Targeting CD73 to augment cancer immunotherapy

High levels of soluble CD73 unveil resistance to BRAF inhibitors in melanoma cells

Melanoma cells express high levels of CD73 that produce extracellular immunosuppressive adenosine. Changes in the CD73 expression occur in response to tumor environmental factors, contributing to tumor phenotype plasticity and therapeutic resistance. Previously, we have observed that CD73 expression can be up-regulated on the surface of melanoma cells in response to nutritional stress. Here, we explore the mechanism by which melanoma cells release soluble CD73 under low nutrient availability and whether this might be affected by agents targeting the proto-oncogene B-Raf (BRAF). We found that starved melanoma cells can release high levels of CD73, able to convert AMP into adenosine, and this activity is abrogated by selective CD73 inhibitors, APCP or PSB-12489. The release of CD73 from melanoma cells is mediated by the matrix metalloproteinase MMP-9. Indeed, MMP-9 inhibitors significantly reduce the levels of CD73 released from the cells, while its surface levels increase. Of relevance, melanoma cells, harboring an activating BRAF mutation, upon treatment with dabrafenib or vemurafenib, show a strong reduction of CD73 cell expression and reduced levels of CD73 released into the extracellular space. Conversely, melanoma cells resistant to dabrafenib show high expression of membrane-bound CD73 and soluble CD73 released into the culture medium. In summary, our data indicate that CD73 is released from melanoma cells. The expression of CD73 is associated with response to BRAF inhibitors. Melanoma cells developing resistance to dabrafenib show increased expression of CD73, including soluble CD73 released from cells, suggesting that CD73 is involved in acquiring resistance to treatment.

COLUMBIA-1: a randomised study of durvalumab plus oleclumab in combination with chemotherapy and bevacizumab in metastatic microsatellite-stable colorectal cancer

BACKGROUND

To determine whether the addition of durvalumab (anti-PD-L1) and oleclumab (anti-CD73) to standard-of-care treatment (FOLFOX and bevacizumab) enhances the anti-tumour effect in patients with metastatic colorectal cancer (mCRC).

METHODS

COLUMBIA-1 (NCT04068610) was a Phase Ib (feasibility; Part 1)/Phase II (randomised; Part 2) trial in patients with treatment-naïve microsatellite stable mCRC. Patients in Part 2 were randomised to receive standard-of-care (control arm) or standard-of-care plus durvalumab and oleclumab (experimental arm). Primary objectives included safety and efficacy.

RESULTS

Seven patients were enrolled in Part 1 and 52 in Part 2 (n = 26 in each arm). Grade ≥3 treatment-emergent adverse events (TEAE) occurred in 80.8% and 65.4% of patients in the control and experimental arms of Part 2, respectively, with 26.9% and 46.3% experiencing serious TEAEs. The confirmed objective response rate (ORR) was numerically higher in the experimental arm compared with the control arm (61.5% [95% confidence interval (CI), 40.6-79.8] vs 46.2% [95% CI, 26.6-66.6]) but did not meet the statistically significant threshold in either arm.

CONCLUSION

The safety profile of FOLFOX and bevacizumab in combination with durvalumab and oleclumab was manageable; however, the efficacy results do not warrant further development of this combination in patients with microsatellite stable mCRC.

REGISTRATION

NCT04068610.

Dysfunction of dendritic cells in tumor microenvironment and immunotherapy

Dendritic cells (DCs) comprise diverse cell populations that play critical roles in antigen presentation and triggering immune responses in the body. However, several factors impair the immune function of DCs and may promote immune evasion in cancer. Understanding the mechanism of DC dysfunction and the diverse functions of heterogeneous DCs in the tumor microenvironment (TME) is critical for designing effective strategies for cancer immunotherapy. Clinical applications targeting DCs summarized in this report aim to improve immune infiltration and enhance the biological function of DCs to modulate the TME to prevent cancer cells from evading the immune system. Herein, factors in the TME that induce DC dysfunction, such as cytokines, hypoxic environment, tumor exosomes and metabolites, and co-inhibitory molecules, have been described. Furthermore, several key signaling pathways involved in DC dysfunction and signal-relevant drugs evaluated in clinical trials were identified. Finally, this review provides an overview of current clinical immunotherapies targeting DCs, especially therapies with proven clinical outcomes, and explores future developments in DC immunotherapies.

The role of CD73 in predicting the response to immunotherapy in head and neck cancer patients

Immunotherapy has a crucial role in the treatment of recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC). However, only a small percentage of patients achieve long-term benefit in terms of overall response and survival. It was shown that HNSCC has an immunosuppressive microenvironment due to high levels of regulatory T cells and immunosuppressive molecules, such as LAG3 and CD73. The aim of our study was to investigate if the expression of CD73 by neoplastic and immune cells could affect the efficacy of anti-PD-1 immunotherapy. We reviewed data from 50 patients with R/M HNSCC receiving first line immunotherapy with or without chemotherapy based on a combined positive score (CPS). CD73 expression by cancer and immune cells was evaluated on pre-treatment and the percentage of stained cells was recorded. We analysed the association between CD73 expression on neoplastic and immune cells and early progression (EP), defined as progression occurring within 3 months. In 88 % of patients the primary tumour site was in the oral cavity or larynx. All patients received pembrolizumab associated in 40 % of cases to chemotherapy. CD73 was positive in 82 % and 96 % of cases on neoplastic and immune cells, respectively. The median value of CD73 was 32 % for neoplastic cells and 10 % for the immune ones. We observed a significant association between the CD73 expression on neoplastic cells over the median value and EP disease. We didn't record a correlation between the expression of CD73 on immune cells and early progression. Our findings suggest that higher expression of CD73 on neoplastic cells could predict resistance to immunotherapy in patients with CPS positive R/M HNSCC. The addition of this biomarker to routine evaluation of CPS could help to select the patients primary resistant to anti-PD-1 immunotherapy.

Discovery of Small and Bifunctional Molecules Targeting PD-L1/CD73 for Cancer Dual Immunotherapy

In this work, a series of bifunctional PD-L1/CD73 (cluster of differentiation 73) small-molecule inhibitors were designed and synthesized. Among them, CC-5 showed the strongest PD-L1 inhibitory effects with an IC50 of 6 nM and potent anti-CD73 activity with an IC50 of 0.773 μM. The high PD-L1/CD73 inhibitory activity of CC-5 was further confirmed by SPR assays with KD of 182 nM for human PD-L1 and 101 nM for CD73, respectively. Importantly, CC-5 significantly suppressed tumor growth in a CT26 and B16-F10 tumor model with TGI of 64.3% and 39.6%, respectively. Immunohistochemical (IHC) and flow cytometry analysis of tumor-infiltrating lymphocytes (TILs) indicated that CC-5 exerted anticancer effects via activating the tumor immune microenvironment. Collectively, CC-5 represents the first dual PD-L1/CD73 inhibitor worthy of further research as a bifunctional immunotherapeutic agent.

