The frequency and suppressor function of CD4+CD25highFoxp3+ T cells in the circulation of patients with squamous cell carcinoma of the head and neck

Translational research in head and neck cancer: Molecular and immunological updates

Head and neck squamous cell carcinoma (HNSCC) has a poor prognosis. Each year, approximately 880,000 patients are newly diagnosed with HNSCC worldwide, and 450,000 patients with HNSCC die. Risk factors for developing HNSCC have been identified, with cigarette smoking, alcohol consumption, and viral infections being the major factors. Owing to the prevalence of human papillomavirus infection, the number of HNSCC cases is increasing considerably. Surgery and chemoradiotherapy are the primary treatments for HNSCC. With advancements in tumor biology, patients are eligible for novel treatment modalities, namely targeted therapies, immunotherapy, and photoimmunotherapy. Because this area of research has rapidly progressed, clinicians should understand the basic biology of HNSCC to choose an appropriate therapy in the upcoming era of personalized medicine. This review summarized recent developments in tumor biology, focusing on epidemiology, genetic/epigenetic factors, the tumor microenvironment, microbiota, immunity, and photoimmunotherapy in HNSCC, as well as how these findings can be translated into clinical settings.

Pharmacogenomic and epigenomic approaches to untangle the enigma of IL-10 blockade in oncology

The host immune system status remains an unresolved mystery among several malignancies. An immune-compromised state or smart immune-surveillance tactics orchestrated by cancer cells are the primary cause of cancer invasion and metastasis. Taking a closer look at the tumour-immune microenvironment, a complex network and crosstalk between infiltrating immune cells and cancer cells mediated by cytokines, chemokines, exosomal mediators and shed ligands are present. Cytokines such as interleukins can influence all components of the tumour microenvironment (TME), consequently promoting or suppressing tumour invasion based on their secreting source. Interleukin-10 (IL-10) is an interlocked cytokine that has been associated with several types of malignancies and proved to have paradoxical effects. IL-10 has multiple functions on cellular and non-cellular components within the TME. In this review, the authors shed the light on the regulatory role of IL-10 in the TME of several malignant contexts. Moreover, detailed epigenomic and pharmacogenomic approaches for the regulation of IL-10 were presented and discussed.

Deciphering the immune landscape of head and neck squamous cell carcinoma: A single-cell transcriptomic analysis of regulatory T cell responses to PD-1 blockade therapy

Immunotherapy is changing the Head and Neck Squamous Cell Carcinoma (HNSCC) landscape and improving outcomes for patients with recurrent or metastatic HNSCC. A deeper understanding of the tumor microenvironment (TME) is required in light of the limitations of patients' responses to immunotherapy. Here, we aimed to examine how Nivolumab affects infiltrating Tregs in the HNSCC TME. We used single-cell RNA sequencing data from eight tissues isolated from four HNSCC donors before and after Nivolumab treatment. Interestingly, the study found that Treg counts and suppressive activity increased following Nivolumab therapy. We also discovered that changes in the CD44-SSP1 axis, NKG2C/D-HLA-E axis, and KRAS signaling may have contributed to the increase in Treg numbers. Furthermore, our study suggests that decreasing the activity of the KRAS and Notch signaling pathways, and increasing FOXP3, CTLA-4, LAG-3, and GZMA expression, may be mechanisms that enhance the killing and suppressive capacity of Tregs. Additionally, the result of pseudo-temporal analysis of the HNSCC TME indicated that after Nivolumab therapy, the expression of certain inhibitory immune checkpoints including TIGIT, ENTPD1, and CD276 and LY9, were decreased in Tregs, while LAG-3 showed an increased expression level. The study also found that Tregs had a dense communication network with cluster two, and that certain ligand-receptor pairs, including SPP1/CD44, HLA-E/KLRC2, HLA-E/KLRK1, ANXA1/FPR3, and CXCL9/FCGR2A, had notable changes after the therapy. These changes in gene expression and cell interactions may have implications for the role of Tregs in the TME and in response to Nivolumab therapy.

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

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

TGF-β in correlation with tumor progression, immunosuppression and targeted therapy in colorectal cancer

Colorectal cancer (CRC) is a complex malignancy responsible for the second-highest cancer deaths worldwide. TGF-β maintains normal cellular homeostasis by inhibiting the cell cycle and inducing apoptosis, but its elevated level is correlated with colorectal cancer progression, as TGF-β is a master regulator of the epithelial-to-mesenchymal transition, a critical step of metastasis. Tumors, including CRC, use elevated TGF-β levels to avoid immune surveillance by modulating immune cell differentiation, proliferation, and effector function. Presently, the treatment of advanced CRC is mainly based on chemotherapy, with multiple adverse effects. Thus, there is a need to develop alternate tactics because CRC continue to be mostly resistant to the present therapeutic regimen. TGF-β blockade has emerged as a promising therapeutic target in cancer therapy. Blocking TGF-β with phytochemicals and other molecules, such as antisense oligonucleotides, monoclonal antibodies, and bifunctional traps, alone or in combination, may be a safer and more effective way to treat CRC. Furthermore, combination immunotherapy comprising TGF-β blockers and immune checkpoint inhibitors is gaining popularity because both molecules work synergistically to suppress the immune system. Here, we summarize the current understanding of TGF-β as a therapeutic target for managing CRC and its context-dependent tumor-promoting or tumor-suppressing nature.

LncRNA AL161431.1 predicts prognosis and drug response in head and neck squamous cell carcinoma

Background

Long non-coding RNAs (lncRNAs) are increasingly recognized as essential players in various biological processes due to their interactions with DNA, RNA, and protein. Emerging studies have demonstrated lncRNAs as prognostic biomarkers in multiple cancers. However, the prognostic effect of lncRNA AL161431.1 in head and neck squamous cell carcinoma (HNSCC) patients has not been reported.

Methods

In the present study, we conducted a series of analyses to identify and validate the prognostic value of lncRNA AL161431.1 in HNSCC, which included differential lncRNAs screening, survival analysis, Cox regression analysis, time ROCanalysis, nomogram prediction, enrichment analysis, tumor infiltration of immune cells, drug sensitivity analysis, and quantitative real-time polymerase chain reaction (qRT-PCR).

Results

In this study, we performed a comprehensive survival and predictive analysis and demonstrated that AL161431.1 was an independent prognostic factor of HNSCC, for which a high AL161431.1 level indicated poor survival in HNSCC. Functional enrichment analyses found that cell growth and immune-related pathways were significantly enriched in HNSCC, suggesting that AL161431.1 may play a role in tumor development and tumor microenvironment (TME). AL161431.1-related immune cells infiltration analysis demonstrated that AL161431.1 expression is significantly positively associated with M0 macrophages in HNSCC (P<0.001). Using "OncoPredict", we recognized chemotherapy drugs sensitive to the high expression group. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to identify the expression level of AL161431.1 in HNSCC, and the results further validated our findings.

Conclusions

Our findings suggest that AL161431.1 is a reliable prognostic marker for HNSCC and can potentially be an effective therapeutic target.

Induction Therapy for Locally Advanced Head and Neck Squamous Cell Carcinoma

The optimal approach to locally advanced head and neck squamous cell carcinoma (LAHNSCC) treatment remains controversial. For non-resectable LAHNSCC, the clinical interest of induction chemotherapy followed by concurrent chemoradiotherapy (CCRT) or radiotherapy has been questioned. With the approval of immunotherapy and targeted therapy for this disease, treatment options have become more complex. Although new trial data have appeared every year, the results are still inconclusive. In this review, we provide readers with information on new strategies for LAHNSCC induction therapy, which will facilitate evidence-based decision making in LAHNSCC treatment.

