A surprising cross-species conservation in the genomic landscape of mouse and human oral cancer identifies a transcriptional signature predicting metastatic disease

Expression profile of diagnostic genes in oral submucous fibrosis

Oral Submucous Fibrosis (OSMF) is a chronic precancerous disorder of the oral mucosa caused by chewing of areca nut and its other variants. Chewing of areca nuts leads to dysregulated expression of specific genes, leading to various premalignant or malignant disorders. This study aimed to determine the differential expression of the diagnostic genes (MYH6, TNNT3, MYL1, and TPM2) in healthy controls and OSMF patients using saliva and tissue samples, determining the histopathological grade of the clinical samples. A total of 20 patients were included in the study and were divided into two groups: Group I consisted of 10 healthy patients (control group) and Group II consisted of 10 OSMF patients. Unstimulated whole saliva samples were collected from both groups, and the tissue samples were divided into two parts: one for RT-qPCR analysis and the other for histopathological assay. The expression profile of genes concerning OSMF saliva and tissue samples was significantly upregulated compared to the healthy control, and all the clinical samples of the study were categorized into histopathological grade 1. The findings of this study concluded that these genes can be referred to as diagnostic genes for OSMF in early and very early clinical samples, and saliva can be used as a promising diagnostic tool for early OSMF studies.

Tumor-infiltrating nerves functionally alter brain circuits and modulate behavior in a male mouse model of head-and-neck cancer

Cancer patients often experience changes in mental health, prompting an exploration into whether nerves infiltrating tumors contribute to these alterations by impacting brain functions. Using a male mouse model for head and neck cancer, we utilized neuronal tracing techniques and show that tumor-infiltrating nerves indeed connect to distinct brain areas via the ipsilateral trigeminal ganglion. The activation of this neuronal circuitry led to behavioral alterations represented by decreased nest-building, increased latency to eat a cookie, and reduced wheel running. Tumor-infiltrating nociceptor neurons exhibited heightened activity, as indicated by increased calcium mobilization. Correspondingly, the specific brain regions receiving these neural projections showed elevated cFos and delta FosB expression in tumor-bearing mice, alongside markedly intensified calcium responses compared to non-tumor-bearing counterparts. The genetic elimination of nociceptor neurons in tumor-bearing mice led to decreased brain Fos expression and mitigated the behavioral alterations induced by the presence of the tumor. While analgesic treatment successfully restored behaviors involving oral movements to normalcy in tumor-bearing mice, it did not have a similar therapeutic effect on voluntary wheel running. This discrepancy points towards an intricate relationship, where pain is not the exclusive driver of such behavioral shifts. Unraveling the interaction between the tumor, infiltrating nerves, and the brain is pivotal to developing targeted interventions to alleviate the mental health burdens associated with cancer.

Acute myeloid leukemia with a novel AKAP9::PDGFRA fusion transformed from essential thrombocythemia: A case report and mini review

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy associated with various combinations of gene mutations, epigenetic abnormalities, and chromosome rearrangement-related gene fusions. Despite the significant degree of heterogeneity in its pathogenesis, many gene fusions and point mutations are recurrent in AML and have been employed in risk stratification over the last several decades. Gene fusions have long been recognized for understanding tumorigenesis and their proven roles in clinical diagnosis and targeted therapies. Advances in DNA sequencing technologies and computational biology have contributed significantly to the detection of known fusion genes as well as for the discovery of novel ones. Several recurring gene fusions in AML have been linked to prognosis, treatment response, and disease progression. In this report, we present a case with a long history of essential thrombocythemia and hallmark CALR mutation transforming to AML characterized by a previously unreported AKAP9::PDGFRA fusion gene. We propose mechanisms by which this fusion may contribute to the pathogenesis of AML and its potential as a molecular target for tyrosine kinase inhibitors.

Momordicine-I Suppresses Head and Neck Cancer Growth by Reprogrammimg Immunosuppressive Effect of the Tumor-Infiltrating Macrophages and B Lymphocytes

Head and neck cancer (HNC) is prevalent worldwide, and treatment options are limited. Momordicine-I (M-I), a natural component from bitter melon, shows antitumor activity against these cancers, but its mechanism of action, especially in the tumor microenvironment (TME), remains unclear. In this study, we establish that M-I reduces HNC tumor growth in two different immunocompetent mouse models using MOC2 and SCC VII cells. We demonstrate that the anticancer activity results from modulating several molecules in the monocyte/macrophage clusters in CD45+ populations in MOC2 tumors by single-cell RNA sequencing. Tumor-associated macrophages (TAM) often pose a barrier to antitumor effects, but following M-I treatment, we observe a significant reduction in the expression of Sfln4, a myeloid cell differentiation factor, and Cxcl3, a neutrophil chemoattractant, in the monocyte/macrophage populations. We further find that the macrophages must be in close contact with the tumor cells to inhibit Sfln4 and Cxcl3, suggesting that these TAMs are impacted by M-I treatment. Coculturing macrophages with tumor cells shows inhibition of Agr1 expression following M-I treatment, which is indicative of switching from M2 to M1 phenotype. Furthermore, the total B-cell population in M-I-treated tumors is significantly lower, whereas spleen cells also show similar results when cocultured with MOC2 cells. M-I treatment also inhibits PD1, PD-L1, and FoxP3 expression in tumors. Collectively, these results uncover the potential mechanism of M-I by modulating immune cells, and this new insight can help to develop M-I as a promising candidate to treat HNCs, either alone or as adjuvant therapy.

Enhanced oral versus flank lymph node T cell response parallels anti-PD1 efficacy in head and neck cancer

OBJECTIVES

Understanding head and neck tissue specific immune responses is important for elucidating immunotherapy resistance mechanisms to head and neck squamous cell carcinoma (HNSCC). In this study, we aimed to investigate HNSCC-specific immune response differences between oral and subcutaneous flank tumor transplantation in preclinical models.

MATERIALS AND METHODS

The MOC1 syngeneic mouse oral carcinoma cell line or versions expressing either the H2Kb-restricted SIINFEKL peptide from ovalbumin (MOC1OVA) or ZsGreen (MOC1ZsGreen) were inoculated into mouse oral mucosa (buccal space) or subcutaneous flank and compared for immune cell kinetics in tumors and tumor-draining lymph nodes (TDLNs) and for anti-PD1 response.

RESULTS

Compared to subcutaneous flank tumors, orthotopic oral MOC1OVA induced a higher number of OVA-specific T cells, PD1 + or CD69 + activated OVA-specific T cells in both primary tumors and TDLNs. Tumors were also larger in the flank site and CD8 depletion eliminated the difference in tumor weight between the two sites. Oral versus flank SIINFEKL peptide vaccination showed enhanced TDLN lymphocyte response in the former site. Notably, cDC1 from oral TDLN showed enhanced antigen uptake and co-stimulatory marker expression, resulting in elicitation of an increased antigen specific T cell response and increased activated T cells. Parental MOC1 in the oral site showed increased endogenous antigen-reactive T cells in TDLNs and anti-PD1 blockade rejected oral MOC1 tumors but not subcutaneous flank MOC1.

CONCLUSION

Collectively, we find distinct immune responses between orthotopic oral and heterotopic subcutaneous models, including priming by cDC1 in TDLN, revealing important implications for head and neck cancer preclinical studies.

Preclinical Evaluation of the ATR Inhibitor BAY 1895344 as a Radiosensitizer for Head and Neck Squamous Cell Carcinoma

PURPOSE

Despite aggressive multimodal treatment that typically includes definitive or adjuvant radiation therapy (RT), locoregional recurrence rates approach 50% for patients with locally advanced human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSCC). Thus, more effective therapeutics are needed to improve patient outcomes. We evaluated the radiosensitizing effects of ataxia telangiectasia and RAD3-related (ATR) inhibitor (ATRi) BAY 1895344 in preclinical models of HNSCC.

METHODS AND MATERIALS

Murine and human HPV-negative HNSCC cells (MOC2, MOC1, JHU-012) were treated with vehicle or ATRi with or without 4 Gy. Checkpoint kinase 1 phosphorylation and DNA damage (γH2AX) were evaluated by Western blot, and ATRi half-maximal inhibitory concentration was determined by MTT assay for HNSCC cells and immortalized murine oral keratinocytes. In vitro radiosensitization was tested by clonogenic assay. Cell cycle distribution and mitotic catastrophe were evaluated by flow cytometry. Mitotic aberrations were quantified by fluorescent microscopy. Tumor growth delay and survival were assessed in mice bearing MOC2 or JHU-012 transplant tumors treated with vehicle, ATRi, RT (10 Gy × 1 or 8 Gy × 3), or combined ATRi + RT.

RESULTS

ATRi caused dose-dependent reduction in checkpoint kinase 1 phosphorylation at 1 hour post-RT (4 Gy) and dose-dependent increase in γH2AX at 18 hours post-RT. Addition of RT to ATRi led to decreased BAY 1895344 half-maximal inhibitory concentration in HNSCC cell lines but not in normal tissue surrogate immortalized murine oral keratinocytes. Clonogenic assays demonstrated radiosensitization in the HNSCC cell lines. ATRi abrogated the RT-induced G2/M checkpoint, leading to mitosis with unrepaired DNA damage and increased mitotic aberrations (multinucleated cells, micronuclei, nuclear buds, nucleoplasmic bridges). ATRi and RT significantly delayed tumor growth in MOC2 and JHU-012 in vivo models, with improved overall survival in the MOC2 model.

