL5A1, exhausted_CD8, Tregs,and NK_CD56dim were upregulated in T relative to TM. Finally, IFN-γ induced upregulation of PD-L1 in the OPMC.

CONCLUSIONS

Our work suggests a role for IFN-γ in PD-L1 upregulation in OPMC and presents novel IO transcriptional signatures for frankly invasive OSCC relative to TM.

Modulation of PD‑L1 expression by standard therapy in head and neck cancer cell lines and exosomes

Although checkpoint inhibitors (CPI) have recently extended the treatment options and improved clinical response of advanced stage head and neck squamous cell carcinoma (HNSCC), treatment success remains unpredictable. Programmed cell death ligand‑1 (PD‑L1) is a key player in immunotherapy. Tumor cells, and exosomes derived therefrom, are carriers of PD‑L1 and efficiently suppress immune responses. The aim of the present study was to analyze the influence of established therapies on PD‑L1 expression of HNSCC cell lines and their exosomes. The HNSCC cell lines, UM‑SCC‑11B, UM‑SCC‑14C and UM‑SCC‑22C were treated with fractionated radiotherapy (RT; 5x2 Gy), cisplatin (CT) and cetuximab (Cetux) as monotherapy, or combined therapy, chemoradiotherapy (CRT; RT and CT) or radioimmunotherapy (RT and Cetux). The expression of PD‑L1 and phosphorylated (p)ERK1/2 as a mediator of radioresistance were assessed using western blotting, immunohistochemistry and an ex vivo vital tissue culture model. Additionally, exosomes were isolated from concentrated supernatants of the (un‑)treated HNSCC cell lines by size exclusion chromatography. Exosomal protein expression levels of PD‑L1 were detected using western blotting and semi‑quantitative levels were calculated. The functional impact of exosomes from the (un‑)treated HNSCC cell lines on the proliferation (MTS assay) and apoptosis (Caspase 3/7 assay) of the untreated HNSCC cell lines were measured and compared. The HNSCC cell lines UM‑SCC‑11B and UM‑SCC‑22B showed strong expression of pERK1/2 and PD‑L1, respectively. RT upregulated the PD‑L1 expression in UM‑SCC‑11B and UM‑SCC‑14C and in exosomes from all three cell lines. CT alone induced PD‑L1 expression in all cell lines. CRT induced the expression of PD‑L1 in all HNSCC cell lines and exosomes from UM‑SCC‑14C and UM‑SCC‑22B. The data indicated a potential co‑regulation of PD‑L1 and activated ERK1/2, most evident in UM‑SCC‑14C. Exosomes from irradiated UM‑SCC‑14C cells protected the unirradiated cells from apoptosis by Caspase 3/7 downregulation. The present study suggested a tumor cell‑mediated regulation of PD‑L1 upon platinum‑based CRT in HNSCC and in exosomes. A co‑regulation of PD‑L1 and MAPK signaling response was hypothesized.

Expression of IDO1 and PD-L2 in Patients with Benign Lymphadenopathies and Association with Autoimmune Diseases

The expression patterns of IDO1 and PD-L2 have not been thoroughly investigated in benign lymphadenopathies. The aim with this study was to elucidate how IDO1 and PD-L2 are expressed in benign lymphadenopathies in patients with autoimmune diseases (AD) compared to patients without AD. Formalin-fixed paraffin-embedded lymph nodes from 22 patients with AD and 57 patients without AD were immunohistochemically stained to detect IDO1 and PD-L2. The material was previously stained with EBER in situ hybridization to detect cells harboring the Epstein-Barr virus (EBV). IDO1 and PD-L2 were generally expressed by leukocytes to low degrees, while follicular IDO1+ cells were very rare. IDO1+ cells in single germinal centers were detected in five patients, and there was a high co-occurrence of follicular EBV+ cells in these cases (three of five patients). There were also significant correlations between interfollicular EBV+ cells and interfollicular IDO1+ cells (Spearman rho = 0.32, p = 0.004) and follicular IDO1+ cells (Spearman rho = 0.34, p = 0.004). High or low amounts of IDO1+ or PD-L2+ cells were not statistically significantly associated with patients with AD. However, the lymphadenopathy with the highest amount of interfollicular IDO1+ cells, which was also the only lymphadenopathy in which endothelial cells expressed IDO1, was in a patient with sarcoidosis. This study further supports that the EBV induces the expression of IDO1 and our findings should be recognized by future studies on IDO1 and PD-L2 in inflammatory and malignant conditions.

In vitro models for head and neck cancer: Current status and future perspective

The 5-year overall survival rate remains approximately 50% for head and neck (H&N) cancer patients, even though new cancer drugs have been approved for clinical use since 2016. Cancer drug studies are now moving toward the use of three-dimensional culture models for better emulating the unique tumor microenvironment (TME) and better predicting in vivo response to cancer treatments. Distinctive TME features, such as tumor geometry, heterogenous cellularity, and hypoxic cues, notably affect tissue aggressiveness and drug resistance. However, these features have not been fully incorporated into in vitro H&N cancer models. This review paper aims to provide a scholarly assessment of the designs, contributions, and limitations of in vitro models in H&N cancer drug research. We first review the TME features of H&N cancer that are most relevant to in vitro drug evaluation. We then evaluate a selection of advanced culture models, namely, spheroids, organotypic models, and microfluidic chips, in their applications for H&N cancer drug research. Lastly, we propose future opportunities of in vitro H&N cancer research in the prospects of high-throughput drug screening and patient-specific drug evaluation.

Potential multi-modal effects of provirus integration on HIV-1 persistence: lessons from other viruses

Despite antiretroviral therapy (ART), HIV-1 persists as proviruses integrated into the genomic DNA of CD4⁺ T cells. The mechanisms underlying the persistence and clonal expansion of these cells remain incompletely understood. Cases have been described in which proviral integration can alter host gene expression to drive cellular proliferation. Here, we review observations from other genome-integrating human viruses to propose additional putative modalities by which HIV-1 integration may alter cellular function to favor persistence, such as by altering susceptibility to cytotoxicity in virus-expressing cells. We propose that signals implicating such mechanisms may have been masked thus far by the preponderance of defective and/or nonreactivatable HIV-1 proviruses, but could be revealed by focusing on the integration sites of intact proviruses with expression potential.

Biomarkers and 3D models predicting response to immune checkpoint blockade in head and neck cancer (Review)

Immunotherapy has evolved into a powerful tool in the fight against a number of types of cancer, including head and neck squamous cell carcinomas (HNSCC). Although checkpoint inhibition (CPI) has definitely enriched the treatment options for advanced stage HNSCC during the past decade, the percentage of patients responding to treatment is widely varying between 14-32% in second-line setting in recurrent or metastatic HNSCC with a sporadic durability. Clinical response and, consecutively, treatment success remain unpredictable in most of the cases. One potential factor is the expression of target molecules of the tumor allowing cancer cells to acquire therapy resistance mechanisms. Accordingly, analyzing and modeling the complexity of the tumor microenvironment (TME) is key to i) stratify subgroups of patients most likely to respond to CPI and ii) to define new combinatorial treatment regimens. Particularly in a heterogeneous disease such as HNSCC, thoroughly studying the interactions and crosstalking between tumor and TME cells is one of the biggest challenges. Sophisticated 3D models are therefore urgently needed to be able to validate such basic science hypotheses and to test novel immuno-oncologic treatment regimens in consideration of the individual biology of each tumor. The present review will first summarize recent findings on immunotherapy, predictive biomarkers, the role of the TME and signaling cascades eliciting during CPI. Second, it will highlight the significance of current promising approaches to establish HNSCC 3D models for new immunotherapies. The results are encouraging and indicate that data obtained from patient-specific tumors in a dish might be finally translated into personalized immuno-oncology.

