Adaptive Immune Resistance: How Cancer Protects from Immune Attack

Oncolytic Maraba virus armed with tumor antigen boosts vaccine priming and reveals diverse therapeutic response patterns when combined with checkpoint blockade in ovarian cancer

BACKGROUND

Cancer immunotherapies are emerging as promising treatment strategies for ovarian cancer patients that experience disease relapse following first line therapy. As such, identifying strategies to bolster anti-tumor immunity and limit immune suppression, while recognizing diverse patterns of tumor response to immunotherapy is critical to selecting treatment combinations that lead to durable therapeutic benefit.

METHODS

Using a pre-clinical mouse model, we evaluated a heterologous prime/boost vaccine in combination with checkpoint blockade to treat metastatic intraperitoneal ovarian cancer. Vaccine-elicited CD8⁺ T cell responses and changes in the tumor microenvironment following treatment were analyzed and compared to treatment outcome. Kinetics of intraperitoneal tumor growth were assessed using non-invasive magnetic resonance imaging (MRI).

RESULTS

Vaccine priming followed by antigen-armed oncolytic Maraba virus boosting elicited robust tumor-specific CD8⁺ T cell responses that improved tumor control and led to unique immunological changes in the tumor, including a signature that correlated with improved clinical outcome of ovarian cancer patients. However, this treatment was not curative and T cells in the tumor microenvironment (TME) were functionally suppressed. Combination PD-1 blockade partially overcame the adaptive resistance in the tumor observed in response to prime/boost vaccination, restoring CD8⁺ T cell function in the TME and enhancing the therapeutic response. Non-invasive MRI of tumors during the course of combination treatment revealed heterogeneous radiologic response patterns following treatment, including pseudo-progression, which was associated with improved tumor control prior to relapse.

CONCLUSIONS

Our findings point to a key hierarchical role for PD-1 signaling and adaptive immune resistance in the ovarian TME in determining the functional fate of tumor-specific CD8⁺ T cells, even in the context of robust therapy mediated anti-tumor immunity, as well as the ability of multiple unique patterns of therapeutic response to result in durable tumor control.

Expanding the Organismal Proteostasis Network: Linking Systemic Stress Signaling with the Innate Immune Response

Stress response pathways regulate proteostasis and mitigate macromolecular damage to promote long-term cellular health. Intercellular signaling is an essential layer of systemic proteostasis in an organism and is facilitated via transcellular signaling molecules that orchestrate the activation of stress responses across tissues and organs. Accumulating evidence indicates that components of the immune response act as signaling factors that regulate the cell-non-autonomous proteostasis network. Here, we review emergent advances in our understanding of cell-non-autonomous regulators of proteostasis networks in multicellular settings, from the model organism, Caenorhabditis elegans, to humans. We further discuss how innate immune responses can be players of the organismal proteostasis network and discuss how both are linked in cancer.

Transient receptor potential ion-channel subfamily V member 4: a potential target for cancer treatment

The transient receptor potential ion-channel superfamily consists of nonselective cation channels located mostly on the plasma membranes of numerous animal cell types, which are closely related to sensory information transmission (e.g., vision, pain, and temperature perception), as well as regulation of intracellular Ca2+ balance and physiological activities of growth and development. Transient receptor potential ion channel subfamily V (TRPV) is one of the largest and most diverse subfamilies, including TRPV1-TRPV6 involved in the regulation of a variety of cellular functions. TRPV4 can be activated by various physical and chemical stimuli, such as heat, mechanical force, and phorbol ester derivatives participating in the maintenance of normal cellular functions. In recent years, the roles of TRPV4 in cell proliferation, differentiation, apoptosis, and migration have been extensively studied. Its abnormal expression has also been closely related to the onset and progression of multiple tumors, so TRPV4 may be a target for cancer diagnosis and treatment. In this review, we focused on the latest studies concerning the role of TRPV4 in tumorigenesis and the therapeutic potential. As evidenced by the effects on cancerogenesis, TRPV4 is a potential target for anticancer therapy.

Recent advances in the clinical development of immune checkpoint blockade therapy

BACKGROUND

The discovery of immune checkpoint proteins and the mechanisms by which cancer cells utilize them to evade the immune system has transformed our approach to cancer immunotherapy. Checkpoint blockade antibodies targeting cytotoxic T lymphocyte antigen 4 (CTLA-4), programmed cell death 1 (PD-1) and its ligands such as programmed cell death ligand 1 (PD-L1) have already revolutionized the treatment of multiple types of cancer and have significantly improved treatment and survival outcomes of patients affected by these malignancies.

CONCLUSIONS

Herein, we summarize current knowledge about the role of, and the mechanisms underlying PD-1/PD-L1 signaling pathways in antitumor immune responses, with particular emphasis on clinical studies evaluating the efficacy of anti-PD-1/PD-L1 blockade in various tumor types. Preliminary clinical investigations with immune-checkpoint blockers highlight broad opportunities with a high potential to enhance antitumor immunity and, as such, to generate significant clinical responses. These preliminary successes open up new avenues towards efficient therapeutics offered to patients.

Avelumab in gastric cancer

Gastric cancer (GC) is the fifth most common malignancy and the third cause of cancer-related deaths worldwide. Currently, surgery and chemotherapy remain the main therapeutic options and the prognosis of the disease is still poor in the metastatic setting. Avelumab is a human IgG1 antibody directed against PD-L1 approved for Merkel cell carcinoma and urothelial carcinoma that could be useful also for the treatment of GC. This review describes the chemical structure, the pharmacologic properties and the current knowledge of the efficacy of avelumab in the treatment of GC from the data available on the first and later phase clinical trials. The ongoing studies testing this drug either alone or in combination with other drugs are also described.

Combining immunotherapies to treat non-small cell lung cancer

Introduction: In recent years, immunotherapy has become an integral part of the treatment of many cancers, including non-small cell lung cancer (NSCLC). Precious therapeutic weapons impacting survival are monoclonal antibodies directed against the programmed death protein-1 (PD-1)/programmed death ligand-1 (PD-L1) immune checkpoint. Areas covered: Unfortunately, not all patients treated with checkpoint inhibitors have durable clinical responses. However, a better understanding of the complexity of interactions between the immune system and cancer, the latter capable of adopting evasion mechanisms, indicates different opportunities to enhance anti-tumor immunity. Expert opinion: In this paper, we review multiple strategies of combining immunotherapies that exploit not only additional immune checkpoint receptors and ligands but also other synergistic approaches such as vaccines or indoleamine 2,3-dioxygenase (IDO) inhibitors with the potential to extend the number of NSCLC patients achieving successful outcomes.

