SHP2 is overexpressed and inhibits pSTAT1-mediated APM component expression, T-cell attracting chemokine secretion, and CTL recognition in head and neck cancer cells

Orlistat facilitates immunotherapy via AKT-FOXO3a-FOXM1-mediated PD-L1 suppression

BACKGROUND

The immunotherapy targeting cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) and programmed cell death ligand-1 (PD-L1) has achieved significant breakthroughs, but further improvements are still needed in cancer treatment.

METHODS

We investigated orlistat, a drug approved by the Food and Drug Administration for the treatment of obesity and found that it can enhance the efficacy of CTLA-4 blockade immunotherapy. We conducted both in vivo and in vitro experiments to explore the mechanism by which orlistat increased antitumor immunity.

RESULTS

Orlistat enhances the efficacy of anti-CTLA-4 immunotherapy by suppressing tumor cell PD-L1 protein expression and boosting the transcription of interferon-stimulated genes (ISGs) and MHC-I. Mechanistically, orlistat inhibits AKT activity and subsequent phosphorylation of forkhead box O3a (FOXO3a) at its threonine (T) 32, serine (S) 253, thereby downregulating Forkhead box M1 (FOXM1) expression, which ultimately suppresses PD-L1 transcription. Specifically, inhibition of FOXM1 leads to FOXO3a accumulation through impaired AKT activity. FOXM1 activates protein kinase B (AKT) via acting as a scaffold to facilitate 3-phosphoinositide-dependent protein kinase 1 (PDK1) and AKT and interaction. In addition, orlistat enhances phosphorylated signal transducer and activator of transcription 1 (p-STAT1) at tyrosine (Y) 701, resulting in upregulation of ISGs and MHC-I.

CONCLUSIONS

Orlistat plays a crucial role in modulating the immune response and supporting the combination with CTLA-4 blockade to promote antitumor immunotherapy.

SHP2 as a primordial epigenetic enzyme expunges histone H3 pTyr-54 to amend androgen receptor homeostasis

Mutations that decrease or increase the activity of the tyrosine phosphatase, SHP2 (encoded by PTPN11), promotes developmental disorders and several malignancies by varying phosphatase activity. We uncovered that SHP2 is a distinct class of an epigenetic enzyme; upon phosphorylation by the kinase ACK1/TNK2, pSHP2 was escorted by androgen receptor (AR) to chromatin, erasing hitherto unidentified pY54-H3 (phosphorylation of histones H3 at Tyr54) epigenetic marks to trigger a transcriptional program of AR. Noonan Syndrome with Multiple Lentigines (NSML) patients, SHP2 knock-in mice, and ACK1 knockout mice presented dramatic increase in pY54-H3, leading to loss of AR transcriptome. In contrast, prostate tumors with high pSHP2 and pACK1 activity exhibited progressive downregulation of pY54-H3 levels and higher AR expression that correlated with disease severity. Overall, pSHP2/pY54-H3 signaling acts as a sentinel of AR homeostasis, explaining not only growth retardation, genital abnormalities and infertility among NSML patients, but also significant AR upregulation in prostate cancer patients.

Small Molecule SHP2 Inhibitor LXQ-217 Affects Lung Cancer Cell Proliferation in Vitro and in Vivo

BACKGROUND

SHP2 is highly expressed in a variety of cancer and has emerged as a potential target for cancer therapeutic agents. The identification of uncharged pTyr mimics is an important direction for the development of SHP2 orthosteric inhibitors.

METHODS

Surface plasmon resonance analysis and cellular thermal shift assay were employed to verify the direct binding of LXQ-217 to SHP2. The inhibitory effect of LXQ-217 was characterized by linear Weaver-Burke enzyme kinetic analysis and BIOVIA Discovery Studio. The inhibition of tumor cell proliferation by LXQ-217 was characterized by cell viability assay, colony formation assays and hoechst 33258 staining. The inhibition of lung cancer proliferation in vivo was studied in nude mice after oral administration of LXQ-217.

RESULTS

An electroneutral bromophenol derivative, LXQ-217, was identified as a competitive SHP2 inhibitor. LXQ-217 induced apoptosis and inhibited growth of human pulmonary epithelial cells by affecting the RAS-ERK and PI3 K-AKT signaling pathways. Long-term oral administration of LXQ-217 significantly inhibited the proliferation ability of lung cancer cells in nude mice. Moreover, mice administered LXQ-217 orally at high doses exhibited no mortality or significant changes in vital signs.

CONCLUSIONS

Our findings on the uncharged orthosteric inhibitor provide a foundation for further development of a safe and effective anti-lung cancer drug.

Immune escape of head and neck cancer mediated by the impaired MHC-I antigen presentation pathway

Tumor immune evasion is a hallmark of Head and Neck Cancers. The advent of immune checkpoint inhibitors (ICIs) in the first-line setting has transformed the management of these tumors. Unfortunately, the response rate of Head and Neck Squamous Cell Carcinomas (HNSCC) to ICIs is below 15%, regardless of the human papillomavirus (HPV) status, which might be partially related with impaired antigen presentation machinery (APM). Mechanistically, HNSCC cells are usually defective in the expression of MHC-I associated APM, while this transcriptional pathway is critical for the activation of tumor-killing effector T-cells. To specifically illuminate the phenomenon and seek for therapeutic strategies, this review summarizes the most recently identified role of genetic and functional dysregulation of the MHC-I pathway, specifically through changes at the genetic, epigenetic, post-transcriptional, and post-translational levels, which substantially contributes to HNSCC immune escape and ICI resistance. Several treatment modalities can be potentially exploited to restore APM signaling in tumors, which improves anti-tumor immunity through the activation of interferons, vaccines or rimantadine against HPV and the inhibition of EGFR, SHP-2, PI3K and MEK. Additionally, the combinatorial use of radiotherapy or cytotoxic agents with ICIs can synergize to potentiate APM signaling. Future directions would include further dissection of MHC-I related APM signaling in HNSCC and whether reversing this inhibition in combination with ICIs would elicit a more robust immune response leading to improved response rates in HNSCC. Therapeutic approaches to restore the MHC-I antigen presentation machinery in Head and Neck Cancer. (Red color texts represent the according strategies and the outcomes).

Rescue of NLRC5 expression restores antigen processing machinery in head and neck cancer cells lacking functional STAT1 and p53

The antigen processing machinery (APM) components needed for a tumor cell to present an antigen to a T cell are expressed at low levels in solid tumors, constituting an important mechanism of immune escape. More than most other solid tumors, head and neck squamous cell carcinoma (HNSCC) cells tend to have low APM expression, rendering them insensitive to immune checkpoint blockade and most other forms of immunotherapy. In HNSCC, this APM deficiency is largely driven by high levels of EGFR and SHP2, leading to low expression and activation of STAT1; however, recent studies suggest that p53, which is often mutated in HNSCCs, may also play a role. In the current study, we aimed to investigate the extent to which STAT1 and p53 individually regulate APM component expression in HNSCC cells. We found that in cells lacking functional p53, APM expression could still be induced by interferon-gamma or DNA-damaging chemotherapy (cisplatin) as long as STAT1 expression remained intact; when both transcription factors were knocked down, APM component expression was abolished. When we bypassed these deficient pathways by rescuing the expression of NLRC5, APM expression was also restored. These results suggest that dual loss of functional STAT1 and p53 may render HNSCC cells incapable of processing and presenting antigens, but rescue of downstream NLRC5 expression may be an attractive strategy for restoring sensitivity to T cell-based immunotherapy.