Human papilloma virus integration sites and genomic signatures in head and neck squamous cell carcinoma

A prevalence of around 26% of human papillomavirus (HPV) in head and neck squamous cell carcinoma (HNSCC) has been previously reported. HPV induced oncogenesis mainly involving E6 and E7 viral oncoproteins. In some cases, HPV viral DNA has been detected to integrate with the host genome and possibly contributes to carcinogenesis by affecting the gene expression. We retrospectively assessed HPV integration sites and signatures in 80 HPV positive patients with HNSCC, by using a double capture‐HPV method followed by next‐generation Sequencing. We detected HPV16 in 90% of the analyzed cohort and confirmed five previously described mechanistic signatures of HPV integration [episomal (EPI), integrated in a truncated form revealing two HPV‐chromosomal junctions colinear (2J‐COL) or nonlinear (2J‐NL), multiple hybrid junctions clustering in a single chromosomal region (MJ‐CL) or scattered over different chromosomal regions (MJ‐SC) of the human genome]. Our results suggested that HPV remained episomal in 38.8% of the cases or was integrated/mixed in the remaining 61.2% of patients with HNSCC. We showed a lack of association of HPV genomic signatures to tumour and patient characteristics, as well as patient survival. Similar to other HPV associated cancers, low HPV copy number was associated with worse prognosis. We identified 267 HPV‐human junctions scattered on most chromosomes. Remarkably, we observed four recurrent integration regions: PDL1/PDL2/PLGRKT (8.2%), MYC/PVT1 (6.1%), MACROD2 (4.1%) and KLF5/KLF12 regions (4.1%). We detected the overexpression of PDL1 and MYC upon integration by gene expression analysis. In conclusion, we identified recurrent targeting of several cancer genes such as PDL1 and MYC upon HPV integration, suggesting a role of altered gene expression by HPV integration during HNSCC carcinogenesis.

The effects of PD-1/PD-L1 checkpoint inhibitors on recurrent/metastatic head and neck squamous cell carcinoma: a critical review of the literature and meta-analysis

INTRODUCTION

50% of patients with locally advanced HNSCC eventually present with disease recurrence or metastasis. Interaction of programmed cell death protein 1 (PD-1) and its ligand, programmed death-ligand 1 (PD-L1), allows tumour cells to evade immune attack by inhibiting T-cell activation. PD-1/PD-L1 checkpoint inhibitors block this immunosuppressive effect. This study aims to investigate the efficacy of anti-PD-1/PD-L1 agents for recurrent/metastatic (R/M) HNSCC in terms of survival, toxicity, and response. It will test the hypothesis that immunotherapy improves treatment outcomes for R/M HNSCC patients.

MATERIAL AND METHODS

Studies were identified through an electronic search of databases EMBASE and Medline. Data on survival, response and toxicity following PD-1/PD-L1 inhibition was extracted from included studies and compared. A subgroup meta-analysis compared these outcomes in PD-1/PD-L1 inhibition versus the standard of care (SOC).

RESULTS

Thirteen studies (n = 1798) were included in this review. Overall survival following PD-1/PD-L1 checkpoint inhibition ranged from 6 to 13 months. The most common treatment-related adverse events (TRAEs) were fatigue, hypothyroidism and nausea; Grade ≥3 TRAEs occurred in 13% of patients. Meta-analysis of RCTs showed that anti-PD-1/PD-L1 agents improved survival and reduced toxicity compared to the SOC. This was demonstrated by a 37% lower risk of death (OR = 0.63, 95% CI = 0.51-0.78, I² = 18%, p ≤ 0.0001) and a 77% lower risk of any-grade TRAEs (OR = 0.23, 95% CI = 0.18-0.29, I² = 90%, p ≤ 0.00001) with immunotherapy versus SOC.

DISCUSSION

Based on the observed safety and efficacy, PD-1/PD-L1 checkpoint inhibition improves treatment outcomes for R/M HNSCC patients. PD-1/PD-L1 inhibitors significantly prolonged survival and reduced toxicity compared to the SOC, however further randomised trials are needed to investigate their role in HNSCC.

Immunotherapy in Recurrent/Metastatic Squamous Cell Carcinoma of the Head and Neck

Head and neck cancer is the 6^th most common cancer worldwide with the most common histology being squamous cell carcinoma (HNSCC). While the majority of patients present at a stage where curative intent therapy is possible, when patients recur and/or develop metastatic disease, outcomes are generally poor, especially with systemic therapy alone, and they lag behind other solid tumors. Over the last decade immunotherapy has revolutionized the field of oncology, and anti-PD-1-based therapy has changed the standard of care in recurrent/metastatic (R/M) HNSCC as well. With these gains have come new questions to continue to move the field forward. In this review, we discuss the tumor immune microenvironment and predictive biomarkers and current status and future directions for immunotherapy in recurrent/metastatic head and neck cancer.

Comprehensive co-expression analysis reveals TMC8 as a prognostic immune-associated gene in head and neck squamous cancer

The occurrence and prognosis of head and neck squamous cell cancer (HNSC) is closely associated with human papillomavirus (HPV) infection. Transmembrane channel-like 8 (TMC8) is a key gene affecting the susceptibility of HPV and that plays an important role in T cell regulation. However, the mechanism by which TMC8 affects T cells and whether it further affects the prognosis of patients with HNSC remains unclear. In the present study, oral cancer cell lines and independent tumor specimens were used to detect TMC8 expression in HNSC. Differential expression of TMC8, methylation status, function and associated signaling pathways were further analyzed. Then, multiple databases were cross-analyzed for the relationship of TMC8 with immune cell infiltration and its impact on the prognosis of numerous types of cancer. The results showed that TMC8 was upregulated in HNSC and high expression was predictive of an improved prognosis. Furthermore, TMC8 was concentrated in multiple immune-associated signaling pathways and the expression of TMC8 was associated with the infiltration of CD4+ T cells and their subsets, including CD8+ T cells, B cells and macrophages, suggesting that TMC8 may play an anti-HPV role by regulating CD4+ T cells. Thus, TMC8 plays an anti-HPV role by regulating the infiltration level of CD4+ T cells, and could therefore be used as a potential prognostic marker for patients with HNSC.