Research progress and clinical application of predictive biomarker for immune checkpoint inhibitors

INTRODUCTION

Immune checkpoint inhibitors (ICIs) have emerged as epochal milestones in the field of anti-cancer immunotherapy. With promising clinical effectiveness, ICIs can significantly prolong the overall survival of patients with advanced cancer of different types. Although their remarkable effectiveness has been demonstrated in clinical application, ICIs display limitations in terms of unique response patterns. Only a subset of patients exhibits objective responses, while others show rapid disease progression. Considering that there is a fair representation of both subsets of patients (responders and non-responders), clinicians ought to effectively stratify patients who will potentially benefit from ICI therapy, and optimize a strategy for patient selection. Areas covered: In this review, the authors have summarized several key factors involved in the biomarker development of ICI therapy, such as neoantigen production and presentation, the tumor microenvironment, and alternation in specific gene signaling pathways. Expert opinion: Considering the extreme complexity of the immune system, a single biomarker may fail to appropriately stratify patients for ICI therapy. Therefore, future biomarker research should focus on designing an integrated biomarker system that will successfully guide combination therapies to overcome resistance to immunotherapy.

Targeting the tumour stroma to improve cancer therapy

Cancers are not composed merely of cancer cells alone; instead, they are complex 'ecosystems' comprising many different cell types and noncellular factors. The tumour stroma is a critical component of the tumour microenvironment, where it has crucial roles in tumour initiation, progression, and metastasis. Most anticancer therapies target cancer cells specifically, but the tumour stroma can promote the resistance of cancer cells to such therapies, eventually resulting in fatal disease. Therefore, novel treatment strategies should combine anticancer and antistromal agents. Herein, we provide an overview of the advances in understanding the complex cancer cell-tumour stroma interactions and discuss how this knowledge can result in more effective therapeutic strategies, which might ultimately improve patient outcomes.

The nephrotoxicity of new immunotherapies

Introduction: Advanced cancers that did not respond to chemotherapy were once a death sentence, but now there are newer therapies utilizing the patient's own immune system to fight cancer that are proving effective in chemotherapy-refractory malignancies. However, this success against cancer cells may be accompanied by immune-related adverse events that can affect the kidneys. Areas covered: Using Medline and Scopus, we compiled all publications through February 2019 that pertained to immune checkpoint inhibitors (ICPIs) and chimeric antigen receptor T-cells (CAR T-cells).  The focus of this review is the discussion of these new cancer therapies, with attention to the reported kidney-related adverse effects.. Expert opinion: Autoimmunity is repressed by molecular pathways that inhibit T-cell activation against selected antigens. These self-protective mechanisms have been appropriated by tumor cells as a means of evading immune detection and destruction. New immunotherapies such as immune checkpoint inhibitors and chimeric antigen receptor T-cell therapy incite an aggressive immune response directed against tumor cells. This unrestrained activation of the immune system may result in kidney injury via multiple mechanisms.

PD-L1 Expression and Immune Cell Infiltration in Gastroenteropancreatic (GEP) and Non-GEP Neuroendocrine Neoplasms With High Proliferative Activity

The potential of neuroendocrine neoplasms (NEN) to respond to checkpoint inhibitors is largely unknown and full of great expectations. Immunohistochemical (IHC) studies of programmed cell death ligand 1 (PD-L1) expression in the tumor microenvironment and its implications in predicting the response to checkpoint inhibition is a very active subject. Currently, the combined analysis of PD-L1 expression and tumor-associated immune cell (TAIC) infiltration is considered the best predictive marker of therapeutic response. Here we investigated the expression of PD-L1 on tumor cells (TC) and tumor-infiltrating immune cells (IC) by IHC in 68 NEN samples with a high proliferation rate (Ki-67 >20%) from 57 patients and in 22 samples we correlated it with TAIC density by assessing intratumoral infiltration of CD3+, CD8+, and CD68+ cells. Furthermore, the tumor microenvironment was evaluated according to the classification of Teng et al. We detected PD-L1 expression in 31.6% of NEN G3. Its expression usually was weak and more IC than TC expressed PD-L1. The proportion of tumors positive for PD-L1 was comparable in NEN from different sites of origin but varied depending on tumor differentiation and disease extension. No positive IHC staining was found in 3 well-differentiated neuroendocrine tumors (NETs) with a proliferation rate above 20% (NET G3). When analyzing TAIC, we rarely (18.2%) detected intratumoral CD8+ cells, whereas infiltration by CD3+ and CD68+ cells was more common (45.5 and 59.1%, respectively). By combining CD3+ cells and PD-L1 status, we identified the immune ignorant phenotype of tumor microenvironment as being the most common phenotype, supporting the concept of a preferably combined immunotherapeutic approach in neuroendocrine carcinoma (NEC).

Immune reaction by cytoreductive prostatectomy

Prostate cancer (PCa) is the most common non-cutaneous cancer among men and the second leading cause of male cancer deaths in the United States. With no effective cure for advanced disease, the survival rates of castration-resistant disease and metastatic disease remains poor. Treatment via hormonal manipulation, immunotherapy, and chemotherapy remain marginally effective, indicating the need for novel treatment strategies. Cytoreductive prostatectomy (CRP) has grown as a treatment modality for metastatic castration resistant prostate cancer (mCRPC) and an emerging body of literature has demonstrated its survival benefits. In this review, we hope to further explore immunologic changes after CRP and the resultant effects on oncologic outcomes. Conclusively, the data and technical considerations of CRS evolve, CRS may continue to expand treat various type of metastatic cancer. Still, there are little reports about immunological changed after CRP. However, based on technical improvement, CRP and combinational immunotherapy are developing treatments of metastatic disease.

Emerging therapies for non-small cell lung cancer

Recent advances in the field of novel anticancer agents prolong patients' survival and show a promising future. Tyrosine kinase inhibitors and immunotherapy for lung cancer are the two major areas undergoing rapid development. Although increasing novel anticancer agents were innovated, how to translate and optimize these novel agents into clinical practice remains to be explored. Besides, toxicities and availability of these drugs in specific regions should also be considered during clinical determination. Herein, we summarize emerging agents including tyrosine kinase inhibitors, checkpoint inhibitors, and other potential immunotherapy such as chimeric antigen receptor T cell for non-small cell lung cancer attempting to provide insights and perspectives of the future in anticancer treatment.

