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STAT3 signaling has been shown to regulate cellular function and cytokine production in the tumor microenvironment (TME). Within the head and neck squamous cell carcinoma (HNSCC) TME, we previously showed that therapeutic targeting of STAT3 in combination with radiation resulted in improved tumor growth delay. However, given the independent regulatory effects STAT3 has on anti-tumor immunity, we aimed to decipher the effects of individually targeting STAT3 in the cancer cell, regulatory T cells (Tregs), and natural killer (NK) cell compartments in driving tumor growth and resistance to therapy in HNSCCs. We utilized a CRISPR knockout system for genetic deletion of STAT3 within the cancer cell as well as two genetic knockout mouse models, FoxP3-Cre/STAT3 fl and NKp46-Cre/STAT3 fl, for Tregs and NK cell targeting, respectively. Our data revealed differences in development of resistance to treatment with STAT3 CRISPR knockout in the cancer cell, driven by differential recruitment of immune cells. Knockout of STAT3 in Tregs overcomes this resistance and results in Treg reprogramming and recruitment and activation of antigen-presenting cells. In contrast, knockout of STAT3 in the NK cell compartment results in NK cell inactivation and acceleration of tumor growth. These data underscore the complex interplay between the cancer cell and the immune TME and carry significant implications for drug targeting and design of combination approaches in HNSCCs.

EphB3 knockdown does not affect cell viability but enhances cell migration in LY2 cell line.

EphB3 and PI3 Kinase p110α are variably expressed in human HNSCC cells.

Eph proteins have emerged as critical drivers affecting tumor growth and progression in human malignancies. Our The Cancer Genome Atlas (TCGA) data analysis showed that EphB3, a receptor tyrosine kinase, is frequently coamplified with PIK3CA in head and neck squamous cell carcinoma (HNSCC). We therefore hypothesized that EphB3 amplification plays a protumorigenic role in HNSCC and that EphB3 and PIK3CA are cooperating oncogenes that contribute toward its pathogenesis. This hypothesis was not experimentally supported, because EphB3 knockdown failed to alter HNSCC tumor cell growth in vitro or in vivo with an orthotopic model. However, responsiveness of EphB3 knockdown tumors to the PI3K inhibitor, BKM120, was significantly decreased in terms of both tumor growth delay and survival. This is correlated with an increase in prosurvival proteins, S6 and BcL-XL, in the EphB3 shRNA tumors treated with BKM120 compared with controls. We further observed that EphB3 knockdown resulted in increased migration in vitro and increased EMT gene signature in vivo. To explain these results, we examined EphB3 phosphorylation levels in HNSCC at baseline. Although total EphB3 levels were high, we found low phospho-EphB3 levels in HNSCCs. Forced EphB3 phosphorylation with an ephrin-B2–Fc fusion protein resulted in decreased HNSCC migration and cell growth, and enhanced response to BKM120 in vitro. These data collectively indicate that progression of HNSCC selects for low/inhibited EphB3 activity to enhance their survival and migratory abilities and decrease response to PI3K signaling. Therefore, strategies focused on activating EphB3 might be helpful to inhibit tumor growth and enhance sensitivity to PI3K inhibitors in HNSCC. Mol Cancer Ther; 17(9); 2049–59. ©2018 AACR.

Microarray analysis showing EphB3 levels in different tumor cell lines

Total number of CD4+T cells remain unchanged following Control-Fc and ephrin-B2-Fc (20 μg/ml) treatment of T cells (A). Correlation analysis was also performed between TGF-β and EFNB2, EphB4 on R2 analysis platform (B-C). Alterations of cell growth and survival markers in western blots performed using lysates of T cells treated with ephrin-B2-Fc and control-Fc (D). These samples were run on the same gel.

Mice implanted with PDX tumors show significantly reduced uptake of supra-paramagnetic iron oxide nanoparticles (SPIO) in the combined sEphB4-HSA and RT group compared to the groups treated with RT alone or with sEphB4-HSA alone in DCE-MRI imaging (A-B). Delta T2 represents magnitude of decrease in T2 signal. One-way ANOVA was used to calculate the significance of the differences between groups. CIBERSORT analysis of a HNSCC TCGA dataset shows that patients with low M2:M1 ratio have improved overall survival (C) and disease-free survival (D). Analysis of HNSCC TCGA showing correlation between M2-related marker-HRH1 and ephrin-B2 (EFNB2) (E), EphB4 (F).

Immunofluorescence staining showing co-expression of EphB4 and pan-keratin in Ly2 tumors.

Purpose: Radiotherapy (RT) can transform the immune landscape and render poorly immunogenic tumors sensitive to PD-L1 inhibition. Here, we established that the response to combined RT and PD-L1 inhibition is transient and investigated mechanisms of resistance.Experimental Design: Mechanisms of resistance to RT and PD-L1 blockade were investigated in orthotopic murine head and neck squamous cell carcinoma (HNSCC) tumors using mass cytometry and whole-genome sequencing. Mice were treated with anti–PD-L1 or anti–TIM-3 alone and in combination with and without RT. Tumor growth and survival were assessed. Flow cytometry was used to assess phenotypic and functional changes in intratumoral T-cell populations. Depletion of regulatory T cells (Treg) was performed using anti-CD25 antibody.Results: We show that the immune checkpoint receptor, TIM-3, is upregulated on CD8 T cells and Tregs in tumors treated with RT and PD-L1 blockade. Treatment with anti–TIM-3 concurrently with anti–PD-L1 and RT led to significant tumor growth delay, enhanced T-cell cytotoxicity, decreased Tregs, and improved survival in orthotopic models of HNSCC. Despite this treatment combination, the response was not durable, and analysis of relapsed tumors revealed resurgence of Tregs. Targeted Treg depletion, however, restored antitumor immunity in mice treated with RT and dual immune checkpoint blockade and resulted in tumor rejection and induction of immunologic memory.Conclusions: These data reveal multiple layers of immune regulation that can promote tumorigenesis and the therapeutic potential of sequential targeting to overcome tumor resistance mechanisms. We propose that targeted Treg inhibitors may be critical for achieving durable tumor response with combined radiotherapy and immunotherapy. Clin Cancer Res; 24(21); 5368–80. ©2018 AACR.