Pharmacological and Genetic Inhibition of PD-1 Demonstrate an Important Role of PD-1 in Ischemia-Induced Skeletal Muscle Inflammation, Oxidative Stress, and Angiogenesis

Angiogenesis is an important process under both physiological and pathophysiological conditions. Here we investigated the role and the underlying mechanism of PD-1 in hindlimb ischemia-induced inflammation and angiogenesis in mice. We found that inhibition of PD-1 by genetic PD-1 knockout or pharmacological PD-1 blocking antibodies dramatically attenuated hindlimb blood perfusion, angiogenesis, and exercise capacity in mice after femoral artery ligation. Mechanistically, we found that PD-1 knockout significantly exacerbated ischemia-induced muscle oxidative stress, leukocyte infiltration and IFN-γ production before abnormal angiogenesis in these mice. In addition, we found that the percentages of IFN-γ positive macrophages and CD8 T cells were significantly increased in P-1 knockout mice after hindlimb ischemia. Macrophages were the major leukocyte subset infiltrated in skeletal muscle, which were responsible for the enhanced muscle leukocyte-derived IFN-γ production in PD-1 knockout mice after hindlimb ischemia. Moreover, we demonstrated that IFN-γ significantly attenuated vascular endothelial cell proliferation, tube formation and migration in vitro. IFN-γ also significantly enhanced vascular endothelial cell apoptosis. In addition, the total number of TNF-α positive leukocytes/muscle weight were significantly increased in PD-1^-/- mice after hindlimb ischemia. These data indicate that PD-1 exerts an important role in ischemia-induced muscle inflammation and angiogenesis.

PD-L1 and PD-L2 Expression Levels Are Low in Primary and Secondary Adenoid Cystic Carcinomas of the Orbit: Therapeutic Implications

PURPOSE

To determine if there is a biologic rationale for using checkpoint inhibitor drugs targeting programmed cell death ligand 1 (PD-L1) and PD-L2 in the treatment of adenoid cystic carcinoma of the orbit.

METHODS

Twenty-three cases of adenoid cystic carcinoma involving the orbit (13 primary lacrimal gland, 5 secondarily extending into the orbit, and 5 unspecified) were examined histopathologically. Immunohistochemistry for PD-L1, PD-L2, and CD8 was performed. Charts were reviewed for clinical correlations.

RESULTS

Expression of PD-L1 and of PD-L2 was overall low in adenoid cystic carcinoma (mean expression 1.4 ± 0.9 of 5 for PD-L1, mean 0.83 ± 1.1 of 5 for PD-L2), and tumor-infiltrating CD8-positive T-lymphocytes were sparse (mean 1.1 ± 0.51 of 3). Only 13 of the 23 (57%) cases expressed PD-L1 as a combined positive score ≥1 of cells. No associations were found between expression levels of these markers and patient sex, tumor site of origin, Tumor, Node, Metastasis stage, or patient outcome. A significant association was observed between stromal PD-L1 expression and tumor histopathologic subtype (p = 0.05), and between tumor PD-L1 expression and prior exposure to radiation (p = 0.03).

CONCLUSIONS

Checkpoint inhibitor drugs may have limited impact in the treatment and clinical course of orbital adenoid cystic carcinoma based on the low frequency of CD8 infiltrate and low expression of PD-L1 and PD-L2. Pretreatment with radiation, however, may improve tumor response to checkpoint inhibitor drugs.

Comprehensive analysis of macrophage-related multigene signature in the tumor microenvironment of head and neck squamous cancer

Macrophages are among the most abundant cells of the tumor microenvironment in head and neck squamous cancer (HNSC). Although the marker gene sets of macrophages have been found, the mechanism by which they affect macrophages and whether they further predict the clinical outcome is unclear. In this study, a univariate COX analysis and a random forest algorithm were used to construct a prognostic model. Differential expression of the key gene, methylation status, function, and signaling pathways were further analyzed. We cross-analyzed multiple databases to detect the relationship between the most critical gene and the infiltration of multiple immune cells, as well as its impact on the prognosis of pan-cancer. FANCE is recognized as hub gene by different algorithms. It was overexpressed in HNSC, and high expression was predictive of better prognosis. It might promote apoptosis through the Wnt/β-catenin pathway. The expression of FANCE is inversely proportional to the infiltration of CD4 + T cells and their subsets, tumor-associated macrophages (TAMs), M2 macrophages, but positively co-expressed with M1 macrophages. In summary, FANCE was identified as the hub gene from the macrophage marker gene set, and it may improve the prognosis of HNSC patients by inhibiting lymphocytes and tumor-associated macrophages infiltration.

PD1 expression and correlation with its ligands in oral cancer specimens and peripheral blood

OBJECTIVES

This study analyzed the expression of the PD1 receptor in tumor tissue and peripheral blood of oral squamous cell carcinoma (OSCC) patients, and correlated it with the PD1 ligands PD-L1 and PD-L2. The currently low response rates of checkpoint inhibitor treatment in OSCC could be increased by a better understanding of immune checkpoint biology. Despite evidence in the literature for upregulation of PD1 checkpoint ligands in OSCC tissue, there has been no correlation analysis of the PD1 receptor with its ligands in tissue specimens and peripheral blood of OSCC patients.

MATERIALS AND METHODS

An RT-qPCR analysis of PD1 mRNA expression was performed in oral cancer specimens, healthy mucosa, and corresponding blood samples. A cut-off point (COP) was determined and a chi-square (χ²) test was carried out. PD1 expression was correlated with previously reported PD-L1 and PD-L2 expression values using the Spearman test.

RESULTS

Tissue and blood specimens of 48 OSCC patients and 26 healthy individuals were analyzed. PD1 expression in OSCC specimens was significantly increased (p = 0.006) compared with healthy oral mucosa. PD1 overexpression in tissue samples showed a significant association with the presence of malignancy (p = 0.006). PD1 expression in tissue samples showed a significant positive correlation (p < 0.001) with the ligands PD-L1 and PD-L2. In contrast, there was no correlation between PD1 and its ligands in blood samples. However, there was a significant positive correlation (p < 0.001) between the ligands PD-L1 and PD-L2, both in tissue and blood samples.

CONCLUSIONS

Increased PD1 expression might be a manifestation of T-cell exhaustion in OSCC specimens, leading to immune tolerance. PD-L1/PD-L2-PD1 interaction may be a major mediator of local immunosuppression in OSCC, requiring advanced multimodal treatment protocols.

Immunosuppressive Property of MSCs Mediated by Cell Surface Receptors

In the past decade, mesenchymal stem cells (MSCs) tend to exhibit inherent tropism for refractory inflammatory diseases and engineered MSCs have appeared on the market as therapeutic agents. Recently, engineered MSCs target to cell surface molecules on immune cells has been a new strategy to improve MSC applications. In this review, we discuss the roles of multiple receptors (ICAM-1, Gal-9, PD-L1, TIGIT, CD200, and CXCR4) in the process of MSCs' immunosuppressive properties. Furthermore, we discuss the principles and strategies for developing receptor-regulated MSCs and their mechanisms of action and the challenges of using MSCs as immunosuppressive therapies.