Assisting anti-PD-1 antibody treatment with a liposomal system capable of recruiting immune cells

Despite the functions of anti-PD-1 antibodies as immune checkpoint regulators, less than 30% of patients exhibit durable therapeutic responses to anti-PD-1 antibodies. Studies have shown that insufficient infiltration of immune cells might limit the outcome of anti-PD-1 therapy. Therefore, we synthesized an immune cell-recruiting liposomal system (FN-nps) to improve this therapeutic strategy. The FN-nps could generate cell debris and expose heat shock protein 70, which could recruit immune cells to tumor sites to assist in anti-PD-1 treatment. In vivo experiments revealed that the FN-nps could assist in anti-PD-1 therapy by increasing the number of lymphocytes in the peripheral blood and tumor site by generating tumor antigens, and this effect was accompanied by an increase in cytokine expression. The number of CTLs increased and mRNA expression levels of cytokines were regulated when the FN-nps were combined with anti-PD-1 therapy. The revealed properties of the liposomal system make it highly promising for assisting in anti-PD-1 antibody immunotherapy in different cancers.

The metabolic milieu in melanoma: Role of immune suppression by CD73/adenosine

The mechanisms leading to immune escape of melanoma have been largely investigated in relation to its tumour immunogenicity and features of inflamed microenvironment that promote the immune suppression during the disease progression. These findings have recently led to advantages in terms of immunotherapy-based approaches as rationale for overcoming the immune escape. However, besides immune checkpoints, other mechanisms including the adenosine produced by ectonucleotidases CD39 and CD73 contribute to the melanoma progression due to the immunosuppression induced by the tumour milieu. On the other hand, CD73 has recently emerged as both promising therapeutic target and unfavourable prognostic biomarker. Here, we review the major mechanisms of immune escape activated by the CD39/CD73/adenosine pathway in melanoma and focus potential therapeutic strategies based on the control of CD39/CD73 downstream adenosine receptor signalling. These evidences provide the basis for translational strategies of immune combination, while CD73 would serve as potential prognostic biomarker in metastatic melanoma.

Regorafenib Promotes Antitumor Immunity via Inhibiting PD-L1 and IDO1 Expression in Melanoma

PURPOSE

Immune checkpoint blockade (ICB) therapy induces durable tumor regressions in a minority of patients with cancer. In this study, we aimed to identify kinase inhibitors that were capable of increasing the antimelanoma immunity.

EXPERIMENTAL DESIGN

Flow cytometry-based screening was performed to identify kinase inhibitors that can block the IFNγ-induced PD-L1 expression in melanoma cells. The pharmacologic activities of regorafenib alone or in combination with immunotherapy in vitro and in vivo were determined. The mechanisms of regorafenib were explored and analyzed in melanoma patients treated with or without anti-PD-1 using The Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) datasets.

RESULTS

Through screening of a kinase inhibitor library, we found approximately 20 agents that caused more than half reduction of cell surface PD-L1 level, and regorafenib was one of the most potent agents. Furthermore, our results showed that regorafenib, in vitro and in vivo, strongly promoted the antitumor efficacy when combined with IFNγ or ICB. By targeting the RET-Src axis, regorafenib potently inhibited JAK1/2-STAT1 and MAPK signaling and subsequently attenuated the IFNγ-induced PD-L1 and IDO1 expression without affecting MHC-I expression much. Moreover, RET and Src co-high expression was an independent unfavorable prognosis factor in melanoma patients with or without ICB through inhibiting the antitumor immune response.

CONCLUSIONS

Our data unveiled a new mechanism of alleviating IFNγ-induced PD-L1 and IDO1 expression and provided a rationale to explore a novel combination of ICB with regorafenib clinically, especially in melanoma with RET/Src axis activation.

The immune profile of small HER2-positive breast cancers: a secondary analysis from the APT trial

BACKGROUND

Previous data suggest that the immune microenvironment plays a critical role in human epidermal growth factor receptor 2 (HER2) -positive breast cancer; however, there is little known about the immune profiles of small HER2-positive tumors. In this study, we aimed to characterize the immune microenvironment of small HER2-positive breast cancers included in the Adjuvant paclitaxel and trastuzumab for node-negative, HER2-positive breast cancer (APT) trial and to correlate the immune markers with pathological and molecular tumor characteristics.

PATIENTS AND METHODS

The APT trial was a multicenter, single-arm, phase II study of paclitaxel and trastuzumab in patients with node-negative HER2-positive breast cancer. The study included 406 patients with HER2-positive, node-negative breast cancer, measuring up to 3 cm. Exploratory analysis of tumor infiltrating lymphocytes (TIL), programmed death-ligand 1 (PD-L1) expression (by immunohistochemistry), and immune gene signatures using data generated by nCounter PanCancer Pathways Panel (NanoString Technologies, Seattle, WA), and their association with pathological and molecular characteristics was carried out.

RESULTS

Of the 406 patients, 328 (81%) had at least one immune assay carried out: 284 cases were evaluated for TIL, 266 for PD-L1, and 213 for immune gene signatures. High TIL (≥60%) were seen with greater frequency in hormone-receptor (HR) negative, histological grades 2 and 3, as well in HER2-enriched and basal-like tumors. Lower stromal PD-L1 (≤1%) expression was seen with greater frequency in HR-positive, histological grade 1, and in luminal tumors. Both TIL and stromal PD-L1 were positively correlated with 10 immune cell signatures, including Th1 and B cell signatures. Luminal B tumors were negatively correlated with those signatures. Significant correlation was seen among these immune markers; however, the magnitude of correlation did not indicate a monotonic relationship between them.

CONCLUSION

Immune profiles of small HER2-positive breast cancers differ according to HR status, histological grade, and molecular subtype. Further work is needed to explore the implication of these findings on disease outcome.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov identifier: NCT00542451.