IHC staining confirming expression of ephrin-B2 in areas stained with fibroblast-expressing α-Smooth muscle actin (α-SMA)

Blockade of EphB4-ephrin-B2 interaction combined with RT suppresses tumor growth in HNSCC tumors

Blockade of EphB4-ephrin-B2 enhances response to EGFR inhibitor (cetuximab) and RT resulting in significant delay in tumor growth and enhanced survival in HNSCC PDX models. Tumor growth volumes are displayed in CUHN013 (A) and CUHN004 (B) tumors including cisplatin-RT treated groups in the absence and presence of sEphB4-HSA. Cisplatin-RT treated groups did not show any significant changes in tumor growth in the absence and presence of sEphB4-HSA in CUHN013 tumors. Survival graphs are shown for CUHN013 (C) and CUHN004 (D) tumors.

(A) ELISA assay measuring the concentration of TNYL-RAW-Fc protein in plasma 7 days after hydrodynamic injection of the TNYL-RAW-Fc plasmid. Data represent mean {plus minus} SD from measurements using different mice (n=2). (B) Inhibition of EphB4-ephrin-B2 signaling by TNYL-RAW-Fc does not affect immune cell populations in the circulation of Ly2 tumor-bearing mice.

qPCR analysis shows elevated expression of EphB4 on intratumoral macrophages harvested from Ly2 tumors compared to ephrin-B2.

Systemic depletion of CD8+ T cells results in increased tumor growth in Ly2 tumors treated with TNYL-RAW-Fc (A). Confirmation of CD8+ T cell depletion by flow cytometry (B). Student's t-test or one-way ANOVA was used to calculate the significance of the differences between the groups.

Schema Utilizing Time-to-Event Continual Reassessment Method (TITE-CRM) Design

Levels of EGFR expression in HNSCC PDX tumors

Purpose: The clinical success of targeted therapies such as cetuximab and radiotherapy (RT) is hampered by the low response rates and development of therapeutic resistance. In the current study, we investigated the involvement of EphB4–ephrin-B2 protumorigenic signaling in mediating resistance to EGFR inhibition and RT in head and neck cancers.Experimental Design: We used patient-derived xenograft (PDX) models of head and neck squamous cell carcinoma (HNSCC) and HNSCC cell lines to test our hypothesis. Tumor tissues were subjected to PhosphoRTK array, and Western blotting to detect changes in EphB4–ephrin-B2 targets. mRNA sequencing and microarray data analysis were performed on PDX tumors and HNSCC cell lines, respectively, to determine differences in gene expression of molecules involved in tumor cell growth, proliferation, and survival pathways. Effects on cell growth were determined by MTT assay on HNSCC cells downregulated for EphB4/ephrin-B2 expression, with and without EGFR inhibitor and radiation.Results: Our data from locally advanced HNSCC patients treated with standard-of-care definitive chemo-RT show elevated EphB4 and ephrin-B2 levels after failure of treatment. We observed significant response toward cetuximab and RT following EphB4–ephrin-B2 inhibition, resulting in improved survival in tumor-bearing mice. Tumor growth inhibition was accompanied by a decrease in the levels of proliferation and prosurvival molecules and increased apoptosis.Conclusions: Our findings underscore the importance of adopting rational drug combinations to enhance therapeutic effect. Our study documenting enhanced response of HNSCC to cetuximab-RT with EphB4–ephrin-B2 blockade has the potential to translate into the clinic to benefit this patient population. Clin Cancer Res; 24(18); 4539–50. ©2018 AACR.

PURPOSE The damage caused by radiation therapy to cancerous and normal cells inevitably leads to changes in the secretome profile of pro and anti-inflammatory mediators. The inflammatory response depends on the dose of radiation and its fractionation, while the inherent radiosensitivity of each patient dictates the intensity and types of adverse reactions. This review will present an overview of two apparently opposite reactions that may occur after radiation treatment: induction of an antitumor immune response and a protumoral response. Emphasis is placed on the molecular and cellular mechanisms involved. CONCLUSIONS By understanding how radiation changes the balance between anti- and protumoral effects, these forces can be manipulated to optimize radiation oncology treatments.

Pancreatic ductal adenocarcinoma (PDAC) has a heterogeneous tumor microenvironment (TME) comprised of myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages, neutrophils, regulatory T cells, and myofibroblasts. The precise mechanisms that regulate the composition of the TME and how they contribute to radiotherapy (RT) response remain poorly understood. In this study, we analyze changes in immune cell populations and circulating chemokines in patient samples and animal models of pancreatic cancer to characterize the immune response to radiotherapy. Further, we identify STAT3 as a key mediator of immunosuppression post-RT. We found granulocytic MDSCs (G-MDSCs) and neutrophils to be increased in response to RT in murine and human PDAC samples. We also found that RT-induced STAT3 phosphorylation correlated with increased MDSC infiltration and proliferation. Targeting STAT3 using an anti-sense oligonucleotide in combination with RT circumvented RT-induced MDSC infiltration, enhanced the proportion of effector T cells, and improved response to RT. In addition, STAT3 inhibition contributed to the remodeling of the PDAC extracellular matrix when combined with RT, resulting in decreased collagen deposition and fibrotic tissue formation. Collectively, our data provide evidence that targeting STAT3 in combination with RT can mitigate the pro-tumorigenic effects of RT and improve tumor response.