Immune Escape Strategies in Head and Neck Cancer: Evade, Resist, Inhibit, Recruit

Head and neck cancers (HNCs) arise from the mucosal lining of the aerodigestive tract and are often associated with alcohol use, tobacco use, and/or human papillomavirus (HPV) infection. Over 600,000 new cases of HNC are diagnosed each year, making it the sixth most common cancer worldwide. Historically, treatments have included surgery, radiation, and chemotherapy, and while these treatments are still the backbone of current therapy, several immunotherapies have recently been approved by the Food and Drug Administration (FDA) for use in HNC. The role of the immune system in tumorigenesis and cancer progression has been explored since the early 20th century, eventually coalescing into the current three-phase model of cancer immunoediting. During each of the three phases-elimination, equilibrium, and escape-cancer cells develop and utilize multiple strategies to either reach or remain in the final phase, escape, at which point the tumor is able to grow and metastasize with little to no detrimental interference from the immune system. In this review, we summarize the many strategies used by HNC to escape the immune system, which include ways to evade immune detection, resist immune cell attacks, inhibit immune cell functions, and recruit pro-tumor immune cells.

Overcoming Immune Checkpoint Therapy Resistance with SHP2 Inhibition in Cancer and Immune Cells: A Review of the Literature and Novel Combinatorial Approaches

SHP2 (Src Homology 2 Domain-Containing Phosphatase 2) is a protein tyrosine phosphatase widely expressed in various cell types. SHP2 plays a crucial role in different cellular processes, such as cell proliferation, differentiation, and survival. Aberrant activation of SHP2 has been implicated in multiple human cancers and is considered a promising therapeutic target for treating these malignancies. The PTPN11 gene and functions encode SHP2 as a critical signal transduction regulator that interacts with key signaling molecules in both the RAS/ERK and PD-1/PD-L1 pathways; SHP2 is also implicated in T-cell signaling. SHP2 may be inhibited by molecules that cause allosteric (bind to sites other than the active site and attenuate activation) or orthosteric (bind to the active site and stop activation) inhibition or via potent SHP2 degraders. These inhibitors have anti-proliferative effects in cancer cells and suppress tumor growth in preclinical models. In addition, several SHP2 inhibitors are currently in clinical trials for cancer treatment. This review aims to provide an overview of the current research on SHP2 inhibitors, including their mechanism of action, structure-activity relationships, and clinical development, focusing on immune modulation effects and novel therapeutic strategies in the immune-oncology field.

Mometasone Furoate Inhibits the Progression of Head and Neck Squamous Cell Carcinoma via Regulating Protein Tyrosine Phosphatase Non-Receptor Type 11

Mometasone furoate (MF) is a kind of glucocorticoid with extensive pharmacological actions, including inhibiting tumor progression; however, the role of MF in head and neck squamous cell carcinoma (HNSCC) is still unclear. This study aimed to evaluate the inhibitory effect of MF against HNSCC and investigate its underlying mechanisms. Cell viability, colony formation, cell cycle and cell apoptosis were analyzed to explore the effect of MF on HNSCC cells. A xenograft study model was used to investigate the effect of MF on HNSCC in vivo. The core targets of MF for HNSCC were identified using network pharmacology analysis, TCGA database analysis and real-time PCR. Molecular docking was performed to determine the binding energy. Protein tyrosine phosphatase non-receptor type 11 (PTPN11)-overexpressing cells were constructed, and then, the cell viability and the expression levels of proliferation- and apoptosis-related proteins were detected after treatment with MF to explore the role of PTPN11 in the inhibitory effect of MF against HNSCC. After cells were treated with MF, cell viability and the number of colonies were decreased, the cell cycle was arrested and cell apoptosis was increased. The xenograft study results showed that MF could inhibit cell proliferation via promoting cell apoptosis in vivo. PTPN11 was shown to be the core target of MF against HNSCC via network pharmacology analysis, TCGA database analysis and real-time PCR. The molecular docking results revealed that PTPN11 exhibited the strongest ability to bind to MF. Finally, MF could attenuate the effects of increased cell viability and decreased cell apoptosis caused by PTPN11 overexpression, suggesting that MF can inhibit the progression of HNSCC by regulating PTPN11. MF targeted PTPN11, promoting cell cycle arrest and cell apoptosis, and consequently exerting effective anti-tumor activity.

Long non-coding RNA FAM239A promotes tumor cell proliferation and migration by regulating tyrosine phosphatase Src homology 2 domain-containing phosphatase 2 in head and neck squamous cell carcinoma

OBJECTIVE

Head and neck squamous cell carcinoma (HNSCC), is one of the malignant tumors with high recurrence and metastasis. The family with sequence similarity (FAM) of non-coding RNAs promoted tumorigenesis and metastasis. But so far, long non-coding RNA (lncRNA) FAM239A's function in HNSCC regulation remains unclear. This study aimed to explore the lncRNA FAM239A function and regulation mechanism in HNSCC cell proliferation and migration.

DESIGN

The expression level of lncRNA FAM239A and tyrosine phosphatase Src homology 2 domain-containing phosphatase 2 (SHP2) in HNSCC tumor tissue was tested by quantitative polymerase chain reaction. The cell proliferation and migration were tested by cell counting kit 8, kinetic live cell assay, and wound healing assay. The differential expression of SHP2 and immune infiltration in HNSCC were analyzed in the tumor immune estimation response and human protein atlas databases. And the survival analysis of SHP2 in HNSCC was analyzed in the gene expression profiling interactive analysis 2 databases. The SHP2 expression was tested by western blotting when lncRNA FAM239A overexpression and knockdown.

RESULTS

LncRNA FAM239A and SHP2 were ectopically expressed in HNSCC tumor tissue. Cell proliferation and wound healing assays showed that lncRNA FAM239A promoted tumor cell proliferation and migration. SHP2 was overexpressed in HNSCC tumor tissue by database analyses, and the higher SHP2 expression caused poorer overall survival and disease-free survival in HNSCC patients. SHP2 expression was positively regulated by lncRNA FAM239A.

CONCLUSIONS

LncRNA FAM239A promoted HNSCC cell proliferation and migration through upregulating SHP2 expression, which potentially provided new regulators for HNSCC.

Novel Insights of Anti-EGFR Therapy in HNSCC: Combined with Immunotherapy or Not?

PURPOSE OF REVIEW

The efficacy of anti-EGFR therapy is still unfavorable in recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) patients. Disorder of antitumor immunity and aberrantly expressed checkpoint biomarkers had been validated to involve anti-EGFR therapy tolerance and efficacy. Here we review the immunomodulation of anti-EGFR therapy in the tumor immune microenvironment (TIME) of HNSCC and assist clinicians in finding the potential strategies to rescue anti-EGFR tolerance therapy in the era of immunotherapy for HNSCC.