Deciphering and overcoming Anti-PD-1 resistance in Melanoma: A comprehensive review of Mechanisms, biomarker Developments, and therapeutic strategies

Worldwide, tens of thousands of people die from melanoma each year, making it the most frequently fatal form of cutaneous cancer. Immunotherapeutic advancements, particularly with anti-PD-1 medications, have significantly enhanced treatment outcomes over recent decades. With the broad application of anti-PD-1 therapies, insights into the mechanisms of resistance have evolved. Despite the development of combination treatments and early predictive biomarkers, a comprehensive synthesis of these advancements is absent in the current literature. This review underscores the prevailing knowledge of anti-PD-1 resistance mechanisms and underscores the critical role of robust predictive biomarkers in stratifying patients for targeted combinations of anti-PD-1 and other conventional or innovative therapeutic approaches. Additionally, we offer insights that may shape future melanoma treatment strategies.

Immunoradiotherapy for NSCLC: mechanisms, clinical outcomes, and future directions

Non-small-cell lung cancer (NSCLC) has an extremely low 5-year survival rate, with the only effective treatment being immunoradiotherapy (iRT). Here, we review the progress of clinical research on iRT for non-small-cell lung cancer (NSCLC) over 2018-2023, as well as the future directions. We first discuss the synergistic mechanisms of iRT, reflected in three aspects: immune regulation of RT, RT-activated immune-related pathways, and RT-related immune sensitization. iRT may include either external-beam or stereotactic-body RT combined with either immune checkpoint inhibitors (e.g., immunoglobulins against immune programmed cell death (PD) 1/PD ligand 1 or CD8+ T lymphocyte antigen 4) or traditional Chinese medicine drugs. Regarding clinical effectiveness and safety, iRT increases overall and progression-free survival and tumor control rate among patients with NSCLC but without a considerable increase in toxicity risk. We finally discuss iRT challenges and future directions reported over 2018-2023.

Current Landscape of Cancer Immunotherapy: Harnessing the Immune Arsenal to Overcome Immune Evasion

Cancer immune evasion represents a leading hallmark of cancer, posing a significant obstacle to the development of successful anticancer therapies. However, the landscape of cancer treatment has significantly evolved, transitioning into the era of immunotherapy from conventional methods such as surgical resection, radiotherapy, chemotherapy, and targeted drug therapy. Immunotherapy has emerged as a pivotal component in cancer treatment, harnessing the body's immune system to combat cancer and offering improved prognostic outcomes for numerous patients. The remarkable success of immunotherapy has spurred significant efforts to enhance the clinical efficacy of existing agents and strategies. Several immunotherapeutic approaches have received approval for targeted cancer treatments, while others are currently in preclinical and clinical trials. This review explores recent progress in unraveling the mechanisms of cancer immune evasion and evaluates the clinical effectiveness of diverse immunotherapy strategies, including cancer vaccines, adoptive cell therapy, and antibody-based treatments. It encompasses both established treatments and those currently under investigation, providing a comprehensive overview of efforts to combat cancer through immunological approaches. Additionally, the article emphasizes the current developments, limitations, and challenges in cancer immunotherapy. Furthermore, by integrating analyses of cancer immunotherapy resistance mechanisms and exploring combination strategies and personalized approaches, it offers valuable insights crucial for the development of novel anticancer immunotherapeutic strategies.

Targeting CD73 with flavonoids inhibits cancer stem cells and increases lymphocyte infiltration in a triple-negative breast cancer mouse model

Introduction

Chemotherapy remains the mainstay treatment for triple-negative breast cancer (TNBC) due to the lack of specific targets. Given a modest response of immune checkpoint inhibitors in TNBC patients, improving immunotherapy is an urgent and crucial task in this field. CD73 has emerged as a novel immunotherapeutic target, given its elevated expression on tumor, stromal, and specific immune cells, and its established role in inhibiting anti-cancer immunity. CD73-generated adenosine suppresses immunity by attenuating tumor-infiltrating T- and NK-cell activation, while amplifying regulatory T cell activation. Chemotherapy often leads to increased CD73 expression and activity, further suppressing anti-tumor immunity. While debulking the tumor mass, chemotherapy also enriches heterogenous cancer stem cells (CSC), potentially leading to tumor relapse. Therefore, drugs targeting both CD73, and CSCs hold promise for enhancing chemotherapy efficacy, overcoming treatment resistance, and improving clinical outcomes. However, safe and effective inhibitors of CD73 have not been developed as of now.

Methods

We used in silico docking to screen compounds that may be repurposed for inhibiting CD73. The efficacy of these compounds was investigated through flow cytometry, RT-qPCR, CD73 activity, cell viability, tumorsphere formation, and other in vitro functional assays. For assessment of clinical translatability, TNBC patient-derived xenograft organotypic cultures were utilized. We also employed the ovalbumin-expressing AT3 TNBC mouse model to evaluate tumor-specific lymphocyte responses.

Results

We identified quercetin and luteolin, currently used as over-the-counter supplements, to have high in silico complementarity with CD73. When quercetin and luteolin were combined with the chemotherapeutic paclitaxel in a triple-drug regimen, we found an effective downregulation in paclitaxel-enhanced CD73 and CSC-promoting pathways YAP and Wnt. We found that CD73 expression was required for the maintenance of CD44highCD24low CSCs, and co-targeting CD73, YAP, and Wnt effectively suppressed the growth of human TNBC cell lines and patient-derived xenograft organotypic cultures. Furthermore, triple-drug combination inhibited paclitaxel-enriched CSCs and simultaneously improved lymphocyte infiltration in syngeneic TNBC mouse tumors.

Discussion

Conclusively, our findings elucidate the significance of CSCs in impairing anti-tumor immunity. The high efficacy of our triple-drug regimen in clinically relevant platforms not only underscores the importance for further mechanistic investigations but also paves the way for potential development of new, safe, and cost-effective therapeutic strategies for TNBC.

Pharmacological suppression of the OTUD4/CD73 proteolytic axis revives antitumor immunity against immune-suppressive breast cancers

Despite widespread utilization of immunotherapy, treating immune-cold tumors remains a challenge. Multiomic analyses and experimental validation identified the OTUD4/CD73 proteolytic axis as a promising target in treating immune-suppressive triple negative breast cancer (TNBC). Mechanistically, deubiquitylation of CD73 by OTUD4 counteracted its ubiquitylation by TRIM21, resulting in CD73 stabilization inhibiting tumor immune responses. We further demonstrated the importance of TGF-β signaling for orchestrating the OTUD4/CD73 proteolytic axis within tumor cells. Spatial transcriptomics profiling discovered spatially resolved features of interacting malignant and immune cells pertaining to expression levels of OTUD4 and CD73. In addition, ST80, a newly developed inhibitor, specifically disrupted proteolytic interaction between CD73 and OTUD4, leading to reinvigoration of cytotoxic CD8+ T cell activities. In preclinical models of TNBC, ST80 treatment sensitized refractory tumors to anti-PD-L1 therapy. Collectively, our findings uncover what we believe to be a novel strategy for targeting the immunosuppressive OTUD4/CD73 proteolytic axis in treating immune-suppressive breast cancers with the inhibitor ST80.