TLR9 Mediated Tumor-Stroma Interactions in Human Papilloma Virus (HPV)-Positive Head and Neck Squamous Cell Carcinoma Up-Regulate PD-L1 and PD-L2

Background: The co-inhibitory receptor PD-1 is expressed in many tumors including head and neck squamous cell carcinoma (HNSCC) and is an important immunotherapy target. However, the role of PD-1 ligands, PD-L1, and particularly PD-L2, in the tumor-stromal cell interactions that cause a tumor-permissive environment in HNSCC is not completely understood and is the focus of our study. Methods: Expression of PD-L1 and PD-L2 was analyzed by immunohistochemistry in situ in HNSCC tumor tissue. Co-cultures were established between stromal cells (fibroblasts and macrophages) and human papilloma virus (HPV)-positive and HPV-negative HNSCC cell lines (HNSCCs) and PD-1 ligands expression was analyzed using flow cytometry. Results: PD-L1 and PD-L2 were expressed both in tumor cells and stroma in HNSCC tissue in situ. In vitro, basal expression of PD-L1 and PD-L2 was low in HNSCCs and high on fibroblasts and macrophages. Interestingly, HPV-positive but not HPV-negative HNSCCs increased the expression of both PD-1 ligands on fibroblasts upon co-culture. This effect was not observed with macrophages. Conversely, both fibroblasts and macrophages increased PD-1 ligands on HPV-positive HNSCCs, whilst this was not observed in HPV-negative HNSCCs. Crucially, we demonstrate that up-regulation of PD-L1 and PD-L2 on fibroblasts by HPV-positive HNSCCs is mediated via TLR9. Conclusions: This work demonstrates in an in vitro model that HPV-positive HNSCCs regulate PD-L1/2 expression on fibroblasts via TLR9. This may open novel avenues to modulate immune checkpoint regulator PD-1 and its ligands by targeting TLR9.

Advances in Immunotherapy and Periocular Malignancy

Immunotherapy has significantly advanced the field of oncology in recent decades. Understanding normal immunosurveillance, as well as the ways in which tumor cells have evolved to evade it, has provided the knowledge for development of drugs that allow one's own immune system to target and destroy malignant cells (immunotherapy). Cutaneous malignancies are particularly sensitive to this class of drugs. In a very sensitive anatomic region such as the periocular tissue, where surgical excision may come with significant morbidity, this technology has had a strong impact in the successful treatment of historically challenging tumors.

Programmed Cell Death 1 Ligand 1 and Programmed Cell Death 1 Ligand 2 Are Expressed in Conjunctival Invasive Squamous Cell Carcinoma: Therapeutic Implications

PURPOSE

Novel cancer immunotherapies, called immune checkpoint inhibitors, have demonstrated clinical efficacy in the treatment of squamous cell carcinomas of the head and neck. Tissue expression of programmed cell death 1 ligand 1 (PD-L1) and programmed cell death 1 ligand 2 (PD-L2) has been shown to predict tumor response to these drugs. We examine the expression of prognostic immune biomarkers, PD-L1 and PD-L2, in invasive ocular surface squamous neoplasia.

DESIGN

Retrospective case series.

METHODS

Eighteen cases of ocular surface or ocular adnexal invasive squamous cell carcinomas were identified in pathology case files of the Massachusetts General Hospital/Massachusetts Eye and Ear Infirmary and at the Wills Eye Hospital accessioned between January 1, 2014 and January 1, 2017. Immunohistochemical staining for PD-L1, PD-L2, CD8, and p16 was performed and graded in a standardized fashion.

RESULTS

PD-L1 and PD-L2 were expressed on tumor cells to varying degrees, and also on some stromal cells and endothelial cells. Stromal and endothelial cell expression was also seen in control conjunctival specimens. Tumor expression of PD-L1 and PD-L2 was present on the cell membranes. All 18 (100%) of the tumors expressed PD-L1: 7 (39%) expressed a high level, 3 (17%) expressed a medium level, and 8 (44%) expressed a low level. Only 9 (50%) tumors expressed PD-L2 and it was at a low level. The expression of PD-L1 in tumor cells correlated with the presence of CD8-positive cytotoxic T lymphocytes among tumor cells (P < .01) and with the presence of CD8-positive cells in the surrounding stroma (P = .04).

CONCLUSIONS

A subset of ocular invasive conjunctival squamous carcinomas express high levels of PD-L1 and CD8 and therefore may respond therapeutically to immune checkpoint inhibition.

The Head and Neck Squamous Cell Carcinoma Microenvironment as a Potential Target for Cancer Therapy

Similarly to other types of malignant tumours, the incidence of head and neck cancer is increasing globally. It is frequently associated with smoking and alcohol abuse, and in a broader sense also with prolonged exposure to these factors during ageing. A higher incidence of tumours observed in younger populations without a history of alcohol and tobacco abuse may be due to HPV infection. Malignant tumours form an intricate ecosystem of cancer cells, fibroblasts, blood/lymphatic capillaries and infiltrating immune cells. This dynamic system, the tumour microenvironment, has a significant impact on the biological properties of cancer cells. The microenvironment participates in the control of local aggressiveness of cancer cells, their growth, and their consequent migration to lymph nodes and distant organs during metastatic spread. In cancers originating from squamous epithelium, a similarity was demonstrated between the cancer microenvironment and healing wounds. In this review, we focus on the specificity of the microenvironment of head and neck cancer with emphasis on the mechanism of intercellular crosstalk manipulation for potential therapeutic application.

The effects of checkpoint inhibition on head and neck squamous cell carcinoma: A systematic review

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is the sixth most frequent malignancy worldwide. Immunotherapy with checkpoint inhibitors such as anti-CTLA-4 anti-PD-l and anti-PD-L1 has shown promising results in treating patients with recurrent/metastatic HNSCC. We aimed to systematically review the literature on immunotherapy with checkpoint inhibitors as treatment for advanced HNSCC.

METHODS

PubMed, EMBASE, Google Scholar, and the Cochrane Library were systematically searched with the purpose of identifying all studies addressing the effects of checkpoint inhibitors as treatment for HNSCC in human clinical trials. We assessed effects of the treatment with checkpoint inhibitors on overall survival (OS), progression-free survival (PFS), HPV-status, PD-L1-status, and adverse events.

RESULTS

We identified eight studies (n = 1431 patients) with an OS ranging from 7.5 to 14.9 months in PD-1 checkpoint inhibition. Two studies (n = 541 patients) observed a significantly (p = 0.01) and (p = 0.007) longer OS with checkpoint inhibition compared to standard-treatment, platinum-based chemotherapy (7.5 versus 5.1 months and 14.9 months versus 10.7 months). Two studies (n = 411 patients) found an increased OS associated with PD-L1-postive patients compared to PD-L1-negative patients. The eight studies have heterogenous design with only three being randomized.

CONCLUSION

Few clinical trials have investigated the treatment with checkpoint inhibition for HNSCC. Solely, two randomized studies comprising 240 patients treated with nivolumab (anti-PD-L) and 301 patients treated with pembrolizumab (anti-PD-L) showed a significantly prolonged survival in patients with recurrent/metastatic HNSCC compared with standard-treatment. There is a further need for randomized clinical trials investigating a putative role of checkpoint inhibition in the treatment of advanced HNSCC.