RECENT FINDINGS

Anti-EGFR therapy, especially cetuximab, was validated to induce the innate and adaptive immune responses of HNSCC patients. It is mainly through inducing natural killer (NK) cells mediating antibody-dependent cell-mediated cytotoxicity (ADCC), recruiting multiple tumor-infiltrating immune cells, and finally remodeling the TIME. Moreover, mountains of preclinical models and clinical trials revealed that combining anti-EGFR agents with immunotherapy could enhance the antitumor effectiveness in HNSCC. Anti-EGFR therapy may usher in another dawn in the treatment of patients with HNSCC through combination with immunotherapy. We offer an overview of the ongoing efforts to make out the immunomodulation of the EGFR pathway in both innate and adaptive immune responses; update the constant preclinical models and clinical trials for the combination of anti-EGFR and immunotherapy in HNSCC; and finally evaluate the efficacy and advantages of the combination therapeutic strategies in clinical use.

Immunomodulatory Therapy in Head and Neck Squamous Cell Carcinoma: Recent Advances and Clinical Prospects

The immune system plays a significant role in the development, invasion, progression, and metastasis of head and neck cancer. Over the last decade, the emergence of immunotherapy has irreversibly altered the paradigm of cancer treatment. The current treatment modalities for head and neck squamous cell carcinoma (HNSCC) include surgery, radiotherapy, and adjuvant or neoadjuvant chemotherapy which has failed to provide satisfactory clinical outcomes. To encounter this, there is a need for a novel or targeted therapy such as immunological targets along with conventional treatment strategy for optimal therapeutic outcomes. The immune system can contribute to promoting metastasis, angiogenesis, and growth by exploiting the tumor's influence on the microenvironment. Immunological targets have been found effective in recent clinical studies and have shown promising results. This review outlines the important immunological targets and the medications acting on them that have already been explored, are currently under clinical trials and are further being targeted.

Major histocompatibility complex class I molecule expression by pancreatic cancer cells is regulated by activation and inhibition of the epidermal growth factor receptor

Pancreatic cancer is one of the deadliest neoplasms, with a dismal 5-year survival rate of only 10%. The ability of pancreatic cancer cells to evade the immune system hinders an anti-tumor response and contributes to the poor survival rate. Downregulation of major histocompatibility complex (MHC) class I cell-surface expression can aid in immune evasion by preventing endogenous tumor antigens from being presented to cytotoxic T cells. Earlier studies suggested that epidermal growth factor receptor (EGFR) signaling can decrease MHC class I expression on certain cancer cell types. However, even though erlotinib (a tyrosine kinase inhibitor that targets EGFR) is an approved drug for advanced pancreatic cancer treatment, the impact of EGFR inhibition or stimulation on pancreatic cancer cell MHC class I surface expression has not previously been analyzed. In this current study, we discovered that EGFR affects MHC class I mRNA and protein expression by human pancreatic cancer cell lines. We demonstrated that cell-surface MHC class I expression is downregulated upon EGFR activation, and the MHC class I level at the surface is elevated following EGFR inhibition. Furthermore, we found that EGFR associates with MHC class I molecules. By defining a role in pancreatic cancer cells for activated EGFR in reducing MHC class I expression and by revealing that EGFR inhibitors can boost MHC class I expression, our work supports further investigation of combined usage of EGFR inhibitors with immunotherapies against pancreatic cancer.

Afatinib and Pembrolizumab for Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma (ALPHA Study): A Phase II Study with Biomarker Analysis

PURPOSE

EGFR pathway inhibition may promote anti-programmed cell death protein 1 (PD-1) responses in preclinical models, but how EGFR inhibition affects tumor antigen presentation during anti-PD-1 monotherapy in humans remain unknown. We hypothesized that afatinib, an irreversible EGFR tyrosine kinase inhibitor, would improve outcomes in patients treated with pembrolizumab for recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) by promoting antigen presentation and immune activation in the tumor microenvironment.

PATIENTS AND METHODS

The ALPHA study (NCT03695510) was a single-arm, Phase II study with Simon's 2-stage design. Afatinib and pembrolizumab were administered to patients with platinum-refractory, recurrent, or metastatic HNSCC. The primary endpoint was the objective response rate (ORR). The study applied gene expression analysis using a NanoString PanCancer Immune Profiling Panel and next-generation sequencing using FoundationOne CDx.

RESULTS

From January 2019 to March 2020, the study enrolled 29 eligible patients. Common treatment-related adverse events were skin rash (75.9%), diarrhea (58.6%), and paronychia (44.8%). Twelve patients (41.4%) had an objective partial response to treatment. The median progression-free survival was 4.1 months, and the median overall survival was 8.9 months. In a paired tissue analysis, afatinib-pembrolizumab were found to upregulate genes involved in antigen presentation, immune activation, and natural killer cell-mediated cytotoxicity. Unaltered methylthioadenosine phosphorylase and EGFR amplification may predict the clinical response to the therapy.

CONCLUSIONS

Afatinib may augment pembrolizumab therapy and improve the ORR in patients with HNSCC. Bioinformatics analysis suggested the enhancement of antigen presentation machinery in the tumor microenvironment.

Immune-Related Mutational Landscape and Gene Signatures: Prognostic Value and Therapeutic Impact for Head and Neck Cancer

Simple Summary

Immunotherapy has emerged as a standard-of-care for most human malignancies, including head and neck cancer, but only a limited number of patients exhibit a durable clinical benefit. An urgent medical need is the establishment of accurate response predictors, which is handicapped by the growing body of molecular, cellular and clinical variables that modify the complex nature of an effective anti-tumor immune response. This review summarizes more recent efforts to elucidate immune-related mutational landscapes and gene expression signatures by integrative analysis of multi-omics data, and highlights their potential therapeutic impact for head and neck cancer. A better knowledge of the underlying principles and relevant interactions could pave the way for rational therapeutic combinations to improve the efficacy of immunotherapy, in particular for those cancer patients at a higher risk for treatment failure.

Abstract

Immunotherapy by immune checkpoint inhibition has become a main pillar in the armamentarium to treat head and neck cancer and is based on the premise that the host immune system can be reactivated to successfully eliminate cancer cells. However, the response rate remains low and only a small subset of head and neck cancer patients achieves a durable clinical benefit. The availability of multi-omics data and emerging computational technologies facilitate not only a deeper understanding of the cellular composition in the tumor immune microenvironment but also enables the study of molecular principles in the complex regulation of immune surveillance versus tolerance. These knowledges will pave the way to apply immunotherapy more precisely and effectively. This review aims to provide a holistic view on how the immune landscape dictates the tumor fate and vice versa, and how integrative analysis of multi-omics data contribute to our current knowledge on the accuracy of predictive biomarkers and on a broad range of factors influencing the response to immunotherapy in head and neck cancer.

Oncogenic Tyrosine Phosphatases: Novel Therapeutic Targets for Melanoma Treatment

Despite a large number of therapeutic options available, malignant melanoma remains a highly fatal disease, especially in its metastatic forms. The oncogenic role of protein tyrosine phosphatases (PTPs) is becoming increasingly clear, paving the way for novel antitumor treatments based on their inhibition. In this review, we present the oncogenic PTPs contributing to melanoma progression and we provide, where available, a description of new inhibitory strategies designed against these enzymes and possibly useful in melanoma treatment. Considering the relevance of the immune infiltrate in supporting melanoma progression, we also focus on the role of PTPs in modulating immune cell activity, identifying interesting therapeutic options that may support the currently applied immunomodulating approaches. Collectively, this information highlights the value of going further in the development of new strategies targeting oncogenic PTPs to improve the efficacy of melanoma treatment.