CONCLUSIONS

These findings demonstrated that BAY 1895344 increased in vitro and in vivo radiosensitivity in HPV-negative HNSCC preclinical models, suggesting therapeutic potential warranting evaluation in clinical trials for patients with locally advanced or recurrent HPV-negative HNSCC.

Complete tumor resection reverses neutrophilia-associated suppression of systemic anti-tumor immunity

OBJECTIVES

Tumor infiltrating neutrophils suppress T cell function, but whether neutrophils in circulation contribute to systemic immunosuppression is unclear. We aimed to study whether peripheral neutrophils that accumulate with tumor progression contribute to systemic immunosuppression, and if observed suppression of systemic anti-tumor immunity could be reversed with complete surgical tumor removal.

MATERIALS AND METHODS

Syngeneic murine oral cancers were established in immunocompetent mice. Proteomic and functional immune assays were used to study plasma cytokine concentration, peripheral immune frequencies, and systemic anti-tumor immunity with and without complete primary tumor resection.

RESULTS

Ly6G+ neutrophilic cells, but not other myeloid cell types, accumulated in the periphery of mice with progressing tumors. This accumulation positively associated with plasma G-CSF concentration. Circulating neutrophils were functionally immunosuppressive. Complete surgical tumor removal reversed the observed neutrophilia, with neutrophil frequencies returning to baseline in 21 days. Multiple independent functional assays revealed enhanced systemic anti-tumor immunity in mice following tumor resection compared to tumor-bearing mice, and the observed enhanced systemic immunity could be reproduced with selective neutrophil depletion.

CONCLUSIONS

Complete primary tumor resection can reverse neutrophilia that develops during tumor progression and result in enhanced systemic anti-tumor immunity. Primary tumor removal relieves neutrophil-driven systemic immunosuppression and may itself contribute to the clinical benefit observed with neoadjuvant immunotherapy.

Enhancing head and neck tumor management with artificial intelligence: Integration and perspectives

Head and neck tumors (HNTs) constitute a multifaceted ensemble of pathologies that primarily involve regions such as the oral cavity, pharynx, and nasal cavity. The intricate anatomical structure of these regions poses considerable challenges to efficacious treatment strategies. Despite the availability of myriad treatment modalities, the overall therapeutic efficacy for HNTs continues to remain subdued. In recent years, the deployment of artificial intelligence (AI) in healthcare practices has garnered noteworthy attention. AI modalities, inclusive of machine learning (ML), neural networks (NNs), and deep learning (DL), when amalgamated into the holistic management of HNTs, promise to augment the precision, safety, and efficacy of treatment regimens. The integration of AI within HNT management is intricately intertwined with domains such as medical imaging, bioinformatics, and medical robotics. This article intends to scrutinize the cutting-edge advancements and prospective applications of AI in the realm of HNTs, elucidating AI's indispensable role in prevention, diagnosis, treatment, prognostication, research, and inter-sectoral integration. The overarching objective is to stimulate scholarly discourse and invigorate insights among medical practitioners and researchers to propel further exploration, thereby facilitating superior therapeutic alternatives for patients.

Pan-glioma analyses reveal species- and tumor-specific regulation of neuron-glioma synapse genes by lncRNAs

Gliomas are highly heterogeneous and aggressive. Malignant cells in gliomas can contact normal neurons through a synapse-like structure (called neuron-to-glioma synapse, NGS) to promote their proliferation, but it is unclear whether NGS gene expression and regulation show species- and tumor-specificity. This question is important in that many anti-cancer drugs are developed upon mouse models. To address this question, we conducted a pan-glioma analysis using nine scRNA-seq datasets from humans and mice. We also experimentally validated the key element of our methods and verified a key result using TCGA datasets of the same glioma types. Our analyses revealed that NGS gene expression and regulation by lncRNAs are highly species- and tumor-specific. Importantly, simian-specific lncRNAs are more involved in NGS gene regulation than lncRNAs conserved in mammals, and transgenic mouse gliomas have little in common with PDX mouse models and human gliomas in terms of NGS gene regulation. The analyses suggest that simian-specific lncRNAs are a new and rich class of potential targets for tumor-specific glioma treatment, and provide pertinent data for further experimentally and clinically exmining the targets.

Tumoral P2Y2 receptor modulates tumor growth and host anti-tumor immune responses in a syngeneic murine model of oral cancer

Head and neck squamous cell carcinomas (HNSCCs) are a heterogenous group of tumors and among the top 10 most common cancers and they arise from the epithelial tissues of the mucosal surfaces of the oral cavity, oropharynx, and larynx. Aberrant purinergic signaling has been associated with various cancer types. Here, we studied the role of the P2Y2 purinergic receptor (P2Y2R) in the context of oral cancer. We utilized bioinformatics analysis of deposited datasets to examine purinome gene expression in HNSCC tumors and cells lines and functionally characterized nucleotide-induced P2 receptor signaling in human FaDu and Cal27 and murine MOC2 oral cancer cell lines. Utilizing tumorigenesis assays with wild-type or P2ry2 knockout MOC2 cells we evaluated the role of P2Y2Rs in tumor growth and the host anti-tumor immune responses. Our data demonstrate that human and murine oral cancer cell lines express numerous P2 receptors, with the P2Y2R being highly expressed. Using syngeneic tumor grafts in wild-type mice, we observed that MOC2 tumors expressing P2Y2R were larger than P2Y2R-/- tumors. Wild-type MOC2 tumors contained a lower population of tumor-infiltrating CD11b+F4/80+ macrophages and CD3+ cells, which were revealed to be CD3+CD4+IFNγ+ T cells, compared to P2Y2R-/- tumors. These results were mirrored when utilizing P2Y2R-/- mice, indicating that the changes in MOC2 tumor growth and to the host anti-tumor immune response were independent of host derived P2Y2Rs. Results suggest that targeted suppression of the P2Y2R in HNSCC cells in vivo, rather than systemic P2Y2R antagonism, may be a more effective treatment strategy for HNSCCs.

HPV-positive murine oral squamous cell carcinoma: development and characterization of a new mouse tumor model for immunological studies

BACKGROUND

Infection with high-risk human papillomavirus (HPV) strains is one of the risk factors for the development of oral squamous cell carcinoma (OSCC). Some patients with HPV-positive OSCC have a better prognosis and respond better to various treatment modalities, including radiotherapy or immunotherapy. However, since HPV can only infect human cells, there are only a few immunocompetent mouse models available that enable immunological studies. Therefore, the aim of our study was to develop a transplantable immunocompetent mouse model of HPV-positive OSCC and characterize it in vitro and in vivo.

METHODS

Two monoclonal HPV-positive OSCC mouse cell lines were established by inducing the expression of HPV-16 oncogenes E6 and E7 in the MOC1 OSCC cell line using retroviral transduction. After confirming stable expression of HPV-16 E6 and E7 with quantitative real-time PCR and immunofluorescence staining, the cell lines were further characterized in vitro using proliferation assay, wound healing assay, clonogenic assay and RNA sequencing. In addition, tumor models were characterized in vivo in C57Bl/6NCrl mice in terms of their histological properties, tumor growth kinetics, and radiosensitivity. Furthermore, immunofluorescence staining of blood vessels, hypoxic areas, proliferating cells and immune cells was performed to characterize the tumor microenvironment of all three tumor models.

RESULTS

Characterization of the resulting MOC1-HPV cell lines and tumor models confirmed stable expression of HPV-16 oncogenes and differences in cell morphology, in vitro migration capacity, and tumor microenvironment characteristics. Although the cell lines did not differ in their intrinsic radiosensitivity, one of the HPV-positive tumor models, MOC1-HPV K1, showed a significantly longer growth delay after irradiation with a single dose of 15 Gy compared to parental MOC1 tumors. Consistent with this, MOC1-HPV K1 tumors had a lower percentage of hypoxic tumor area and a higher percentage of proliferating cells. Characteristics of the newly developed HPV-positive OSCC tumor models correlate with the transcriptomic profile of MOC1-HPV cell lines.

CONCLUSIONS

In conclusion, we developed and characterized a novel immunocompetent mouse model of HPV-positive OSCC that exhibits increased radiosensitivity and enables studies of immune-based treatment approaches in HPV-positive OSCC.

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

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

Mutant p53 drives an immune cold tumor immune microenvironment in oral squamous cell carcinoma

The critical role of the tumor immune microenvironment (TIME) in determining response to immune checkpoint inhibitor (ICI) therapy underscores the importance of understanding cancer cell-intrinsic mechanisms driving immune-excluded ("cold") TIMEs. One such cold tumor is oral cavity squamous cell carcinoma (OSCC), a tobacco-associated cancer with mutations in the TP53 gene which responds poorly to ICI therapy. Because altered TP53 function promotes tumor progression and plays a potential role in TIME modulation, here we developed a syngeneic OSCC models with defined Trp53 (p53) mutations and characterized their TIMEs and degree of ICI responsiveness. We observed that a carcinogen-induced p53 mutation promoted a cold TIME enriched with immunosuppressive M2 macrophages highly resistant to ICI therapy. p53-mutated cold tumors failed to respond to combination ICI treatment; however, the combination of a programmed cell death protein 1 (PD-1) inhibitor and stimulator of interferon genes (STING) agonist restored responsiveness. These syngeneic OSCC models can be used to gain insights into tumor cell-intrinsic drivers of immune resistance and to develop effective immunotherapeutic approaches for OSCC and other ICI-resistant solid tumors.