The evolving role of immuno-oncology for the treatment of head and neck cancer

Monoclonal antibodies (mAbs) that target immune co‐signaling pathways have the potential to enable immune mediated tumor eradication. While early adoption of these agents for the treatment of advanced squamous cell carcinoma of the head and neck (SCCHN) has produced some astounding clinical successes, the majority of patients fail to respond to therapy. The purpose of this review is to first provide a broad overview of the immuno‐oncology (I‐O) landscape and to then focus on the current status of mAb‐based I‐O (mAb:I‐O) for the treatment of SCCHN, with particular attention to the development of strategies for improving treatment responses.

Optimization and validation of PD-L1 immunohistochemistry staining protocols using the antibody clone 28-8 on different staining platforms

Several immunohistochemistry (IHC) assays have been developed to assess tumor programmed death-ligand 1 (PD-L1) expression levels in patients who are candidates for programmed death-1 (PD-1)/PD-L1 inhibitor therapy. The PD-L1 IHC 28-8 pharmDx kit is FDA-approved as a complementary diagnostic and CE-marked as an in vitro diagnostic device for nivolumab therapy in melanoma and specific lung cancer subtypes (and for squamous cell carcinoma of the head and neck/urothelial carcinoma in Europe only). Kit availability is limited outside the United States, and its use requires the Dako Autostainer Link 48 platform, which is unavailable in many laboratories. Validated laboratory-developed tests based on 28-8 concentrated antibody outside the kit are needed. This study compared the results from PD-L1 expression level analysis across four immunohistochemistry platforms (Dako Autostainer Link 48, Dako Omnis, Leica Bond-III, and Ventana BenchMark ULTRA) with the 28-8 pharmDx kit in lung cancer (multiple histologies), melanoma, and head and neck cancer (multiple histologies). Samples were prepared per protocol for each platform and stained using PD-L1 IHC 28-8 pharmDx kit on Dako Autostainer Link 48, and per protocol for each platform. The control samples (tonsil and placenta tissue; cell lines with prespecified PD-L1 expression levels) were tested to evaluate the specificity and the sensitivity of test assays. An agreement level of 0.90 with the pharmDx kit was set for each platform. Inter- and intra-assay reliability were assessed. Evaluable samples were lung cancer = 29; melanoma = 31; head and neck cancer = 30. Mean agreement was calculated for PD-L1 expression levels of ≥1%, ≥5%, ≥10%, and ≥50%. Mean overall agreement for all indications was 0.87-0.99. Inter- and intra-assay of scoring/classification repeatability was 100%. Analysis of PD-L1 expression levels using laboratory-developed immunohistochemistry assays with 28-8 antibody may be permissible if the platform is validated using reference samples with defined expression levels.

Immune response and evasion mechanisms in lip carcinogenesis: An immunohistochemical study

OBJECTIVES

Programmed death ligand-1 (PD-L1) and human leukocyte antigen-G (HLA-G) are considered immune checkpoint molecules that inhibit T-cell effectiveness, contributing to tumor immune escape. This study investigated PD-L1, HLA-G, CD8, and granzyme B (GrB) expression at different stages of lip carcinogenesis.

DESIGN AND RESULTS

Forty cases of lip squamous cell carcinoma (LSCC), 55 actinic cheilitis (AC), and 10 healthy lip mucosa (HLM) were submitted to immunohistochemistry. Semiquantitative (PD-L1, HLA-G), and quantitative (CD8, GrB) analysis were performed. PD-L1 and HLA-G expression in neoplastic cells/keratinocytes and stroma/connective tissue was significantly higher in LSCC and AC, compared to HLM (p<0.05). PD-L1 was not associated with clinicopathological features of the lesions. HLA-G expression by malignant cells was significantly higher in LSCCs with distant metastasis (p = 0.041).CD8⁺ and GrB⁺ cell numbers progressively increased from HLMs to LSCC, with AC exhibiting intermediate numbers (p<0.01). Most LSCCs showed coexistence of PD-L1⁺ and CD8⁺ cells (72.5%). PD-L1 was directly correlated to CD8⁺ and GrB⁺ lymphocytic infiltration in LSCCs (p<0.05). Low cytotoxic immune response was associated with lymph node metastasis in LSCC (p<0.05).

CONCLUSIONS

PD-L1 and HLA-G-mediated immune evasion mechanisms are likely to occur from early pre-malignant to advanced malignant stages of lip carcinogenesis, which might provide a rationale for therapeutic blockade of these pathways. PD-L1 expression in LSCCs was correlated with the cytotoxic markers, suggesting that PD-L1 may appear as an escape mechanism in response to an active antitumor response.

Restoration of Facial Form and Lip Competence in a Patient with a Midfacial Defect

Squamous cell carcinoma (SCC) of the head and neck can be treated with a combination of modalities. There is an esthetic and functional compromise with midfacial defects secondary to ablative surgery and adjuvant therapies for SCC. Osteoradionecrosis, tissue contracture, and trismus, are all negative side effects of treatment and can impact a patient's function and possibly their nutrition. In this report, we describe a procedure for fabrication of a prosthesis that provides cosmetic improvement and labial competence to maintain caloric intake.

Nivolumab vs investigator's choice in recurrent or metastatic squamous cell carcinoma of the head and neck: 2-year long-term survival update of CheckMate 141 with analyses by tumor PD-L1 expression

OBJECTIVES

We report 2-year results from CheckMate 141 to establish the long-term efficacy and safety profile of nivolumab and outcomes by tumor PD-L1 expression in patients with recurrent or metastatic (R/M),platinum-refractory squamous cell carcinoma of the head and neck (SCCHN).

METHODS

Patients with R/M SCCHN with tumor progression/recurrence within 6 months of platinum therapy were randomized 2:1 to nivolumab 3 mg/kg every 2 weeks or investigator's choice (IC). Primary endpoint: overall survival (OS). Data cutoff: September 2017.

RESULTS

With 24.2 months' minimum follow-up, nivolumab (n = 240) continued to improve OS vs IC (n = 121), hazard ratio (HR) = 0.68 (95% CI 0.54-0.86). Nivolumab nearly tripled the estimated 24-month OS rate (16.9%) vs IC (6.0%), and demonstrated OS benefit across patients with tumor PD-L1 expression ≥1% (HR [95% CI] = 0.55 [0.39-0.78]) and  < 1% (HR [95% CI] = 0.73 [0.49-1.09]), and regardless of tumor HPV status. Estimated OS rates at 18, 24, and 30 months with nivolumab were consistent irrespective of PD-L1 expression (<1%/≥1%). In the nivolumab arm, there were no observed differences in baseline characteristics or safety profile between long-term survivors and the overall population. Grade 3-4 treatment-related adverse event rates were 15.3% and 36.9% for nivolumab and IC, respectively.