The aggressive nature of glioblastoma multiforme (GBM) may be attributed to the dysregulation of pathways driving both proliferation and invasion. EphrinB2, a membrane-bound ligand for some of the Eph receptors, has emerged as a critical target regulating these pathways. In this study, we investigated the role of ephrinB2 in regulating proliferation and invasion in GBM using intracranial and subcutaneous xenograft models. The Cancer Genome Atlas analysis suggested high transcript and low methylation levels of ephrinB2 as poor prognostic indicators in GBM, consistent with its role as an oncogene. EphrinB2 knockdown, however, increased tumor growth, an effect that was reversed by ephrinB2 Fc protein. This was associated with EphB4 receptor activation, consistent with the data showing a significant decrease in tumor growth with ephrinB2 overexpression. Mechanistic analyses showed that ephrinB2 knockdown has anti-invasive but pro-proliferative effects in GBM. EphB4 stimulation following ephrinB2 Fc treatment in ephrinB2 knockdown tumors was shown to impart strong anti-proliferative and anti-invasive effects, which correlated with decrease in PCNA, p-ERK, vimentin, Snail, Fak, and increase in the E-cadherin levels. Overall, our study suggests that ephrinB2 cannot be used as a sole therapeutic target. Concomitant inhibition of ephrinB2 signaling with EphB4 activation is required to achieve maximal therapeutic benefit in GBM.

BackgroundRadiotherapy (RT) is commonly used to treat solid tumors but its efficacy varies widely. In non-virally driven head and neck cancer (HNC), radioresistance is responsible for most cases of tumor progression and tumor recurrence. The combination of RT and immunotherapy (IT), in the form of anti-PD-1/PD-L1, improved survival for a minority of patients with tumors that have pre-existing immunity or which are susceptible to RT-induced tumor immunity. In contrast, tumors with an immunosuppressive microenvironment show resistance to RT and/or IT. Regulatory T cells (Tregs) have been shown to be prevalent in HNC tumors and can promote treatment resistance. We identified the chemokine, CCL20 as a factor that can promote infiltration of Tregs into HNC tumors. CCL20 is secreted by the cancer cell and binds to its sole receptor, CCR6, expressed on Tregs. We therefore hypothesized that radiation induces CCL20 secretion resulting in infiltration of Tregs and radioresistance. We further hypothesized that blocking CCL20 in HNCs where CCL20 is induced in response to RT can decrease tumor growth.MethodsHuman and murine HNC cell lines (SCC9, Cal27, MOC1, MOC2) were irradiated at doses of 2Gy or 10Gy. Conditioned media (CM), RNA and protein were obtained 24h and 72h after radiation. The concentration of CCL20 was analyzed using a chemokine array. Gene expression was determined using qPCR. For in vivo studies, the MOC2 cell line was used. Mice were inoculated in the buccal cavity. Neutralizing CCL20 antibody was administered alone and in combination with RT. Blood samples were collected before and after RT for analysis of serum levels of CCL20.ResultsGene expression analysis showed that Cal27 and MOC2 tumors had a gene signature associated with immune-suppression and Treg cell infiltration. In contrast, SCC9 and MOC1 tumors displayed a gene signature associated with an inflamed microenvironment. In vitro, radiation induced a significant increase in CCL20 gene expression and secreted CCL20 in Cal27 and MOC2 cells relative to control. In contrast, MOC1 and SCC9 did not show a significant increase in CCL20 after radiation. In vivo, inhibition of CCL20 decreased tumor growth compared to control in MOC2 tumors. The combination of RT and anti-CCL20 showed a significant decrease in tumor growth compared to RT alone.ConclusionsCollectively, our data suggest that radiation promotes the induction of CCL20 in tumors with immune-suppressive mechanisms and inhibition of CCL20 can enhance the response to RT.Ethics ApprovalAll animal studies were conducted in accordance with the animal protection and ethics committee of the faculty of medicine at Universite de Sherbrooke (Le Comité facultaire de protection des animaux). Protocol #: 2019–2333.

Resistance to radiation therapy (RT) remains an obstacle in HPV-negative head and neck squamous cell carcinomas (HNSCCs)-even with a combined RT-immunotherapy approach. Jak-Stat proteins have long been studied for both their immune regulatory role in the host immune response as well as their cancer cell signaling role in shaping the tumor microenvironment (TME). Here, we identify STAT1 as a mediator of radioresistance in HPV-negative preclinical mouse models of HNSCC, by which knockout of STAT1 in the cancer cell (STAT1 KO)-but not in the host-resulted in decreased tumor growth alongside increased immune activation. We show that RT increases STAT1/pSTAT1 expression, which may act as a marker of radioresistance. Whereas RT increased JAK-STAT and interferon (IFN) signaling, transcriptomic analysis revealed that STAT1 KO in the cancer cell resulted in decreased expression of IFN-associated genes of resistance. In vitro experiments showed that STAT1 KO increased T cell chemoattraction and decreased baseline growth. These results indicate that STAT1 may serve a tumor-promoting role in the cancer cell and will inform biomarker development and treatment regimens for HNSCC incorporating RT.

Background Treatment for pediatric posterior fossa group A (PFA) ependymoma with gain of chromosome 1q (1q+) has not improved over the past decade owing partially to lack of clinically relevant models. We described the first 2 1q+ PFA cell lines, which have significantly enhanced our understanding of PFA tumor biology and provided a tool to identify specific 1q+ PFA therapies. However, cell lines do not accurately replicate the tumor microenvironment. Our present goal is to establish patient-derived xenograft (PDX) mouse models. Methods Disaggregated tumors from 2 1q+ PFA patients were injected into the flanks of NSG mice. Flank tumors were then transplanted into the fourth ventricle or lateral ventricle of NSG mice. Characterization of intracranial tumors was performed using imaging, histology, and bioinformatics. Results MAF-811_XC and MAF-928_XC established intracranially within the fourth ventricle and retained histological, methylomic, and transcriptomic features of primary patient tumors. We tested the feasibility of treating PDX mice with fractionated radiation or chemotherapy. Mice tolerated radiation despite significant tumor burden, and follow-up imaging confirmed radiation can reduce tumor size. Treatment with fluorouracil reduced tumor size but did not appear to prolong survival. Conclusions MAF-811_XC and MAF-928_XC are novel, authentic, and reliable models for studying 1q+ PFA in vivo. Given the successful response to radiation, these models will be advantageous for testing clinically relevant combination therapies to develop future clinical trials for this high-risk subgroup of pediatric ependymoma.