Digesting the Role of JAK-STAT and Cytokine Signaling in Oral and Gastric Cancers

When small proteins such as cytokines bind to their associated receptors on the plasma membrane, they can activate multiple internal signaling cascades allowing information from one cell to affect another. Frequently the signaling cascade leads to a change in gene expression that can affect cell functions such as proliferation, differentiation and homeostasis. The Janus kinase-signal transducer and activator of transcription (JAK-STAT) and the tumor necrosis factor receptor (TNFR) are the pivotal mechanisms employed for such communication. When deregulated, the JAK-STAT and the TNF receptor signaling pathways can induce chronic inflammatory phenotypes by promoting more cytokine production. Furthermore, these signaling pathways can promote replication, survival and metastasis of cancer cells. This review will summarize the essentials of the JAK/STAT and TNF signaling pathways and their regulation and the molecular mechanisms that lead to the dysregulation of the JAK-STAT pathway. The consequences of dysregulation, as ascertained from founding work in haematopoietic malignancies to more recent research in solid oral-gastrointestinal cancers, will also be discussed. Finally, this review will highlight the development and future of therapeutic applications which modulate the JAK-STAT or the TNF signaling pathways in cancers.

Stress Keratin 17 Expression in Head and Neck Cancer Contributes to Immune Evasion and Resistance to Immune-Checkpoint Blockade

PURPOSE

We investigated whether in human head and neck squamous cell carcinoma (HNSCC) high levels of expression of stress keratin 17 (K17) are associated with poor survival and resistance to immunotherapy.

EXPERIMENTAL DESIGN

We investigated the role of K17 in regulating both the tumor microenvironment and immune responsiveness of HNSCC using a syngeneic mouse HNSCC model, MOC2. MOC2 gives rise to immunologically cold tumors that are resistant to immune-checkpoint blockade (ICB). We engineered multiple, independent K17 knockout (KO) MOC2 cell lines and monitored their growth and response to ICB. We also measured K17 expression in human HNSCC of patients undergoing ICB.

RESULTS

MOC2 tumors were found to express K17 at high levels. When knocked out for K17 (K17KO MOC2), these cells formed tumors that grew slowly or spontaneously regressed and had a high CD8+ T-cell infiltrate in immunocompetent syngeneic C57BL/6 mice compared with parental MOC2 tumors. This phenotype was reversed when we depleted mice for T cells. Whereas parental MOC2 tumors were resistant to ICB treatment, K17KO MOC2 tumors that did not spontaneously regress were eliminated upon ICB treatment. In a cohort of patients with HNSCC receiving pembrolizumab, high K17 expression correlated with poor response. Single-cell RNA-sequencing analysis revealed broad differences in the immune landscape of K17KO MOC2 tumors compared with parental MOC2 tumors, including differences in multiple lymphoid and myeloid cell types.

CONCLUSIONS

We demonstrate that K17 expression in HNSCC contributes to immune evasion and resistance to ICB treatment by broadly altering immune landscapes of tumors.

Cure of syngeneic carcinomas with targeted IL-12 through obligate reprogramming of lymphoid and myeloid immunity

Therapeutic IL-12 has demonstrated the ability to reduce local immune suppression in preclinical models, but clinical development has been limited by severe inflammation-related adverse events with systemic administration. Here, we show that potent immunologic tumor control of established syngeneic carcinomas can be achieved by i.t. administration of a tumor-targeted IL-12 antibody fusion protein (NHS–rmIL-12) using sufficiently low doses to avoid systemic toxicity. Single-cell transcriptomic analysis and ex vivo functional assays of NHS–rmIL-12–treated tumors revealed reinvigoration and enhanced proliferation of exhausted CD8⁺ T lymphocytes, induction of Th1 immunity, and a decrease in Treg number and suppressive capacity. Similarly, myeloid cells transitioned toward inflammatory phenotypes and displayed reduced suppressive capacity. Cell type–specific IL-12 receptor–KO BM chimera studies revealed that therapeutic modulation of both lymphoid and myeloid cells is required for maximum treatment effect and tumor cure. Study of single-cell data sets from human head and neck carcinomas revealed IL-12 receptor expression patterns similar to those observed in murine tumors. These results describing the diverse mechanisms underlying tumor-directed IL-12–induced antitumor immunity provide the preclinical rationale for the clinical study of i.t. NHS–IL-12.

Checkpoint blockade-induced CD8+ T cell differentiation in head and neck cancer responders

Background

Immune checkpoint blockade (ICB) response in recurrent/metastatic head and neck squamous cell carcinoma (HNSCC) is limited to 15%–20% of patients and underpinnings of resistance remain undefined.

Methods

Starting with an anti-PD1 sensitive murine HNSCC cell line, we generated an isogenic anti-PD1 resistant model. Mass cytometry was used to delineate tumor microenvironments of both sensitive parental murine oral carcinoma (MOC1) and resistant MOC1esc1 tumors. To examine heterogeneity and clonal dynamics of tumor infiltrating lymphocytes (TILs), we applied paired single-cell RNA and TCR sequencing in three HNSCC models.

Results

Anti-PD1 resistant MOC1esc1 line displayed a conserved cell intrinsic immune evasion signature. Immunoprofiling showed distinct baseline tumor microenvironments of MOC1 and MOC1esc1, as well as the remodeling of immune compartments on ICB in MOC1esc1 tumors. Single cell sequencing analysis identified several CD8 +TIL subsets including Tcf7 +Pd1− (naïve/memory-like), Tcf7 +Pd1+ (progenitor), and Tcf7-Pd1+ (differentiated effector). Mapping TCR shared fractions identified that successful anti-PD1 or anti-CTLA4 therapy-induced higher post-treatment T cell lineage transitions.

Conclusions

These data highlight critical aspects of CD8 +TIL heterogeneity and differentiation and suggest facilitation of CD8 +TIL differentiation as a strategy to improve HNSCC ICB response.

MED12 and BRD4 cooperate to sustain cancer growth upon loss of mediator kinase

Mediator kinases (CDK8/19) are transcriptional regulators broadly implicated in cancer. Despite their central role in fine-tuning gene-expression programs, we find complete loss of CDK8/19 is tolerated in colorectal cancer (CRC) cells. Using orthogonal functional genomic and pharmacological screens, we identify BET protein inhibition as a distinct vulnerability in CDK8/19-depleted cells. Combined CDK8/19 and BET inhibition led to synergistic growth retardation in human and mouse models of CRC. Strikingly, depletion of CDK8/19 in these cells led to global repression of RNA polymerase II (Pol II) promoter occupancy and transcription. Concurrently, loss of Mediator kinase led to a profound increase in MED12 and BRD4 co-occupancy at enhancer elements and increased dependence on BET proteins for the transcriptional output of cell-essential genes. In total, this work demonstrates a synthetic lethal interaction between Mediator kinase and BET proteins and exposes a therapeutic vulnerability that can be targeted using combination therapies.

AKAP9 Upregulation Predicts Unfavorable Prognosis in Pediatric Acute Myeloid Leukemia and Promotes Stemness Properties via the Wnt/β-Catenin Pathway

Background

PRKA kinase anchor protein 9 (AKAP9) is a scaffold protein involved in various cellular processes, including cell adhesion, proliferation, differentiation, and apoptosis. Although the oncogenic role of AKAP9 in solid tumors is well elucidated, the functions and mechanisms of AKAP9 in acute myeloid leukemia (AML) are still not understood.

Methods

We used the gene expression omnibus (GEO) database (GSE2191) to determine the mRNA expression of AKAP9 in the bone marrow of pediatric AML and healthy patients. We further used the therapeutically available research to generate effective treatments (TARGET) database to elucidate the relationship between AKAP9 expression and clinical outcomes in pediatric patients with AML. In addition, cell proliferation, cell cycle, apoptosis, RT-PCR, and Western blotting assays were applied to reveal the functions of AKAP9 and the underlying mechanisms of AKAP9 silencing in THP1 and HL60 cell lines.

Results

AKAP9 is overexpressed in the bone marrow of pediatric AML patients as compared with that of healthy patients. High expression of AKAP9 was found to be a predictor of poor overall survival (OS) and event-free survival (EFS). Using univariate and multivariate survival analyses, we found that high AKAP9 expression is an independent predictor of a worse OS and EFS. Functionally, AKAP9 silencing significantly inhibited AML cell proliferation, and cell cycle progression and promoted apoptosis. Moreover, AKAP9 silencing significantly downregulated the expression of stemness markers and β-catenin.

Conclusion

AKAP9 upregulation is a predictor of unfavorable prognosis, promotes stemness, and activates the Wnt/β-catenin pathway in AML patients. AKAP9 may act as a prognostic biomarker of AML in pediatric patients and a future therapeutic target.