Improving head and neck cancer therapies by immunomodulation of the tumour microenvironment

Targeted immunotherapy has improved patient survival in head and neck squamous cell carcinoma (HNSCC), but less than 20% of patients produce a durable response to these treatments. Thus, new immunotherapies that consider all key players of the complex HNSCC tumour microenvironment (TME) are necessary to further enhance tumour-specific T cell responses in patients. HNSCC is an ideal tumour type in which to evaluate immune and non-immune cell differences because of two distinct TME aetiologies (human papillomavirus (HPV)-positive and HPV-negative disease), multiple anatomic sites for tumour growth, and clear distinctions between patients with locally advanced disease and those with recurrent and/or metastatic disease. Recent technological and scientific advancements have provided a more complete picture of all cellular constituents within this complex TME and have evaluated the interplay of both immune and non-immune cells within HNSCC. Here, we include a comprehensive analysis of the complete ecosystem of the HNSCC TME, performed utilizing data-rich resources such as The Cancer Genome Atlas, and cutting-edge techniques, such as single-cell RNA sequencing, high-dimensional flow cytometry and spatial multispectral imaging, to generate improved treatment strategies for this diverse disease.

Identification and classification of distinct surface markers of T regulatory cells

Background

Regulatory T (Treg) cells have emerged as key players in the maintenance of immune homeostasis. Although significant progress has been made in recent years to define the Treg surface markers involved with or identifying their suppressive function, there remains much to be elucidated, and many questions persist. This study determined the expression of surface markers on human peripheral Treg cells and conventional T (Tconv) cells in a steady state and after activation to gain insight into their mechanism of action and more precisely characterize this regulatory population in humans.

Methods

To screen Treg and Tconv cells, peripheral blood mononuclear cells (PBMCs) were isolated from volunteers, stained with a commercially available lyophilized antibody array comprising 371 surface antigens, and analyzed by flow cytometry. To compare Treg cells with activated Tconv cells, PBMCs were stimulated with PMA and further stained similar to freshly isolated cells.

Results

Treg and Tconv cells were positive for 135 and 168 of the 371 antigens, respectively. Based on the frequency distribution, all of the most highly expressed markers identified were shared by both Treg and Tconv cells and participate in T cell activation, act as costimulatory and signaling molecules, or exhibit adhesion and migratory functions. Additionally, we identified several differences in marker expression between Treg and Tconv cells, with most found in the expression of co-stimulatory (ICOS, GITR, 4-1BB) and co-inhibitory (TIGIT, CTLA-4) molecules, as well as chemokine receptors (CXCR4, CXCR5, CCR4, CCR5, CCR7, CCR8, and CXCR7). Furthermore, post-activation expression of surface molecules identified molecules capable of discriminating Treg cells from activated Tconv cells (GITR, 4-1BB, TIGIT, CD120b, and CD39); however, almost all of these markers were also expressed in a small fraction of activated Tconv cells.

Conclusions

These results offer insight into the biology of Tregs and contribute to their accurate identification and characterization in variety of immunological diseases as well as physiological processes.

High density of CD8 T cell and immune imbalance of T lymphocytes subsets are associated with proliferative verrucous leukoplakia

Oral leukoplakia (OL) and proliferative verrucous leukoplakia (PVL) are oral potentially malignant disorders (OPMDs) that microscopically show no or varying degrees of dysplasia. Even sharing clinical and microscopic aspects, PVL shows a more aggressive clinical behaviour, with a malignant transformation rate greater than 40%. Inflammatory infiltrate associated with dysplastic lesions may favour malignant transformation of OPMDs. This study aimed to evaluate the density of T cells and cytokines in dysplastic lesions from OL and PVL patients. Additionally, we evaluated whether soluble products produced in vitro by dysplastic keratinocytes are capable of modulating apoptosis rates and Th phenotype (Th1, Th2, Th17 and Treg) of peripheral blood mononuclear cells. The density of CD3, CD4 and CD8 T cells was assessed by immunohistochemistry. Cytokines and chemokines profile from frozen tissue samples were analysed using the LUMINEX system. Apoptosis rates and Th phenotype modulation were evaluated by flow cytometry. Our results showed an increase in the number of CD8 T cell in the subepithelial region from PVL dysplastic lesions in relation to OL samples. PVL showed increased levels of IL-5 and a decrease in IL-1β and IFN-γ levels compared to OL. Soluble products of PVL and oral carcinoma cell cultures were able to reduce apoptosis rate and promote an imbalance of Th1/Th2 and Th17/Treg. The high-subepithelial density of CD8 T cells and immune imbalance of T lymphocytes subsets probably play an important role in the pathogenesis of PVL and may explain its more aggressive behaviour in relation to OL.

Mature dendritic cells enriched in regulatory molecules may control regulatory T cells and the prognosis of head and neck cancer

We previously reported that regulatory T (Treg) cells expressing CTLA-4 on the cell surface are abundant in head and neck squamous cell carcinoma (HNSCC). The role of expanded Treg cells in the tumor microenvironment of HNSCC remains unclear. In this study, we reveal that the tumor microenvironment of HNSCC is characterized by the high expression of genes related to Treg cells, dendritic cells (DCs), and interleukin (IL)-17-related molecules. Increased expression of IL17A, IL17F, or IL23A contributes to a favorable prognosis of HNSCC. In the tumor microenvironment of HNSCC, IL23A and IL12B are expressed in mature dendritic cells enriched in regulatory molecules (mregDCs). The mregDCs in HNSCC are a migratory and mature phenotype; their signature genes strongly correlate with Treg signature genes in HNSCC. We also observed that IL17A was highly expressed in Th17 cells and exhausted CD8⁺ T cells in HNSCC. These data suggest that mregDCs in HNSCC may contribute to the prognosis by balancing Treg cells and effector T cells that produce IL-17. Targeting mregDCs may be a novel strategy for developing new immune therapies against HNSCC.

The mouse oral carcinoma (MOC) model: A 10-year retrospective on model development and head and neck cancer investigations

Preclinical models of cancer have long been paramount to understanding tumor development and advancing the treatment of cancer. Creating preclinical models that mimic the complexity and heterogeneity of human tumors is a key challenge in the advancement of cancer therapy. About ten years ago, we created the mouse oral carcinoma (MOC) cell line models that were derived from 7, 12-dimethylbenz(a) anthracene (DMBA)-induced mouse oral squamous cell cancers. This model has been used in numerous investigations, including studies on tumor biology and therapeutics. We have seen remarkable progress in cancer immunology in recent years, and these cell lines, which are syngeneic to C57BL/6 background, have also been used to study the anti-tumor immune response. Herein, we aim to review the MOC model from its development and characterization to its use in non-immunological and immunological preclinical head and neck squamous cell carcinoma (HNSCC) studies. Integrating and refining these MOC model studies and extending findings to other systems will provide crucial insights for translational approaches aimed at improving head and neck cancer treatment.

Hypoxia promotes the tolerogenic phenotype of plasmacytoid dendritic cells in head and neck squamous cell carcinoma

Objective

We aim to review the roles of plasmacytoid dendritic cells (pDCs) in head and neck squamous cell carcinoma (HNSCC) and explore the effects of hypoxia on the tolerogenic transformation of pDCs.

Background

pDCs, best known as professional type I interferon‐secreting cells, play key roles in immune surveillance and antitumor immunity. Recently, pDCs have been shown to be tolerogenic and correlate with poor prognosis in a variety of cancers, including HNSCC. However, it remains unclear what drives the tolerogenic transformation of pDCs in the HNSCC microenvironment. Hypoxia, a prominent hallmark of the tumor microenvironment (TME) of HNSCC, can interfere with multiple immune cells and establish an immunosuppressive TME.

Methods

In this review, we summarize the antitumor and protumor functions of pDCs, explore the effects of hypoxia on the migration and maturation of pDCs, and discuss related mechanisms in HNSCC.