CONCLUSION

Nivolumab significantly improved OS at the primary analysis and demonstrated prolonged OS benefit vs IC and maintenance of a manageable and consistent safety profile with 2-year follow-up. OS benefit was observed with nivolumab irrespective of PD-L1 expression and HPV status. (Clinicaltrials.gov: NCT02105636).

Detection of high PD-L1 expression in oral cancers by a novel monoclonal antibody L1Mab-4

Programmed cell death-ligand 1 (PD-L1), which is a ligand of programmed cell death-1 (PD-1), is a type I transmembrane glycoprotein that is expressed on antigen-presenting cells and several tumor cells, including melanoma and lung cancer cells. There is a strong correlation between human PD-L1 (hPD-L1) expression on tumor cells and negative prognosis in cancer patients. In this study, we produced a novel anti-hPD-L1 monoclonal antibody (mAb), L₁Mab-4 (IgG_2b, kappa), using cell-based immunization and screening (CBIS) method and investigated hPD-L1 expression in oral cancers. L₁Mab-4 reacted with oral cancer cell lines (Ca9-22, HO-1-u-1, SAS, HSC-2, HSC-3, and HSC-4) in flow cytometry and stained oral cancers in a membrane-staining pattern. L₁Mab-4 stained 106/150 (70.7%) of oral squamous cell carcinomas, indicating the very high sensitivity of L₁Mab-4. These results indicate that L₁Mab-4 could be useful for investigating the function of hPD-L1 in oral cancers.

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Programmed cell death-ligand 1 (PD-L1) is expressed in many cancers.

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PD-L1 expression has not been fully investigated in oral cancers.

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A novel anti-PD-L1 mAb L₁Mab-4 was developed in this study.

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L₁Mab-4 stained 70.7% of oral SCCs in a membrane-staining pattern.

Immunotherapy in head and neck cancers: A new challenge for immunologists, pathologists and clinicians

Cancer occurrence can be understood as the result of dysfunctions in immune tumoral microenvironment. Here we review the recent understandings of those microenvironment changes, regarding their causes and prognostic significance in head and neck (HN) carcinoma. We will focus on HN squamous cell cancer (SCC) and nasopharyngeal carcinomas (NPC). Their overall poor prognosis may be improved with immunotherapy in a subset of patients, as supported by current clinical trials. However, finding reliable markers of therapeutic response is crucial for patient selection, due to potential severe adverse reactions and high costs. Half of HNSCC exhibit PD-L1 expression, this expression being higher in HPV-positive tumors. In recent clinical trials, a better therapeutic response to anti-PD-1 was obtained in patients with higher PD-L1 expression. The Food and Drug Administration (FDA) approved the use of these therapeutics without stating a need for patient selection regarding PD-L1 status. Activation status, density and localization of TIL as well as PD-L2, γ-interferon, inflammatory cytokines, epithelial-mesenchymal transition phenotype and mutational burden may all be potential therapeutic response markers. In Epstein-Barr Virus (EBV)-induced nasopharyngeal non-keratinizing cancer, PD-L1 is over-expressed compared to EBV-negative tumors. A 22% response rate has been observed under anti-PD-1 treatment among PD-L1-positive NPC patients. A better understanding of immune checkpoint regulation processes may allow patients to benefit from these promising immunotherapies.

Chemotherapy and immunotherapy for recurrent and metastatic head and neck cancer: a systematic review

Head and neck cancer (HNC) is a fatal malignancy with an overall long-term survival of about 50% for all stages. The diagnosis is not rarely delayed, and the majority of patients present with loco-regionally advanced disease. The rate of second primary tumors after a diagnosis of HNC is about 3-7% per year, the highest rate among solid tumors. Currently, a single-modality or a combination of surgery, radiotherapy and chemotherapy (CHT), is the standard treatment for stage III-IV HNC. For the recurrent/metastatic setting, in the last 40 years great efforts have been made in order to develop a more effective CHT regimen, from the use of methotrexate alone, to the combination of cisplatin (CDDP) and 5-fluorouracile (5FU) or paclitaxel. Recently, the introduction of cetuximab, an anti-EGFR monoclonal antibody, to the CDDP-5FU doublet (EXTREME regimen) has improved the overall response rate, the progression-free survival and the overall survival (OS) compared to CHT alone. Nowadays, the EXTREME regimen is the standard of care for the first-line treatment of recurrent/metastatic head and neck carcinoma (RMHNC). In the last years, new promising therapies for RMHNC such as immune checkpoint inhibitors (ICIs), which have demonstrated favorable results in second-line clinical trials, gained special interest. Nivolumab and pembrolizumab are the first two ICIs able to prolong OS in the second-, later-line and platinum-refractory setting, with tolerable toxicities. This review summarizes the current state of the art in RMHNC treatment options.

Semaphorin 4D in human head and neck cancer tissue and peripheral blood: A dense fibrotic peri-tumoral stromal phenotype

The search for stromal biomarkers in carcinoma patients is a challenge in the field. Semaphorin 4D (Sema4D), known for its various developmental, physiological and pathological effects, plays a role in pro and anti-inflammatory responses. It is expressed in many epithelial tumors including head and neck squamous cell carcinoma (HNSCC). Recently, we found that HNSCC-associated Sema4D modulates an immune-suppressive, tumor-permissible environment by inducing the expansion of myeloid derived suppressor cells. The purpose of this study was to determine the value of Sema4D as a biomarker for the peri-tumoral stromal phenotype in human HNSCC. Our data showed Sema4D^+ve/high tumor cells in 34% of the studied cohort with positive correlation to Stage III (p=0.0001). Sema4D^+ve/high tumor cells correlated directly with dense fibrotic peri-tumoral stroma (p=0.0001) and inversely with infiltrate of Sema4D^+ve/high tumor-associated inflammatory cells (TAIs) (p=0.01). Most of the Sema4D^+ve/high TAIs were co-positive for the macrophage biomarker CD163. Knockdown of Sema4D in WSU-HN6 cells inhibited collagen production by fibroblasts, and decreased activated TGF-β1 levels in culture medium of HNSCC cell lines. In a stratification model of HNSCC using combined Sema4D and the programmed death ligand 1 (PDL-1), Sema4D^+ve/high tumor cells represented a phenotype distinct from the PDL-1 positive tumors. Finally,Sema4D was detected in plasma of HNC patients at significantly higher levels (115.44, ± 39.37) compared to healthy donors (38.60± 12.73) (p <0.0001). In conclusion, we present a novel HNSCC tumor stratification model, based on the expression of the biomarker Sema4D. This model opens new avenues to novel targeted therapeutic strategies.

Postoperative anti-PD-1 antibody treatment to reduce recurrence in a cancer ablation surgical wound

BACKGROUND

Postoperative radiation and chemotherapy are routinely applied for microscopic residual diseases; however, treatment outcomes are not optimal, and patients frequently suffer from treatment-related toxicities. To search for an effective and less-toxic adjuvant treatment for patients with high risk of recurrence, the preventive effect of anti-programmed cell death protein 1 (PD-1) treatment was evaluated in an in vivo animal model of post-surgical tumor recurrence.