Objective Management of tracheal squamous cell carcinoma (TSCC) has been complicated by the lack of prognostic data and staging. We describe the epidemiology of TSCC and current treatment approaches. Methods Five hundred thirty-two adult patients with primary TSCC from 2004 to 2012 in the National Cancer Database were identified. Demographic, clinical factors, and 5-year overall survival were analyzed. Staging was classified as localized, regional extension, and distant spread. Treatment modality was defined as "no treatment (NT)," "limited surgery (LS)," "curative surgery (CS)," "LS with any adjuvant therapy (AT) (LS+AT)," "CS with AT (CS+AT)," "radiation therapy (RT)," or "chemoradiation (CRT)." Results Overall survival was 25%. Majority of cases were males, white, and occurred in sixth/seventh decades. Twenty-six percent of cases received CRT, 20% underwent LS+AT or CS+AT, 20% underwent LS or CS only, and 17% underwent RT alone. On multivariate analysis, CS (HR 0.42, 95% CI: 0.26-0.69), CS+AT (HR 0.44, 95% CI: 0.36-0.77), CRT (HR 0.48, 95% CI: 0.35-0.67), and RT (HR, 0.66 95% CI: 0.46-0.94) were associated with decreased likelihood of death compared to NT. Elderly patients and those with poor performance status had worse outcomes even on multivariate analysis. Conclusions TSCC is increasingly treated with surgery and systemic therapy in addition to RT, with improved survival outcomes. CS, CS+AT, CRT, or RT provided improved survival advantage in patients with variable levels of improvement based on the extent of the disease. Prospective trials would help differentiate survival advantages between treatment modalities. Patients' goals of care, comorbidities, and age should be considered when deciding appropriate treatment recommendations. Level of evidence NA Laryngoscope, 130:405-412, 2020.

Background Radioresistance represents a major problem in the treatment of head and neck cancer (HNC) patients. To improve response, understanding tumor microenvironmental factors that contribute to radiation resistance is important. Regulatory T cells (Tregs) are enriched in numerous cancers and can dampen the response to radiation by creating an immune-inhibitory microenvironment. The purpose of this study was to investigate mechanisms of Treg modulation by radiation in HNC. Methods We utilized an orthotopic mouse model of HNC. Anti-CD25 was used for Treg depletion. Image-guided radiation was delivered to a dose of 10 Gy. Flow cytometry was used to analyze abundance and function of intratumoral immune cells. Enzyme-linked immunosorbent assay was performed to assess secreted factors. For immune-modulating therapies, anti–PD-L1, anti-CTLA-4, and STAT3 antisense oligonucleotide (ASO) were used. All statistical tests were two-sided. Results Treatment with anti-CD25 and radiation led to tumor eradication (57.1%, n = 4 of 7 mice), enhanced T-cell cytotoxicity compared with RT alone (CD4 effector T cells [Teff]: RT group mean = 5.37 [ 0.58] vs RT + αCD25 group mean =10.71 [0.67], P = .005; CD8 Teff: RT group mean = 9.98 [0.81] vs RT + αCD25 group mean =16.88 [2.49], P = .01) and induced tumor antigen-specific memory response (100.0%, n = 4 mice). In contrast, radiation alone or when combined with anti-CTLA4 did not lead to durable tumor control (0.0%, n = 7 mice). STAT3 inhibition in combination with radiation, but not as a single agent, improved tumor growth delay, decreased Tregs, myeloid-derived suppressor cells, and M2 macrophages and enhanced effector T cells and M1 macrophages. Experiments in nude mice inhibited the benefit of STAT3 ASO and radiation. Conclusion We propose that STAT3 inhibition is a viable and potent therapeutic target against Tregs. Our data support the design of clinical trials integrating STAT3 ASO in the standard of care for cancer patients receiving radiation.

Stromal fibrosis activates prosurvival and proepithelial-to-mesenchymal transition (EMT) pathways in pancreatic ductal adenocarcinoma (PDAC). In patient tumors treated with neoadjuvant stereotactic body radiation therapy (SBRT), we found upregulation of fibrosis, extracellular matrix (ECM), and EMT gene signatures, which can drive therapeutic resistance and tumor invasion. Molecular, functional, and translational analysis identified two cell-surface proteins, a disintegrin and metalloprotease 10 (ADAM10) and ephrinB2, as drivers of fibrosis and tumor progression after radiation therapy (RT). RT resulted in increased ADAM10 expression in tumor cells, leading to cleavage of ephrinB2, which was also detected in plasma. Pharmacologic or genetic targeting of ADAM10 decreased RT-induced fibrosis and tissue tension, tumor cell migration, and invasion, sensitizing orthotopic tumors to radiation killing and prolonging mouse survival. Inhibition of ADAM10 and genetic ablation of ephrinB2 in fibroblasts reduced the metastatic potential of tumor cells after RT. Stimulation of tumor cells with ephrinB2 FC protein reversed the reduction in tumor cell invasion with ADAM10 ablation. These findings represent a model of PDAC adaptation that explains resistance and metastasis after RT and identifies a targetable pathway to enhance RT efficacy. Significance: Targeting a previously unidentified adaptive resistance mechanism to radiation therapy in PDAC tumors in combination with radiation therapy could increase survival of the 40% of PDAC patients with locally advanced disease. See related commentary by Garcia Garcia et al., p. 3158