Conclusions

pDCs mainly display protumor functions in HNSCC. The hypoxic TME in HNSCC can enhance the migration of pDCs and inhibit the differentiation and maturation of pDCs, promoting the tolerogenic phenotype of pDCs.

Tumor microenvironment and immune evasion in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC), an aggressive malignancy, is characterized by high morbidity and low survival rates with limited therapeutic options outside of regional surgery, conventional cytotoxic chemotherapy, and irradiation. Increasing studies have supported the synergistic role of the tumor microenvironment (TME) in cancer advancement. The immune system, in particular, plays a key role in surveillance against the initiation, development, and progression of HNSCC. The understanding of how neoplastic cells evolve and evade the immune system whether through self-immunogenicity manipulation, or expression of immunosuppressive mediators, provides the foundation for the development of advanced therapies. Furthermore, the crosstalk between cancer cells and the host immune system have a detrimental effect on the TME promoting angiogenesis, proliferation, and metastasis. This review provides a recent insight into the role of the key inflammatory cells infiltrating the TME, with a focus on reviewing immunological principles related to HNSCC, as cancer immunosurveillance and immune escape, including a brief overview of current immunotherapeutic strategies and ongoing clinical trials.

Comparison of the composition of lymphocyte subpopulations in non-relapse and relapse patients with squamous cell carcinoma of the head and neck before, during radiochemotherapy and in the follow-up period: a multicenter prospective study of the German Cancer Consortium Radiation Oncology Group (DKTK-ROG)

Background

Radiochemotherapy (RCT) has been shown to induce changes in immune cell homeostasis which might affect antitumor immune responses. In the present study, we aimed to compare the composition and kinetics of major lymphocyte subsets in the periphery of patients with non-locoregional recurrent (n = 23) and locoregional recurrent (n = 9) squamous cell carcinoma of the head and neck (SCCHN) upon primary RCT.

Methods

EDTA-blood of non-locoregional recurrent SCCHN patients was collected before (t0), after application of 20–30 Gy (t1), in the follow-up period 3 (t2) and 6 months (t3) after RCT. In patients with locoregional recurrence blood samples were taken at t0, t1, t2 and at the time of recurrence (t5). EDTA-blood of age-related, healthy volunteers (n = 22) served as a control (Ctrl). Major lymphocyte subpopulations were phenotyped by multiparameter flow cytometry.

Results

Patients with non-recurrent SCCHN had significantly lower proportions of CD19⁺ B cells compared to healthy individuals before start of any therapy (t0) that dropped further until 3 months after RCT (t2), but reached initial levels 6 months after RCT (t3). The proportion of CD3⁺ T and CD3⁺/CD4⁺ T helper cells continuously decreased between t0 and t3, whereas that of CD8⁺ cytotoxic T cells and CD3⁺/CD56⁺ NK-like T cells (NKT) gradually increased in the same period of time in non-recurrent patients. The percentage of CD4⁺/CD25⁺/FoxP3⁺ regulatory T cells (Tregs) decreased directly after RCT, but increased above initial levels in the follow-up period 3 (t2) and 6 (t3) months after RCT. Patients with locoregional recurrence showed similar trends with respect to B, T cells and Tregs between t0 and t5. CD4⁺ T helper cells remained stably low between t0 and t5 in patients with locoregional recurrence compared to Ctrl. NKT/NK cell subsets (CD56⁺/CD69⁺, CD3⁻/CD56⁺, CD3⁻/CD94⁺, CD3⁻/NKG2D⁺, CD3⁻/NKp30⁺, CD3⁻/NKp46⁺) increased continuously up to 6 months after RCT (t0-t3) in patients without locoregional recurrence, whereas in patients with locoregional recurrence, these subsets remained stably low until time of recurrence (t5).

Conclusion

Monitoring the kinetics of lymphocyte subpopulations especially activatory NK cells before and after RCT might provide a clue with respect to the development of an early locoregional recurrence in patients with SCCHN. However, studies with larger patient cohorts are needed.

Trial registration

Observational Study on Biomarkers in Head and Neck Cancer (HNprädBio), NCT02059668. Registered on 11 February 2014, https://clinicaltrials.gov/ct2/show/NCT02059668.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13014-021-01868-5.

Increase in polymorphonuclear myeloid-derived suppressor cells and regulatory T-cells in children with B-cell acute lymphoblastic leukemia

Our study aimed to evaluate the levels of MDSCs and Tregs in pediatric B-cell acute lymphoblastic leukemia (B-ALL), their relation to patients' clinical and laboratory features, and the impact of these cells on the induction response. This study included 31 pediatric B-ALL patients and 27 healthy controls. All patients were treated according to the protocols of the modified St. Jude Children's Research Hospital total therapy study XIIIB for ALL. Levels of MDSCs and Tregs were analyzed using flow cytometry. We observed a reduction in the levels of CD4 + T-cells and an increase in both the polymorphonuclear MDSCs (PMN-MDSCs) and Tregs. The frequencies of PMN-MDSCs and Tregs were directly related to the levels of peripheral and bone marrow blast cells and CD34 + cells. Complete postinduction remission was associated with reduced percentages of PMN-MDSCs and Tregs, with the level of PMN-MDCs in this subpopulation approaching that of healthy controls. PMN-MDSCs and Tregs jointly play a critical role in maintaining an immune-suppressive state suitable for B-ALL tumor progression. Thereby, they could be independent predictors of B-ALL progress, and finely targeting both PMN-MDSCs and Tregs may be a promising approach for the treatment of B-ALL.

Preoperative Immunotherapy in the Multidisciplinary Management of Oral Cavity Cancer

Despite advances in multimodal treatment for oral cavity squamous cell carcinoma, recurrence rates remain high, providing an opportunity for new therapeutic modalities that may improve oncologic outcomes. Much recent attention has been paid to the molecular interactions between the tumor cells with the adjacent peritumoral microenvironment, in which immunosuppressive molecular changes create a landscape that promotes tumor progression. The rationale for the introduction of immunotherapy is to reverse the balance of these immune interactions in a way that utilizes the host immune system to attack tumor cells. In the preoperative setting, immunotherapy has the advantage of priming the unresected tumor and the associated native immune infiltration, supercharging the adaptive anti-tumor immune response. It also provides the basis for scientific discovery where the molecular profile of responders can be interrogated to elucidate prognostic markers to aid in future patient selection. Preoperative immunotherapy is not without limitations. The risk of surgical delay due to immune adverse events must be carefully discussed by members of a multidisciplinary treatment team and patient selection will be critical. One day, the discovery of predictive biomarkers may allow for algorithms where pre-surgical immunotherapy decreases the size of surgical defect and impacts the intensity of adjuvant therapy leading to improved patient survival and decreased morbidity. With further study, immunotherapy could become a key component of future treatment algorithm.

Treg: A Promising Immunotherapeutic Target in Oral Diseases

With the pandemic of COVID-19, maintenance of oral health has increasingly become the main challenge of global health. Various common oral diseases, such as periodontitis and oral cancer, are closely associated with immune disorders in the oral mucosa. Regulatory T cells (Treg) are essential for maintaining self-tolerance and immunosuppression. During the process of periodontitis and apical periodontitis, two typical chronic immune-inflammatory diseases, Treg contributes to maintain host immune homeostasis and minimize tissue damage. In contrast, in the development of oral precancerous lesions and oral cancer, Treg is expected to be depleted or down-regulated to enhance the anti-tumor immune response. Therefore, a deeper understanding of the distribution, function, and regulatory mechanisms of Treg cells may provide a prospect for the immunotherapy of oral diseases. In this review, we summarize the distribution and multiple roles of Treg in different oral diseases and discuss the possible mechanisms involved in Treg cell regulation, hope to provide a reference for future Treg-targeted immunotherapy in the treatment of oral diseases.