Caspase-8 mutations associated with head and neck cancer differentially retain functional properties related to TRAIL-induced apoptosis and cytokine induction

The cysteine protease, caspase-8, undergoes dimerization, processing, and activation following stimulation of cells with death ligands such as TRAIL, and mediates TRAIL induction of the extrinsic apoptosis pathway. In addition, caspase-8 mediates TRAIL-induced activation of NF-κB and upregulation of immunosuppressive chemokines/cytokines, via a mechanism independent of caspase-8 catalytic activity. The gene encoding procaspase-8 is mutated in 10% of human head and neck squamous cell carcinomas (HNSCCs). Despite a paucity of experimental evidence, HNSCC-associated caspase-8 mutations are commonly assumed to be loss of function. To investigate their functional properties and phenotypic effects, 18 HNSCC-associated caspase-8 mutants were expressed in doxycycline-inducible fashion in cell line models wherein the endogenous wild-type caspase-8 was deleted. We observed that 5/8 mutants in the amino-terminal prodomain, but 0/10 mutants in the carboxyl-terminal catalytic region, retained an ability to mediate TRAIL-induced apoptosis. Caspase-8 proteins with mutations in the prodomain were defective in dimerization, whereas all ten of the catalytic region mutants efficiently dimerized, revealing an inverse relationship between dimerization and apoptosis induction for the mutant proteins. Roughly half (3/8) of the prodomain mutants and 9/10 of the catalytic region mutants retained the ability to mediate TRAIL induction of immunosuppressive CXCL1, IL-6, or IL-8. Doxycycline-induced expression of wild-type caspase-8 or a representative mutant led to an increased percentage of T and NKT cells in syngeneic HNSCC xenograft tumors. These findings demonstrate that HNSCC-associated caspase-8 mutants retain properties that may influence TRAIL-mediated apoptosis and cytokine induction, as well as the composition of the tumor microenvironment.

Making External Validation Valid for Molecular Classifier Development

PURPOSE

Accurate assessment of a molecular classifier that guides patient care is of paramount importance in precision oncology. Recent years have seen an increasing use of external validation for such assessment. However, little is known about how it is affected by ubiquitous unwanted variations in test data because of disparate experimental handling and by the use of data normalization for alleviating such variations.

METHODS

In this paper, we studied these issues using two microarray data sets for the same set of tumor samples and additional data simulated by resampling under various levels of signal-to-noise ratio and different designs for array-to-sample allocation.

RESULTS

We showed that (1) unwanted variations can lead to biased classifier assessment and (2) data normalization mitigates the bias to varying extents depending on the specific method used. In particular, frozen normalization methods for test data outperform their conventional forms in terms of both reducing the bias in accuracy estimation and increasing robustness to handling effects. We make available our benchmarking tool as an R package on GitHub for performing such evaluation on additional methods for normalization and classification.

CONCLUSION

Our findings thus highlight the importance of proper test-data normalization for valid assessment by external validation and call for caution on the choice of normalization method for molecular classifier development.

Systems genetics analysis of oral squamous cell carcinoma susceptibility using the mouse model: current position and new perspective

Oral squamous cell carcinoma (OSCC) is one of the most common human malignancies with complex etiology and poor prognosis. Although environmental carcinogens and carcinogenic viruses are still considered the main etiologic factors for OSCC development, genetic factors obviously play a key role in the initiation and progression of this neoplasm, given that not all individuals exposed to carcinogens develop the same severity of the disease, if any. Identifying genetic loci modulating OSCC risk may have several important clinical implications, including early detection, prevention and developing new treatment strategies. Due to limitations in controlled and standardized genetic studies in humans, genetic components underlying susceptibility of OSCC development remain largely unknown. A combination of quantitative trait loci mapping in mice, with complementary association studies in humans, has the potential to discover novel cancer risk loci. As of today, a limited number of genetic analyses were applied on rodent models to locate novel genetic loci associated with human OSCC. Here, we discuss the current status of the mouse models use for dissecting the genetic basis of OSCC and highlight how systems genetics analysis using mouse models, may increase our understanding of human OSCC susceptibility.

PD-L1 targeting high-affinity NK (t-haNK) cells induce direct antitumor effects and target suppressive MDSC populations

Background

Although immune checkpoint inhibitors have revolutionized cancer treatment, clinical benefit with this class of agents has been limited to a subset of patients. Hence, more effective means to target tumor cells that express immune checkpoint molecules should be developed. For the first time, we report a novel natural killer (NK) cell line, programmed death-ligand 1 (PD-L1) targeting high-affinity natural killer (t-haNK), which was derived from NK-92 and was engineered to express high-affinity CD16, endoplasmic reticulum-retained interleukin (IL)-2, and a PD-L1-specific chimeric antigen receptor (CAR). We show that PD-L1 t-haNK cells also retained the expression of native NK receptors and carried a high content of granzyme and perforin granules.

Methods

NanoString, flow cytometry, and immunofluorescence analyses were performed to characterize the phenotype of irradiated PD-L1 t-haNK cells. In vitro PD-L1 t-haNK cell activity against cancer cell lines and human peripheral blood mononuclear cells (PBMCs) was determined via flow-based and ¹¹¹In-release killing assays. The antitumor effect of PD-L1 t-haNK cells in vivo was investigated using MDA-MB-231, H460, and HTB1 xenograft models in NOD-scid IL2Rgamma^null (NSG) mice. Additionally, the antitumor effect of PD-L1 t-haNK cells, in combination with anti-PD-1 and N-803, an IL-15 superagonist, was evaluated using mouse oral cancer 1 syngeneic model in C57BL/6 mice.

Results

We show that PD-L1 t-haNK cells expressed PD-L1-targeting CAR and CD16, retained the expression of native NK receptors, and carried a high content of granzyme and perforin granules. In vitro, we demonstrate the ability of irradiated PD-L1 t-haNK cells to lyse 20 of the 20 human cancer cell lines tested, including triple negative breast cancer (TNBC) and lung, urogenital, and gastric cancer cells. The cytotoxicity of PD-L1 t-haNK cells was correlated to the PD-L1 expression of the tumor targets and can be improved by pretreating the targets with interferon (IFN)-γ. In vivo, irradiated PD-L1 t-haNK cells inhibited the growth of engrafted TNBC and lung and bladder tumors in NSG mice. The combination of PD-L1 t-haNK cells with N-803 and anti-PD-1 antibody resulted in superior tumor growth control of engrafted oral cavity squamous carcinoma tumors in C57BL/6 mice. In addition, when cocultured with human PBMCs, PD-L1 t-haNK cells preferentially lysed the myeloid-derived suppressor cell population but not other immune cell types.

Conclusion

These studies demonstrate the antitumor efficacy of PD-L1 t-haNK cells and provide a rationale for the potential use of these cells in clinical studies.

FLASH Proton Pencil Beam Scanning Irradiation Minimizes Radiation-Induced Leg Contracture and Skin Toxicity in Mice

Simple Summary

Dose and efficacy of radiation therapy are limited by the toxicity to normal tissue adjacent to the treated tumor region. Recently, ultra-high dose rate radiotherapy (FLASH radiotherapy) has shown beneficial reduction of normal tissue damage while preserving similar tumor efficacy with electron, photon and scattered proton beam irradiation in preclinical models. Proton therapy is increasingly delivered by pencil beam scanning (PBS) technology, and we therefore set out to test PBS FLASH radiotherapy on normal tissue toxicity and tumor control in vivo in mouse using a clinical proton delivery system. This validation of the FLASH normal tissue-sparing hypothesis with a clinical delivery system provides supporting data for PBS FLASH radiotherapy and its potential role in improving radiotherapy outcomes.

Abstract

Ultra-high dose rate radiation has been reported to produce a more favorable toxicity and tumor control profile compared to conventional dose rates that are used for patient treatment. So far, the so-called FLASH effect has been validated for electron, photon and scattered proton beam, but not yet for proton pencil beam scanning (PBS). Because PBS is the state-of-the-art delivery modality for proton therapy and constitutes a wide and growing installation base, we determined the benefit of FLASH PBS on skin and soft tissue toxicity. Using a pencil beam scanning nozzle and the plateau region of a 250 MeV proton beam, a uniform physical dose of 35 Gy (toxicity study) or 15 Gy (tumor control study) was delivered to the right hind leg of mice at various dose rates: Sham, Conventional (Conv, 1 Gy/s), Flash60 (57 Gy/s) and Flash115 (115 Gy/s). Acute radiation effects were quantified by measurements of plasma and skin levels of TGF-β1 and skin toxicity scoring. Delayed irradiation response was defined by hind leg contracture as a surrogate of irradiation-induced skin and soft tissue toxicity and by plasma levels of 13 different cytokines (CXCL1, CXCL10, Eotaxin, IL1-beta, IL-6, MCP-1, Mip1alpha, TNF-alpha, TNF-beta, VEGF, G-CSF, GM-CSF and TGF- β1). Plasma and skin levels of TGF-β1, skin toxicity and leg contracture were all significantly decreased in FLASH compared to Conv groups of mice. FLASH and Conv PBS had similar efficacy with regards to growth control of MOC1 and MOC2 head and neck cancer cells transplanted into syngeneic, immunocompetent mice. These results demonstrate consistent delivery of FLASH PBS radiation from 1 to 115 Gy/s in a clinical gantry. Radiation response following delivery of 35 Gy indicates potential benefits of FLASH versus conventional PBS that are related to skin and soft tissue toxicity.