Targeting MHC Regulation Using Polycyclic Polyprenylated Acylphloroglucinols Isolated from Garcinia bancana

Modulation of major histocompatibility complex (MHC) expression using drugs has been proposed to control immunity. Phytochemical investigations on Garcinia species have allowed the isolation of bioactive compounds such as polycyclic polyprenylated acylphloroglucinols (PPAPs). PPAPs such as guttiferone J (1), display anti-inflammatory and immunoregulatory activities while garcinol (4) is a histone acetyltransferases (HAT) p300 inhibitor. This study reports on the isolation, identification and biological characterization of two other PPAPs, i.e., xanthochymol (2) and guttiferone F (3) from Garcinia bancana, sharing structural analogy with guttiferone J (1) and garcinol (4). We show that PPAPs 1-4 efficiently downregulated the expression of several MHC molecules (HLA-class I, -class II, MICA/B and HLA-E) at the surface of human primary endothelial cells upon inflammation. Mechanistically, PPAPs 1-4 reduce MHC proteins by decreasing the expression and phosphorylation of the transcription factor STAT1 involved in MHC upregulation mediated by IFN-γ. Loss of STAT1 activity results from inhibition of HAT CBP/p300 activity reflected by a hypoacetylation state. The binding interactions to p300 were confirmed through molecular docking. Loss of STAT1 impairs the expression of CIITA and GATA2 but also TAP1 and Tapasin required for peptide loading and transport of MHC. Overall, we identified new PPAPs issued from Garcinia bancana with potential immunoregulatory properties.

Expression level of PD-L1 is involved in ALDH1A1-mediated poor prognosis in patients with head and neck squamous cell carcinoma

OBJECTIVE

To evaluate the expression levels of ALDH1A1, PDL1, and PDL2 in head and neck squamous cell carcinoma (HNSCC) patients, and explore their clinical relevance in prognosis of patients with HNSCC.

METHODS

Immunohistochemistry of ALDH1A1 and PD-L1/PD-L2 in 85 primary HNSCC patients was carried out. The expression level of PD-L2 was assessed with the modified Moratin's immune response scoring (IRS) system. tumor proportion score (TPS) was defined as the percentage of viable tumor cells showing partial or complete membrane staining at any intensity. The chi-square test and Fisher's exact test were used to analyze the associations between ALDH1A1 expression and clinicopathological features. The Spearman's correlation was applied to analyze the correlation of ALDH1A1 expression with PD-L1/PD-L2 expression.

RESULTS

kaplan-Meier analysis showed that the expression levels of ALDH1A1 and PD-L1/PD-L2 were inversely associated with recurrence-free survival (RFS; P = 0.001, 0.014, and 0.023, respectively). Moreover, expression levels of ALDH1A1 and PD-L1 were correlated with poor overall survival (OS; P = 0.002 and 0.039, respectively). Furthermore, multivariate logistics regression analyses demonstrated that expression level of ALDH1A1 was independently associated with shorter RFS (P = 0.013) and poorer OS (P = 0.014) in HNSCC patients, and the expression level of PD-L2 was only negatively associated with RFS (P = 0.041), rather than PD-L1. Spearman's correlation analysis unveiled that expression levels of PD-L1 and PD-L2 were positively correlated with ALDH1A1 expression in HNSCC patients (P = 0.000 and 0.015, respectively). Especially, the patients with expression levels of ALDH1A1 and PD-L1 had the worst prognosis.

CONCLUSIONS

Our results indicated that ALDH1A1 is an independent prognostic factor in patients with HNSCC, and the expression level of PDL-1 may be involved in ALDH1A1-mediated poor prognosis in patients with HNSCC.

MHC Class I Downregulation in Cancer: Underlying Mechanisms and Potential Targets for Cancer Immunotherapy

In recent years, major advances have been made in cancer immunotherapy. This has led to significant improvement in prognosis of cancer patients, especially in the hematological setting. Nonetheless, translation of these successes to solid tumors was found difficult. One major mechanism through which solid tumors can avoid anti-tumor immunity is the downregulation of major histocompatibility complex class I (MHC-I), which causes reduced recognition by- and cytotoxicity of CD8⁺ T-cells. Downregulation of MHC-I has been described in 40-90% of human tumors, often correlating with worse prognosis. Epigenetic and (post-)transcriptional dysregulations relevant in the stabilization of NFkB, IRFs, and NLRC5 are often responsible for MHC-I downregulation in cancer. The intrinsic reversible nature of these dysregulations provides an opportunity to restore MHC-I expression and facilitate adaptive anti-tumor immunity. In this review, we provide an overview of the mechanisms underlying reversible MHC-I downregulation and describe potential strategies to counteract this reduction in MHC-I antigen presentation in cancer.

PTPN21-CDSlong isoform inhibits the response of acute lymphoblastic leukemia cells to NK-mediated lysis via the KIR/HLA-I axis

Protein tyrosine phosphatase non-receptor type 21 (PTPN21) is a member of the non-receptor tyrosine phosphatase family. We have found that PTPN21 is mutated in relapsed Philadelphia chromosome-negative acute lymphoblastic leukemia (ALL) after allogeneic hematopoietic stem cell transplantation. PTPN21 consists of three types of isoforms according to the length of the protein encoded. However, the roles of different isoforms in leukemic cells have not been elucidated. In the study, PTPN21 isoform constitution in five ALL cell lines were identified by transcriptome polymerase chain reaction combined with Sanger sequencing, and the relationship between PTPN21 isoforms and sensitivity to natural killer (NK) cells mediated killing in ALL cell lines were further assessed by knock-out of different isoforms of PTPN21 using CRISPR-Cas9 technique. Subsequently, we explored the functional mechanisms through RNA sequencing and confirmatory testing. The results showed that there was no significant change when all PTPN21 isoforms were knocked out in ALL cells, but the sensitivity of NALM6 cells with PTPN21-CDS_long knock-out (NALM6-PTPN21_lk ) to NK-mediated killing was significantly increased. Whole transcriptome sequencing and further validation testing showed that human leukocyte antigen class I (HLA-I) molecules were significantly decreased, accompanied by a significantly downregulated expression of antigen presenting-related chaperones in NALM6-PTPN21_lk cells. Our results uncovered a previously unknown mechanism that PTPN21-CDS_long and CDS_short isoforms may play opposite roles in NK-mediated killing in ALL cells, and showed that the endogenous PTPN21-CDS_long isoform inhibited ALL cells to NK cell-mediated lysis by regulating the KIR-HLA-I axis.

Targeting SHP2 as a promising strategy for cancer immunotherapy

Src homology-2-containing protein tyrosine phosphatase 2 (SHP2) is a major phosphatase involved in several cellular processes. In recent years, SHP2 has been the focus of significant attention in human diseases, particular in cancer. Several studies have shown that SHP2 plays an important role in regulating immune cell functions in tumor microenvironment. A few clinical trials conducted using SHP2 allosteric inhibitors have shown remarkable anti-tumor benefits and good safety profiles. This review focuses on the current understanding of the regulation of SHP2 and highlights the vital roles of SHP2 in T lymphocytes, macrophages and cancer cells. It also summarizes the current development of SHP2 inhibitors as a promising strategy for cancer immunotherapy.