A Novel CAR Expressing NK Cell Targeting CD25 With the Prospect of Overcoming Immune Escape Mechanism in Cancers

For many years, high-affinity subunit of IL-2 receptor (CD25) has been considered as a promising therapeutic target for different pathologic conditions like allograft rejection, autoimmunity, and cancers. Although CD25 is transiently expressed by newly-activated T cells, it is the hallmark of regulatory T (Treg) cells which are the most important immunosuppressive elements in tumor microenvironment. Thus, Tregs can be considered as a potential target for chimeric antigen receptor (CAR)-based therapeutic approaches. On the other hand, due to some profound adverse effects pertaining to the use of CAR T cells, CAR NK cells have caught researchers’ attention as a safer choice. Based on these, the aim of this study was to design and develop a CAR NK cell against CD25 as the most prominent biomarker of Tregs with the prospect of overcoming immune escape mechanism in solid and liquid cancers. In the current study, an anti-CD25 CAR was designed and evaluated by comprehensive in silico analyses. Then, using lentiviral transduction system, NK-92 cell line was engineered to express this anti-CD25 CAR construct. In vitro functional analyses of anti-CD25 CAR for its reactivity against CD25 antigen as well as for cytotoxicity and cytokine production assays against CD25 bearing Jurkat cell line were done. In silico analyses demonstrated that the anti-CD25 CAR transcript and scFv protein structures were stable and had proper interaction with the target. Also, in vitro analyses showed that the anti-CD25 CAR-engineered NK-92 cells were able to specifically detect and lyse target cells with an appropriate cytokine production and cytotoxic activity. To conclude, the results showed that this novel CAR NK cell is functional and warrant further investigations.

Tumor microenvironment in head and neck squamous cell carcinoma: Functions and regulatory mechanisms

The tumor microenvironment has been recently reported to play a pivotal role in sustaining tumor cells survival and protecting them from immunotherapy and chemotherapy-induced death. It remains largely unknown how the specific signaling pathway exerts the tumor microenvironment in head and neck squamous cell carcinoma though previous studies have elucidated the regulatory mechanisms involve in tumor immune microenvironment, stromal cells, tumor angiogenesis and cancer stem cell. These components are responsible for tumor progression as well as anti-cancer therapy resistance, leading to rapid tumor growth and treatment failure. In this review, we focus on discussing the interaction between tumor cells and the surrounding components for better understanding of anti-cancer treatment ineffectiveness and its underlying molecular mechanisms.

Neoadjuvant immunotherapy in resectable head and neck cancer: oral cavity carcinoma as a potential research model

Squamous cell carcinoma of oral cavity (OCSCC) accounts for approximately 25% of cases of head and neck squamous cell carcinoma (HNSCC). Tobacco and alcohol consumption are the main risk factors for both cancers. Surgical resection, combined with adjuvant radiotherapy or radiochemotherapy in patients with high risk of relapse, is the key element in management in the initial stages. However, despite the availability of aggressive multidisciplinary treatments, advanced resectable OCSCC carries poor prognosis; only half of the patients are disease-free 5 years after the surgery. Immunotherapy based on the use of immune checkpoint inhibitors has been proven to be effective in a wide variety of tumours, including recurrent and metastatic HNSCC. These positive results resulted in investigations into its effectiveness in earlier stages of the disease with OCSCC emerging as an interesting research model because of the accessible location of the tumours. This article reviews the potential advantages of emerging immunotherapeutic agents [mainly monoclonal antibodies against programmed cell death-1 (PD-1) immune checkpoint inhibitors] as neoadjuvant treatment for OCSCC at locoregional stages as well as the ongoing clinical trials, challenges in evaluating tumour response, and possible predictive biomarkers of response with highlights regarding the role of oral microbiota as modulators of immune response. The efficacy and safety of anti-PD-1 drugs in these patients have been proven in preliminary trials. If there is a decrease in the relapse rate and an improvement in the overall survival after surgical resection in ongoing trials, preoperative immunotherapy may be established as a treatment option for patients with early stages of the disease.

CD26 expression and adenosine deaminase activity in regulatory T cells (Treg) and CD4(+) T effector cells in patients with head and neck squamous cell carcinoma

Adenosine deaminase (ADA) is responsible for the deamination of immunosuppressive adenosine to inosine. In human T lymphocytes, ADA is associated with dipeptidyl peptidase IV (CD26). ADA expression and activity were evaluated in regulatory T cells (Treg) and CD4(+) T effector cells (Teff) of patients with head and neck squamous cell cancer (HNSCC). CD4(+)CD39(+) and CD4(+)CD39(neg) T cells were isolated by single-cell sorting from the peripheral blood of 15 HNSCC patients and 15 healthy donors (NC). CD26/ADA expression in these cells was studied by multicolor flow cytometry, confocal microscopy, RT-PCR and immunohistochemistry in tumor tissues. ADA activity was evaluated by mass spectrometry, suppression of Teff proliferation in CFSE assays and cytokine production by Luminex. CD4(+)CD39(+) Treg had low and CD4(+)CD39(neg) Teff high CD26/ADA expression and ADA activity in NC or HNSCC. The frequency and suppressor activity of CD39(+)CD26(neg) Treg were elevated in patients relative to NC (p < 0.01). However, ADA activity in patients' CD4(+)CD39(neg) Teff was decreased (p < 0.05), resulting in extracellular adenosine accumulation. Also, patients' Teff were more sensitive to inhibitory signals delivered via adenosine receptors. IL-2, IL12 and INFγ upregulated ADA expression and activity in CD4(+)CD39(neg) Teff, whereas IL-10, PGE(2) and CADO downregulated it. The differentially expressed CD26/ADA can serve as surface markers for functionally-active CD39(+)CD26(neg) Treg.

Computational study for suppression of CD25/IL-2 interaction

Cancer recurrence presents a huge challenge in cancer patient management. Immune escape is a key mechanism of cancer progression and metastatic dissemination. CD25 is expressed in regulatory T (Treg) cells including tumor-infiltrating Treg cells (TI-Tregs). These cells specially activate and reinforce immune escape mechanism of cancers. The suppression of CD25/IL-2 interaction would be useful against Treg cells activation and ultimately immune escape of cancer. Here, software, web servers and databases were used, at which in silico designed small interfering RNAs (siRNAs), de novo designed peptides and virtual screened small molecules against CD25 were introduced for the prospect of eliminating cancer immune escape and obtaining successful treatment. We obtained siRNAs with low off-target effects. Further, small molecules based on the binding homology search in ligand and receptor similarity were introduced. Finally, the critical amino acids on CD25 were targeted by a de novo designed peptide with disulfide bond. Hence we introduced computational-based antagonists to lay a foundation for further in vitro and in vivo studies.

The Therapeutic Potential of Regulatory T Cells: Challenges and Opportunities

Regulatory T cells (Tregs) are an immunosuppressive subgroup of CD4+ T cells which are identified by the expression of forkhead box protein P3 (Foxp3). The modulation capacity of these immune cells holds an important role in both transplantation and the development of autoimmune diseases. These cells are the main mediators of self-tolerance and are essential for avoiding excessive immune reactions. Tregs play a key role in the induction of peripheral tolerance that can prevent autoimmunity, by protecting self-reactive lymphocytes from the immune reaction. In contrast to autoimmune responses, tumor cells exploit Tregs in order to prevent immune cell recognition and anti-tumor immune response during the carcinogenesis process. Recently, numerous studies have focused on unraveling the biological functions and principles of Tregs and their primary suppressive mechanisms. Due to the promising and outstanding results, Tregs have been widely investigated as an alternative tool in preventing graft rejection and treating autoimmune diseases. On the other hand, targeting Tregs for the purpose of improving cancer immunotherapy is being intensively evaluated as a desirable and effective method. The purpose of this review is to point out the characteristic function and therapeutic potential of Tregs in regulatory immune mechanisms in transplantation tolerance, autoimmune diseases, cancer therapy, and also to discuss that how the manipulation of these mechanisms may increase the therapeutic options.