MATERIALS AND METHODS

An animal model of postsurgical tumor recurrence (SCCVII tumors in C3H mice) was established by reinoculating tumor cells (10⁵ cells) into surgical wound of primary tumor resection. Initial and recurrent tumors were compared by an immunohistochemistry and complementary DNA microarray. Using this in vivo model, tumor recurrence rates were evaluated in the animals receiving anti-PD-1 treatments. Animals were rechallenged with tumor cells, and interferon gamma secretion from spleen cells was analyzed to determine tumor-specific antitumor immunity.

RESULTS

FoxP3^high cell population was significantly elevated in recurrent tumors compared with that in primary tumors. Some immune response-related factors (granzyme F, neuronal leucine-rich repeat protein 1, myosin heavy chain 3, and transmembrane protein 8C) showed significant differences between primary and recurrent tumors. In this animal model, anti-PD-1 treatments significantly suppressed tumor recurrence. Importantly, tumor induction was significantly reduced when anti-PD-1-treated mice were rechallenged with tumor cells. Tumor cell-specific interferon gamma production was increased in these animals.

CONCLUSIONS

Postoperative anti-PD-1 treatment significantly reduced recurrence in a cancer ablation surgical wound in an in vivo model of tumor recurrence. Our data lay the preclinical groundwork for the future clinical validation of adjuvant anti-PD-1 treatments in patients.

PD-L1 expression in tumor tissue and peripheral blood of patients with oral squamous cell carcinoma

Background

Immune checkpoints like programmed cell death-1 (PD-1) and its ligand PD-L1 are involved in immune escape mechanisms of solid tumors including oral squamous cell carcinoma (OSCC). Inhibitors of the pathway are successfully used for treating especially advanced disease. However, the physiological relevance of PD-1/PD-L1-signaling in OSCC is insufficiently understood. The aim of the study was to analyze if PD-L1 expression in tumor tissue and peripheral blood samples of OSCC patients is associated with histomorphological tumor parameters and if PD-L1 expression in patients is different from controls.

Results

OSCC tumor specimens showed a significantly higher PD-L1 expression than oral mucosa controls (p < 0.001; upregulation more than 3-fold). Cross-tabulation revealed an association of increased expression of PD-L1 mRNA in tissue specimens with malignancy (p < 0.001).

OSCC cases with higher tumor grade and cases with lymph node metastases (N+) were significantly (p < 0.05) associated with increased PD-L1 expression in peripheral blood. Cross-tabulation revealed an significant association with lymph node metastases (N+) (p ≤ 0.002).

Materials and Methods

PD-L1 mRNA expression was analyzed in tumor specimens and corresponding samples of healthy oral mucosa and peripheral blood of 45 OSCC patients and 36 healthy control persons using RT-qPCR analysis. A Mann-Whitney U-test, a cut-off point analysis and a Chi-square test were carried out.

Conclusions

PD-L1 expression in OSCC could contribute to the immunosuppressive local tumor microenvironment. Increased malignant behavior (higher tumor grade, positive nodal status) might be associated with PD-L1 mediated systemic immune tolerance. Thus, PD-L1 expression in peripheral blood might be an indicator of the existence of metastatic disease (N+) in OSCC.

Immunohistochemical investigations on the expression of programmed cell death ligand 1, human leukocyte antigens G and E, and granzyme B in intraoral mucoepidermoid carcinoma

OBJECTIVE

To identify the expression of nonclassical human leukocyte antigen G and E (HLA-G and -E), programmed cell death ligand-1 (PD-L1) and granzyme B (GB) in intraoral mucoepidermoid carcinomas (MECs), and to assess whether such expressions are related to metastasis, survival, staging, tumor grade and number of GB-positive cells.

DESIGN

For this cross-sectional study, samples of MEC (n=30) were selected and classified as low-grade (LG), intermediate-grade (IG) or high-grade (HG), according to the WHO grading system. HLA-G, -E and PD-L1 were identified by immunohistochemistry and quantified as the proportion of positive neoplastic cells. The density of GB+ cells was also evaluated. The Kruskal-Wallis test was used with a 5% significance level.

RESULTS

Expressions of HLA-G, -E and PD-L1 were identified in the majority of epidermoid, intermediate and clear cells, but not in the mucous cells of the MECs. The quantitative analysis of the total percentage of positive neoplastic cells showed overexpression of this set of proteins in all MEC samples. The expression of these proteins and histological grading were positively correlated [HLA-G (LG=79% positive cells, IG=96%, HG=99%; p=0.0004), HLA-E (LG=70%, IG=96%, HG=99%; p<0.0001) and PD-L1 (LG=34%, IG=79%, HG=80%; p=0.01)]. No relationship was observed between the immunosuppressive proteins and other clinicopathological parameters. Low GB density was found in all MEC samples.

CONCLUSIONS

The augmented expression of HLA-G, -E and PD-L1 in the intraoral MEC might suggest a role of these molecules in the scape of neoplastic cells from immunosurveillance.

Overexpression of immunomodulatory mediators in oral precancerous lesions

Human leukocyte antigen (HLA) G and E, programmed cell death 1 ligand 1 (PD-L1), IL-10 and TGF-β are proteins involved in failure of the antitumor immune response. We investigated the expression of these immunomodulatory mediators in oral precancerous lesions (oral leukoplakia-OL; n=80) and whether these molecules were related to the risk of malignant transformation. Samples of normal mucosa (n=20) and oral squamous cells carcinoma (OSCC, n=20) were included as controls. Tissue and saliva samples were analyzed by immunohistochemistry and ELISA respectively. Fifteen OL samples showed severe dysplasia (18.7%) and 40 samples (50%) presented combined high Ki-67/p53. Irrespective of the degree of epithelial dysplasia and the proliferation/apoptosis index of OL, the expression of HLA-G, -E, PD-L1, IL-10, TGF-β2 and -β3 was higher to control (P<0.05) and similar to OSCC (P>0.05). The number of granzyme B+ cells in OL was similar to control (P=0.28) and lower compared to OSCC (P<0.01). Salivary concentrations of sHLA-G, IL-10 and TGF-β did not allow for a distinction between OL and healthy individuals. Overexpression of immunosuppressive mediators in the OL reflects the immune evasion potential of this lesion, which is apparently independent of at cytological and proliferation/apoptosis status.