Inhibition of PI3K Isoform p110γ Increases Both Anti-Tumor and Immunosuppressive Responses to Aggressive Murine Head and Neck Squamous Cell Carcinoma with Low Immunogenicity

Simple Summary

Poorly immunogenic head and neck squamous carcinomas (HNSCC) remain difficult to treat due to poor response rates to immunotherapy. Inhibition of the PI3K catalytic subunit p110γ, which is expressed in leukocytes and some HNSCCs, has shown promise in treating HNSCC; with clinical trials underway to gauge its effectiveness. However, the effect of PI3K p110γ inhibition on the host immune system in poorly immunogenic HNSCC has not been fully described. In this study, our group characterized the immune response to poorly immunogenic HNSCC in the absence of PI3K p110γ using an orthotopic mouse model with the MOC2 cell line. We found that mice lacking p110γ did not demonstrate significantly different tumor growth or metastasis, though we observed substantial elevation in both anti-tumor and immunosuppressive activity at the primary tumor site. Our results indicate that PI3K p110γ inhibition may potentially enhance anti-tumor immunity against poorly immunogenic HNSCC if administered with checkpoint inhibitors.

Abstract

HNSCC is the sixth most common cancer, with around 650,000 new cases yearly. Gain of function mutations in the PI3K pathway are common in HNSCC, and inhibition of the PI3K p110γ subunit has shown promise in HNSCC treatment. However, given that PI3K p110γ plays an important role in myeloid and lymphoid immune cell function, it is essential to understand how PI3K p110γ inhibition affects the anti-tumor immune response independent of tumor cells. To elucidate PI3K p110γ function in HNSCC, we employed an orthotopic mouse model using poorly immunogenic and aggressive cell line MOC2 on Pik3cg^−/− mice. We observed that wild-type and Pik3cg^−/− mice displayed similar rates of HNSCC tumor growth and metastasis after 20 days following tumor injection. T-cell infiltration and intrinsic T-cell responses to MOC2 oral tumors were comparable between wild-type and Pik3cg^−/− mice. Interestingly, the immune response of tumor-bearing Pik3cg^−/− mice was marked by increased anti-tumor cytotoxic molecules (IFN-γ, IL-17)) by T-cells and immune checkpoint marker (PD-L1, PD-1) expression by myeloid cells and T-cells compared to tumor-bearing wild-type mice. Taken together, our findings demonstrate that inhibition of PI3K p110γ modulates tumor-associated immune cells, which likely potentiates HNSCC treatment when used in combination with selective checkpoint inhibitors.

Deep Learning in Head and Neck Tumor Multiomics Diagnosis and Analysis: Review of the Literature

Head and neck tumors are the sixth most common neoplasms. Multiomics integrates multiple dimensions of clinical, pathologic, radiological, and biological data and has the potential for tumor diagnosis and analysis. Deep learning (DL), a type of artificial intelligence (AI), is applied in medical image analysis. Among the DL techniques, the convolution neural network (CNN) is used for image segmentation, detection, and classification and in computer-aided diagnosis. Here, we reviewed multiomics image analysis of head and neck tumors using CNN and other DL neural networks. We also evaluated its application in early tumor detection, classification, prognosis/metastasis prediction, and the signing out of the reports. Finally, we highlighted the challenges and potential of these techniques.

Identification of KEY lncRNAs and mRNAs Associated with Oral Squamous Cell Carcinoma Progression

Background:

Oral squamous cell carcinoma (OSCC) has been the sixth most common cancer worldwide. Emerging studies showed long non-coding RNAs to play a key role in human cancers. However, the molecular mechanisms underlying the initiation and progression of OSCC remained to be further explored.

Objective:

The present study aimed to identify differentially expressed lncRNAs and mRNAs in OSCC.

Methods:

GSE30784 was analyzed to identify differentially expressed lncRNAs and mRNAs in OSCC. Protein-protein interaction network and co-expression network analyses were performed to reveal the potential roles of OSCC related mRNAs and lncRNAs.

Results:

In the present study, we identified 21 up-regulated lncRNAs and 54 down-regulated lncRNAs in OSCC progression. Next, we constructed a lncRNA related co-expression network in OSCC, which included 692 mRNAs and 2193 edges. Bioinformatics analysis showed that lncRNAs were widely co-expressed with regulating type I interferon signaling pathway, extracellular matrix organization, collagen catabolic process, immune response, ECM-receptor interaction, Focal adhesion, and PI3K-Akt signaling pathway. A key network, including lncRNA C5orf66-AS1, C21orf15, LOC100506098, PCBP1-AS1, LOC284825, OR7E14P, HCG22, and FLG-AS1, was found to be involved in the regulation of immune response to tumor cell, Golgi calcium ion transport, negative regulation of vitamin D receptor signaling pathway, and glycerol- 3-phosphate catabolic process. Moreover, we found higher expressions of CYP4F29P, PCBP1- AS1, HCG22, and C5orf66-AS1, which were associated with shorter overall survival time in OSCC samples.

Conclusions:

Our analysis can provide novel insights to explore the potential mechanisms underlying OSCC progression.

Screening the key genes of prognostic value in the microenvironment for head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth common malignancy worldwide. The tumor microenvironment is highly related to tumor initiation, progression, and prognosis. This study aims to screen the tumor microenvironment related key genes of prognostic value for HNSCC.The gene expression and clinical data for HNSCC were downloaded from the cancer genome atlas (TCGA). The immune/stromal/ESTIMATE scores were downloaded from the website of the MD Anderson Cancer Center. Correlation of patient gender and tumor grade with immune/stromal/ESTIMATE score was tested. Patients were divided into low and high immune/stromal/ESTIMATE score subgroups. Survival analysis was performed to evaluate the prognostic value of the immune/stromal/ESTIMATE score. Tumor microenvironment related differentially expressed genes were determined and applied for functional enrichment analysis and protein-protein interaction network was predicted. The prediction value of the common differentially expressed genes on patient survival was tested.Four hundred eighty samples with complete clinical, expression data, and immune/stromal/ESTIMATE scores were enrolled for analysis. Immune/stromal/ESTIMATE score was higher in female patients than males. A total of 44 common differentially expressed genes were screened in high and low immune/stromal/ESTIMATE score subgroups. Of the 44 genes, 7 genes (ADGRG7, CSN3, CST8, KRT81, MUC7, MYH6, and SEZ6) were found to be closely related to patient survival. Enrichment analysis showed that the differentially expressed genes mainly enriched in the protein-coupled receptor signaling pathway, extracellular region, G-protein coupled receptor activity, salivary secretion, and regulation of lipolysis in adipocytes. Protein-protein interaction analysis revealed that POSTN and OGN were crucial microenvironments related genes.Tumor microenvironment related genes ADGRG7, CSN3, CST8, KRT81, MUC7, MYH6, and SEZ6 are valuable predictors for HNSCC patient survival. POSTN and OGN are crucial in modulating the microenvironment and tumor biology for HNSCC.

Mediator's Kinase Module: A Modular Regulator of Cell Fate

Selective gene expression is crucial in maintaining the self-renewing and multipotent properties of stem cells. Mediator is a large, evolutionarily conserved, multi-subunit protein complex that modulates gene expression by relaying signals from cell type-specific transcription factors to RNA polymerase II. In humans, this complex consists of 30 subunits arranged in four modules. One critical module of the Mediator complex is the kinase module consisting of four subunits: MED12, MED13, CDK8, and CCNC. The kinase module exists in variable association with the 26-subunit Mediator core and affects transcription through phosphorylation of transcription factors and by controlling Mediator structure and function. Many studies have shown the kinase module to be a key player in the maintenance of stem cells that is distinct from a general role in transcription. Genetic studies have revealed that dysregulation of this kinase subunit contributes to the development of many human diseases. In this review, we discuss the importance of the Mediator kinase module by examining how this module functions with the more recently identified transcriptional super-enhancers, how changes in the kinase module and its activity can lead to the development of human disease, and the role of this unique module in directing and maintaining cell state. As we look to use stem cells to understand human development and treat human disease through both cell-based therapies and tissue engineering, we need to remain aware of the on-going research and address critical gaps in knowledge related to the molecular mechanisms that control cell fate.