Investigation of co-treatment multi-targeting approaches in breast cancer cell lines

In 2020, breast cancer (BC) has surpassed lung cancer as the most diagnosed cancer in the world. Tumor microenvironment (TME) plays a critical role in resistance to standard therapies and tumor progression. Two key factors within the TME include adenosine, an immunosuppressive molecule, and glucose, which serves as the primary energy source for tumor cells. In this scenario, inhibiting the purinergic pathway and glucose uptake might be a promising strategy. Therefore, we sought to evaluated different treatment approaches in BC cells (Dapagliflozin, a SGLT2 inhibitor; Paclitaxel, the standard chemotherapy for BC; and ARL67156/APCP, inhibitors of CD39 and CD73, respectively). The expression of some membrane markers relevant to resistance was assessed. BC cell-lines (MCF-7 and MDA-MB-231) were co-treated and cell viability, cell cycle, and annexin/PI assays were performed. Our analysis showed promising results, where the combination of these compounds led to cell death by apoptosis/necrosis and cell cycle arrest. Dapagliflozin showed more impact on early apoptosis, whereas Paclitaxel led to late apoptosis/necrosis as the main mechanism of cell death. Inhibiting purinergic signaling also contributed to reducing cell viability together with the other drugs, suggesting it could have an influence on breast cancer survival mechanisms. Indeed, the overexpression of the NT5E gene in patients with ER+ tumors is strongly associated with reduced overall survival and progression-free interval. However, more studies are needed to fully understand the interactions and mechanism underlying these co-treatment multi-targeting approaches.

CD8+ T cells sustain antitumor response by mediating crosstalk between adenosine A2A receptor and glutathione/GPX4

Antitumor responses of CD8+ T cells are tightly regulated by distinct metabolic fitness. High levels of glutathione (GSH) are observed in the majority of tumors, contributing to cancer progression and treatment resistance in part by preventing glutathione peroxidase 4-dependent (GPX4-dependent) ferroptosis. Here, we show the necessity of adenosine A2A receptor (A2AR) signaling and the GSH/GPX4 axis in orchestrating metabolic fitness and survival of functionally competent CD8+ T cells. Activated CD8+ T cells treated ex vivo with simultaneous inhibition of A2AR and lipid peroxidation acquire a superior capacity to proliferate and persist in vivo, demonstrating a translatable means to prevent ferroptosis in adoptive cell therapy. Additionally, we identify a particular cluster of intratumoral CD8+ T cells expressing a putative gene signature of GSH metabolism (GMGS) in association with clinical response and survival across several human cancers. Our study addresses a key role of GSH/GPX4 and adenosinergic pathways in fine-tuning the metabolic fitness of antitumor CD8+ T cells.

Transcriptional profile and immune infiltration in colorectal cancer reveal the significance of inducible T-cell costimulator as a crucial immune checkpoint molecule

BACKGROUND

Emergence of novel immuno-therapeutics has shown promising improvement in the clinical outcome of colorectal cancer (CRC).

OBJECTIVE

To identify robust immune checkpoints based on expression and immune infiltration profiles of clinical CRC samples.

METHODS

One dataset from The Cancer Genome Atlas database and two from Gene Expression Omnibus were independently employed for the analysis. Genes associated with overall survival were identified, and distribution of each immune checkpoint with respect to different clinical features was determined to explore key immune checkpoints. Multiple staining methods were used to verify the correlation between key immune checkpoint ICOS and clinical pathological features. Differentially expressed mRNA and long non-coding RNA (lncRNA) were then detected for gene set enrichment analysis and gene set variation analysis to investigate the differentially enriched biological processes between low- and high-expression groups. Significant immune-related mRNAs and lncRNA were subjected to competing endogenous RNA (ceRNA) network analysis. Correlation of inducible T-cell costimulator (ICOS) and top 10 genes in ceRNA network were further considered for validation.

RESULTS

ICOS was identified from 14 immune checkpoints as the most highly correlated gene with survival and clinical features in CRC. The expression of ICOS protein in the poorly differentiated group was lower than that in the moderately differentiated group, and the expression in different pathological stages was significant. In addition, the expressions of ICOS were negatively correlated with Ki67. A conspicuous number of immune-related pathways were enriched in differentially expressed genes in the ICOS high- and low-expression groups. Integration with immune infiltration data revealed a multitude of differentially expressed immune-related genes enriched for ceRNA network. Furthermore, expression of top 10 genes investigated from ceRNA network showed high correlation with ICOS.

CONCLUSION

ICOS might serve as a robust immune checkpoint for prognosis with several genes being potential targets of ICOS-directed immunotherapy in CRC.

Mesenchymal stromal cells in myeloid malignancies: Immunotherapeutic opportunities

Myeloid malignancies are clonal disorders of the progenitor cells or hematopoietic stem cells, including acute myeloid leukemia, myelodysplastic syndromes, myeloproliferative malignancies, and chronic myelomonocytic leukemia. Myeloid neoplastic cells affect the proliferation and differentiation of other hematopoietic lineages in the bone marrow and peripheral blood, leading to severe and life-threatening complications. Mesenchymal stromal cells (MSCs) residing in the bone marrow exert immunosuppressive functions by suppressing innate and adaptive immune systems, thus creating a supportive and tolerant microenvironment for myeloid malignancy progression. This review summarizes the significant features of MSCs in myeloid malignancies, including their role in regulating cell growth, cell death, and antineoplastic resistance, in addition to their immunosuppressive contributions. Understanding the implications of MSCs in myeloid malignancies could pave the path for potential use in immunotherapy.

Immunometabolic Regulation of Bacterial Infection, Biofilms, and Antibiotic Susceptibility

BACKGROUND

Upon infection, mucosal tissues activate a brisk inflammatory response to clear the pathogen, i.e., resistance to disease. Resistance to disease is orchestrated by tissue-resident macrophages, which undergo profound metabolic reprogramming after sensing the pathogen. These metabolically activated macrophages release many inflammatory factors, which promote their bactericidal function. However, in immunocompetent individuals, pathogens like Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella evade this type of immunity, generating communities that thrive for the long term.

SUMMARY

These organisms develop features that render them less susceptible to eradication, such as biofilms and increased tolerance to antibiotics. Furthermore, after antibiotic therapy withdrawal, "persister" cells rapidly upsurge, triggering inflammatory relapses that worsen host health. How these pathogens persisted in inflamed tissues replete with activated macrophages remains poorly understood.

KEY MESSAGES

In this review, we discuss recent findings indicating that the ability of P. aeruginosa, S. aureus, and Salmonella to evolve biofilms and antibiotic tolerance is promoted by the similar metabolic routes that regulate macrophage metabolic reprogramming.

Intercellular crosstalk shapes purinergic metabolism and signaling in cancer cells

CD73-derived adenosine suppresses anti-cancer immunity, and CD73 inhibitors are currently evaluated in several clinical trials. Here, we have assessed enzyme kinetics of all key purinergic ectoenzymes in five cancer cell lines (Hodgkin lymphoma, multiple myeloma, pancreas adenocarcinoma, urinary bladder carcinoma, and glioblastoma) under normoxia and hypoxia. We found that adenosine metabolism varied considerably between individual cancer types. All cell lines investigated exhibited high ecto-adenosine deaminase (ADA) activity, which critically influenced the kinetics of adenosine accumulation. Combining kinetics data with single-cell RNA sequencing data on myeloma and glioblastoma cancerous tissue revealed that purine metabolism is not homogeneously organized, but it differs in a cancer type-specific fashion between malignant cells, stromal cells, and immune cells. Since purine metabolism in cancerous tissue is most likely spatially heterogeneous and differs between the various cell types, diffusion distances in the microenvironment as well as ADA activity may be important variables that influence the level of bioactive adenosine.