Tumor Microenvironment and Immunotherapy Response in Head and Neck Cancer

The tumor microenvironment (TME) encompasses cellular and non-cellular components which play an important role in tumor evolution, invasion, and metastasis. A complicated interplay between tumor cells and adjacent TME cells, such as stromal cells, immune cells, inflammatory cells, and cytokines, leads to severe immunosuppression and the proliferation of cancer cells in several solid tumors. An immunosuppressive TME has a significant impact on treatment resistance and may guide response to immunotherapy. In head and neck cancer (HNC), immunotherapeutic drugs have been incorporated in everyday clinical practice. However, despite an exceptional rate of durable responses, only a low percentage of patients respond. In this review, we will focus on the complex interactions occurring in this dynamic system, the TME, which orchestrate key events that lead to tumor progression, immune escape, and resistance. Furthermore, we will summarize current clinical trials that depict the TME as a potential therapeutic target for improved patient selection.

Prognostic impact of regulatory T cell in head and neck squamous cell carcinoma: A systematic review and meta-analysis

OBJECTIVES

The impact of regulatory T (Treg) cells as a prognostic factor of survival in head and neck squamous cell carcinoma (HNSCC) remains controversial. We aimed to evaluate the prognostic value of Treg cells in patients with HNSCC through a meta-analysis.

MATERIALS AND METHODS

Through a literature search in PubMed, Embase, and Cochrane, we included 11 articles in this meta-analysis and investigated the effect of Treg cell level on the survival of patients with HNSCC. Also, we performed a subgroup analysis according to the study sample (blood vs. tumor tissue), primary tumor site, HPV infectivity, or Treg cell marker.

RESULTS

High levels of circulating Treg cells in the peripheral blood of patients with HNSCC can significantly increase the disease specific survival rate of patients. Moreover, subgroup analysis showed that high levels of Treg in peripheral blood were significantly associated with better disease specific survival in patients with oral cancer, a subsite of HNSCC, but not in those with other head and neck subsite. Positivity of HPV infection did not influence the prognosis of patients with HNSCC.

CONCLUSION

Increase in the levels of circulating Treg cells in peripheral blood can be a prognostic factor of survival in patients with oral cancer.

Tumor-Derived Exosomes in Immunosuppression and Immunotherapy

Tumor-derived exosomes (TEX) are involved in cancer development, metastasis, and disease progression. They can modulate angiogenesis to elevate the malignant degree of tumor cells. TEX carry immunosuppressive factors affecting the antitumor activities of immune cells. Tumor cells as well as immune cells secrete immunologically active exosomes which affect intercellular communication, antigen presentation, activation of immune cells, and immune surveillance. Cell proliferation and immune response suppression create a favorable microenvironment for tumor. TEX can inhibit immune cell proliferation, induce apoptosis of activated CD8+ Teffs, suppress NK cell activity, interfere with monocyte differentiation, and promote Treg as well as MDSC expansion. Exosomes of microenvironment cells may also contribute to the development of drug resistance in cancer therapy. An important role of TEX in modulating the sensitivity of tumor cells to immunotherapy is a promising area of research to make the cancer therapy more successful.

Molecular biology of oral cavity squamous cell carcinoma

Oral cavity squamous cell carcinoma (OCSCC) is a heterogeneous and complex disease that arises due to dysfunction of multiple molecular signaling pathways. Recent advances in high-throughput genetic sequencing technologies coupled with innovative analytical techniques have begun to characterize the molecular determinants driving OCSCC. An understanding of the key molecular signaling networks underlying the initiation and progression of is essential for informing treatment of the disease. In this chapter, we discuss recent findings of key genes altered in OCSCC and potential treatments targeting these genes.

Targeting the Immune Microenvironment in the Treatment of Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a highly aggressive solid tumor, with a 5-year mortality rate of ~50%. The development of immunotherapies has improved the survival of patients with HNSCC, but, the long-term prognosis of patients with recurrent or metastatic HNSCC remains poor. HNSCC is characterized by intratumoral infiltration of regulatory T cells, dysfunctional natural killer cells, an elevated Treg/CD8+ T cell ratio, and increased programmed cell death ligand 1 protein on tumor cells. This leads to an immunocompromised niche in favor of the proliferation and treatment resistance of cancer cells. To achieve an improved treatment response, several potential combination strategies, such as increasing the neoantigens for antigen presentation and therapeutic agents targeting components of the tumor microenvironment, have been explored and have shown promising results in preclinical studies. In addition, large-scale bioinformatic studies have also identified possible predictive biomarkers of HNSCC. As immunotherapy has shown survival benefits in recent HNSCC clinical trials, a comprehensive investigation of immune cells and immune-related factors/cytokines and the immune profiling of tumor cells during the development of HNSCC may provide more insights into the complex immune microenvironment and thus, facilitate the development of novel immunotherapeutic agents.

CD8+ and Regulatory T cells Differentiate Tumor Immune Phenotypes and Predict Survival in Locally Advanced Head and Neck Cancer

Background: The tumor immune status “inflamed”, “immune excluded”, and “desert” might serve as a predictive parameter. We studied these three cancer immune phenotypes while using a simple immunohistochemical algorithm. Methods: Pre-treatment tissue samples of 280 patients with locally advanced HNSCC treated with radiochemotherapy were analyzed. A double staining of CD8+ cytotoxic T cells (CTL) and FoxP3+ (Treg) was performed and the cell density was evaluated in the intraepithelial and stromal compartment of the tumor. Results: The classification of tumors as “immune desert” when stromal CTL were ≤ 50 cells/mm², “inflamed” when intraepithelial CTL were > 500 cells/mm², and as “excluded” when neither of these definitions met these cut off values allowed the best discrimination regarding overall survival. These groups had median OS periods of 37, 61, and 85 months, respectively. In “immune desert” and “immune excluded” tumors high Treg tended to worsen OS, but in “inflamed” tumors high Treg clearly improved OS. Conclusions: We propose that, in locally advanced HNSCC, the tumor immune state “inflamed”, “immune excluded”, and “immune desert” can be defined by intraepithelial and stromal CTL. Tregs can further subdivide these groups. The opposing effects of Tregs in the different groups might be the reason for the inconsistency of Tregs prognostic values published earlier.

Radiotherapy-Induced Changes in the Systemic Immune and Inflammation Parameters of Head and Neck Cancer Patients

Though radiotherapy is a local therapy, it has systemic effects mainly influencing immune and inflammation processes. This has important consequences in the long-term prognosis and therapy individualization. Our objective was to investigate immune and inflammation-related changes in the peripheral blood of head and neck cancer patients treated with radiotherapy. Peripheral blood cells, plasma and blood cell-derived RNA were isolated from 23 patients before and at two time points after radiotherapy and cellular immune parameters, plasma protein changes and gene expression alterations were studied. Increased regulatory T cells and increased CTLA4 and PD-1 expression on CD4 cells indicated an immune suppression induced by the malignant condition, which was accentuated by radiotherapy. Circulating dendritic cells were strongly elevated before treatment and were not affected by radiotherapy. Decreased endoglin levels in the plasma of patients before treatment were further decreased by radiotherapy. Expression of the FXDR, SESN1, GADD45, DDB2 and MDM2 radiation-response genes were altered in the peripheral blood cells of patients after radiotherapy. All changes were long-lasting, detectable one month after radiotherapy. In conclusion we demonstrated radiotherapy-induced changes in systemic immune parameters of head and neck cancer patients and proposed markers suitable for patient stratification worth investigating in larger patient cohorts.