Comprehensive Exome Analysis of Immunocompetent Metastatic Head and Neck Cancer Models Reveals Patient Relevant Landscapes

Immunocompetent metastatic head and neck cancer (HNC) models, although scarce, can help understanding cancer progression and therapy responses in vivo. Their comprehensive genome characterizations are essential for translational research. We first exome-sequenced the two most widely used spontaneous metastatic immunocompetent models, namely AT-84 and SCC VII, followed by comprehensive genomic analyses with three prior-sequenced models (MOC2, MOC2-10, and 4MOSC2), together with patient tumors for utility assessment. AT-84 and SCC VII bear high HNC tumor resemblance regarding mutational signatures-Trp53, Fanconi anemia, and MAPK and PI3K pathway defects. Collectively, the five models harbor genetic aberrations across 10 cancer hallmarks and 14 signaling pathways and machineries (metabolic, epigenetic, immune evasion), to extents similar in patients. Immune defects in HLA-A (H2-Q10, H2-Q4, H2-Q7, and H2-K1), Pdcd1, Tgfb1, Il2ra, Il12a, Cd40, and Tnfrsf14 are identified. Invasion/metastatic genome analyses first highlight potential druggable ERBB4 and KRAS mutations, for advanced/metastatic oral cavity cancer, as well as known metastasis players (Muc5ac, Trem3, Trp53, and Ttn) frequently captured by all models. Notable immunotherapy and precision druggable targets (Pdcd1, Erbb4, Fgfr1, H/Kras, Jak1, and Map2k2) and three druggable hubs (RTK family, MAPK, and DNA repair pathways) are frequently represented by these models. Immunocompetent metastatic HNC models are worth developing to address therapy- and invasion/metastasis-related questions in host immunity contexts.

Tumor control via targeting PD-L1 with chimeric antigen receptor modified NK cells

Failed T cell-based immunotherapies in the presence of genomic alterations in antigen presentations pathways may be overcome by NK cell-based immunotherapy. This approach may still be limited by the presence of immunosuppressive myeloid populations. Here, we demonstrate that NK cells (haNKs) engineered to express a PD-L1 chimeric antigen receptor (CAR) haNKs killed a panel of human and murine head and neck cancer cells at low effector-to-target ratios in a PD-L1-dependent fashion. Treatment of syngeneic tumors resulted in CD8 and PD-L1-dependent tumor rejection or growth inhibition and a reduction in myeloid cells endogenously expressing high levels of PD-L1. Treatment of xenograft tumors resulted in PD-L1-dependent tumor growth inhibition. PD-L1 CAR haNKs reduced levels of macrophages and other myeloid cells endogenously expressing high PD-L1 in peripheral blood from patients with head and neck cancer. The clinical study of PD-L1 CAR haNKs is warranted.

Tumor Membrane Vesicle Vaccine Augments the Efficacy of Anti-PD1 Antibody in Immune Checkpoint Inhibitor-Resistant Squamous Cell Carcinoma Models of Head and Neck Cancer

Immune checkpoint inhibitor (ICI) immunotherapy improved the survival of head and neck squamous cell carcinoma (HNSCC) patients. However, more than 80% of the patients are still resistant to this therapy. To test whether the efficacy of ICI therapy can be improved by vaccine-induced immunity, we investigated the efficacy of a tumor membrane-based vaccine immunotherapy in murine models of HNSCC. The tumors, grown subcutaneously, are used to prepare tumor membrane vesicles (TMVs). TMVs are then incorporated with glycolipid-anchored immunostimulatory molecules GPI-B7-1 and GPI-IL-12 by protein transfer to generate the TMV vaccine. This TMV vaccine inhibited tumor growth and improved the survival of mice challenged with SCCVII tumor cells. The tumor-free mice survived for several months, remained tumor-free, and were protected following a secondary tumor cell challenge, suggesting that the TMV vaccine induced an anti-tumor immune memory response. However, no synergy with anti-PD1 mAb was observed in this model. In contrast, the TMV vaccine was effective in inhibiting MOC1 and MOC2 murine oral cancer models and synergized with anti-PD1 mAb in extending the survival of tumor-bearing mice. These observations suggest that tumor tissue based TMV vaccines can be harnessed to develop an effective personalized immunotherapy for HNSCC that can enhance the efficacy of immune checkpoint inhibitors.

The emerging role of mediator complex subunit 12 in tumorigenesis and response to chemotherapeutics

Transcriptional dysregulation induced by disease-defining genetic alterations of proteins in transcriptional machinery is a key feature of cancers. Mediator complex subunit 12 (MED12) is the central architectural subunit in the kinase module of Mediator, a large transcriptional regulatory complex that controls essential steps of transcription. Emerging evidence links deregulated MED12 to human cancers. MED12 is frequently mutated in benign tumors and cancers. Although the missense mutations of MED12 in benign tumors disrupt the kinase activity of Mediator, MED12 mutations in cancers could eliminate the interaction between Mediator complex and RNA polymerase II, leading to severe transcriptional misregulation. Aberrant expression of MED12 is associated with the prognosis of various types of human cancers. Loss of MED12 function has been associated with the development of resistance to chemotherapeutics. Moreover, MED12 is modified by posttranscriptional regulations. Arginine methylation of MED12 has been shown to regulate MED12-mediated transcriptional regulation and response to chemotherapeutics in human cancer cell lines. In this mini-review, the authors provide an overview of the roles of MED12 in the development of benign and malignant tumors as well as its roles in chemoresistance. The studies of MED12 exemplify that aberrant transcriptional programming is a therapeutic vulnerability for certain types of cancer.

Inhibition of MDSC Trafficking with SX-682, a CXCR1/2 Inhibitor, Enhances NK-Cell Immunotherapy in Head and Neck Cancer Models

PURPOSE

Natural killer (NK)-cell-based immunotherapy may overcome obstacles to effective T-cell-based immunotherapy such as the presence of genomic alterations in IFN response genes and antigen presentation machinery. All immunotherapy approaches may be abrogated by the presence of an immunosuppressive tumor microenvironment present in many solid tumor types, including head and neck squamous cell carcinoma (HNSCC). Here, we studied the role of myeloid-derived suppressor cells (MDSC) in suppressing NK-cell function in HNSCC.

EXPERIMENTAL DESIGN

The ability of peripheral and tumor-infiltrating MDSC from mice bearing murine oral cancer 2 (MOC2) non-T-cell-inflamed tumors and from patients with HNSCC to suppress NK-cell function was studied with real-time impedance and ELISpot assays. The therapeutic efficacy of SX-682, a small-molecule inhibitor of CXCR1 and CXCR2, was assessed in combination with adoptively transferred NK cells.

RESULTS

Mice bearing MOC2 tumors pathologically accumulate peripheral CXCR2⁺ neutrophilic-MDSC (PMN-MDSC) that traffic into tumors and suppress NK-cell function through TGFβ and production of H₂O₂. Inhibition of MDSC trafficking with orally bioavailable SX-682 significantly abrogated tumor MDSC accumulation and enhanced the tumor infiltration, activation, and therapeutic efficacy of adoptively transferred murine NK cells. Patients with HNSCC harbor significant levels of circulating and tumor-infiltrating CXCR1/2⁺ CD15⁺ PMN-MDSC and CD14⁺ monocytic-MDSC. Tumor MDSC exhibited greater immunosuppression than those in circulation. HNSCC tumor MDSC immunosuppression was mediated by multiple, independent, cell-specific mechanisms including TGFβ and nitric oxide.

CONCLUSIONS

The clinical study of CXCR1/2 inhibitors in combination with adoptively transferred NK cells is warranted.

Neoadjuvant PD-1 Immune Checkpoint Blockade Reverses Functional Immunodominance among Tumor Antigen-Specific T Cells

PURPOSE

Surgical resection of primary tumor with regional lymphadenectomy remains the treatment of choice for patients with advanced human papillomavirus-negative head and neck squamous cell carcinoma. However, even when pathologic disease-free margins can be achieved, locoregional and/or distant disease relapse remains high. Perioperative immunotherapy may improve outcomes, but mechanistic data supporting the use of neoadjuvant or adjuvant treatment clinically are sparse.

EXPERIMENTAL DESIGN

Two syngeneic models of oral cavity carcinoma with defined T-cell antigens were treated with programmed death receptor 1 (PD-1) mAb before or after surgical resection of primary tumors, and antigen-specific T-cell responses were explored with functional and in vivo challenge assays.

RESULTS

We demonstrated that functional immunodominance developed among T cells targeting multiple independent tumor antigens. T cells specific for subdominant antigens expressed greater levels of PD-1. Neoadjuvant, but not adjuvant, PD-1 immune checkpoint blockade broke immunodominance and induced T-cell responses to dominant and subdominant antigens. Using tumors lacking the immunodominant antigen as a model of antigen escape, neoadjuvant PD-1 immune checkpoint blockade induced effector T-cell immunity against tumor cells lacking immunodominant but retaining subdominant antigen. When combined with complete surgical excision, neoadjuvant PD-1 immune checkpoint blockade led to formation of immunologic memory capable of preventing engraftment of tumors lacking the immunodominant but retaining subdominant antigen.

CONCLUSIONS

Together, these results implicate PD-1 expression by T cells in the mechanism of functional immunodominance among independent T-cell clones within a progressing tumor and support the use of neoadjuvant PD-1 immune checkpoint blockade in patients with surgically resectable carcinomas.