CD73 contributes to the pathogenesis of fusion-negative rhabdomyosarcoma through the purinergic signaling pathway

Rhabdomyosarcoma (RMS) is the most common type of soft tissue sarcoma in children and adolescents. Fusion-negative RMS (FN-RMS) accounts for more than 80% of all RMS cases. The long-term event-free survival rate for patients with high-grade FN-RMS is below 30%, highlighting the need for improved therapeutic strategies. CD73 is a 5' ectonucleotidase that hydrolyzes AMP to adenosine and regulates the purinergic signaling pathway. We found that CD73 is elevated in FN-RMS tumors that express high levels of TWIST2. While high expression of CD73 contributes to the pathogenesis of multiple cancers, its role in FN-RMS has not been investigated. We found that CD73 knockdown decreased FN-RMS cell growth while up-regulating the myogenic differentiation program. Moreover, mutation of the catalytic residues of CD73 rendered the protein enzymatically inactive and abolished its ability to stimulate FN-RMS growth. Overexpression of wildtype CD73, but not the catalytically inactive mutant, in CD73 knockdown FN-RMS cells restored their growth capacity. Likewise, treatment with an adenosine receptor A2A-B agonist partially rescued FN-RMS cell proliferation and bypassed the CD73 knockdown defective growth phenotype. These results demonstrate that the catalytic activity of CD73 contributes to the pathogenic growth of FN-RMS through the activation of the purinergic signaling pathway. Therefore, targeting CD73 and the purinergic signaling pathway represents a potential therapeutic approach for FN-RMS patients.

Vdelta1 T cells are more resistant than Vdelta2 T cells to the immunosuppressive properties of galectin-3

Ovarian carcinomas have the highest lethality amongst gynecological tumors. A problem after primary resection is the recurrence of epithelial ovarian carcinomas which is often associated with chemotherapy resistance. To improve the clinical outcome, it is of high interest to consider alternative therapy strategies. Due to their pronounced plasticity, γδ T cells are attractive for T-cell-based immunotherapy. However, tumors might escape by the release of lectin galectin-3, which impairs γδ T-cell function. Hence, we tested the effect of galectin-3 on the different γδ T-cell subsets. After coculture between ovarian tumor cells and Vδ1 or Vδ2 T cells enhanced levels of galectin-3 were released. This protein did not affect the cytotoxicity of both γδ T-cell subsets, but differentially influenced the proliferation of the two γδ T-cell subsets. While increased galectin-3 levels and recombinant galectin-3 inhibited the proliferation of Vδ2 T cells, Vδ1 T cells were unaffected. In contrast to Vδ1 T cells, the Vδ2 T cells strongly upregulated the galectin-3 binding partner α3β1-integrin after their activation correlating with the immunosuppressive properties of galectin-3. In addition, galectin-3 reduced the effector memory compartment of zoledronate-activated Vδ2 T cells. Therefore, our data suggest that an activation of Vδ1 T-cell proliferation as part of a T-cell-based immunotherapy can be of advantage.

Adenosinergic metabolism pathway: an emerging target for improving outcomes of solid organ transplantation

Extracellular nucleotides are widely recognized as crucial modulators of immune responses in peripheral tissues. Adenosine triphosphate (ATP) and adenosine are key components of extracellular nucleotides, the balance of which contributes to immune homeostasis. Under tissue injury, ATP exerts its pro-inflammatory function, while the adenosinergic pathway rapidly degrades ATP to immunosuppressive adenosine, thus inhibiting excessive and uncontrolled inflammatory responses. Previous reviews have explored the immunoregulatory role of extracellular adenosine in various pathological conditions, especially inflammation and malignancy. However, current knowledge regarding adenosine and adenosinergic metabolism in the context of solid organ transplantation remains fragmented. In this review, we summarize the latest information on adenosine metabolism and the mechanisms by which it suppresses the effector function of immune cells, as well as highlight the protective role of adenosine in all stages of solid organ transplantation, including reducing ischemia reperfusion injury during organ procurement, alleviating rejection, and promoting graft regeneration after transplantation. Finally, we discuss the potential for future clinical translation of adenosinergic pathway in solid organ transplantation.

Biomaterial-assisted local oxygenation safeguards the prostimulatory phenotype and functions of human dendritic cells in hypoxia

Dendritic cells (DCs), professional antigen-presenting cells, function as sentinels of the immune system. DCs initiate and fine-tune adaptive immune responses by presenting antigenic peptides to B and T lymphocytes to mount an effective immune response against cancer and pathogens. However, hypoxia, a condition characterized by low oxygen (O2) tension in different tissues, significantly impacts DC functions, including antigen uptake, activation and maturation, migration, as well as T-cell priming and proliferation. In this study, we employed O2-releasing biomaterials (O2-cryogels) to study the effect of localized O2 supply on human DC phenotype and functions. Our results indicate that O2-cryogels effectively mitigate DC exposure to hypoxia under hypoxic conditions. Additionally, O2-cryogels counteract hypoxia-induced inhibition of antigen uptake and migratory activity in DCs through O2 release and hyaluronic acid (HA) mediated mechanisms. Furthermore, O2-cryogels preserve and restore DC maturation and co-stimulation markers, including HLA-DR, CD86, and CD40, along with the secretion of proinflammatory cytokines in hypoxic conditions. Finally, our findings demonstrate that the supplemental O2 released from the cryogels preserves DC-mediated T-cell priming, ultimately leading to the activation and proliferation of allogeneic CD3+ T cells. This work emphasizes the potential of local oxygenation as a powerful immunomodulatory agent to improve DC activation and functions in hypoxia, offering new approaches for cancer and infectious disease treatments.

The interaction of mast cells with membranes from lung cancer cells induces the release of extracellular vesicles with a unique miRNA signature

Mast cells (MCs) are immune cells that play roles in both normal and abnormal processes. They have been linked to tumor progression in several types of cancer, including non-small cell lung cancer (NSCLC). However, the exact role of MCs in NSCLC is still unclear. Some studies have shown that the presence of a large number of MCs is associated with poor prognosis, while others have suggested that MCs have protective effects. To better understand the role of MCs in NSCLC, we aimed to identify the initial mechanisms underlying the communication between MCs and lung cancer cells. Here, we recapitulated cell-to-cell contact by exposing MCs to membranes derived from lung cancer cells and confirming their activation, as evidenced by increased phosphorylation of the ERK and AKT kinases. Profiling of the microRNAs that were selectively enriched in the extracellular vesicles (EVs) released by the lung cancer-activated MCs revealed that they contained significantly increased amounts of miR-100-5p and miR-125b, two protumorigenic miRNAs. We explored the pathways regulated by these miRNAs via enrichment analysis using the KEGG database, demonstrating that these two miRNAs regulate p53 signaling, cancer pathways, and pathways associated with apoptosis and the cell cycle.