PD-1/PD-L1 antagonists in gastric cancer: Current studies and perspectives

Immune checkpoints release suppressive signals for T cells, which enable the tumors to escape from immune destruction and provide a new concept that uses the capabilities of the immune system as a therapeutic target for tumors. At present, programmed death receptor 1 (PD-1)/programmed death ligand-1 (PD-L1) has become the most promising therapeutic target. PD-1/PD-L1 blockades exhibit long-lasting antitumor efficacy and safety in patients with various cancers, such as melanoma and non-small-cell lung cancer. Moreover, PD-L1 is highly expressed in the peripheral blood and tumor specimens of patients with cancer, and the expression of PD-L1 is positively correlated with various pathological features and may serve as a predictor of poor prognosis or a diagnostic tool. Clinical trials have verified that PD-1/PD-L1 blockade therapy benefits patients with advanced gastric cancer or gastroesophageal junction cancer. Furthermore, there are many molecules involved in the regulation of PD-1/PD-L1 expression, and the modification of these molecules via drugs and combinations with PD-1/PD-L1 inhibitors may further improve the efficacy of immunotherapy for gastric cancer. In this review, the efficacy, safety, and possible combination treatment options of PD-1/PD-L1 in gastric cancer are reviewed in experimental and clinical settings.

IFN-γ Promotes Epithelial-Mesenchymal Transition and the Expression of PD-L1 in Pancreatic Cancer

BACKGROUND

Tumor immune reactions not only provide host defense but also accelerate tumor immune escape and phenotype switching. Here, we examined the association of programmed cell death ligand 1 (PD-L1) expression with epithelial-mesenchymal transition (EMT)-associated markers in pancreatic ductal adenocarcinoma (PDA) within the context of the tumor microenvironment.

MATERIALS AND METHODS

PDA samples from 36 patients were analyzed for PD-L1, vimentin, E-cadherin, and Snail expressions and for PDA cell and immune cell infiltration. PD-L1 expression and EMT in PDA cell lines under conditions of altering interferon gamma (IFN-γ) signals were also assessed.

RESULTS

Immunohistochemistry revealed a significant correlation between vimentin and PD-L1 expression, whereas double staining showed them to be simultaneously expressed by PDA cells. Positive vimentin expression was associated with the infiltration of a lower number of CD8⁺ T cells and a higher number of FoxP3⁺ cells and poor patient prognosis (P = 0.03). PDA tumor cells promoted PD-L1 expression and EMT under the presence of IFN-γ, which was inhibited by the signal transducer and activator of transcription (STAT)1 small interfering RNA.

CONCLUSIONS

Strong correlations were observed between PD-L1 expression, EMT, and the immunosuppressive tumor microenvironment. Targeting STAT1 combined with PD-1/PD-L1 immunotherapy may improve outcomes for patients with PDA.

Mechanisms of Resistance to PD-1 and PD-L1 Blockade

Cancer immunotherapy utilizing blockade of the PD-1/PD-L1 checkpoint has revolutionized the treatment of a wide variety of malignancies, leading to durable therapeutic responses not typically seen with traditional cytotoxic anticancer agents. However, these therapies are ineffective in a significant percentage of patients, and some initial responders eventually develop resistance to these therapies with relapsed disease. The mechanisms leading to both primary and acquired resistance to PD-1/PD-L1 inhibition are varied and can be both multifactorial and overlapping in an individual patient. As the mechanisms of resistance to PD-1/PD-L1 blockade continue to be further characterized, new strategies are being developed to prevent or reverse resistance to therapy, leading to improved patient outcomes.

Novel Approaches to Improve the Efficacy of Immuno-Radiotherapy

Radiotherapy (RT) has been applied for decades as a treatment modality in the management of various types of cancer. Ionizing radiation induces tumor cell death, which in turn can either elicit protective anti-tumor immune responses or immunosuppression in the tumor micromilieu that contributes to local tumor recurrence. Immunosuppression is frequently accompanied by the attraction of immunosuppressive cells such as myeloid-derived suppressor cells (MDSCs), M2 tumor-associated macrophages (TAMs), T regulatory cells (Tregs), N2 neutrophils, and by the release of immunosuppressive cytokines (TGF-β, IL-10) and chemokines. Immune checkpoint pathways, particularly of the PD-1/PD-L1 axis, have been determined as key regulators of cancer immune escape. While IFN-dependent upregulation of PD-L1 has been extensively investigated, up-to-date studies indicated the importance of DNA damage signaling in the regulation of PD-L1 expression following RT. DNA damage dependent PD-L1 expression is upregulated by ATM/ATR/Chk1 kinase activities and cGAS/STING-dependent pathway, proving the role of DNA damage signaling in PD-L1 induced expression. Checkpoint blockade immunotherapies (i.e., application of anti-PD-1 and anti-PD-L1 antibodies) combined with RT were shown to significantly improve the objective response rates in therapy of various primary and metastatic malignancies. Further improvements in the therapeutic potential of RT are based on combinations of RT with other immunotherapeutic approaches including vaccines, cytokines and cytokine inducers, and an adoptive immune cell transfer (DCs, NK cells, T cells). In the current review we provide immunological rationale for a combination of RT with various immunotherapies as well as analysis of the emerging preclinical evidences for these therapies.

Spatially distinct tumor immune microenvironments stratify triple-negative breast cancers

Understanding the tumor immune microenvironment (TIME) promises to be key for optimal cancer therapy, especially in triple-negative breast cancer (TNBC). Integrating spatial resolution of immune cells with laser capture microdissection gene expression profiles, we defined distinct TIME stratification in TNBC, with implications for current therapies including immune checkpoint blockade. TNBCs with an immunoreactive microenvironment exhibited tumoral infiltration of granzyme B+CD8+ T cells (GzmB+CD8+ T cells), a type 1 IFN signature, and elevated expression of multiple immune inhibitory molecules including indoleamine 2,3-dioxygenase (IDO) and programmed cell death ligand 1 (PD-L1), and resulted in good outcomes. An "immune-cold" microenvironment with an absence of tumoral CD8+ T cells was defined by elevated expression of the immunosuppressive marker B7-H4, signatures of fibrotic stroma, and poor outcomes. A distinct poor-outcome immunomodulatory microenvironment, hitherto poorly characterized, exhibited stromal restriction of CD8+ T cells, stromal expression of PD-L1, and enrichment for signatures of cholesterol biosynthesis. Metasignatures defining these TIME subtypes allowed us to stratify TNBCs, predict outcomes, and identify potential therapeutic targets for TNBC.

Recent Advances in Therapeutic Genome Editing in China

Editing of the genome to correct disease-causing mutations is a promising approach for the treatment of human diseases. Recent advances in the development of programmable nuclease-based genome editing tools have substantially improved the ability to make precise changes in the human genome. Genome editing technologies are already being used to correct genetic mutations in affected tissues and cells to treat diseases that are refractory to traditional gene therapies. Chinese scientists have made remarkable breakthroughs in the field of therapeutic genome editing, particularly with the first clinical trial involving the clustered regularly interspaced short palindromic repeats-caspase 9 system that began in China. Herein, current progress toward developing programmable nuclease-based gene therapies is introduced, as well as future prospects and challenges in China.