The Complex Interaction between the Tumor Micro-Environment and Immune Checkpoints in Breast Cancer

The progression of breast cancer and its association with clinical outcome and treatment remain largely unexplored. Accumulating data has highlighted the interaction between cells of the immune system and the tumor microenvironment in cancer progression, and although studies have identified multiple facets of cancer progression within the development of the tumor microenvironment (TME) and its constituents, there is lack of research into the associations between breast cancer subtype and staging. Current literature has provided insight into the cells and pathways associated with breast cancer progression through expression analysis. However, there is lack of co-expression studies between immune pathways and cells of the TME that form pro-tumorigenic relationships contributing to immune-evasion. We focus on the immune checkpoint and TME elements that influence cancer progression, particularly studies in molecular subtypes of breast cancer.

Targeting Cellular Metabolism Modulates Head and Neck Oncogenesis

Considering the great energy and biomass demand for cell survival, cancer cells exhibit unique metabolic signatures compared to normal cells. Head and neck squamous cell carcinoma (HNSCC) is one of the most prevalent neoplasms worldwide. Recent findings have shown that environmental challenges, as well as intrinsic metabolic manipulations, could modulate HNSCC experimentally and serve as clinic prognostic indicators, suggesting that a better understanding of dynamic metabolic changes during HNSCC development could be of great benefit for developing adjuvant anti-cancer schemes other than conventional therapies. However, the following questions are still poorly understood: (i) how does metabolic reprogramming occur during HNSCC development? (ii) how does the tumorous milieu contribute to HNSCC tumourigenesis? and (iii) at the molecular level, how do various metabolic cues interact with each other to control the oncogenicity and therapeutic sensitivity of HNSCC? In this review article, the regulatory roles of different metabolic pathways in HNSCC and its microenvironment in controlling the malignancy are therefore discussed in the hope of providing a systemic overview regarding what we knew and how cancer metabolism could be translated for the development of anti-cancer therapeutic reagents.

pDC depletion induced by CD317 blockade drives the antitumor immune response in head and neck squamous cell carcinoma

OBJECTIVES

Dysregulation of immune cells in the tumor microenvironment is a hallmark of head and neck squamous cell carcinoma (HNSCC). Increased infiltration of pDCs has been reported in the microenvironment of HNSCC. However, the precise immunological role of pDC and the therapeutic effects of pDC depletion in HNSCC need to be further investigated.

MATERIALS AND METHODS

CD317 antibodies were applied for depleting pDCs in an immunocompetent transgenic HNSCC mouse model. Tumor volume was monitored. Flow cytometric analysis was conducted for studying the immune profile changes after pDC depletion. In addition, immunohistochemical staining was carried out in a human HNSCC tissue microarray for detecting the infiltration of pDCs. We also analyzed the survival implication of pDCs and its correlation with other immune related markers in human HNSCC.

RESULTS

pDC depletion in the transgenic HNSCC mouse model significantly delayed tumor growth. After pDCs were depleted, T cells were markedly revitalized, and the proportions of regulatory T cells (Tregs) and monocytic myeloid-derived suppressor cells (MDSCs) were decreased. In human HNSCC microenvironment, pDC infiltration was upregulated and its high infiltration conferred a poor prognosis. Moreover, pDC infiltration was closely correlated with the expression of Foxp-3, PD-1, TIM-3, and LAG-3.

CONCLUSION

Our findings demonstrated that pDCs play a negative immunomodulatory role in HNSCC and may present as a target for effective immunotherapy.

Expression of PD-L1 on Immune Cells Shows Better Prognosis in Laryngeal, Oropharygeal, and Hypopharyngeal Cancer

Despite great enthusiasm towards immunotherapy, reliable biomarkers are still lacking. The importance of subsets based on human papillomavirus (HPV) status is supported by a growing body of evidence. However, role of other possible subgroups such as anatomic localization of primary tumor remains controversial. Our objective was to investigate immune cell infiltrate and checkpoint inhibitor proteins in above-mentioned head and neck cancer subsets. Archival tumor samples of 106 laryngeal, oropharyngeal, and hypopharyngeal cancer patients were stained with PD-L1, PD-L2, PD-1, and CTLA-4 antibodies. Proportion of tumor-infiltrating lymphocytes was assessed as well. In HPV-negative tumors, PD-L1 immune cell positivity was associated with better disease-specific survival. PD-L1 expression on immune cells correlated with improved disease-specific survival in laryngeal tumors. Furthermore, PD-L1 immune cell positivity correlated with CTLA-4 expression on immune cells and it was accompanied by high tumor-infiltrating lymphocyte rate. PD-L1 expression on tumor cells and PD-1 status showed strong correlation in all patients and in oropharyngeal and laryngeal localization, but not in hypopharynx. HPV-negative oropharyngeal cancers showed negative PD-L1 status on tumor cells. CTLA-4 positivity was observed in 49.5% and 20.6% on immune cells and on tumor cells, respectively. We concluded that PD-L1 expression on immune cells indicates better prognosis in laryngeal squamous cell carcinoma and in HPV-negative head and neck squamous cell carcinoma. We have not found any essential differences between anatomic subgroups. A possibly distinct role of hypopharyngeal localization regarding immune activity requires further clarification.

Human regulatory T cells (Treg) and their response to cancer

INTRODUCTION

Regulatory T cells (Treg) and their role in health and disease is being intensively investigated. Today, human Treg emerge as a highly heterogeneous subset of CD4+ T cells which mediate immune suppression but also regulate responses of non-immune cells. In cancer, Treg occupy a critical although not yet entirely understood role.

AREAS COVERED

Newly acquired insights into Treg indicate a much greater plasticity and functional heterogeneity of this T cell subset than was previously known. Functional redundancy of Treg and their interactions with a variety of immune and non-immune cellular targets emphasize the central role Treg play in cancer. Treg not only regulate the host responses to cancer; they may also regulate responses to immune therapies. The impact of immune checkpoint blockade on Treg survival, stability and suppressive activity remains to be elucidated. T cell reprogramming by tumor-derived factors, including tumor-derived exosomes (TEX), plays a key role in shaping the Treg repertoire in the tumor microenvironment (TME). The reprogrammed or induced iTreg acquire capabilities to strongly down-regulate anti-tumor immune responses by mechanisms that are specific for each TME. Therapeutic silencing of such Treg calls for the discrimination of "bad" from "good" Treg subsets, an approach that remains elusive in the absence of a definitive "Treg signature."

EXPERT OPINION

Context-related plasticity and heterogeneity of Treg in the TME are significant barriers to selective therapeutic depletion of those Treg subsets that are reprogramed by the tumor to suppress anti-tumor immunity.

Adaptive Responses to Monotherapy in Head and Neck Cancer: Interventions for Rationale-Based Therapeutic Combinations

Most Phase II and III clinical trials in head and neck cancer (HNC) combine two or more treatment modalities, which are based, in part, on knowledge of the molecular mechanisms of innate and acquired resistance to monotherapy. In this review, we describe the range of tumor-cell autonomously derived (intrinsic) and tumor-microenvironment-derived (extrinsic) acquired-resistance mechanisms to various FDA-approved monotherapies for HNC. Specifically, we describe how tumor cells and the tumor microenvironment (TME) respond to radiation, chemotherapy, targeted therapy (cetuximab), and immunotherapies [programmed cell death 1 (PD-1) inhibitors] and adapt to the selective pressure of these monotherapies. Due to the diversity of adaptive responses to monotherapy, monitoring the response to treatment in patients is critical to understand the path that leads to resistance and to guide the optimal therapeutic drug combinations in the clinical setting. We envisage that applying such a rationale-based therapeutic strategy will improve treatment efficacy in HNC patients.