Adenosine in cancer immunotherapy: Taking off on a new plane

As a new pillar of cancer therapy, tumor immunotherapy has brought irreplaceable durable responses in tumors. Considering its low response rate, additional immune regulatory mechanisms will be critical for the development of next-generation immune therapeutics. As a key regulatory mechanism, adenosine (ADO) protects tissues from excessive immune responses, but as a metabolite highly concentrated in tumor microenvironments, extracellular adenosine acts on adenosine receptors (mainly A2A receptors) expressed on MDSCs, Tregs, NK cells, effector T cells, DCs, and macrophages to promote tumor cell escape from immune surveillance by inhibiting the immune response. Amounting preclinical studies have demonstrated the adenosine pathway as a novel checkpoint for immunotherapy. Large number of adenosine pathway targeting clinical trials are now underway, including antibodies against CD39 and CD73 as well as A2A receptor inhibitors. There has been evidence of antitumor efficacy of these inhibitors in early clinical trials among a variety of tumors such as breast cancer, prostate cancer, non-small cell lung cancer, etc. As more clinical trial results are published, the combination of blockade of this pathway with immune checkpoint inhibitors, targeted drugs, traditional chemotherapy medications, radiotherapy and endocrine therapy will provide cancer patients with better clinical outcomes. We would elaborate on the role of CD39-CD73-A2AR pathway in the contribution of tumor microenvironment and the targeting of the adenosinergic pathway for cancer therapy in the review.

Human placental mesenchymal stromal cells modulate IFN-γ and IL-10 secretion by CD4+T cells via CD73, and alleviate intestinal damage in mice with graft-versus-host disease

BACKGROUND

Intestinal inflammatory damage is an important factor in the development of graft-versus-host disease (GVHD). IFN-γ and IL-10 play key roles in gastrointestinal inflammation, and human placental mesenchymal stromal cells (hPMSCs) can alleviate inflammatory damage during GVHD. CD73 is highly expressed by hPMSCs. We aimed to study whether hPMSCs could alleviate intestinal damage in GVHD mice by modulating IFN-γ and IL-10 in CD4+T cells by CD73.

METHODS

A GVHD mouse model was induced using 8-week-old C57BL/6J and BALB/c mice, which were treated with regular hPMSCs (hPMSCs) or hPMSCs expressing low level of CD73 (shCD73). Then, the levels of IFN-γ and IL-10 in CD4+T cells were determined using flow cytometry. Transmission electron microscopy, western blotting, and morphological staining were employed to observe the intestinal damage.

RESULTS

hPMSCs ameliorated pathological damage and inhibited the reduction of the tight junction molecules occludin and ZO-1. They also downregulated IFN-γ and upregulated IL-10 secretion in CD4+T cells via CD73. Moreover, IL-10 mitigated the inhibitory effects of IFN-γ on the expression of occludin in both Caco-2 and NCM460 cells in vitro, but did not affect ZO-1. In addition, hPMSCs upregulated the level of AMPK phosphorylation in CD4+T cells by CD73, which is positively associated with the proportion of CD4+IFN-γ+IL-10+T, and CD4+IFN-γ-IL-10+T cells.

CONCLUSIONS

Our findings suggested that hPMSCs may balance the levels of IFN-γ and IL-10 in CD4+T cells by promoting the phosphorylation of AMPK via CD73, which alleviates the loss of occludin and ZO-1 in intestinal epithelial cells and, in turn, reduces inflammatory injury in GVHD mice.

Precisely Amplifying Intracellular Oxidative Storm by Metal-Organic Coordination Polymers to Augment Anticancer Immunity

Oxidative stress accompanying the reactive oxygen species (ROS) burst governs immunocyte infiltration, activation, and differentiation in tumor microenvironments and thus can elicit robust antitumor immunity. Here, we identify a photoactive metal-organic coordination polymer (MOCP), composed of an organometallic core formed by cytotoxic mitoxantrone (MTX) acylates and photosensitive Ru(BIQ)-HDBB [BIQ = 2,2'-biquinoline, HDBB = 4,4'-di(4-benzoato)-2,2'-bipyridine] linked by Fe(II) ions via coordinate covalent bonds and an amphipathic shell encapsulating cholesterol-modified siRNA against GPX4 (siGPX4) via hydrophobic force, to precisely amplify intracellular oxidative storm. MOCPs simultaneously encapsulated MTX, Ru, and siGPX4 with efficiencies >98% and loaded Fe with efficiencies of ∼0.49%. With longer blood circulation and higher tumor accumulation, MOCPs with a 670 nm LED irradiation generate abundant ROS to induce biomembrane dysfunction and subsequently contribute to ferroptotic and immunogenic cell death, which drive tumor-associated antigen-specific immunity. MTX analogs contributed to Type I immunogenic cell death (ICD), while oxidative storm served as a damager for endo/lysosomal escape, an initiator for ferroptosis, and an inducer for type II ICD. Moreover, the blockade of CD73 that reduces extoATP catabolism unleashes immunosuppression, finally enhancing antitumor immune stimulation of MOCPs to promote orthotopic mammary cancer regression and prevent postoperative advanced cancer from recurrence and metastasis. MOCPs by exposing sufficient antigenicity thus provide a platform to synergize immune checkpoint inhibitors for the treatment of immunologically cold tumors.

Radiomics using computed tomography to predict CD73 expression and prognosis of colorectal cancer liver metastases

BACKGROUND

Finding a noninvasive radiomic surrogate of tumor immune features could help identify patients more likely to respond to novel immune checkpoint inhibitors. Particularly, CD73 is an ectonucleotidase that catalyzes the breakdown of extracellular AMP into immunosuppressive adenosine, which can be blocked by therapeutic antibodies. High CD73 expression in colorectal cancer liver metastasis (CRLM) resected with curative intent is associated with early recurrence and shorter patient survival. The aim of this study was hence to evaluate whether machine learning analysis of preoperative liver CT-scan could estimate high vs low CD73 expression in CRLM and whether such radiomic score would have a prognostic significance.

METHODS

We trained an Attentive Interpretable Tabular Learning (TabNet) model to predict, from preoperative CT images, stratified expression levels of CD73 (CD73^High vs. CD73^Low) assessed by immunofluorescence (IF) on tissue microarrays. Radiomic features were extracted from 160 segmented CRLM of 122 patients with matched IF data, preprocessed and used to train the predictive model. We applied a five-fold cross-validation and validated the performance on a hold-out test set.

RESULTS

TabNet provided areas under the receiver operating characteristic curve of 0.95 (95% CI 0.87 to 1.0) and 0.79 (0.65 to 0.92) on the training and hold-out test sets respectively, and outperformed other machine learning models. The TabNet-derived score, termed rad-CD73, was positively correlated with CD73 histological expression in matched CRLM (Spearman's ρ = 0.6004; P < 0.0001). The median time to recurrence (TTR) and disease-specific survival (DSS) after CRLM resection in rad-CD73^High vs rad-CD73^Low patients was 13.0 vs 23.6 months (P = 0.0098) and 53.4 vs 126.0 months (P = 0.0222), respectively. The prognostic value of rad-CD73 was independent of the standard clinical risk score, for both TTR (HR = 2.11, 95% CI 1.30 to 3.45, P < 0.005) and DSS (HR = 1.88, 95% CI 1.11 to 3.18, P = 0.020).

CONCLUSIONS

Our findings reveal promising results for non-invasive CT-scan-based prediction of CD73 expression in CRLM and warrant further validation as to whether rad-CD73 could assist oncologists as a biomarker of prognosis and response to immunotherapies targeting the adenosine pathway.