Background Squamous cell lung cancer (SCLC) is the second most common type of lung cancer. Treatment is complicated due to the lack of mutated molecular targets.1 Radiotherapy (RT) is commonly used to treat SCLC, but relapse and tumor progression are common. The combination of immunotherapy (IT) with RT can enhance the effect observed with RT alone.2 Effective combination of IT and RT requires an understanding of the pathways that synergize to enhance tumor cell kill in SCLC. Our lab has identified Toll-like receptor 3 (TLR3) as a molecule that is regulated by RT and can be targeted with IT. Toll-like receptors serve a crucial role against tumor cells by activating innate and adaptive immune responses that boost antitumor immunity.3 4 TLR3 is the only receptor whose molecular mechanism functions independent of MyD88, leading to NF-κB mediated apoptosis.5 We hypothesized that increased TLR3 expression would be associated with improved response to RT. We further hypothesized that RT can downregulate TLR3 and that this effect can be reversed with TLR3 agonists leading to enhanced tumor antigen recognition. We aim to use this data to formulate further studies using combined RT and IT. Methods Mouse (KLN205) and human (SW900) squamous cell carcinoma (SCC) cell lines were used to study the effect of radiation on TLR3 expression. Irradiation was performed using the gammacell 3000 elan irradiator. Cells were irradiated with 0, 5, 10 and 20 Gy. Protein extraction was performed 48 and 72 hours after RT. Protein extracts were analyzed by Western Blot. Further, TLR3 mRNA expression and 5-year overall survival of SCLC patients was obtained from public databases. Kaplan-Meier method was used to correlate between TLR3 mRNA expression and survival. Results In vitro studies and western blot analysis demonstrated a decrease of TLR3 expression in response to increasing doses of radiation. This observation was consistent in mouse and human SCC cell lines. In silico analysis of SCLC patients who received RT showed that increased TLR3 mRNA expression was associated with improved overall survival and disease-free survival. Conclusions Our findings point to an important role for TLR3 in SCLC. Combining RT with TLR3 agonists may enhance the tumor response to RT. Several complementary experiments are underway in our lab to use the TLR3 agonist, Poly I:C, which will allow a better understanding of the effect of RT on TLR3. References George J, Lim SJ, Jang SJ, et al. Comprehensive genomic profiles of small cell lung cancer. Nature 2015;524:47–53. Darragh L, Oweida A, Karam SD. Overcoming resistance to combination radiation-immunotherapy: a focus on contributing pathways withing the tumor microenvironment. Frontiers in Immunology 2019;9:3154. Shcheblyakov D, Logunov DY, Tukhvatulin AI, et al. Toll-Like Receptors (TLRs): The Role in Tumor Progression. Acta Naturae 2010;2(3):21-9. Kawai T, Akira S. The role of pattern-recognition receptors in innate immunity: update on Toll-like receptors. Nat Immunol 2010;11:373–384. Bianchi F, Alexiadis S, Camiasaschi C, et al. TLR3 expression induces apoptosis in Human Non-Small-Cell Lung Cancer. Int J Mol Sci 2020 Feb;21(4):1440.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has recently emerged in China and caused a disease called coronavirus disease 2019 (COVID-19). The virus quickly spread around the world, causing a sustained global outbreak. Although SARS-CoV-2, and other coronaviruses, SARS-CoV and Middle East respiratory syndrome CoV (MERS-CoV) are highly similar genetically and at the protein production level, there are significant differences between them. Research has shown that the structural spike (S) protein plays an important role in the evolution and transmission of SARS-CoV-2. So far, studies have shown that various genes encoding primarily for elements of S protein undergo frequent mutation. We have performed an in-depth review of the literature covering the structural and mutational aspects of S protein in the context of SARS-CoV-2, and compared them with those of SARS-CoV and MERS-CoV. Our analytical approach consisted in an initial genome and transcriptome analysis, followed by primary, secondary and tertiary protein structure analysis. Additionally, we investigated the potential effects of these differences on the S protein binding and interactions to angiotensin-converting enzyme 2 (ACE2), and we established, after extensive analysis of previous research articles, that SARS-CoV-2 and SARS-CoV use different ends/regions in S protein receptor-binding motif (RBM) and different types of interactions for their chief binding with ACE2. These differences may have significant implications on pathogenesis, entry and ability to infect intermediate hosts for these coronaviruses. This review comprehensively addresses in detail the variations in S protein, its receptor-binding characteristics and detailed structural interactions, the process of cleavage involved in priming, as well as other differences between coronaviruses.

Purpose: SMAD4 loss causes genomic instability and the initiation/progression of head and neck squamous cell carcinoma (HNSCC). Here, we study whether SMAD4 loss sensitizes HNSCCs to olaparib (PARP inhibitor) in combination with radiotherapy (RT). Experimental Design: We analyzed HNSCC The Cancer Genome Atlas data for SMAD4 expression in association with FANC/BRCA family gene expression. Human HNSCC cell lines were screened for sensitivity to olaparib. Isogenic HNSCC cell lines were generated to restore or reduce SMAD4 expression and treated with olaparib, radiation, or the combination. HNSCC pretreatment specimens from a phase I trial investigating olaparib were analyzed. Results: SMAD4 levels correlated with levels of FANC/BRCA genes in HNSCC. HNSCC cell lines with SMAD4 homozygous deletion were sensitive to olaparib. In vivo, olaparib or RT monotherapy reduced tumor volumes in SMAD4-mutant but not SMAD4-positive tumors. Olaparib with RT dual therapy sustained tumor volume reduction in SMAD4-deficient (mutant or knockdown) xenografts, which exhibited increased DNA damage and cell death compared with vehicle-treated tumors. In vitro, olaparib alone or in combination with radiation caused lower clonogenic survival, more DNA damage–associated cell death, and less proliferation in SMAD4-deficient cells than in SMAD4-positive (endogenous SMAD4 or transduced SMAD4) cells. Applicable to clinic, 5 out of 6 SMAD4-negative HNSCCs and 4 out of 8 SMAD4-positive HNSCCs responded to a standard treatment plus olaparib in a phase I clinical trial, and SMAD4 protein levels inversely correlated with DNA damage. Conclusions: SMAD4 levels are causal in determining sensitivity to PARP inhibition in combination with RT in HNSCCs.