Effect of tumor microenvironment on pathogenesis of the head and neck squamous cell carcinoma: a systematic review

The tumor microenvironment (TME) is comprised of many different cell populations, such as cancer-associated fibroblasts and various infiltrating immune cells, and non-cell components of extracellular matrix. These crucial parts of the surrounding stroma can function as both positive and negative regulators of all hallmarks of cancer development, including evasion of apoptosis, induction of angiogenesis, deregulation of the energy metabolism, resistance to the immune detection and destruction, and activation of invasion and metastasis. This review represents a summary of recent studies focusing on describing these effects of microenvironment on initiation and progression of the head and neck squamous cell carcinoma, focusing on oral squamous cell carcinoma, since it is becoming clear that an investigation of differences in stromal composition of the head and neck squamous cell carcinoma microenvironment and their impact on cancer development and progression may help better understand the mechanisms behind different responses to therapy and help define possible targets for clinical intervention.

Immune Evasion by Head and Neck Cancer: Foundations for Combination Therapy

Head and neck cancer is disfiguring and deadly, and contemporary treatment has fallen short in terms of morbidity and mortality. The rich immune infiltrate within these tumors designates them as prime candidates for immunotherapy and success with these drugs has been documented for recurrent and metastatic head and neck cancer. Still, single-agent immunotherapy has generated either only transient responses or durable response in only a minority subset of patients. Mapping the immune escape mechanisms enacted by head and neck cancer within the tumor microenvironment allows for rational design of strategies to overcome this tolerance. We outline the immune pathway derangements within the head and neck cancer microenvironment and discuss combination treatment strategies to overcome the limitations of immunologic monotherapy.

Infiltration of FoxP3+ Regulatory T Cells is a Strong and Independent Prognostic Factor in Head and Neck Squamous Cell Carcinoma

Head and Neck Squamous Cell Carcinomas (HNSCC) are characterized by a large heterogeneity in terms of the location and risk factors. For a few years now, immunotherapy seems to be a promising approach in the treatment of these cancers, but a better understanding of the immune context could allow to offer a personalized treatment and thus probably increase the survival of HNSCC patients. In this context, we evaluated the infiltration of FoxP3+ Tregs on 205 human formalin-fixed paraffin-embedded HNSCC and we assessed its prognostic value compared to other potential prognostic factors, including HPV infection. First, we found a positive correlation of FoxP3+ Treg infiltration between the intra-tumoral (IT) and the stromal (ST) compartments of the tumors (p < 0.0001). A high infiltration of these cells in both compartments was associated with longer recurrence-free (ST, RFS, p = 0.007; IT, RFS, p = 0.019) and overall survivals (ST, OS, p = 0.002; ST, OS, p = 0.002) of HNSCC patients. Early tumor stage (OS, p = 0.002) and differentiated tumors (RFS, p = 0.022; OS, p = 0.043) were also associated with favorable prognoses. Multivariate analysis revealed that FoxP3+ Treg stromal infiltration, tumor stage and histological grade independently influenced patient prognosis. In conclusion, the combination of these three markers seem to be an interesting prognostic signature for HNSCC.

Immune and genomic signatures in oral (head and neck) cancer

Head and neck squamous cell carcinoma (HNSCC) is responsible for a large number of deaths each year. Oral cancer is the most frequent subtype of HNSCC. Historically, oral cancer has been associated with an increase in the consumption of tobacco and alcohol products, seen especially in the Asian subcontinent. It has also been associated with infection by the human papilloma virus (HPV), particularly strain HPV16. Treatment usually involves a multidisciplinary approach of surgery combined with chemotherapy and radiation. The advent of immunotherapy has broadened the scope for treatment. A better immune response to the tumour can also elicit the action of other therapeutic approaches. A heightened immune response, on the other hand, can lead to resistant tumour formation through the process of immunoediting. Molecular profiling of the tumour microenvironment (TME) can provide us with better insight into the mechanism and progression of the disease, ultimately opening up new therapeutic options. High-throughput molecular profiling techniques over the past decade have enabled us to appreciate the heterogeneity of the TME. In this review, we will be describing the clinicopathological role of the immune and genomic landscape in oral cancer. This study will update readers on the several immunological and genetic factors that can play an important function as predictive and prognostic biomarkers in various forms of head and neck cancer, with a special emphasis on oral carcinoma.

Co-inhibitory immune checkpoints in head and neck squamous cell carcinoma

The upregulation of co-inhibitory immune checkpoints hampers the immune response toward tumor cells and facilitates the tumor cells ability to evade immunosurveillance. Specific inhibitory immune checkpoint delivers inhibitory signals to T cells using multiple mechanisms. More in-depth understanding of the co-inhibitory immune checkpoints could be exploited for head and neck squamous cell carcinoma (HNSCC) treatment. In this review, we summarize the expression and the mechanism of partial co-inhibitory immune checkpoint signals and discuss targeting co-inhibitory immune checkpoints as an immunotherapeutic target for cancer therapy. This review may provide a better understanding of the co-inhibitory immune checkpoints and could promote applications of immunotherapy.

Cyclophosphamide with or without fluorouracil followed by subcutaneous or intravenous interleukin-2 use in solid tumors: A feasibility off-label experience

BACKGROUND

Immune tolerance seems to correlate with disease progression and T regulatory cells (Tregs) and myeloid-derived suppressor cells play a relevant role in immunosuppression. Cyclophosphamide (Cyt) and Fluorouracil (FU) seem to reduce these cell populations.

METHODS AND OBJECTIVE

Establishing safety, feasibility, activity and impact on the immune system (neutrophil/lymphocyte [N/L], platelet/L [Plt/L], monocyte [M] and lymphocyte subpopulation (CD3, CD4, CD8, CD16, HLADR/CD3, Tregs, cells count), CD8/Treg and C-reactive protein (CRP).

TREATMENT

1) Cyt 300 mg/sqm ± FU 500 mg/sqm day (d) 1 and interleukin 2 (IL-2) 18 MUI/sqm intravenous (I.V.) d 4-6, 18-20 or 2) Cyt 300 mg/sqm + FU 500 mg/sqm day d 1, IL-2 4.5 MUI subcutaneous (S.C.) d 3-6, 17-20. The cycle was repeated every four weeks for 2 cycles. Stable or responding patients (pts) continued therapy for 3 cycles.

RESULTS

From February 2014 to December 2016, 13/14 pre-treated pts (mean 3 lines) with solid tumors were enrolled. Male/Female: 1/1. The median age and Eastern Cooperative Oncology Group Performance Status (ECOG PS) was 68 years and 1 respectively. Mean 2 cycles of therapy were administered. G3-4 toxicities presented as diarrhea and bleeding anemia in 2 pts and proteinuria and erhytroderma in 1pt, respectively. Regarding the hematological profile, a more reduction in Plt, less decrease of Plt/Ly, and less increase of Treg with I.V. than S.C. IL-2 administration was observed. However a transient decrease of Treg on day 7 of first cycle in the I.V. IL-2 was reported.

RESPONSE

PR 3 (23%), SD 3 (23%), PD 7 (54%). The response duration was 2+ and 3 months in 2 HCC and 18+ months in the pancreatic cancer (PC). Pathological CR was reported in one HCC treated with I.V. IL-2. The median progression-free-survival (PFS) and overall survival (OS) were 1 and 7 months.

CONCLUSION

Cyt-FU-IL-2 can be considered safe, feasible and moderately active in heavily pre-treated pts. Plt, Plt/Ly, CD8/Treg and a transient Tregs reduction were observed without significative difference on survival.

Checkpoint inhibitors in head and neck cancer: current knowledge and perspectives

The emergence of immunotherapy has provided significant clinical improvements in the treatment of metastatic solid tumors. Recurrent/metastatic head and neck squamous cell carcinoma (HNSCC) has dismal prognosis with median survival ranging between 6and12 months. Our aim is to review the current knowledge on the role of the immune system and immune checkpoint inhibitors in HNSCC. We will focus on the landmark trials that led to the regulatory approvals of pembrolizumab and nivolumab, and discuss a few promising contenders in clinical development and highlight the need to identify better biomarkers other than programmed death-ligand 1 to improve patient selection and help predict response.