Therapeutic Targets of Monoclonal Antibodies Used in the Treatment of Cancer: Current and Emerging

Cancer is one of the leading global causes of death and disease, and treatment options are constantly evolving. In this sense, the use of monoclonal antibodies (mAbs) in immunotherapy has been considered a fundamental aspect of modern cancer therapy. In order to avoid collateral damage, it is indispensable to identify specific molecular targets or biomarkers of therapy and/or diagnosis (theragnostic) when designing an appropriate immunotherapeutic regimen for any type of cancer. Furthermore, it is important to understand the currently employed mAbs in immunotherapy and their mechanisms of action in combating cancer. To achieve this, a comprehensive understanding of the biology of cancer cell antigens, domains, and functions is necessary, including both those presently utilized and those emerging as potential targets for the design of new mAbs in cancer treatment. This review aims to provide a description of the therapeutic targets utilized in cancer immunotherapy over the past 5 years, as well as emerging targets that hold promise as potential therapeutic options in the application of mAbs for immunotherapy. Additionally, the review explores the mechanisms of actin of the currently employed mAbs in immunotherapy.

The Clinical Significance of CD73 in Cancer

The search for new and effective treatment targets for cancer immunotherapy is an ongoing challenge. Alongside the more established inhibitory immune checkpoints, a novel potential target is CD73. As one of the key enzymes in the purinergic signalling pathway CD73 is responsible for the generation of immune suppressive adenosine. The expression of CD73 is higher in tumours than in the corresponding healthy tissues and associated with a poor prognosis. CD73, mainly by the production of adenosine, is critical in the suppression of an adequate anti-tumour immune response, but also in promoting cancer cell proliferation, tumour growth, angiogenesis, and metastasis. The upregulation of CD73 and generation of adenosine by tumour or tumour-associated immune cells is a common resistance mechanism to many cancer treatments such as chemotherapy, radiotherapy, targeted therapy, and immunotherapy. Therefore, the inhibition of CD73 represents a new and promising approach to increase therapy efficacy. Several CD73 inhibitors have already been developed and successfully demonstrated anti-cancer activity in preclinical studies. Currently, clinical studies evaluate CD73 inhibitors in different therapy combinations and tumour entities. The initial results suggest that inhibiting CD73 could be an effective option to augment anti-cancer immunotherapeutic strategies. This review provides an overview of the rationale behind the CD73 inhibition in different treatment combinations and the role of CD73 as a prognostic marker.

First-in-human study of oleclumab, a potent, selective anti-CD73 monoclonal antibody, alone or in combination with durvalumab in patients with advanced solid tumors

BACKGROUND

CD73 upregulation in tumors leads to local immunosuppression. This phase I, first-in-human study evaluated oleclumab (MEDI9447), an anti-CD73 human IgG1λ monoclonal antibody, alone or with durvalumab in patients with advanced colorectal cancer (CRC), pancreatic ductal adenocarcinoma (PDAC), or epidermal growth factor receptor-mutant non-small-cell lung cancer (NSCLC).

METHODS

Patients received oleclumab 5-40 mg/kg (dose-escalation) or 40 mg/kg (dose-expansion) intravenously every 2 weeks (Q2W), alone (escalation only) or with durvalumab 10 mg/kg intravenously Q2W.

RESULTS

192 patients were enrolled, 66 during escalation and 126 (42 CRC, 42 PDAC, 42 NSCLC) during expansion. No dose-limiting toxicities occurred during escalation. In the monotherapy and combination therapy escalation cohorts, treatment-related adverse events (TRAEs) occurred in 55 and 54%, respectively, the most common being fatigue (17 and 25%). In the CRC, PDAC, and NSCLC expansion cohorts, 60, 57, and 45% of patients had TRAEs, respectively; the most common were fatigue (15%), diarrhea (9%), and rash (7%). Free soluble CD73 and CD73 expression on peripheral T cells and tumor cells showed sustained decreases, accompanied by reduced CD73 enzymatic activity in tumor cells. Objective response rate during escalation was 0%. Response rates in the CRC, PDAC, and NSCLC expansion cohorts were 2.4% (1 complete response [CR]), 4.8% (1 CR, 1 partial response [PR]), and 9.5% (4 PRs), respectively; 6-month progression-free survival rates were 5.4, 13.2, and 16.0%.

CONCLUSIONS

Oleclumab ± durvalumab had a manageable safety profile, with pharmacodynamic activity reflecting oleclumab's mechanism of action. Evidence of antitumor activity was observed in tumor types that are generally immunotherapy resistant.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov, NCT02503774; date of registration, July 17, 2015.

The Current State of Neoadjuvant Therapy in Resectable Advanced Stage Melanoma

The advent of effective immunotherapy and targeted therapy has significantly improved outcomes in advanced-stage resectable melanoma. Currently, the mainstay of treatment of malignant melanoma is surgery followed by adjuvant systemic therapies. However, recent studies have shown a potential role for neoadjuvant therapy in the treatment of advanced-stage resectable melanoma. Mechanistically, neoadjuvant immunotherapy may yield a more robust response than adjuvant immunotherapy, as the primary tumor serves as an antigen in this setting rather than only micrometastatic disease after the index procedure. Additionally, targeted therapy has been shown to yield effective neoadjuvant cytoreduction, and oncolytic viruses may also increase the immunogenicity of primary tumors. Effective neoadjuvant therapy may serve to decrease tumor size and thus reduce the extent of required surgery and thus morbidity. It also allows for assessment of pathologic response, facilitating prognostication as well as tailoring future therapy. The current literature consistently supports that neoadjuvant therapy, even as little as one dose, is associated with improved outcomes and is well-tolerated. Some patients with a complete pathological response may even avoid surgery completely. These results challenge the current paradigm of a surgery-first approach and provide further evidence supporting neoadjuvant therapy in advanced-stage resectable melanoma. Further research into the optimal treatment schedule and dose timing is warranted, as is the continued investigation of novel therapies and combinations of therapies.

Human soluble CD39 displays substrate inhibition in a substrate-specific manner

CD39 (ectonucleoside triphosphate diphosphohydrolase-1; ENTPD1) metabolizes extracellular ATP and ADP to AMP. AMP is subsequently metabolized by CD79 to adenosine. CD39 activity is therefore a key regulator of purinergic signalling in cancer, thrombosis, and autoimmune diseases. In this study we demonstrate that soluble, recombinant CD39 shows substrate inhibition with ADP or ATP as the substrate. Although CD39 activity initially increased with increasing substrate concentration, at high concentrations of ATP or ADP, CD39 activity was markedly reduced. Although the reaction product, AMP, inhibits CD39 activity, insufficient AMP was generated under our conditions to account for the substrate inhibition seen. In contrast, inhibition was not seen with UDP or UTP as substrates. 2-methylthio-ADP also showed no substrate inhibition, indicating the nucleotide base is an important determinant of substrate inhibition. Molecular dynamics simulations revealed that ADP can undergo conformational rearrangements within the CD39 active site that were not seen with UDP or 2-methylthio-ADP. Appreciating the existence of substrate inhibition of CD39 will help the interpretation of studies of CD39 activity, including investigations into drugs that modulate CD39 activity.