Purpose: Our goal was to evaluate the safety and toxicity of combining a PARP inhibitor, olaparib, with cetuximab and fractionated intensity-modulated radiotherapy for patients with locally advanced head and neck cancer and heavy smoking histories. Patients and Methods: Patients with ≥10 packs/year history of smoking were treated with olaparib at doses ranging from 25–200 mg orally twice daily beginning approximately 10 days prior to initiation of and with concurrent radiation (69.3 Gy in 33 fractions) using a time-to-event continual reassessment method model. Cetuximab was administered starting approximately 5 days prior to radiation per standard of care. Results: A total of 16 patients were entered onto the study, with 15 evaluable for acute toxicity. The most common treatment-related grade 3–4 side effects were radiation dermatitis and mucositis (38% and 69%, respectively). The MTD was determined to be 50 mg orally twice daily, but the recommended phase II dose was deemed to be 25 mg orally twice daily. At a median follow-up of 26 months, the actuarial median overall survival was 37 months, but was not reached for other endpoints. Two-year overall survival, progression-free survival, local control, and distant control rates were 72%, 63%, 72%, and 79%, respectively. Patients who continued to smoke during therapy experienced higher recurrence rates. MYC and KMT2A were identified as potential correlatives of response on gene amplification and mutational analysis. Conclusions: Olaparib at 25 mg orally twice daily with concurrent cetuximab and radiation was well tolerated with reduced dermatitis within the radiation field. Response rates were promising for this high-risk population. Clin Cancer Res; 24(20); 4949–59. ©2018 AACR.

Eph proteins have emerged as critical drivers affecting tumor growth and progression in human malignancies. Our The Cancer Genome Atlas (TCGA) data analysis showed that EphB3, a receptor tyrosine kinase, is frequently coamplified with PIK3CA in head and neck squamous cell carcinoma (HNSCC). We therefore hypothesized that EphB3 amplification plays a protumorigenic role in HNSCC and that EphB3 and PIK3CA are cooperating oncogenes that contribute toward its pathogenesis. This hypothesis was not experimentally supported, because EphB3 knockdown failed to alter HNSCC tumor cell growth in vitro or in vivo with an orthotopic model. However, responsiveness of EphB3 knockdown tumors to the PI3K inhibitor, BKM120, was significantly decreased in terms of both tumor growth delay and survival. This is correlated with an increase in prosurvival proteins, S6 and BcL-XL, in the EphB3 shRNA tumors treated with BKM120 compared with controls. We further observed that EphB3 knockdown resulted in increased migration in vitro and increased EMT gene signature in vivo. To explain these results, we examined EphB3 phosphorylation levels in HNSCC at baseline. Although total EphB3 levels were high, we found low phospho-EphB3 levels in HNSCCs. Forced EphB3 phosphorylation with an ephrin-B2–Fc fusion protein resulted in decreased HNSCC migration and cell growth, and enhanced response to BKM120 in vitro. These data collectively indicate that progression of HNSCC selects for low/inhibited EphB3 activity to enhance their survival and migratory abilities and decrease response to PI3K signaling. Therefore, strategies focused on activating EphB3 might be helpful to inhibit tumor growth and enhance sensitivity to PI3K inhibitors in HNSCC. Mol Cancer Ther; 17(9); 2049–59. ©2018 AACR.

Background Patients with melanoma brain metastases (MBM) have been excluded from trials evaluating immunotherapy in melanoma. As such, immunotherapy's role in MBM is poorly understood, particularly in combination with radiotherapy. Methods The National Cancer Database was queried for patients with MBM receiving brain radiotherapy. They were classified according to immunotherapy receipt. Multivariate Cox regression was performed to identify factors associated with survival. Results Among 1287 patients, 185 received immunotherapy. Factors associated with improved survival included younger age, academic facility, lower extracranial disease burden, stereotactic radiotherapy, chemotherapy, and immunotherapy. Conclusions Adding immunotherapy to radiotherapy for MBM is associated with improved survival.

Stereotactic ablative radiotherapy (SABR) is the main treatment for inoperable early-stage non-small cell lung cancer (NSCLC). Despite the widespread use of SABR, the biological determinants of response to SABR remain poorly investigated. We developed an orthotopic NSCLC animal model to study the response to clinically-relevant doses of SABR. Image-guided intra-thoracic injection of NSCLC cells was performed in the right lung of nude rats. A highly conformal dose of 34 Gy was delivered in a single fraction using clinical photon energies. Animals were sacrificed 10–60 days post treatment. Lung tumors were assessed for tumor differentiation, proliferation and invasiveness. An analysis of 770 cancer-related genes was performed on tumor-derived cell lines from treated animals at early and late time points after SABR. The majority of animals receiving SABR demonstrated complete response (67%), while 33% demonstrated local failure. 50% of animals with complete response failed distantly. Analysis of cancer-related genes revealed significant differences between tumors treated with SABR and untreated tumors. SABR significantly modulated expression of genes involved in adhesion, migration and angiogenesis. In particular, interleukin-8 (IL8) which plays a critical role in promoting tumor invasion was found to be secreted at high levels after SABR. In vitro invasion assays confirmed SABR-induced invasion and demonstrated induction of IL-8 secretion in multiple NSCLC cell lines. Our findings underscore the importance of developing targeted therapies that can circumvent the pro-invasive effects of SABR in NSCLC.