Tumour Microenvironment and Immune Evasion in EGFR Addicted NSCLC: Hurdles and Possibilities

In the last few years, the treatment strategy in Non-Small Cell Lung Cancer (NSCLC) patients has been heavily modified by the introduction of the immune-checkpoint inhibitors. Anti-programmed cell death 1/programmed cell death ligand 1 (PD-1/PD-L1) therapy has improved both progression-free and the overall survival in almost all subgroups of patients, with or without PDL1 expression, with different degrees of responses. However, there are patients that are not benefitting from this treatment. A defined group of immune-checkpoint inhibitors non-responder tumours carry EGFR (epidermal growth factor receptor) mutations: nowadays, anti-PD-1/PD-L1 clinical trials often do not involve this type of patient and the use of immune-checkpoint inhibitors are under evaluation in this setting. Our review aims to elucidate the mechanisms underlying this resistance: we focused on evaluating the role of the tumour microenvironment, including infiltrating cells, cytokines, secreted factors, and angiogenesis, and its interaction with the tumour tissue. Finally, we analysed the possible role of immunotherapy in EGFR mutated tumours.

Phosphoinositide 3-Kinase Signaling Can Modulate MHC Class I and II Expression

Molecular events activating the PI3K pathway are frequently detected in human tumors and the activation of PI3K signaling alters numerous cellular processes including tumor cell proliferation, survival, and motility. More recent studies have highlighted the impact of PI3K signaling on the cellular response to interferons and other immunologic processes relevant to antitumor immunity. Given the ability of IFNγ to regulate antigen processing and presentation and the pivotal role of MHC class I (MHCI) and II (MHCII) expression in T-cell-mediated antitumor immunity, we sought to determine the impact of PI3K signaling on MHCI and MHCII induction by IFNγ. We found that the induction of cell surface MHCI and MHCII molecules by IFNγ is enhanced by the clinical grade PI3K inhibitors dactolisib and pictilisib. We also found that PI3K inhibition increases STAT1 protein levels following IFNγ treatment and increases accessibility at genomic STAT1-binding motifs. Conversely, we found that pharmacologic activation of PI3K signaling can repress the induction of MHCI and MHCII molecules by IFNγ, and likewise, the loss of PTEN attenuates the induction of MHCI, MHCII, and STAT1 by IFNγ. Consistent with these in vitro studies, we found that within human head and neck squamous cell carcinomas, intratumoral regions with high phospho-AKT IHC staining had reduced MHCI IHC staining. IMPLICATIONS: Collectively, these findings demonstrate that MHC expression can be modulated by PI3K signaling and suggest that activation of PI3K signaling may promote immune escape via effects on antigen presentation.

Fractionated ionizing radiation facilitates interferon-γ signaling and anticancer activity in lung adenocarcinoma cells

Fractionated ionizing radiation (FIR) is a radiotherapy regimen that is regularly performed as part of lung cancer treatment. In contrast to the growth inhibition caused by DNA damage, immunomodulation in post-irradiated cancer cells is not well documented. Interferon (IFN)-γ confers anticancer activity by triggering both growth inhibition and cytotoxicity. This study investigated the priming effects of FIR with immunomodulation on the anticancer IFN-γ. Cell morphology, cell growth, and cytotoxicity were observed in FIR-treated A549 lung adenocarcinoma. Induction of p53 and epithelial-mesenchymal transition (EMT) were monitored. Following FIR, activation of IFN-γ signaling pathways were detected. FIR caused changes in cell morphology, inhibited cell growth, and induced cytotoxicity. While p53 was induced by FIR, no epithelial-mesenchymal transition could be found. Following IFN-γ stimulation, FIR-induced p53-associated cell cytotoxicity was significantly enhanced. Additionally, FIR increased the downstream response to IFN-γ by facilitating IFN-γ-induced signal transducer and activator of transcription 1 (STAT1) signaling without affecting the receptor expression. FIR-facilitated STAT1 activation through the mechanism involving mitogen-activated protein kinase activation and Src-homology 2 domain-containing tyrosine phosphatase 2 inactivation. These results demonstrate the FIR-facilitated IFN-γ signaling and its anticancer activity.

How patients with an intact immune system develop head and neck cancer

Although the adaptive immune system can detect and eliminate malignant cells, patients with intact and fully functional immune systems develop head and neck cancer. How is this paradox explained? Manuscripts published in the English language from 1975 to 2018 were reviewed using search inputs related to tumor cell antigenicity and immunogenicity, immunodominance, cancer immunoediting and genomic alterations present within carcinomas. Early in tumor development, T cell responses to immunodominant antigens may lead to the elimination of cancer cells expressing these antigens and a tumor composed to tumor cells expressing only immunorecessive antigens. Conversely, other tumor cells may acquire genomic or epigenetic alterations that result in an antigen processing or presentation defect or other inability to be detected or killed by T cells. Such T cell insensitive tumor cells may also be selected for in a progressing tumor. Tumors harboring subpopulations of cells that cannot be eliminated by T cells may require non-T cell-based treatments, such as NK cell immunotherapies. Recognition of such tumor cell populations within a heterogeneous cancer may inform the selection of treatment for HNSCC in the future.

Role of Tumor-Associated Macrophages in the Clinical Course of Pancreatic Neuroendocrine Tumors (PanNETs)

PURPOSE

This study evaluated the potential role of immune cells and molecules in the pathogenesis and clinical course of pancreatic neuroendocrine tumors (PanNET).

EXPERIMENTAL DESIGN

Surgically resected PanNETs (N = 104) were immunohistochemically analyzed for Ki67 index, mitotic rate, macrophage, CD4⁺ cells, and CD8⁺ T-cell infiltration, as well as HLA class I, PD-L1, and B7-H3 expression. Results were correlated with clinicopathologic characteristics as well as with disease-free (DFS) and disease-specific (DSS) survival.

RESULTS

The median age of the 57 WHO grade 1 and 47 WHO grade 2 patients was 55 years. High intratumoral CD8⁺ T-cell infiltration correlated with prolonged DFS (P = 0.05), especially when the number of tumor-associated macrophages (TAM) was low. In contrast, high peritumoral CD4⁺ cell and TAM infiltration was associated with a worse DFS and DSS. PD-L1 and B7-H3 were expressed in 53% and 78% PanNETs, respectively. HLA class I expression was defective in about 70% PanNETs. HLA-A expression correlated with favorable DSS in PD-L1-negative tumors (P = 0.02). TAM infiltration (P = 0.02), WHO grade (P = 0.04), T stage (P = 0.01), and lymph node positivity (P = 0.04) were independent predictors of DFS. TAM infiltration (P = 0.026) and T stage (P = 0.012) continued to be predictors of DFS in WHO grade 1 PanNET patients. TAM infiltration was the sole independent predictor of DSS for WHO grade 1 and 2 patients (P = 0.02). Therefore, this biomarker may contribute to identifying WHO grade 1 patients with poor prognosis.