Differential gene expression analysis of HNSCC tumors deciphered tobacco dependent and independent molecular signatures

Head and neck cancer is the sixth most common cancer worldwide, with tobacco as the leading cause. However, it is increasing in non-tobacco users also, hence limiting our understanding of its underlying molecular mechanisms. RNA-seq analysis of cancers has proven as effective tool in understanding disease etiology. In the present study, RNA-Seq of 86 matched Tumor/Normal pairs, of tobacco smoking (TOB) and non-smokers (N-TOB) HNSCC samples analyzed, followed by validation on 375 similar datasets. Total 2194 and 2073 differentially expressed genes were identified in TOB and N-TOB tumors, respectively. GO analysis found muscle contraction as the most enriched biological process in both TOB and N-TOB tumors. Pathway analysis identified muscle contraction and salivary secretion pathways enriched in both categories, whereas calcium signaling and neuroactive ligand-receptor pathway was more enriched in TOB and N-TOB tumors respectively. Network analysis identified muscle development related genes as hub node i. e. ACTN2, MYL2 and TTN in both TOB and N-TOB tumors, whereas EGFR and MYH6, depicts specific role in TOB and N-TOB tumors. Additionally, we found enriched gene networks possibly be regulated by tumor suppressor miRNAs such as hsa-miR-29/a/b/c, hsa-miR-26b-5p etc., suggestive to be key riboswitches in regulatory cascade of HNSCC. Interestingly, three genes PKLR, CST1 and C17orf77 found to show opposite regulation in each category, hence suggested to be key genes in separating TOB from N-TOB tumors. Our investigation identified key genes involved in important pathways implicated in tobacco dependent and independent carcinogenesis hence may help in designing precise HNSCC diagnostics and therapeutics strategies.

Identifying Cancer Targets Based on Machine Learning Methods via Chou's 5-steps Rule and General Pseudo Components

In recent years, the successful implementation of human genome project has made people realize that genetic, environmental and lifestyle factors should be combined together to study cancer due to the complexity and various forms of the disease. The increasing availability and growth rate of 'big data' derived from various omics, opens a new window for study and therapy of cancer. In this paper, we will introduce the application of machine learning methods in handling cancer big data including the use of artificial neural networks, support vector machines, ensemble learning and naïve Bayes classifiers.

Enhancing direct cytotoxicity and response to immune checkpoint blockade following ionizing radiation with Wee1 kinase inhibition

Tumor cells activate the G2/M cell cycle checkpoint in response to ionizing radiation (IR) and effector immune cell-derived granzyme B to facilitate repair and survival. Wee1 kinase inhibition reverses the ability of tumor cells to pause at G2/M. Here, we hypothesized that AZD1775, a small molecule inhibitor of Wee1 kinase, could sensitize tumor cells to IR and T-lymphocyte killing and improve responses to combination IR and programmed death (PD)-axis immune checkpoint blockade (ICB). Multiple models of head and neck carcinoma, lung carcinoma and melanoma were used in vitro and in vivo to explore this hypothesis. AZD1775 reversed G2/M cell cycle checkpoint activation following IR, inducing cell death. Combination IR and AZD1775 induced accumulation of DNA damage in M-phase cells and was rescued with nucleoside supplementation, indicating mitotic catastrophe. Combination treatment enhanced control of syngeneic MOC1 tumors in vivo, and on-target effects of systemic AZD1775 could be localized with targeted IR. Combination treatment enhanced granzyme B-dependent T-lymphocyte killing through reversal of additive G2/M cell cycle block induced by IR and granzyme B. Combination IR and AZ1775-enhanced CD8⁺ cell-dependent MOC1 tumor growth control and rate of complete rejection of established tumors in the setting of PD-axis ICB. Functional assays demonstrated increased tumor antigen-specific immune responses in sorted T-lymphocytes. The combination of IR and AZD1775 not only lead to enhanced tumor-specific cytotoxicity, it also enhanced susceptibility to T-lymphocyte killing and responses to PD-axis ICB. These data provide the pre-clinical rationale for the combination of these therapies in the clinical trial setting.

Inhibiting myeloid-derived suppressor cell trafficking enhances T cell immunotherapy

Recruitment of myeloid-derived suppressor cells (MDSCs) into tumors induces local immunosuppression in carcinomas. Here, we assessed whether SX-682, an orally bioavailable small-molecule inhibitor of CXCR1 and CXCR2, could block tumor MDSC recruitment and enhance T cell activation and antitumor immunity following multiple forms of immunotherapy. CXCR2+ neutrophilic MDSCs (PMN-MDSCs) were the most abundant myeloid cell subset within oral and lung syngeneic carcinomas. PMN-MDSCs demonstrated greater suppression of tumor-infiltrating lymphocyte killing of targets compared with macrophages. SX-682 significantly inhibited trafficking of PMN-MDSCs without altering CXCR2 ligand expression. Trafficking of CXCR1+ macrophages was unaltered, possibly due to coexpression of CSF1R. Reduced PMN-MDSC tumor infiltration correlated with enhanced accumulation of endogenous or adoptively transferred T cells. Accordingly, tumor growth inhibition or the rate of established tumor rejection following programed death-axis (PD-axis) immune checkpoint blockade or adoptive cell transfer of engineered T cells was enhanced in combination with SX-682. Despite CXCR1/2 expression on tumor cells, SX-682 appeared to have little direct antitumor effect on these carcinoma models. These data suggest that tumor-infiltrating CXCR2+ PMN-MDSCs may prevent optimal responses following both PD-axis immune checkpoint blockade and adoptive T cell transfer therapy. Abrogation of PMN-MDSC trafficking with SX-682 enhances T cell-based immunotherapeutic efficacy and may be of benefit to patients with MDSC-infiltrated cancers.

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

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

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

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

Semaphorin4D Inhibition Improves Response to Immune-Checkpoint Blockade via Attenuation of MDSC Recruitment and Function

Tumor infiltration by immunosuppressive myeloid cells, such as myeloid-derived suppressor cells (MDSCs), causes resistance to immunotherapy. Semaphorin4D, originally characterized for its axonal guidance properties, also contributes to endothelial cell migration and survival and modulates global immune cytokine profiles and myeloid cell polarization within the tumor microenvironment. Here, we show how a therapeutic murine Sema4D mAb improves responses to immune-checkpoint blockade (ICB) in two murine carcinoma models. Treatment of tumor-bearing mice with Sema4D mAb abrogated Ly6G^hi PMN-MDSC recruitment through reducing MAPK-dependent chemokine production by tumor cells in Murine oral cancer-1 (MOC1) tumors. PMN-MDSC suppressive capacity was reduced through inhibition of Sema4D-driven arginase expression. These changes led to enhanced tumor infiltration by CD8⁺ TIL and activation of tumor-draining lymph node T lymphocytes in response to tumor antigen. Sema4D mAb in combination with either CTLA-4 or PD-1 blockade enhanced rejection of tumors or tumor growth delay, resulting in prolonged survival with either treatment. This function of Sema4D mAb provides a rationale for its evaluation in combination with ICB to treat tumors with immunosuppressive myeloid infiltration.

Insights from multidimensional analyses of the pan-cancer DNA methylome heterogeneity and the uncanonical CpG-gene associations

Although the DNA methylome profiles have been available in large cancer cohorts such as The Cancer Genome Atlas (TCGA), integrative analysis of the DNA methylome architectures in a pan-cancer manner remains limited. In the present study, we aimed to systematically dissect the insightful features related to the inter-tumoral DNA methylome heterogeneity in a pan-cancer context of 21 cancers in TCGA. First, pan-cancer clustering of the DNA methylomes revealed convergence of cancers and, meanwhile, new classifications of cancer subtypes, which are often associated to prognostic differences. Next, within each type of cancer, we showed that the transcription factor (TF) genes tend to bear more dynamic promoter DNA methylation profiles than the other genes, which serves as a potential source of the transcriptome heterogeneity in cancers. Finally, we found unanticipated significant numbers of the non-canonical promoter CpG sites that are positively correlated with the gene expression. Distribution patterns of these CpG sites in the CpG islands, ChIP-seq, DNaseI-seq, PMD regions and histone modification landscapes suggested against a pervasive mechanism of transcriptional activation due to mCpG-dependent binding of TFs, which is not in complete agreement with previous hypothesis. In summary, our deep mining of the highly heterogeneous DNA methylome data in a pan-cancer context generated novel insights into the architecture of cancer epigenetics and provided a series of resources for further investigations in the related fields of cancer genomics and epigenetics.

Antagonist of cIAP1/2 and XIAP enhances anti-tumor immunity when combined with radiation and PD-1 blockade in a syngeneic model of head and neck cancer

Head and neck squamous cell carcinomas (HNSCCs) frequently harbor genomic mutations in cell death pathways. Nearly 30% of HNSCCs overexpress Fas-Associated Death Domain (FADD), with or without BIRC2/3 genes encoding cellular Inhibitor of Apoptosis Proteins 1/2 (cIAP1/2), critical components of the Tumor Necrosis Factor (TNF) Receptor signaling pathways. ASTX660 is a novel non-peptidomimetic antagonist of cIAP1/2 and XIAP under evaluation in a clinical trial for advanced solid tumors and lymphomas. Herein, we show that ASTX660, at nanomolar concentrations, sensitized Murine Oral Cancer (MOC1) cells to TNFα. Using syngeneic mouse models, ASTX660 showed additive anti-tumor activity with radiation therapy (XRT), cisplatin chemotherapy, and PD-1 blockade to significantly delay or eradicate MOC1 tumors. These combinations significantly increased CD8 + T cells and dendritic cells, as well as T cell activity. ASTX660 stimulated cytotoxic T lymphocyte (CTL) killing of MOC1 cells expressing ovalbumin. Early stages of CTL killing were predominantly mediated by perforin/granzyme B, whereas later stages were mediated by death ligands TNFα, TRAIL, and FasL. Correspondingly, depletion of CD8 + T cells and NK cells in vivo revealed both types of immune cells to be important components of the complete anti-tumor response enhanced by ASTX660+XRT. These findings serve to inform future studies of IAP inhibitors and support the potential for future clinical trials investigating ASTX660 with XRT and immunotherapies like PD-1/PD-L1 blockade in HNSCC.