CD73 blockade alleviates intestinal inflammatory responses by regulating macrophage differentiation in ulcerative colitis

Ulcerative colitis (UC) is a type of inflammatory bowel disease characterized by excessive and persistent inflammation. Intestinal macrophages play a considerable role in regulating inflammatory immune reactions in the gut mucosa. It has previously been reported that CD73 is related to the pathogenesis of inflammatory or immune-related diseases; however, the roles of CD73 in UC remain unclear. In this study, CD73 expression in the inflamed mucosa of patients with UC was examined using reverse transcription-quantitative PCR (RT-qPCR), western blotting, and immunohistochemistry. Adenosine 5'-(α, β-methylene) diphosphate (APCP) was used to block the expression of CD73. Furthermore, the mRNA levels of proinflammatory mediators associated with macrophages following the blocking of CD73 were examined using RT-qPCR. Finally, the regulatory function of CD73 in intestinal inflammation was assessed by administering APCP in a mouse model of dextran sulfate sodium salt (DSS)-induced colitis. Notably, it was found that CD73 expression was significantly increased in the colonic mucosal tissues of patients with UC. Blockade of CD73 inhibited the expression of pro-inflammatory cytokines but promoted the production of anti-inflammatory cytokines in macrophages, while its promotion of M2 macrophage polarization was also verified. In vivo, CD73 blockade markedly alleviated DSS-induced colitis in mice, as characterized by reduced weight loss, reduction in the incidence of diarrhea, and reduced amount of bloody stool. Mechanistically, it was shown that CD73 regulated macrophage differentiation via the NF-κB and ERK signaling pathways. In conclusion, the findings of the present study indicate that CD73 may have a potential impact on the pathogenesis of UC by modulating the immune response of macrophage differentiation; thus, providing a novel pathway for modulating mucosal inflammation in UC.

Emerging connections between GPI-anchored proteins and their extracellular carriers in colorectal cancer

Although extracellular vesicles (EVs) were discovered over 40 years ago, there has been a resurgence of interest in secreted vesicles and their attendant cargo as novel modes of intracellular communication. In addition to vesicles, two amembranous nanoparticles, exomeres and supermeres, have been isolated and characterized recently. In this rapidly expanding field, it has been challenging to assign cargo and specific functions to a particular carrier. Refinement of isolation methods, well-controlled studies, and guidelines detailed by Minimal Information for Studies of Extracellular Vesicles (MISEV) are being employed to "bring order to chaos." In this review, we will briefly summarize three types of extracellular carriers - small EVs (sEVs), exomeres, and supermeres - in the context of colorectal cancer (CRC). We found that a number of GPI-anchored proteins (GPI-APs) are overexpressed in CRC, are enriched in exosomes (a distinct subset of sEVs), and can be detected in exomeres and supermeres. This affords the opportunity to elaborate on GPI-AP biogenesis, modifications, and trafficking using DPEP1, a GPI-AP upregulated in CRC, as a prime example. We have cataloged the GPI-anchored proteins secreted in CRC and will highlight features of select CRC-associated GPI-anchored proteins we have detected. Finally, we will discuss the remaining challenges and future opportunities in studying these secreted GPI-APs in CRC.

CD73 mediated host purinergic metabolism in intestine contributes to the therapeutic efficacy of a novel mesenchymal-like endometrial regenerative cells against experimental colitis

Background

The disruption of intestinal barrier functions and the dysregulation of mucosal immune responses, mediated by aberrant purinergic metabolism, are involved in the pathogenesis of inflammatory bowel diseases (IBD). A novel mesenchymal-like endometrial regenerative cells (ERCs) has demonstrated a significant therapeutic effect on colitis. As a phenotypic marker of ERCs, CD73 has been largely neglected for its immunosuppressive function in regulating purinergic metabolism. Here, we have investigated whether CD73 expression on ERCs is a potential molecular exerting its therapeutic effect against colitis.

Methods

ERCs either unmodified or with CD73 knockout (CD73-/-ERCs), were intraperitoneally administered to dextran sulfate sodium (DSS)-induced colitis mice. Histopathological analysis, colon barrier function, the proportion of T cells, and maturation of dendritic cells (DCs) were investigated. The immunomodulatory effect of CD73-expressing ERCs was evaluated by co-culture with bone marrow-derived DCs under LPS stimulation. FACS determined DCs maturation. The function of DCs was detected by ELISA and CD4+ cell proliferation assays. Furthermore, the role of the STAT3 pathway in CD73-expressing ERCs-induced DC inhibition was also elucidated.

Results

Compared with untreated and CD73-/-ERCs-treated groups, CD73-expressing ERCs effectively attenuated body weight loss, bloody stool, shortening of colon length, and pathological damage characterized by epithelial hyperplasia, goblet cell depletion, the focal loss of crypts and ulceration, and the infiltration of inflammatory cells. Knockout of CD73 impaired ERCs-mediated colon protection. Surprisingly, CD73-expressing ERCs significantly decreased the populations of Th1 and Th17 cells but increased the proportions of Tregs in mouse mesenteric lymph nodes. Furthermore, CD73-expressing ERCs markedly reduced the levels of pro-inflammatory cytokines (IL-6, IL-1β, TNF-α) and increased anti-inflammatory factors (IL-10) levels in the colon. CD73-expressing ERCs inhibited the antigen presentation and stimulatory function of DCs associated with the STAT-3 pathway, which exerted a potent therapeutic effect against colitis.

Conclusions

The knockout of CD73 dramatically abrogates the therapeutic ability of ERCs for intestinal barrier dysfunctions and the dysregulation of mucosal immune responses. This study highlights the significance of CD73 mediates purinergic metabolism contributing to the therapeutic effects of human ERCs against colitis in mice.

Nucleotide metabolism: a pan-cancer metabolic dependency

Metabolic alterations are a key hallmark of cancer cells, and the augmented synthesis and use of nucleotide triphosphates is a critical and universal metabolic dependency of cancer cells across different cancer types and genetic backgrounds. Many of the aggressive behaviours of cancer cells, including uncontrolled proliferation, chemotherapy resistance, immune evasion and metastasis, rely heavily on augmented nucleotide metabolism. Furthermore, most of the known oncogenic drivers upregulate nucleotide biosynthetic capacity, suggesting that this phenotype is a prerequisite for cancer initiation and progression. Despite the wealth of data demonstrating the efficacy of nucleotide synthesis inhibitors in preclinical cancer models and the well-established clinical use of these drugs in certain cancer settings, the full potential of these agents remains unrealized. In this Review, we discuss recent studies that have generated mechanistic insights into the diverse biological roles of hyperactive cancer cell nucleotide metabolism. We explore opportunities for combination therapies that are highlighted by these recent advances and detail key questions that remain to be answered, with the goal of informing urgently warranted future studies.