CONCLUSIONS

TAM infiltration appears to be the most informative prognostic biomarker in PanNET. It may represent a useful immunotherapeutic target in patients with PanNET.

Tailoring cells for clinical needs: Meeting report from the Advanced Therapy in Healthcare symposium (October 28-29 2017, Doha, Qatar)

New technologies and therapies designed to facilitate development of personalized treatments are rapidly emerging in the field of biomedicine. Strikingly, the goal of personalized medicine refined the concept of therapy by developing cell-based therapies, the so-called “living drugs”. Breakthrough advancements were achieved in this regard in the fields of gene therapy, cell therapy, tissue-engineered products and advanced therapeutic techniques. The Advanced Therapies in Healthcare symposium, organized by the Clinical Research Center Department of Sidra Medicine, in Doha, Qatar (October 2017), brought together world-renowned experts from the fields of oncology, hematology, immunology, inflammation, autoimmune disorders, and stem cells to offer a comprehensive picture of the status of worldwide advanced therapies in both pre-clinical and clinical development, providing insights to the research phase, clinical data and regulatory aspects of these therapies. Highlights of the meeting are provided in this meeting report.

Protein Tyrosine Phosphatases as Potential Regulators of STAT3 Signaling

The signal transducer and activator of transcription 3 (STAT3) protein is a major transcription factor involved in many cellular processes, such as cell growth and proliferation, differentiation, migration, and cell death or cell apoptosis. It is activated in response to a variety of extracellular stimuli including cytokines and growth factors. The aberrant activation of STAT3 contributes to several human diseases, particularly cancer. Consequently, STAT3-mediated signaling continues to be extensively studied in order to identify potential targets for the development of new and more effective clinical therapeutics. STAT3 activation can be regulated, either positively or negatively, by different posttranslational mechanisms including serine or tyrosine phosphorylation/dephosphorylation, acetylation, or demethylation. One of the major mechanisms that negatively regulates STAT3 activation is dephosphorylation of the tyrosine residue essential for its activation by protein tyrosine phosphatases (PTPs). There are seven PTPs that have been shown to dephosphorylate STAT3 and, thereby, regulate STAT3 signaling: PTP receptor-type D (PTPRD), PTP receptor-type T (PTPRT), PTP receptor-type K (PTPRK), Src homology region 2 (SH-2) domain-containing phosphatase 1(SHP1), SH-2 domain-containing phosphatase 2 (SHP2), MEG2/PTP non-receptor type 9 (PTPN9), and T-cell PTP (TC-PTP)/PTP non-receptor type 2 (PTPN2). These regulators have great potential as targets for the development of more effective therapies against human disease, including cancer.

Engineering Vaccines to Reprogram Immunity against Head and Neck Cancer

The recent Food and Drug Administration's approval of monoclonal antibodies targeting immune checkpoint receptors (ICRs) for recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) offers exciting promise to improve patient outcome and reduce morbidities. A favorable response to ICR blockade relies on an extensive collection of preexisting tumor-specific T cells in the tumor microenvironment (TME). ICR blockade reinvigorates exhausted CD8+ T cells and enhances immune killing. However, resistance to ICR blockade is observed in about 85% of patients with HNSCC, therefore highlighting the importance of characterizing the mechanisms underlying HNSCC immune escape and exploring combinatorial strategies to sensitize hypoimmunogenic cold HNSCC to ICR inhibition. Cancer vaccines are designed to bypass the cold TME and directly deliver cancer antigens to antigen-presenting cells (APCs); these vaccines epitomize a priming strategy to synergize with ICR inhibitors. Cancer cells are ineffective antigen presenters, and poor APC infiltration as well as the M2-like polarization in the TME further dampens antigen uptake and processing, both of which render ineffective innate and adaptive immune detection. Cancer vaccines directly activate APC and expand the tumor-specific T-cell repertoire. In addition, cancer vaccines often contain an adjuvant, which further improves APC function, promotes epitope spreading, and augments host intrinsic antitumor immunity. Thus, the vaccine-induced immune priming generates a pool of effectors whose function can be enhanced by ICR inhibitors. In this review, we summarize the major HNSCC immune evasion strategies, the ongoing effort toward improving HNSCC vaccines, and the current challenges limiting the efficacy of cancer vaccines.

A novel bispecific antibody for EGFR-directed blockade of the PD-1/PD-L1 immune checkpoint

PD-L1-blocking antibodies produce significant clinical benefit in selected cancer patients by reactivating functionally-impaired antigen-experienced anticancer T cells. However, the efficacy of current PD-L1-blocking antibodies is potentially reduced by ‘on-target/off-tumor’ binding to PD-L1 widely expressed on normal cells. This lack of tumor selectivity may induce a generalized activation of all antigen-experienced T cells which may explain the frequent occurrence of autoimmune-related adverse events during and after treatment.

To address these issues, we constructed a bispecific antibody (bsAb), designated PD-L1xEGFR, to direct PD-L1-blockade to EGFR-expressing cancer cells and to more selectively reactivate anticancer T cells. Indeed, the IC50 of PD-L1xEGFR for blocking PD-L1 on EGFR⁺ cancer cells was ∼140 fold lower compared to that of the analogous PD-L1-blocking bsAb PD-L1xMock with irrelevant target antigen specificity. Importantly, activation status, IFN-γ production, and oncolytic activity of anti-CD3xanti-EpCAM-redirected T cells was enhanced when cocultured with EGFR-expressing carcinoma cells. Similarly, the capacity of PD-L1xEGFR to promote proliferation and IFN-γ production by CMVpp65-directed CD8⁺ effector T cells was enhanced when cocultured with EGFR-expressing CMVpp65-transfected cancer cells. In contrast, the clinically-used PD-L1-blocking antibody MEDI4736 (durvalumab) promoted T cell activation indiscriminate of EGFR expression on cancer cells. Additionally, in mice xenografted with EGFR-expressing cancer cells ¹¹¹In-PD-L1xEGFR showed a significantly higher tumor uptake compared to ¹¹¹In-PD-L1xMock. In conclusion, PD-L1xEGFR blocks the PD-1/PD-L1 immune checkpoint in an EGFR-directed manner, thereby promoting the selective reactivation of anticancer T cells. This novel targeted approach may be useful to enhance efficacy and safety of PD-1/PD-L1 checkpoint blockade in EGFR-overexpressing malignancies.

T lymphocyte SHP2-deficiency triggers anti-tumor immunity to inhibit colitis-associated cancer in mice

Nonresolving inflammation is involved in the initiation and progression process of tumorigenesis. Src homology 2 domain-containing tyrosine phosphatase 2 (SHP2) is known to inhibit acute inflammation but its role in chronic inflammation-associated cancer remains unclear. The role of SHP2 in T cells in dextran sulfate sodium (DSS)-induced colitis and azoxymethane-DSS-induced colitis-associated carcinogenesis was examined using SHP2^CD4−/− conditional knockout mice. SHP2 deficiency in T cells aggravated colitis with increased level of pro-inflammatory cytokines including IFN-γ and IL-17A. In contrast, the SHP2^CD4−/− mice developed much fewer and smaller tumors than wild type mice with higher level of IFN-γ and enhanced cytotoxicity of CD8⁺ T cells in the tumor and peritumoral areas. At the molecular level, STAT1 was hyper-phosphorylated in T cells lacking SHP2, which may account for the increased Th1 differentiation and IFN-γ secretion. IFN-γ neutralization or IFN-γ receptor knockout but not IL-17A neutralization, abrogated the anti-tumor effect of SHP2 knockout with lowered levels of perforin 1, FasL and granzyme B. Finally, the expression of granzyme B was negatively correlated with the malignancy of colon cancer in human patients. In conclusion, these findings suggest a new strategy to treat colitis-associated cancer via targeting SHP2.