A single dose of neoadjuvant PD-1 blockade predicts clinical outcomes in resectable melanoma

Immunologic responses to anti-PD-1 therapy in melanoma patients occur rapidly with pharmacodynamic T cell responses detectable in blood by 3 weeks. It is unclear, however, whether these early blood-based observations translate to the tumor microenvironment. We conducted a study of neoadjuvant/adjuvant anti-PD-1 therapy in stage III/IV melanoma. We hypothesized that immune reinvigoration in the tumor would be detectable at 3 weeks and that this response would correlate with disease-free survival. We identified a rapid and potent anti-tumor response, with 8 of 27 patients experiencing a complete or major pathological response after a single dose of anti-PD-1, all of whom remain disease free. These rapid pathologic and clinical responses were associated with accumulation of exhausted CD8 T cells in the tumor at 3 weeks, with reinvigoration in the blood observed as early as 1 week. Transcriptional analysis demonstrated a pretreatment immune signature (neoadjuvant response signature) that was associated with clinical benefit. In contrast, patients with disease recurrence displayed mechanisms of resistance including immune suppression, mutational escape, and/or tumor evolution. Neoadjuvant anti-PD-1 treatment is effective in high-risk resectable stage III/IV melanoma. Pathological response and immunological analyses after a single neoadjuvant dose can be used to predict clinical outcome and to dissect underlying mechanisms in checkpoint blockade.

Neoadjuvant anti-PD-1 immunotherapy promotes a survival benefit with intratumoral and systemic immune responses in recurrent glioblastoma

Glioblastoma is the most common primary malignant brain tumor in adults and is associated with poor survival. The Ivy Foundation Early Phase Clinical Trials Consortium conducted a randomized, multi-institution clinical trial to evaluate immune responses and survival following neoadjuvant and/or adjuvant therapy with pembrolizumab in 35 patients with recurrent, surgically resectable glioblastoma. Patients who were randomized to receive neoadjuvant pembrolizumab, with continued adjuvant therapy following surgery, had significantly extended overall survival compared to patients that were randomized to receive adjuvant, post-surgical programmed cell death protein 1 (PD-1) blockade alone. Neoadjuvant PD-1 blockade was associated with upregulation of T cell- and interferon-γ-related gene expression, but downregulation of cell-cycle-related gene expression within the tumor, which was not seen in patients that received adjuvant therapy alone. Focal induction of programmed death-ligand 1 in the tumor microenvironment, enhanced clonal expansion of T cells, decreased PD-1 expression on peripheral blood T cells and a decreasing monocytic population was observed more frequently in the neoadjuvant group than in patients treated only in the adjuvant setting. These findings suggest that the neoadjuvant administration of PD-1 blockade enhances both the local and systemic antitumor immune response and may represent a more efficacious approach to the treatment of this uniformly lethal brain tumor.

Gynecological Cancers Translational, Research Implementation, and Harmonization: Gynecologic Cancer InterGroup Consensus and Still Open Questions

In the era of personalized medicine, the introduction of translational studies in clinical trials has substantially increased their costs, but provides the possibility of improving the productivity of trials with a better selection of recruited patients. With the overall goal of creating a roadmap to improve translational design for future gynecological cancer trials and of defining translational goals, a main discussion was held during a brainstorming day of the Gynecologic Cancer InterGroup (GCIG) Translational Research Committee and overall conclusions are here reported. A particular emphasis was dedicated to the new frontier of the immunoprofiling of gynecological cancers. The discussion pointed out that to maximize patients' benefit, translational studies should be integral to clinical trial design with standardization and optimization of procedures including a harmonization program of Standard Operating Procedures. Pathology-reviewed sample collection should be mandatory and ensured by dedicated funding. Biomarker validation and development should be made public and transparent to ensure rapid progresses with positive outcomes for patients. Guidelines/templates for patients' informed consent are needed. Importantly for the public, recognized goals are to increase the involvement of advocates and to improve the reporting of translational data in a forum accessible to patients.

The immunomodulatory potential of natural compounds in tumor-bearing mice and humans

Cancer is considered a fetal disease caused by uncontrolled proliferation and progression of abnormal cells. The most efficient cancer therapies suppress tumor growth, prevent progression and metastasis, and are minimally toxic to normal cells. Natural compounds have shown a variety of chemo-protective effects alone or in combination with standard cancer therapies. Along with better understanding of the dynamic interactions between our immune system and cancer development, nutritional immunology-the use of natural compounds as immunomodulators in cancer patients-has begun to emerge. Cancer cells evolve strategies that target many aspects of the immune system to escape or even edit immune surveillance. Therefore, the immunesuppressive tumor microenvironment is a major obstacle in the development of cancer therapies. Because interaction between the tumor microenvironment and the immune system is a complex topic, this review focuses mainly on human clinical trials and animal studies, and it highlights specific immune cells and their cytokines that have been modulated by natural compounds, including carotenoids, curcumin, resveratrol, EGCG, and β-glucans. These natural compounds have shown promising immune-modulating effects, such as inhibiting myeloid-derived suppressor cells and enhancing natural killer and cytolytic T cells, in tumor-bearing animal models, but their efficacy in cancer patients remains to be determined.

Inhibition of urothelial carcinoma through targeted type I interferon-mediated immune activation

Type I interferon (IFN-I) has potent anti-tumor effects against urothelial carcinoma (UC) and may be an alternative treatment option for patients who do not respond to Bacillus Calmette-Guerin. However, the mechanisms that mediate the IFN-I-stimulated immune responses against UC have yet to be elucidated. Herein, we evaluated the anti-tumor mechanisms of IFN-I in UC in human patients and in mice. Patient tumors from a Phase I clinical trial with adenoviral interferon-α (Ad-IFNα/Syn3) showed increased expression of T cell and checkpoint markers following treatment with Ad-IFNα/Syn3 by RNAseq and immunohistochemistry analysis in 25% of patients. In mice, peritumoral injections of poly(I:C) into MB49 UC tumors was used to incite an IFN-driven inflammatory response that significantly inhibited tumor growth. IFN-I engaged both innate and adaptive cells, seen in increased intratumoral CD8 T cells, NK cells, and CD11b+Ly6G+ cells, but tumor inhibition was not reliant on any one immune cell type. Nonetheless, poly(I:C)-mediated tumor regression and change in the myeloid cell landscape was dependent on IL-6. Mice were also treated with poly(I:C) in combination with anti-PD-1 monoclonal antibody (mAb) to assess for additional benefit to tumor growth and animal survival. When used in combination with anti-PD-1 mAb, IFN-I stimulation prolonged survival, coinciding with inhibition of angiogenesis and enriched gene signatures of metabolism, extracellular matrix organization, and MAPK/AKT signaling. Altogether, these findings suggest IFN-I's immune-driven antitumor response in UC is mediated by IL-6 and a collaboration of immune cells, and its use in combination with checkpoint blockade therapy can increase clinical benefit.