WEE1 kinase inhibition reverses G2/M cell cycle checkpoint activation to sensitize cancer cells to immunotherapy

Intrinsic resistance to cytotoxic T-lymphocyte (CTL) killing limits responses to immune activating anti-cancer therapies. Here, we established that activation of the G2/M cell cycle checkpoint results in tumor cell cycle pause and protection from granzyme B-induced cell death. This was reversed with WEE1 kinase inhibition, leading to enhanced CTL killing of antigen-positive tumor cells. Similarly, but at a later time point, cell cycle pause following TNFα exposure was reversed with WEE1 kinase inhibition, leading to CTL transmembrane TNFα-dependent induction of apoptosis and necroptosis in bystander antigen-negative tumor cells. Results were reproducible in models of oral cavity carcinoma, melanoma and colon adenocarcinoma harboring variable Tp53 genomic alterations. WEE1 kinase inhibition sensitized tumors to PD-1 mAb immune checkpoint blockade in vivo, resulting in CD8⁺-dependent rejection of established tumors harboring antigen-positive or mixed antigen-positive and negative tumor cells. Together, these data describe activation of the G2/M cell cycle checkpoint in response to early and late CTL products as a mechanism of resistance to CTL killing, and provide pre-clinical rationale for the clinical combination of agents that inhibit cell cycle checkpoints and activate anti-tumor immunity.

Inhibition of WEE1 kinase and cell cycle checkpoint activation sensitizes head and neck cancers to natural killer cell therapies

Background

Natural killer (NK) cells recognize and lyse target tumor cells in an MHC-unrestricted fashion and complement antigen- and MHC-restricted killing by T-lymphocytes. NK cells and T-lymphocytes mediate early killing of targets through a common granzyme B-dependent mechanism. Tumor cell resistance to granzyme B and how this alters NK cell killing is not clearly defined.

Methods

Tumor cell sensitivity to cultured murine KIL and human high affinity NK (haNK) cells in the presence or absence of AZD1775, a small molecule inhibitor of WEE1 kinase, was assessed via real time impedance analysis. Mechanisms of enhanced sensitivity to NK lysis were determined and in vivo validation via adoptive transfer of KIL cells into syngeneic mice was performed.

Results

Cultured murine KIL cells lyse murine oral cancer 2 (MOC2) cell targets more efficiently than freshly isolated peripheral murine NK cells. MOC2 sensitivity to granzyme B-dependent KIL cell lysis was enhanced by inhibition of WEE1 kinase, reversing G2/M cell cycle checkpoint activation and resulting in enhanced DNA damage and apoptosis. Treatment of MOC2 tumor-bearing wild-type C57BL/6 mice with AZD1775 and adoptively transferred KIL cells resulted in enhanced tumor growth control and survival over controls or either treatment alone. Validating these findings in human models, WEE1 kinase inhibition sensitized two human head and neck cancer cell lines to direct lysis by haNK cells. Further, WEE1 kinase inhibition sensitized these cell lines to antibody-dependent cell-mediated cytotoxicity when combined with the anti-PD-L1 IgG1 mAb Avelumab.

Conclusions

Tumor cell resistance to granzyme B-induced cell death can be reversed through inhibition of WEE1 kinase as AZD1775 sensitized both murine and human head and neck cancer cells to NK lysis. These data provide the pre-clinical rationale for the combination of small molecules that reverse cell cycle checkpoint activation and NK cellular therapies.

Mitigating SOX2-potentiated Immune Escape of Head and Neck Squamous Cell Carcinoma with a STING-inducing Nanosatellite Vaccine

Purpose: The response rates of Head and Neck Squamous Cell Carcinoma (HNSCC) to checkpoint blockade are below 20%. We aim to develop a mechanism-based vaccine to prevent HNSCC immune escape.Experimental Design: We performed RNA-Seq of sensitive and resistant HNSCC cells to discover central pathways promoting resistance to immune killing. Using biochemistry, animal models, HNSCC microarray, and immune cell deconvolution, we assessed the role of SOX2 in inhibiting STING-type I interferon (IFN-I) signaling-mediated antitumor immunity. To bypass SOX2-potentiated STING suppression, we engineered a novel tumor antigen-targeted nanosatellite vehicle to enhance the efficacy of STING agonist and sensitize SOX2-expressing HNSCC to checkpoint blockade.Results: The DNA-sensing defense response is the most suppressed pathway in immune-resistant HNSCC cells. We identified SOX2 as a novel inhibitor of STING. SOX2 facilitates autophagy-dependent degradation of STING and inhibits IFN-I signaling. SOX2 potentiates an immunosuppressive microenvironment and promotes HNSCC growth in vivo in an IFN-I-dependent fashion. Our unique nanosatellite vehicle significantly enhances the efficacy of STING agonist. We show that the E6/E7-targeted nanosatellite vaccine expands the tumor-specific CD8⁺ T cells by over 12-fold in the tumor microenvironment and reduces tumor burden. A combination of nanosatellite vaccine with anti-PD-L1 significantly expands tumor-specific CTLs and limits the populations expressing markers for exhaustion, resulting in more effective tumor control and improved survival.Conclusions: SOX2 dampens the immunogenicity of HNSCC by targeting the STING pathway for degradation. The nanosatellite vaccine offers a novel and effective approach to enhance the adjuvant potential of STING agonist and break cancer tolerance to immunotherapy. Clin Cancer Res; 24(17); 4242-55. ©2018 AACR.

Expressional analysis of disease-relevant signalling-pathways in primary tumours and metastasis of head and neck cancers

Head and neck squamous cell carcinoma (HNSCC) often metastasize to lymph nodes resulting in poor prognosis for patients. Unfortunately, the underlying molecular mechanisms contributing to tumour aggressiveness, recurrences, and metastasis are still not fully understood. However, such knowledge is key to identify biomarkers and drug targets to improve prognosis and treatments. Consequently, we performed genome-wide expression profiling of 15 primary HNSSCs compared to corresponding lymph node metastases and non-malignant tissue of the same patient. Differentially expressed genes were bioinformatically exploited applying stringent filter criteria, allowing the discrimination between normal mucosa, primary tumours, and metastases. Signalling networks involved in invasion contain remodelling of the extracellular matrix, hypoxia-induced transcriptional modulation, and the recruitment of cancer associated fibroblasts, ultimately converging into a broad activation of PI3K/AKT-signalling pathway in lymph node metastasis. Notably, when we compared the diagnostic and prognostic value of sequencing data with our expression analysis significant differences were uncovered concerning the expression of the receptor tyrosine kinases EGFR and ERBB2, as well as other oncogenic regulators. Particularly, upregulated receptor tyrosine kinase combinations for individual patients varied, implying potential compensatory and resistance mechanisms against specific targeted therapies. Collectively, we here provide unique transcriptional profiles for disease predictions and comprehensively analyse involved signalling pathways in advanced HNSCC.

Nanocomplex-based TP53 gene therapy promotes anti-tumor immunity through TP53- and STING-dependent mechanisms

Loss or mutation of TP53 has been linked to alterations in anti-tumor immunity as well as dysregulation of cell cycle and apoptosis. We explored immunologic effects and mechanisms following restoration of wild-type human TP53 cDNA in murine oral cancer cells using the therapeutic nanocomplex scL-53. We demonstrated scL-53 induces dose-dependent expression of TP53 and induction of apoptosis and immunogenic cell death. We further demonstrated both TP53-dependent and independent induction of tumor cell immunogenicity through the use of blocking mAbs, nanocomplex loaded with DNA plasmid with or without TP53 cDNA, empty nanocomplex and siRNA knockdown techniques. TP53-independent immune modulation was observed following treatment with nanocomplex loaded with DNA plasmid lacking TP53 cDNA and abrogated in STING-deficient tumor cells, supporting the presence of a cytoplasmic DNA sensing, STING-dependent type-I IFN response. Cooperatively, TP53- and STING-dependent alterations sensitized tumor cells to CTL-mediated lysis, which was further enhanced following reversal of adaptive immune resistance with PD-1 mAb. In vivo, combination scL-53 and PD-1 mAb resulted in growth control or rejection of established tumors that was abrogated in mice depleted of CD8+ cells or in STING deficient mice. Cumulatively, this work demonstrates 1) a direct anti-tumor effects of functional TP53; 2) non-redundant TP53- and STING-dependent induction of tumor cell immunogenicity following scL-53 treatment; and 3) that adaptive immune resistance following scL-53 treatment can be reversed with PD-based immune checkpoint blockade, resulting in the rejection or control of syngeneic murine tumors. These data strongly support the clinical combination of scL-53 and immune checkpoint blockade.