Cisplatin Alters Antitumor Immunity and Synergizes with PD-1/PD-L1 Inhibition in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) has been treated for decades with cisplatin chemotherapy, and anti-PD-1 immunotherapy has recently been approved for the treatment of this disease. However, preclinical studies of how antitumor immunity in HNSCC is affected by cisplatin alone or in combination with immunotherapies are lacking. Here, we show that sublethal doses of cisplatin may enhance antigen presentation and T-cell killing in vitro, though cisplatin also upregulates tumor cell expression of PD-L1 and may impair T-cell function at higher doses. In a syngeneic mouse model of HNSCC, concurrent use of cisplatin and anti-PD-L1/PD-1 delayed tumor growth and enhanced survival without significantly reducing the number or function of tumor-infiltrating immune cells or increasing cisplatin-induced toxicities. These results suggest that moderate doses of cisplatin may enhance antitumor immunity by mechanisms other than direct tumor cell killing, which may be further enhanced by anti-PD-L1/PD-1 therapy. Cancer Immunol Res; 5(12); 1141-51. ©2017 AACR.

Shp2 regulates migratory behavior and response to EGFR-TKIs through ERK1/2 pathway activation in non-small cell lung cancer cells

In the clinical treatment of lung cancer, therapy failure is mainly caused by cancer metastasis and drug resistance. Here, we investigated whether the tyrosine phosphatase Shp2 is involved in the development of metastasis and drug resistance in non-small cell lung cancer (NSCLC). Shp2 was overexpressed in a subset of lung cancer tissues, and Shp2 knockdown in lung cancer cells inhibited cell proliferation and migration, downregulated c-Myc and fibronectin expression, and upregulated E-cadherin expression. In H1975 cells, which carry double mutations (L858R + T790M) in epidermal growth factor receptor (EGFR) that confers resistance toward the tyrosine kinase inhibitor gefitinib, Shp2 knockdown increased cellular sensitivity to gefitinib; conversely, in H292 cells, which express wild-type EGFR and are sensitive to gefitinib, Shp2 overexpression increased cellular resistance to gefitinib. Moreover, by overexpressing Shp2 or using U0126, a small-molecule inhibitor of extracellular signal-regulated kinase 1/2 (ERK1/2), we demonstrated that Shp2 inhibited E-cadherin expression and enhanced the expression of fibronectin and c-Myc through activation of the ERK1/2 pathway. Our findings reveal that Shp2 is overexpressed in clinical samples of NSCLC and that Shp2 knockdown reduces the proliferation and migration of lung cancer cells, and further suggest that co-inhibition of EGFR and Shp2 is an effective approach for overcoming EGFR T790M mutation acquired resistance to EGFR tyrosine kinase inhibitors (TKIs). Thus, we propose that Shp2 could serve as a new biomarker in the treatment of NSCLC.

Reversing EGFR Mediated Immunoescape by Targeted Monoclonal Antibody Therapy

Uncontrolled growth is a signature of carcinogenesis, in part mediated by overexpression or overstimulation of growth factor receptors. The epidermal growth factor receptor (EGFR) mediates activation of multiple oncogenic signaling pathways and escape from recognition by the host immune system. We discuss how EGFR signaling downregulates tumor antigen presentation, upregulates suppressive checkpoint receptor ligand programmed death ligand (PD-L1), induces secretion of inhibitory molecules such as transforming growth factor beta (TGFβ) and reprograms the metabolic pathways in cancer cells to upregulate aerobic glycolysis and lactate secretion that ultimately lead to impaired cellular immunity mediated by natural killer (NK) cell and cytotoxic T lymphocytes (CTL). Ultimately, our understanding of EGFR-mediated escape mechanisms has led us to design EGFR-specific monoclonal antibody therapies that not only inhibit tumor cell metabolic changes and intrinsic oncogenic signaling but also activates immune cells that mediate tumor clearance. Importantly, targeted immunotherapy may also benefit from combination with antibodies that target other immunosuppressive pathways such PD-L1 or TGFβ and ultimately enhance clinical efficacy.

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.

Oncogenic growth factor signaling mediating tumor escape from cellular immunity

Unrestrained growth factor signals can promote carcinogenesis, as well as other hallmarks of cancer such as immune evasion. Our understanding of the function and complex regulation of HER family of receptors has led to the development of targeted therapeutic agents that suppress tumor growth. However, these receptors also mediate escape from recognition by the host immune system. We discuss how HER family of oncogenic receptors downregulate tumor antigen presentation and upregulate suppressive membrane-bound or soluble secreted inhibitory molecules that ultimately lead to impaired cellular immunity mediated by cytotoxic T lymphocyte (CTL) recognition. Implementing this knowledge into new therapeutic strategies to enhance tumor immunogenicity may restore effector cell mediated immune clearance of tumors and clinical efficacy of tumor-targeted immunotherapy against HER receptor overexpression.

SHP2 phosphatase as a novel therapeutic target for melanoma treatment

Melanoma ranks among the most aggressive and deadly human cancers. Although a number of targeted therapies are available, they are effective only in a subset of patients and the emergence of drug resistance often reduces durable responses. Thus there is an urgent need to identify new therapeutic targets and develop more potent pharmacological agents for melanoma treatment. Herein we report that SHP2 levels are frequently elevated in melanoma, and high SHP2 expression is significantly associated with more metastatic phenotype and poorer prognosis. We show that SHP2 promotes melanoma cell viability, motility, and anchorage-independent growth, through activation of both ERK1/2 and AKT signaling pathways. We demonstrate that SHP2 inhibitor 11a-1 effectively blocks SHP2-mediated ERK1/2 and AKT activation and attenuates melanoma cell viability, migration and colony formation. Most importantly, SHP2 inhibitor 11a-1 suppresses xenografted melanoma tumor growth, as a result of reduced tumor cell proliferation and enhanced tumor cell apoptosis. Taken together, our data reveal SHP2 as a novel target for melanoma and suggest SHP2 inhibitors as potential novel therapeutic agents for melanoma treatment.

A dual specificity kinase, DYRK1A, as a potential therapeutic target for head and neck squamous cell carcinoma

Despite advances in clinical management, 5-year survival rate in patients with late-stage head and neck squamous cell carcinoma (HNSCC) has not improved significantly over the past decade. Targeted therapies have emerged as one of the most promising approaches to treat several malignancies. Though tyrosine phosphorylation accounts for a minority of total phosphorylation, it is critical for activation of signaling pathways and plays a significant role in driving cancers. To identify activated tyrosine kinase signaling pathways in HNSCC, we compared the phosphotyrosine profiles of a panel of HNSCC cell lines to a normal oral keratinocyte cell line. Dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (DYRK1A) was one of the kinases hyperphosphorylated at Tyr-321 in all HNSCC cell lines. Inhibition of DYRK1A resulted in an increased apoptosis and decrease in invasion and colony formation ability of HNSCC cell lines. Further, administration of the small molecular inhibitor against DYRK1A in mice bearing HNSCC xenograft tumors induced regression of tumor growth. Immunohistochemical labeling of DYRK1A in primary tumor tissues using tissue microarrays revealed strong to moderate staining of DYRK1A in 97.5% (39/40) of HNSCC tissues analyzed. Taken together our results suggest that DYRK1A could be a novel therapeutic target in HNSCC.