Complete response associated with immune checkpoint inhibitors in advanced non-small-cell lung cancer: a meta-analysis of nine randomized controlled trials

Purpose

The purposes of this study were to investigate whether the use of immune checkpoint inhibitors (ICIs) in advanced non-small-cell lung cancer (NSCLC) would increase the possibility of archiving complete response (CR) and assess the surrogate end points for overall survival (OS).

Methods

We calculated the incidence and relative risk (RR) of CR events in patients assigned to ICIs compared to that in controls. Simple linear regression models were fitted for median OS and each surrogate (median progression-free survival [PFS], CRs, and objective response rate [ORR]).

Results

A total of 4,803 NSCLC patients from nine randomized controlled trials (RCTs) were included for analysis. The incidence of CR in NSCLC patients treated with ICIs was 1.5% (95% CI: 0.8–3.0) compared to 0.7% (95% CI: 0.4–1.2) in chemotherapy (CT) groups. The use of ICIs in advanced NSCLC significantly improved the possibility of archiving CR (RR 2.89, 95% CI: 1.44–5.81, P=0.003) compared to CT. Subgroup analysis according to ICIs showed that the use of atezolizumab (RR 3.26, P=0.01) and nivolumab (RR 4.83, P=0.042) in advanced NSCLC significantly improved the CR rate in comparison with CT alone, but not pembrolizumab and ipilimumab. We also found that the use of ICIs as first-line (RR 2.39, 95% CI: 1.08–5.3, P=0.032) or second-line (RR 4.99, 95% CI: 1.10–22.66, P=0.038) therapy significantly increased the change in obtaining a CR. In addition, correlation analysis indicates that PFS was strongly correlated with OS in NSCLC patients who received ICIs (r=0.89 for PFS, P=0.017). No marked correlation was found between OS and CR (r=0.19, P=0.75) and OS and ORR (r=0.52, P=0.28).

Conclusion

The CR is a rate event in advanced NSCLC, but the use of ICIs significantly increases the possibility of archiving CR in comparison with CT. PFS is significantly correlated with OS and could be used as a surrogate end point, but not for CRs and ORRs.

Inflammation-induced glycolytic switch controls suppressivity of mesenchymal stem cells via STAT1 glycosylation

Mesenchymal stem cells (MSCs) represent key contributors to tissue homeostasis and promising therapeutics for hyperinflammatory conditions including graft-versus-host disease. Their immunomodulatory effects are controlled by microenvironmental signals. The MSCs' functional response towards inflammatory cues is known as MSC-"licensing" and includes indoleamine 2,3-dioxygenase (IDO) upregulation. MSCs use tryptophan-depleting IDO to suppress T-cells. Increasing evidence suggests that several functions are (co-)determined by the cells' metabolic commitment. MSCs are capable of both, high levels of glycolysis and of oxidative phosphorylation. Although several studies have addressed alterations of the immune regulatory phenotype elicited by inflammatory priming metabolic mechanisms controlling this process remain unknown. We demonstrate that inflammatory MSC-licensing causes metabolic shifts including enhanced glycolysis and increased fatty acid oxidation. Yet, only interfering with glycolysis impacts IDO upregulation and impedes T-cell-suppressivity. We identified the Janus kinase (JAK)/signal transducer and activator of transcription (STAT)1 pathway as a regulator of both glycolysis and IDO, and show that enhanced glucose turnover is linked to abundant STAT1 glycosylation. Inhibiting the responsible O-acetylglucosamine (O-GlcNAc) transferase abolishes STAT1 activity together with IDO upregulation. Our data suggest that STAT1-O-GlcNAcylation increases its stability towards degradation thus sustaining downstream effects. This pathway could represent a target for interventions aiming to enhance the MSCs' immunoregulatory potency.

The Emergence of Natural Killer Cells as a Major Target in Cancer Immunotherapy

Immune 'checkpoint' inhibitors can increase the activity of tumor-resident cytotoxic lymphocytes and have revolutionized cancer treatment. Current therapies block inhibitory pathways in tumor-infiltrating CD8⁺ T cells and recent studies have shown similar programs in other effector populations such as natural killer (NK) cells. NK cells are critical for immunosurveillance, particularly the control of metastatic cells or hematological cancers. However, how NK cells specifically recognize transformed cells and dominant negative feedback pathways, as well as how tumors escape NK cell control, remains undefined. This review summarizes recent advances that have illuminated inhibitory checkpoints in NK cells, some of which are shared with conventional cytotoxic T lymphocytes. It also outlines emerging approaches aimed at unleashing the potential of NK cells in immunotherapy.

Programmed death ligand 1 immunohistochemistry in non-small cell lung carcinoma

Lung cancer is the leading cause of cancer death worldwide with low response rates to conventional chemotherapy. New promising therapies have emerged based on programmed cell death protein 1 (PD-1) immunity checkpoint inhibitors (ICI), including anti-PD-1, such as nivolumab and pembrolizumab, or programmed death ligand 1 (PD-L1) inhibitors, such as atezolizumab, durvalumab, and avelumab. The prescription of pembrolizumab has been approved by FDA and EMA for advanced stages non-small cell lung carcinoma (NSCLC), restricted for first-line setting to patients whose tumor presents ≥50% of PD-L1 positive tumor cells (TC), and ≥1% for second-line and beyond, leading to consider PD-L1 assay as a companion diagnostic tool for pembrolizumab. Very recently, the EMA has approved durvalumab for the treatment of patients with unresectable stage III NSCLC not progressing after chemoradiotherapy and whose tumors express PD-L1 on ≥1% of TC. Four standardized PD-L1 immunohistochemistry assays have been used in clinical trials; 22C3 and 28-8 PharmDx assays on Dako/Agilent platforms, and SP142 and SP263 assays on Ventana platforms, each test having been developed initially for a specific ICI. They differ in terms of primary monoclonal antibody, platform, detection system and scoring methods with different thresholds of positivity validated in clinical trials. Several studies have shown a close analytical performance of the 22C3, 28-8 and SP263 assays regarding TC staining in NSCLC, with poor concordance with SP142 assay and for immune cells. However, as dedicated platforms are not available in all pathology laboratories and because of the high cost of these assays, laboratory developed tests are widely used in many countries. Their validation must guarantee the same sensitivities and specificities as compared to standardized assays. Overall, PD-L1 test is of great help to select patients who could benefit for ICI and most pathologists have included this test in their daily practice for advanced stages NSCLC, besides ALK and ROS1 IHC.