The optimal management of recurrent glioblastoma (GBM) has yet to be determined. We aim to assess the benefits of re-operation and salvage therapies (chemotherapy and/or re-irradiation) for recurrent GBM and to identify prognostic factors associated with better survival. All patients who underwent surgery for GBM between January 2005 and December 2012 followed by adjuvant radiotherapy, and who developed GBM recurrence on imaging were included in this retrospective study. Univariate and multivariate analysis was performed using Cox models in order to identify factors associated with overall survival (OS). One hundred and eighty patients treated to a dose of 60 Gy were diagnosed with recurrent GBM. At a median follow-up time of 6.2 months, the median survival (MS) from time of recurrence was 6.6 months. Sixty-nine patients underwent repeat surgery for recurrence based on imaging. To establish the benefits of repeat surgery and salvage therapies, 68 patients who underwent repeat surgery were matched to patients who did not based on extent of initial resection and presence of subventricular zone involvement at recurrence. MS for patients who underwent re-operation was 9.6 months, compared to 5.3 months for patients who did not have repeat surgery (p

Head and neck squamous cell carcinoma (HNSCC) is a debilitating and deadly disease with a high prevalence of recurrence and treatment failure. To develop better therapeutic strategies, understanding tumor microenvironmental factors that contribute to the treatment resistance is important. A major impediment to understanding disease mechanisms and improving therapy has been a lack of murine cell lines that resemble the aggressive and metastatic nature of human HNSCCs. Furthermore, a majority of murine models employ subcutaneous implantations of tumors which lack important physiological features of the head and neck region, including high vascular density, extensive lymphatic vasculature, and resident mucosal flora. The purpose of this study is to develop and characterize an orthotopic model of HNSCC. We employ two genetically distinct murine cell lines and established tumors in the buccal mucosa of mice. We optimize collagenase-based tumor digestion methods for the optimal recovery of single cells from established tumors. The data presented here show that mice develop highly vascularized tumors that metastasize to regional lymph nodes. Single-cell multiparametric mass cytometry analysis shows the presence of diverse immune populations with myeloid cells representing the majority of all immune cells. The model proposed in this study has applications in cancer biology, tumor immunology, and preclinical development of novel therapeutics. The resemblance of the orthotopic model to clinical features of human disease will provide a tool for enhanced translation and improved patient outcomes.

Identifying targets present in the tumor microenvironment that contribute to immune evasion has become an important area of research. In this study, we identified EphB4–ephrin-B2 signaling as a regulator of both innate and adaptive components of the immune system. EphB4 belongs to receptor tyrosine kinase family that interacts with ephrin-B2 ligand at sites of cell–cell contact, resulting in bidirectional signaling. We found that EphB4–ephrin-B2 inhibition alone or in combination with radiation (RT) reduced intratumoral regulatory T cells (Tregs) and increased activation of both CD8+ and CD4+Foxp3− T cells compared with the control group in an orthotopic head and neck squamous cell carcinoma (HNSCC) model. We also compared the effect of EphB4–ephrin-B2 inhibition combined with RT with combined anti-PDL1 and RT and observed similar tumor growth suppression, particularly at early time-points. A patient-derived xenograft model showed reduction of tumor-associated M2 macrophages and favored polarization towards an antitumoral M1 phenotype following EphB4–ephrin-B2 inhibition with RT. In vitro, EphB4 signaling inhibition decreased Ki67-expressing Tregs and Treg activation compared with the control group. Overall, our study is the first to implicate the role of EphB4–ephrin-B2 in tumor immune response. Moreover, our findings suggest that EphB4–ephrin-B2 inhibition combined with RT represents a potential alternative for patients with HNSCC and could be particularly beneficial for patients who are ineligible to receive or cannot tolerate anti-PDL1 therapy. Significance: These findings present EphB4–ephrin-B2 inhibition as an alternative to anti-PDL1 therapeutics that can be used in combination with radiation to induce an effective antitumor immune response in patients with HNSCC.

BackgroundNumerous trials combining radiation therapy (RT) and immunotherapy in head and neck squamous cell carcinoma (HNSCC) are failing. Using preclinical immune cold models of HNSCC resistant to RT-immune checkpoint inhibitors, we investigate therapeutic approaches of overcoming such resistance by examining the differential microenvironmental response to RT.MethodsWe subjected two HPV-negative orthotopic mouse models of HNSCC to combination RT, regulatory T cells (Treg) depletion, and/or CD137 agonism. Tumor growth was measured and intratumorous and lymph node immune populations were compared among treatment groups. Human gene sets, genetically engineered mouse models DEREG and BATF3–/–, flow and time-of-flight cytometry, RNA-Seq, Treg adoptive transfer studies, and in vitro experiments were used to further evaluate the role of dendritic cells (DCs) and Tregs in these treatments.ResultsIn MOC2 orthotopic tumors, we find no therapeutic benefit to targeting classically defined immunosuppressive myeloids, which increase with RT. In these radioresistant tumors, supplementing combination RT and Treg depletion with anti-CD137 agonism stimulates CD103+ DC activation in tumor-draining lymph nodes as characterized by increases in CD80+ and CCR7+ DCs, resulting in a CD8 T cell-dependent response. Simultaneously, Tregs are reprogrammed to an effector phenotype demonstrated by increases in interferonγ+, tumor necrosis factorα+, PI3K+, pAKT+ and Eomes+ populations as well as decreases in CTLA4+ and NRP-1+ populations. Tumor eradication is observed when RT is increased to an 8 Gy x 5 hypofractionated regimen and combined with anti-CD25+ anti-CD137 treatment. In a human gene set from oral squamous cell carcinoma tumors, high Treg number is associated with earlier recurrence.ConclusionsRegulating Treg functionality and DC activation status within the lymph node is critical for generating a T cell effector response in these highly radioresistant tumors. These findings underscore the plasticity of Tregs and represent a new therapeutic opportunity for reprogramming the tumor microenvironment in HNSCCs resistant to conventional radioimmunotherapy approaches.