Immunological and clinical significance of HLA class I antigen processing machinery component defects in malignant cells

Experimental as well as clinical studies demonstrate that the immune system plays a major role in controlling generation and progression of tumors. The cancer immunoediting theory supports the notion that tumor cell immunogenicity is dynamically shaped by the immune system, as it eliminates immunogenic tumor cells in the early stage of the disease and then edits their antigenicity. The end result is the generation of a tumor cell population able to escape from immune recognition and elimination by tumor infiltrating lymphocytes. Two major mechanisms, which affect the target cells and the effector phase of the immune response, play a crucial role in the editing process. One is represented by the downregulation of tumor antigen (TA) processing and presentation because of abnormalities in the HLA class I antigen processing machinery (APM). The other one is represented by the anergy of effector immune infiltrates in the tumor microenvironment caused by aberrant inhibitory signals triggered by immune checkpoint receptor (ICR) ligands, such as programmed death ligand-1 (PD-L1). In this review, we will focus on tumor immune escape mechanisms caused by defects in HLA class I APM component expression and/or function in different types of cancer, with emphasis on head and neck cancer (HNC). We will also discuss the immunological implications and clinical relevance of these HLA class I APM abnormalities. Finally, we will describe strategies to counteract defective TA presentation with the expectation that they will enhance tumor recognition and elimination by tumor infiltrating effector T cells.

Changing the paradigm: the potential for targeted therapy in laryngeal squamous cell carcinoma

Laryngeal squamous cell carcinoma (LSCC) remains a highly morbid and fatal disease. Historically, it has been a model example for organ preservation and treatment stratification paradigms. Unfortunately, survival for LSCC has stagnated over the past few decades. As the era of next-generation sequencing and personalized treatment for cancer approaches, LSCC may be an ideal disease for consideration of further treatment stratification and personalization. Here, we will discuss the important history of LSCC as a model system for organ preservation, unique and potentially targetable genetic signatures of LSCC, and methods for bringing stratified, personalized treatment strategies to the 21(st) century.

Expression and prognosis value of SHP2 in patients with pancreatic ductal adenocarcinoma

SHP2 is an src homology (SH) 2 domain-containing protein tyrosine phosphatase (PTP). SHP2 implicitly contributes to tumorigenesis, but the role of SHP2 in pancreatic ductal adenocarcinoma is still unknown. The purpose of this study was to evaluate the prognostic significance and associated expression of SHP2 in pancreatic ductal adenocarcinoma (PDAC) patients. We used immunohistochemistry to assess the protein expression levels of SHP2 in 79 PDAC specimens. The correlations between SHP2 expression and various clinicopathological features were evaluated by Pearson's chi-square (χ (2)) test, Fisher's exact test, and Spearman's rank. Univariate and multivariate Cox regression analyses were used to identify correlations between the immunohistochemical data for SHP2 expression and the clinicopathologic characteristics in PDAC. Kaplan-Meier survival analysis was used to demonstrate the relation between overall survival and the expression of SHP2. Immunohistochemistry revealed significantly higher rates of high SHP2 expression in PDAC tissues (55.7 %) versus adjacent non-cancer tissues (10.1 %) (P < 0.05). Expression of SHP2 was only significantly correlated with histological differentiation (P = 0.033) and vital status (P = 0.025). Patients with high SHP2 expression had shorter overall survival times compared to those with low SHP2 expression (P = 0.000). Multivariate Cox regression analysis revealed that SHP2 overexpression was an independent prognostic factor in PDAC (P = 0.012). Our study demonstrated for the first time that higher expression of SHP2 might be involved in the progression of pancreatic ductal adenocarcinoma, suggesting that SHP2 may be a potential prognostic marker and target for therapy.

Identification of the Cell-Intrinsic and -Extrinsic Pathways Downstream of EGFR and IFNγ That Induce PD-L1 Expression in Head and Neck Cancer

Many cancer types, including head and neck cancers (HNC), express programmed death ligand 1 (PD-L1). Interaction between PD-L1 and its receptor, programmed death 1 (PD-1), inhibits the function of activated T cells and results in an immunosuppressive microenvironment, but the stimuli that induce PD-L1 expression are not well characterized. Interferon gamma (IFNγ) and the epidermal growth factor receptor (EGFR) utilize Janus kinase 2 (JAK2) as a common signaling node to transmit tumor cell-mediated extrinsic or intrinsic signals, respectively. In this study, we investigated the mechanism by which these factors upregulate PD-L1 expression in HNC cells in the context of JAK/STAT pathway activation, Th1 inflammation, and HPV status. We found that wild-type, overexpressed EGFR significantly correlated with JAK2 and PD-L1 expression in a large cohort of HNC specimens. Furthermore, PD-L1 expression was induced in an EGFR- and JAK2/STAT1-dependent manner, and specific JAK2 inhibition prevented PD-L1 upregulation in tumor cells and enhanced their immunogenicity. Collectively, our findings suggest a novel role for JAK2/STAT1 in EGFR-mediated immune evasion, and therapies targeting this signaling axis may be beneficial to block PD-L1 upregulation found in a large subset of HNC tumors.

The good and the bad faces of STAT1 in solid tumours

Signal transducer and activator of transcription (STAT) 1 is part of the Janus kinase (JAK)/STAT signalling cascade and is best known for its essential role in mediating responses to all types of interferons (IFN). STAT1 regulates a variety of cellular processes, such as antimicrobial activities, cell proliferation and cell death. It exerts important immune modulatory activities both in the innate and the adaptive arm of the immune system. Based on studies in mice and data from human patients, STAT1 is generally considered a tumour suppressor but there is growing evidence that it can also act as a tumour promoter. This review aims at contrasting the two faces of STAT1 in tumourigenesis and providing an overview on the current knowledge of the underlying mechanisms or pathways.

Immunology and Immunotherapy of Head and Neck Cancer

The immune system plays a key role in the development, establishment, and progression of head and neck squamous cell carcinoma (HNSCC). A greater understanding of the dysregulation and evasion of the immune system in the evolution and progression of HNSCC provides the basis for improved therapies and outcomes for patients. HNSCC cells evade the host immune system through manipulation of their own immunogenicity, production of immunosuppressive mediators, and promotion of immunomodulatory cell types. Through the tumor's influence on the microenvironment, the immune system can be exploited to promote metastasis, angiogenesis, and growth. This article provides a brief overview of key components of the immune infiltrating cells in the tumor microenvironment, reviewing immunological principles related to head and neck cancer, including the concept of cancer immunosurveillance and immune escape. Current immunotherapeutic strategies and emerging results from ongoing clinical trials are presented.