Pneumonitis in Combined Anti-programmed Death-1 Immunotherapy and Radiation Therapy for Renal Cell Carcinoma

Anti-programed cell death-1 (Anti-PD-1) is a promising immunotherapy for advanced cancers. Autoimmune pneumonitis is a rare but potentially serious toxicity induced by anti-PD-1 immunotherapy. We report a case of therapy-induced pneumonitis in the setting of combined nivolumab, anti-PD-1 immunotherapy, and radiation therapy for metastatic renal cell carcinoma (RCC).

Gene code CD274/PD-L1: from molecular basis toward cancer immunotherapy

The programmed death 1 receptor (PD-1) and its ligand (PD-L1) are key molecules of immune checkpoint mechanisms in cancer and actually represent one of the main targets of immunotherapy. The predictive and prognostic values of PD-L1 expression alone in cancer patients is currently under debate due to the methodological assessment of PD-L1 expression and its temporal variations. Better detailed studies about the molecular basis of immunotherapy biomarkers are necessary. Here we summarize the current knowledge of PD-L1 gene modifications at genetic and epigenetic levels in different tumors, thus highlighting their reported correlation with cellular processes and potential impact on patient outcomes.

Cytokines, Chemokines, and Other Biomarkers of Response for Checkpoint Inhibitor Therapy in Skin Cancer

Immunotherapy for skin malignancies has ushered in a new era for cancer treatments by demonstrating unprecedented durable responses in the setting of metastatic Melanoma. Consequently, checkpoint inhibitors are now the first-line treatment of metastatic melanoma and widely used as adjuvant therapy for stage III disease. With the observation that higher tumor mutational burden correlates with a better response, checkpoint inhibitors are tested in other skin cancer types of known high tumor mutational burden with promising results and recently became the first-ever FDA-approved treatment for metastatic Merkel cell carcinoma. The emerging new standards-of-care will necessitate more precise biomarkers and predictors for treatment response and immune-related adverse events. Measurable immune-related mediators are currently under investigation as factors that promote or block the response to cancer immunotherapy and may provide insights into the underlying immune response to the tumor. Cytokines and chemokines are such mediators and are crucial for facilitating the recruitment and activation of specific subsets of leukocytes within the microenvironment of skin cancers. The exact mechanisms of how these meditators, both immunological and non-immunological, operate in the tumor microenvironment is an area of active research, so to reliable biomarkers of responses to cancer immunotherapy. Here, we will review and summarize the expanding body of literature for immune-related biomarkers pertaining to Melanoma, Basal cell carcinoma, Squamous cell carcinoma, and Merkel cell carcinoma, highlighting clinically relevant checkpoint inhibitor therapy biomarker advancements.

IFNγ-activated dermal lymphatic vessels inhibit cytotoxic T cells in melanoma and inflamed skin

Mechanisms of immune suppression in peripheral tissues counteract protective immunity to prevent immunopathology and are coopted by tumors for immune evasion. While lymphatic vessels facilitate T cell priming, they also exert immune suppressive effects in lymph nodes at steady-state. Therefore, we hypothesized that peripheral lymphatic vessels acquire suppressive mechanisms to limit local effector CD8+ T cell accumulation in murine skin. We demonstrate that nonhematopoietic PD-L1 is largely expressed by lymphatic and blood endothelial cells and limits CD8+ T cell accumulation in tumor microenvironments. IFNγ produced by tissue-infiltrating, antigen-specific CD8+ T cells, which are in close proximity to tumor-associated lymphatic vessels, is sufficient to induce lymphatic vessel PD-L1 expression. Disruption of IFNγ-dependent crosstalk through lymphatic-specific loss of IFNγR boosts T cell accumulation in infected and malignant skin leading to increased viral pathology and tumor control, respectively. Consequently, we identify IFNγR as an immunological switch in lymphatic vessels that balances protective immunity and immunopathology leading to adaptive immune resistance in melanoma.

Organ-specific response to nivolumab in patients with non-small cell lung cancer (NSCLC)

BACKGROUND

Response to immune checkpoint inhibitors depends on tumor intrinsic properties and also on host factors in the tumour microenvironment including the presence of immune cells (IC). We hypothesized that nivolumab efficacy varies across different metastatic sites.

METHODS

We retrospectively analyzed computed tomography scans of patients with metastatic non-small cell lung carcinoma (NSCLC) receiving nivolumab. RECIST 1.1 criteria were applied to assess the overall response rate (ORR) and organ-specific response rate (OSRR).

RESULTS

We analyzed 52 patients including 44% females, 58% adenocarcinoma and 8% never smokers. Involved organs had target-lesions in the lung (42%), liver (25%), lymph nodes (56%) and soft tissue (13%) and non-target lesions in the bones (23%). ORR and disease control rate (DCR) were 20% and 45%, respectively. Median overall survival, progression-free survival and duration of response were 11.9, 2.3 and 10.3 months. OSRR and organ-specific DCR (OSDCR) were 28% and 90% in lymph nodes, 8% and 54 in the liver, and 9% and 55% in lung metastases. Nine out of 12 patients with bone metastases had progressive lesions. The cumulative incidence probability of organ-specific progression at 6 months was 14% in lymph nodes, 42% in the liver, 36% in lung metastases and 26% in the primary tumor, 29% in soft tissue and 33% in adrenal metastases.

CONCLUSION

In conclusion, the efficacy of immunotherapy is dependent on the metastatic location. Treatment appears more active in lymph nodes compared to other organ sites such as liver, adrenals and bone. Future strategies may include additional local treatment in case of oligoprogression in these organs in patients with otherwise sustained treatment benefit.