HPV Integration in HNSCC Correlates with Survival Outcomes, Immune Response Signatures, and Candidate Drivers

The incidence of human papillomavirus (HPV)-related oropharynx cancer has steadily increased over the past two decades and now represents a majority of oropharyngeal cancer cases. Integration of the HPV genome into the host genome is a common event during carcinogenesis that has clinically relevant effects if the viral early genes are transcribed. Understanding the impact of HPV integration on clinical outcomes of head and neck squamous cell carcinoma (HNSCC) is critical for implementing deescalated treatment approaches for HPV⁺ HNSCC patients. RNA sequencing (RNA-seq) data from HNSCC tumors (n = 84) were used to identify and characterize expressed integration events, which were overrepresented near known head and neck, lung, and urogenital cancer genes. Five genes were recurrent, including CD274 (PD-L1) A significant number of genes detected to have integration events were found to interact with Tp63, ETS, and/or FOX1A. Patients with no detected integration had better survival than integration-positive and HPV^- patients. Furthermore, integration-negative tumors were characterized by strongly heightened signatures for immune cells, including CD4⁺, CD3⁺, regulatory, CD8⁺ T cells, NK cells, and B cells, compared with integration-positive tumors. Finally, genes with elevated expression in integration-negative specimens were strongly enriched with immune-related gene ontology terms, while upregulated genes in integration-positive tumors were enriched for keratinization, RNA metabolism, and translation.Implications: These findings demonstrate the clinical relevancy of expressed HPV integration, which is characterized by a change in immune response and/or aberrant expression of the integration-harboring cancer-related genes, and suggest strong natural selection for tumor cells with expressed integration events in key carcinogenic genes. Mol Cancer Res; 16(1); 90-102. ©2017 AACR.

Head and neck cancer: improving outcomes with a multidisciplinary approach

For early-stage head and neck cancer (HNC), surgery (S) or radiotherapy (RT) is a standard treatment. The multidisciplinary approach, which includes multimodality treatment with S followed by RT, with or without chemotherapy (CT) or concurrent chemoradiotherapy (CRT), is required for locally advanced head and neck cancer (LAHNC). CRT improves prognosis, locoregional control (LRC), and organ function in LAHNC, compared to RT alone. Prognosis in recurrent/metastatic HNC (R/M HNC) is dismal. Platinum-based CT, combined with the anti-Epidermal Growth Factor Receptor (EGFR) antibody (Ab) cetuximab, is used in first-line setting, while no further validated options are available at progression. The complexity of disease is, in part, due to the heterogeneity of organs and functions involved and the need for a multimodality approach. In addition, the patient population (often elderly and/or patients with smoking and alcohol habits) argues for an individually tailored treatment plan. Furthermore, treatment goals - which include cure, organ, and function preservation, quality of life and palliation - must also be considered. Thus, optimal management of patients with HNC should involve a range of healthcare professionals with relevant expertise. The purpose of the present review is to 1) highlight the importance and necessity of the multidisciplinary approach in the treatment of HNC; 2) update the knowledge regarding modern surgical techniques, new medical and RT treatment approaches, and their combination; 3) identify the treatment scenario for LAHNC and R/M HNC; and 4) discuss the current role of immunotherapy in HNC.

Inhibitors of the PD-1/PD-L1 axis for the treatment of head and neck cancer: current status and future perspectives

Head and neck cancer (HNC) is a common malignant tumor, but traditional therapeutic methods have unsatisfactory curative effects and many complications occur. Hence, there is an urgent need to develop therapeutic methods that can elicit curative effects as well as low toxic and few side effects. With the development of cancer molecular biology and immunology, targeted therapy for immune checkpoints of programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) has shown enormous development prospects for HNC treatment. Groundbreaking progress has been achieved in the treatment of recurrent/metastatic head and neck squamous cell carcinoma (HNSCC). This review describes current treatment by PD-1- and PD-L1-targeted drugs for HNC.

Unknown primary head and neck squamous cell carcinoma in the era of fluorodeoxyglucose-positron emission tomography/CT and intensity-modulated radiotherapy

BACKGROUND

The diagnosis and treatment of head and neck carcinoma of unknown primary (CUP) have changed with the introduction of fluorodeoxyglucose-positron emission tomography (FDG-PET)/CT and intensity-modulated radiotherapy (IMRT), with potential implications for outcome.

METHODS

We conducted a retrospective analysis of 80 patients with head and neck CUP who were PET-staged and treated with curative intention using IMRT between 2006 and 2016 in the Netherlands Cancer Institute. Patient, tumor, and treatment demographics were recorded and oncologic outcomes were analyzed.

RESULTS

Local control was 100% in mucosal irradiated patients. Regional control was 90%. Ten patients developed distant metastases, which were associated with N3, extracapsular extension (ECE) and lower neck positive lymph nodes. Overall survival (OS) at 5 years was 62% and disease-specific survival was 78%. ECE, N3 neck, multiple levels of positive lymph nodes, and positive lymph nodes in the lower neck were associated with worse prognosis.

CONCLUSION

Locoregional outcome of head and neck CUP managed with modern techniques is good. Future research needs to focus on reducing toxicity and patients prone for distant metastasis.

Biological mechanisms of immune escape and implications for immunotherapy in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy with high morbidity and mortality. Despite advances in cytotoxic therapies and surgical techniques, overall survival (OS) has not improved over the past few decades. This emphasises the need for intense investigation into novel therapies with good tumour control and minimal toxicity. Cancer immunotherapy has led this endeavour, attempting to improve tumour recognition and expand immune responses against tumour cells. While various forms of HNSCC immunotherapy are in preclinical trials, the most promising direction thus far has been with monoclonal antibodies (mAbs), targeting growth factor and immune checkpoint receptors. Preclinical and early phase trials have shown unprecedented efficacy with minimal adverse effects. This article will review biological mechanisms of immune escape and implications for immunotherapy in HNSCC.

Is There Evidence for the Presence and Relevance of the PD-1/PD-L1 Pathway in Oral Squamous Cell Carcinoma? Hints From an Immunohistochemical Study

PURPOSE

To examine oral squamous cell carcinoma (OSCC) specimens for programmed death ligand-1 (PD-L1) expression and presence of programmed death-1 (PD-1)-positive tumor-infiltrating lymphocytes (TILs) and to determine possible clinicopathologic implications. It was hypothesized that PD-L1 expression and PD-1-positive TIL presence in OSCC would have no clinical relevance.

MATERIALS AND METHODS

The authors implemented a retrospective cohort study design. The study cohort was chosen in compliance with predefined inclusion criteria. Demographic, clinical, and histopathologic data were gathered. Tissue microarrays were obtained from paraffin-embedded OSCC specimens and analyzed immunohistochemically for PD-L1 expression and PD-1-positive TIL infiltration. PD-L1 positivity of OSCC specimens served as the predictor variable and neck node metastasis served as the primary outcome variable. Descriptive and inferential statistics were computed and the significance level was set at a P value less than or equal to .05.

RESULTS

The study sample was composed of 88 patients (48 men, 40 women; mean age, 61.34 yr). Marked PD-L1 expression was detected in 29% of OSCC specimens (26 of 88) and 83% of specimens (73 of 88) exhibited a high rate of PD-1-positive TIL infiltration. PD-L1 positivity of OSCC samples was significantly associated with the anatomic origin of OSCC (P = .039), presence of cervical metastasis (P = .039), and high PD-L1-positive TIL infiltration (P = .033).

CONCLUSION

A considerable proportion of OSCCs exhibited marked PD-L1 expression. This could be associated with clinical parameters. PD-L1 expression in OSCC might differ depending on its anatomic origin. PD-1-positive TILs could be detected in most OSCC specimens. These findings might indicate a potential role for the PD-1 and PD-L1 pathway in OSCC.