Ephrin B2 is variably expressed on tumor cells and its blockade has been shown to inhibit angiogenesis in animal models of pancreatic, colorectal, lung and head, and neck squamous cell carcinomas. However, the implications of ephrinB2 expression in cancer patients have remained elusive. In this study, we analyzed the cancer genome atlas (TCGA) for ephrinB2 expression. We report significant correlations between EFNB2 expression, overall survival and disease-free survival in head and neck squamous cell carcinoma (HNSCC, n = 519), pancreatic adenocarcinoma (n = 186), and bladder urothelial carcinoma (n = 410). In HNSCC patients, high-EFNB2 mRNA expression was associated with tumor HPV negativity, oral cavity location, alcohol intake, higher TP53 mutation, and EGFR amplification. EphrinB2 overexpression also correlated with worse response to chemotherapy and radiotherapy. The therapeutic potential of blocking ephrinB2 was validated in HNSCC patient-derived tumor xenografts and showed significant improvement in survival and tumor growth delay. Our data shows that ephrinB2 overexpression can serve as a critical biomarker for patient prognosis and response to therapy. These results should guide design of future clinical trials exploring EphrinB2 inhibition in cancer patients. © 2016 Wiley Periodicals, Inc.

BACKGROUND Diffuse intrinsic pontine glioma (DIPG) and diffuse midline glioma (DMG) are metastatic diseases, as demonstrated by early convection-enhanced delivery (CED) clinical trials in which prolonged local tumor control can sometimes be achieved, but fatal disseminated disease then develops. We hypothesize that improvements in treatment of both focal disease and the entire neuraxis are necessary for long-term survival, and patient-derived xenograft (PDX) models can help advance these efforts. METHODS We used a BT245 murine orthotopic DIPG PDX model for this work. We developed a protocol and specialized platform to deliver craniospinal irradiation (CSI) with a pontine boost. We separately compared intratumoral drug concentration by CED and intraperitoneal delivery. In our CED model, mice receive gemcitabine 60 ug x1 in 15 ul at 0.5 ul/minute through a stepped catheter design with silica tubing extending 2mm beyond a 27G needle. RESULTS Mice receiving CSI (4 Gy x2d) plus boost (4 Gy x2d) showed minimal spinal and brain leptomeningeal metastatic disease by bioluminescence, MRI, and pathology compared to mice receiving radiation to the pons only (4 Gy x4d) or no radiation. CED achieved an intratumoral gemcitabine concentration 50-fold greater than intraperitoneal dosing when controlled for dose. CONCLUSIONS In a DIPG PDX model, CSI+boost minimizes tumor dissemination compared to focal radiation, and CED achieves clinically significant improvements in intratumoral chemotherapy concentration compared to systemic delivery. Adding these modalities to current treatment could improve both focal and metastatic tumor control, leading to meaningful improvements in survival.

Radiation therapy has been used for many years to treat tumors based on its DNA-damage-mediated ability to kill cells. More recently, RT has been shown to exert beneficial modulatory effects on immune responses, such as triggering immunogenic cell death, enhancing antigen presentation, and activating cytotoxic T cells. Consequently, combining radiation therapy with immunotherapy represents an important area of research. Thus far, immune-checkpoint inhibitors targeting programmed death-ligand 1 (PD-L1), programmed cell death protein 1 (PD-1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) have been the focus of many research studies and clinical trials. The available data suggest that such immunotherapies are enhanced when combined with radiation therapy. However, treatment resistance, intrinsic or acquired, is still prevalent. Various theories as to how to enhance these combination therapies to overcome treatment resistance have been proposed. In this review, we focus on the principles surrounding radiation therapy's positive and negative effects on the tumor microenvironment. We explore mechanisms underlying radiation therapy's synergistic and antagonistic effects on immune responses and provide a base of knowledge for radio-immunology combination therapies to overcome treatment resistance. We provide evidence for targeting regulatory T cells, tumor-associated macrophages, and cancer-associated fibroblasts in combination radio-immunotherapies to improve cancer treatment.

Purpose: A driving factor in pancreatic ductal adenocarcinoma (PDAC) treatment resistance is the tumor microenvironment, which is highly immunosuppressive. One potent immunologic adjuvant is radiotherapy. Radiation, however, has also been shown to induce immunosuppressive factors, which can contribute to tumor progression and formation of fibrotic tumor stroma. To capitalize on the immunogenic effects of radiation and obtain a durable tumor response, radiation must be rationally combined with targeted therapies to mitigate the influx of immunosuppressive cells and fibrosis. One such target is ephrinB2, which is overexpressed in PDAC and correlates negatively with prognosis. Experimental Design: On the basis of previous studies of ephrinB2 ligand-EphB4 receptor signaling, we hypothesized that inhibition of ephrinB2-EphB4 combined with radiation can regulate the microenvironment response postradiation, leading to increased tumor control in PDAC. This hypothesis was explored using both cell lines and in vivo human and mouse tumor models. Results: Our data show this treatment regimen significantly reduces regulatory T-cell, macrophage, and neutrophil infiltration and stromal fibrosis, enhances effector T-cell activation, and decreases tumor growth. Furthermore, our data show that depletion of regulatory T cells in combination with radiation reduces tumor growth and fibrosis. Conclusions: These are the first findings to suggest that in PDAC, ephrinB2–EphB4 interaction has a profibrotic, protumorigenic role, presenting a novel and promising therapeutic target.

Background: Anaplastic thyroid cancer (ATC) is an aggressive and highly lethal disease with poor outcomes and resistance to therapy. Despite multimodality treatment, including radiation therapy and chemotherapy, response rates remain