Investigation of immune cell markers in feline oral squamous cell carcinoma

Squamous cell carcinoma is the most common oral cancer in the cat and presents as a locally aggressive lesion for which an effective therapeutic protocol remains elusive. Feline oral squamous cell carcinoma (OSCC) shares many clinical characteristics with human head and neck squamous cell carcinoma (HNSCC). Accordingly, present studies were conducted to determine similarities for immune markers shared by feline OSCC and human HNSCC. Biopsies harvested from a feline patient cohort-1 (n = 12) were analyzed for lymphoid cell infiltrates by immunohistochemistry (IHC). Results revealed unique patterns of T cell infiltration involving both neoplastic epithelium and stroma that were detected in most patient tumor biopsies (92%) examined by IHC staining for CD3. Intratumoral B cell infiltrates were detected within tumor stroma only, based on IHC staining for CD79a and CD20 for all patients within the same cohort-1. Infiltration of tumors by a regulatory CD4 T cell subset (Tregs) defined by expression of the forkhead transcription factor FoxP3, was also detected in biopsies from 57% of patients and involved infiltration of neoplastic epithelium and stroma. Patient biopsies were also examined for expression of immunomodulator cyclooxygenase (COX)-2 and revealed positive but weak staining of neoplastic epithelium in a significant proportion of cases (75%). Interestingly, COX-2 expression was detected in both neoplastic epithelium and stroma. Blood collected from a second cohort of feline OSCC patients (n = 9) revealed an increased frequency of circulating CD4+FoxP3+ T cells when compared to healthy adult controls (n = 7) (P = 0.045), although frequencies of CD4+CD25+FoxP3+ T cells were comparable between patients and healthy pet cat controls. Lastly, biopsies from feline OSCC patients were characterized for histologic subtype using a classification scheme previously described for human HNSCC. This analysis revealed the conventional subtype as the predominant variant (75%) with conventional subtypes split evenly between well differentiated and moderately differentiated carcinomas. Two cases were classified as papillary and one case as basaloid subtypes. Correlations between subtype, immune marker scores or circulating Treg frequencies and clinical characteristics or outcome were not detected, most likely due to small patient numbers within patient cohorts. However, findings from these studies provide a preliminary step in the characterization of immune and histologic markers that will be critical to defining prognostic immune markers for feline OSCC and potential targets for testing of immunotherapeutics also relevant to human HNSCC in future studies.

Immunotherapy for Head and Neck Squamous Cell Carcinoma

PURPOSE OF REVIEW

Discussion of current strategies targeting the immune system related to solid tumors with emphasis on head and neck squamous cell carcinoma (HNSCC).This review will outline the current challenges with immunotherapy and future goals for treatment using these agents.

RECENT FINDINGS

Agents targeting immune checkpoint receptors (IR) such as program death 1 (PD1) have been used in the clinical realm for melanoma and non-small cell lung cancer (NSCLC), and the use of these agents for these malignancies has provided crucial information about how and why patients respond or not to inhibitory checkpoint receptor blockade therapy (ICR). The anti PD1 agent, nivolumab, was recently approved by the FDA as a standard of care regimen for patients with platinum refractory recurrent/metastatic (R/M) HNSCC. Molecular pathways leading to resistance are starting to be identified, and work is underway to understand the most optimal treatment regimen with incorporation of immunotherapy. ICR has renewed interest in the immunology of cancer, but resistance is not uncommon, and thus understanding of these mechanisms will allow the clinician to appropriately select patients that will benefit from this therapy.

Stromal PD-L1-Positive Regulatory T cells and PD-1-Positive CD8-Positive T cells Define the Response of Different Subsets of Non-Small Cell Lung Cancer to PD-1/PD-L1 Blockade Immunotherapy

INTRODUCTION

Inhibition of programmed cell death-1 (PD-1) and its ligand programmed death ligand 1 (PD-L1) by using an immune checkpoint inhibitor has emerged as a promising immunotherapy for NSCLC. The correlation of PD-L1 expression in tumor cells with treatment outcomes has been reported in many pivotal trials; however, the relationship remains unclear. Here, we demonstrate that those patients with both high density of PD-1-positive CD8 and PD-L1-positive CD4-positive CD25-positive (PD-1^hi PD-L1^hi) regulatory T cells (Tregs) have a better response to PD1/PD-L1 blockade.

METHODS

In our study between April 1, 2014, and May 30, 2017, a total of 73 NSCLC peripheral blood samples and fresh tumor specimens were collected for study. Of these, 42 large (10-mm³) fresh tumor specimens were obtained from surgical procedures and checked for expression of immunology biomarkers, including PD-L1, PD-1, CD8, CD4, and CD25, in tumor cells and tumor-infiltrating lymphocytes (TILs) by flow cytometry, immunohistochemistry, and immunofluorescence (IF). Moreover, 31 small biopsy specimens from patients who received immunotherapy (pembrolizumab or nivolumab) were analyzed by immunohistochemistry and IF. The correlation between flow cytometry and IF detected for TILs' density was evaluated by Spearman's rank correlation test; the primary end point was progression-free survival. For the PD-1/PD-L1 blockade assay, the TILs and peripheral blood mononuclear CD8 T cells were cultured (1×10⁵ per well) with anti-PD-1 (clone MIH4), anti-PD-L1 (clone MIH1). The cytotoxic activity of TILs in killing NSCLC cells after stimulation by anti-PD-1 and anti-PD-L1 was measured by a conventional ⁵¹Cr release assay.

RESULTS

We first identified a population of high-PD-L1-expressing CD25-positive CD4-positive T cells (PD-L1^hi Tregs) in the tumor microenvironment. The frequency of PD-L1^hi Tregs was higher in tumor tissue (mean 48.6 ± 14.3% in CD25-positive CD3-positive CD4-positive T cells) than in blood (mean 35.4 ± 10.2% in CD25-positive CD3-positive CD4-positive T cells) and normal tissue (mean 38.6 ± 9.7% in CD25-positive CD3-positive CD4-positive T cells) (p < 0.05), as determined by flow cytometry. The frequency of PD-L1^hi Tregs was positively correlated with PD-1-positive CD8 in Tregs. In addition, the TILs from these patients (PD-1^hi PD-L1^hi) showed PD-1/PD-L1 pathway dependence and could induce a greater killing effect of TILs by PD-1/PD-L1 blockade treatment. The patients with PD-L1-positive NSCLC with PD-1^hi PD-L1^hi TILs showed a better clinical outcome than those with a low frequency of PD-1^hi CD8 or PD-L1^hi Tregs (median progression-free survival not reached versus 2 months).

CONCLUSIONS

Our findings suggested that the density of PD-L1-positive CD4-positive CD25-positive Tregs in the tumor microenvironment can serve as a diagnostic factor to supplement PD-L1 expression in tumor cells and predict the response to PD-1/PD-L1 blockade immunotherapy in NSCLC.

The Dual Role of Treg in Cancer

Regulatory T cells (Tregs) represent a small subpopulation of CD4⁺ cells. Tregs are characterized by the expression of transcription factor Forkhead box protein 3 (FoxP3), also known as scurfin. Tregs are modulators of adaptive immune responses and play an important role in maintaining tolerance to self-antigens, providing the suppression associated with tumour microenvironment as well. These immunomodulatory properties are the main reason for the development of numerous therapeutic strategies, designed to inhibit the activity of cancer cells. However, due to Treg subpopulation diversity and its many functional pathways, the role of these cells in the cancer development and progression is still not fully understood.