Sno-derived RNAs are prevalent molecular markers of cancer immunity

Small nucleolar RNAs (snoRNAs) constitute a family of noncoding RNAs that are classically known as guide RNAs for processing and modification of ribosomal RNAs. Recently, it was discovered that snoRNAs can be further processed into sno-derived RNAs (sdRNAs), some of which are known to exhibit microRNA-like properties. SdRNAs have been implicated in human cancer; however, a systems-level sdRNA landscape in human cancers is lacking. Through integrative analysis of ~22 nt size-selected smRNA-seq datasets from 10,262 patient samples across 32 cancer types, we mapped a pan-cancer sdRNAome and interrogated its signatures in multiple clinically relevant features, particularly cancer immunity and clinical outcome. Aggregating sdRNA abundances by parental snoRNAs, these expression signatures alone are sufficient to distinguish patients with distinct cancer types. Interestingly, a large panel of sdRNAs are significantly correlated with features of the tumor-immune microenvironment, such as immunosuppressive markers, CD8+ T cell infiltration, cytolytic T cell activity, and tumor vasculature. A set of individual sdRNAs with tumor-immune signatures can also stratify patient survival. These findings implicate snoRNAs and their derivative sdRNAs as a class of prevalent noncoding molecular markers of human cancer immunity.

Engineering therapeutic bispecific antibodies using CrossMab technology

Bispecific antibodies have recently gained major interest as they allow novel mechanisms-of-action and/or therapeutic applications that cannot be achieved using conventional IgG-based antibodies. A major issue in engineering IgG-based bispecific antibodies has been to enable the correct association of heavy and light chains resulting in correct assembly of the desired bispecific antibody in sufficient yield. Various approaches have been described during recent years to tackle this challenge. We have developed the so-called CrossMab technology that enforces correct light chain association based on the domain crossover of immunoglobulin domains in the Fab region of the bispecific antibody. This versatile technology allows the generation of different bispecific antibody formats including asymmetric heterodimeric monovalent 1 + 1 bispecific antibodies and asymmetric heterodimeric bispecific antibodies with 2 + 1 valency in combination with approaches enabling Fc-hetermodimerization like knob-into-hole technology as well as the generation of tetravalent symmetric bispecific antibodies with 2 + 2 valency, also known as Tandem-Fab based IgG antibodies, using processes suitable for the large scale production of therapeutic bispecific antibodies. Notably, as of now, at least eight different bispecific antibodies using CrossMab technology entered clinical development, and additional CrossMabs are in late preclinical development. This review provides a summary of the status and progress with the engineering and generation of CrossMab technology based bispecific antibodies as well as their therapeutic application.

Modifying the cancer-immune set point using vaccinia virus expressing re-designed interleukin-2

The complex immune tumour microenvironment requires an equally complex immunotherapy approach, especially when the cancer-immune set point is non-inflamed. Oncolytic viruses expressing immune activating cytokines might optimally modify the immune microenvironment and improve the antitumour effects. In this study, we have explored a variety of IL-2 constructs expressed by a tumour-selective oncolytic vaccinia virus, designed to maintain IL-2 in the tumour microenvironment to reduce systemic toxicity. An IL-2 construct combining a glycosylphosphatidylinositol (GPI) anchor with a rigid peptide linker leads to functional IL-2 expression on the tumour cell surface and in the tumour microenvironment. This virus construct effectively modifies the cancer-immune set point and treats a variety of murine tumour models with no toxic side effects. In combination with PD-1/PD-L1 blockade this virus cures most of the mice with a high tumour burden. This combination represents a treatment for cancers which are to date unresponsive to immunotherapy.

IL-2 is used systemically for cancer therapy but it is associated with severe toxicity. Here, the authors design a recombinant vaccinia virus expressing membrane-bound IL-2 that shows therapeutic efficacy alone or in combination with checkpoint inhibitors in colon cancer-bearing mice.

Immunotherapy for non-small cell lung cancers: biomarkers for predicting responses and strategies to overcome resistance

Recent breakthroughs in targeted therapy and immunotherapy have revolutionized the treatment of lung cancer, the leading cause of cancer-related deaths in the United States and worldwide. Here we provide an overview of recent progress in immune checkpoint blockade therapy for treatment of non-small cell lung cancer (NSCLC), and discuss biomarkers associated with the treatment responses, mechanisms underlying resistance and strategies to overcome resistance. The success of immune checkpoint blockade therapies is driven by immunogenicity of tumor cells, which is associated with mutation burden and neoantigen burden in cancers. Lymphocyte infiltration in cancer tissues and interferon-γ-induced PD-L1 expression in tumor microenvironments may serve as surrogate biomarkers for adaptive immune resistance and likelihood of responses to immune checkpoint blockade therapy. In contrast, weak immunogenicity of, and/or impaired antigen presentation in, tumor cells are primary causes of resistance to these therapies. Thus, approaches that increase immunogenicity of cancer cells and/or enhance immune cell recruitment to cancer sites will likely overcome resistance to immunotherapy.

An osteopontin/CD44 immune checkpoint controls CD8+ T cell activation and tumor immune evasion

Despite breakthroughs in immune checkpoint inhibitor (ICI) immunotherapy, not all human cancers respond to ICI immunotherapy and a large fraction of patients with the responsive types of cancers do not respond to current ICI immunotherapy. This clinical conundrum suggests that additional immune checkpoints exist. We report here that interferon regulatory factor 8 (IRF8) deficiency led to impairment of cytotoxic T lymphocyte (CTL) activation and allograft tumor tolerance. However, analysis of chimera mice with competitive reconstitution of WT and IRF8-KO bone marrow cells as well as mice with IRF8 deficiency only in T cells indicated that IRF8 plays no intrinsic role in CTL activation. Instead, IRF8 functioned as a repressor of osteopontin (OPN), the physiological ligand for CD44 on T cells, in CD11b+Ly6CloLy6G+ myeloid cells and OPN acted as a potent T cell suppressor. IRF8 bound to the Spp1 promoter to repress OPN expression in colon epithelial cells, and colon carcinoma exhibited decreased IRF8 and increased OPN expression. The elevated expression of OPN in human colon carcinoma was correlated with decreased patient survival. Our data indicate that myeloid and tumor cell-expressed OPN acts as an immune checkpoint to suppress T cell activation and confer host tumor immune tolerance.