CD73-Positive Cell Spheroid Transplantation Attenuates Colonic Atrophy

The incidence of inflammatory bowel diseases (IBD) is increasing worldwide. Mesenchymal stem/stromal cells (MSCs) have immunomodulatory functions and are a promising source for cell transplantation therapy for IBD. However, owing to their heterogeneous nature, their therapeutic efficacy in colitis is controversial and depends on the delivery route and form of transplanted cells. Cluster of differentiation (CD) 73 is widely expressed in MSCs and used to obtain a homogeneous MSC population. Herein, we determined the optimal method for MSC transplantation using CD73+ cells in a colitis model. mRNA sequencing analysis showed that CD73+ cells exhibited a downregulation of inflammatory gene expression and an upregulation of extracellular matrix-related gene expression. Furthermore, three-dimensional CD73+ cell spheroids showed enhanced engraftment at the injured site through the enteral route, facilitated extracellular matrix remodeling, and downregulated inflammatory gene expression in fibroblasts, leading to the attenuation of colonic atrophy. Therefore, the interaction between intestinal fibroblasts and exogenous MSCs via tissue remodeling is one mechanism that can be exploited for colitis prevention. Our results highlight that the transplantation of homogeneous cell populations with well-characterized properties is beneficial for IBD treatment.

Pharmacology, pharmacokinetics, and toxicity characterization of a novel anti-CD73 therapeutic antibody IBI325 for cancer immunotherapy

It is an intriguing approach to target the ecto-5'-nucleotidase CD73 to confer synergetic beneficial survival in cancer patients, along with clinically established immunotherapy targets. In this study, a fully human, subnanomolar affinity CD73 antibody IBI325 was developed using the yeast display platform. Compared with Oleclumab, IBI325 was equivalent in hCD73 affinity and more potent in cell-bound and soluble CD73 enzymatic inhibition, and no hook effects were observed. Correspondingly, adenosine monophosphate-mediated immune suppression was reversed by IBI325, and significant T cell proliferation and release of cytokines were observed. Also, IBI325 enhanced the T cell recall response by inducing interferon-γ secretion. The antitumor efficacy of IBI325 was investigated in a hPBMC-reconstituted NOG mouse model, and a hCD73 knock-in mouse model. Consequently, IBI325 induced a significant tumor regression by inducing intratumoral immune cell expansion, and a combo therapy of IBI325 and aPD-1 was superior in efficacy than aCD73 or aPD-1 monotherapy. Additionally, the binding epitopes of CD73 to IBI325 were distinct from previously reported aCD73 therapeutics. IBI325 displayed acceptable pharmacokinetics and sufficient tolerable safety profiles to support clinical development. In conclusion, the pharmacology, pharmacokinetics, and toxicity profiles of IBI325 with complete CD73 inhibition were characterized, and encouraging preclinical outcomes were reported.

CD73, a Promising Therapeutic Target of Diclofenac, Promotes Metastasis of Pancreatic Cancer through a Nucleotidase Independent Mechanism

CD73, a cell surface-bound nucleotidase, facilitates extracellular adenosine formation by hydrolyzing 5'-AMP to adenosine. Several studies have shown that CD73 plays an essential role in immune escape, cell proliferation and tumor angiogenesis, making it an attractive target for cancer therapies. However, there are limited clinical benefits associated with the mainstream enzymatic inhibitors of CD73, suggesting that the mechanism underlying the role of CD73 in tumor progression is more complex than anticipated, and further investigation is necessary. In this study, CD73 is found to overexpress in the cytoplasm of pancreatic ductal adenocarcinoma (PDAC) cells and promotes metastasis in a nucleotidase-independent manner, which cannot be restrained by the CD73 monoclonal antibodies or small-molecule enzymatic inhibitors. Furthermore, CD73 promotes the metastasis of PDAC by binding to the E3 ligase TRIM21, competing with the Snail for its binding site. Additionally, a CD73 transcriptional inhibitor, diclofenac, a non-steroidal anti-inflammatory drug, is more effective than the CD73 blocking antibody for the treatment of PDAC metastasis. Diclofenac also enhances the therapeutic efficacy of gemcitabine in the spontaneous KPC (LSL-Kras^G12D/+ , LSL-Trp53^R172H/+ , and Pdx-1-Cre) pancreatic cancer model. Therefore, diclofenac may be an effective anti-CD73 therapy, when used alone or in combination with gemcitabine-based chemotherapy regimen, for metastatic PDAC.

Targets of Immune Escape Mechanisms in Cancer: Basis for Development and Evolution of Cancer Immune Checkpoint Inhibitors

Immune checkpoint blockade (ICB) has emerged as a novel therapeutic tool for cancer therapy in the last decade. Unfortunately, a small number of patients benefit from approved immune checkpoint inhibitors (ICIs). Therefore, multiple studies are being conducted to find new ICIs and combination strategies to improve the current ICIs. In this review, we discuss some approved immune checkpoints, such as PD-L1, PD-1, and CTLA-4, and also highlight newer emerging ICIs. For instance, HLA-E, overexpressed by tumor cells, represents an immune-suppressive feature by binding CD94/NKG2A, on NK and T cells. NKG2A blockade recruits CD8+ T cells and activates NK cells to decrease the tumor burden. NKG2D acts as an NK cell activating receptor that can also be a potential ICI. The adenosine A2A and A2B receptors, CD47-SIRPα, TIM-3, LAG-3, TIGIT, and VISTA are targets that also contribute to cancer immunoresistance and have been considered for clinical trials. Their antitumor immunosuppressive functions can be used to develop blocking antibodies. PARPs, mARTs, and B7-H3 are also other potential targets for immunosuppression. Additionally, miRNA, mRNA, and CRISPR-Cas9-mediated immunotherapeutic approaches are being investigated with great interest. Pre-clinical and clinical studies project these targets as potential immunotherapeutic candidates in different cancer types for their robust antitumor modulation.

Discovery of a Series of Potent, Selective, and Orally Bioavailable Nucleoside Inhibitors of CD73 That Demonstrates In Vivo Antitumor Activity

CD73 (ecto-5'-nucleotidase) has emerged as an attractive target for cancer immunotherapy of many cancers. CD73 catalyzes the hydrolysis of adenosine monophosphate (AMP) into highly immunosuppressive adenosine that plays a critical role in tumor progression. Herein, we report our efforts in developing orally bioavailable and highly potent small-molecule CD73 inhibitors from the reported hit molecule 2 to lead molecule 20 and then finally to compound 49. Compound 49 was able to reverse AMP-mediated suppression of CD8⁺ T cells and completely inhibited CD73 activity in serum samples from various cancer patients. In preclinical in vivo studies, orally administered 49 showed a robust dose-dependent pharmacokinetic/pharmacodynamic (PK/PD) relationship that correlated with efficacy. Compound 49 also demonstrated the expected immune-mediated antitumor mechanism of action and was efficacious upon oral administration not only as a single agent but also in combination with either chemotherapeutics or checkpoint inhibitor in the mouse tumor model.

Proteolytic regulation of CD73 by TRIM21 orchestrates tumor immunogenicity

Despite the rapid utilization of immunotherapy, emerging challenges to the current immune checkpoint blockade need to be resolved. Here, we report that elevation of CD73 levels due to its aberrant turnover is correlated with poor prognosis in immune-cold triple-negative breast cancers (TNBCs). We have identified TRIM21 as an E3 ligase that governs CD73 destruction. Disruption of TRIM21 stabilizes CD73 that in turn enhances CD73-catalyzed production of adenosine, resulting in the suppression of CD8+ T cell function. Replacement of lysine 133, 208, 262, and 321 residues by arginine on CD73 attenuated CD73 ubiquitylation and degradation. Diminishing of CD73 ubiquitylation remarkably promotes tumor growth and impedes antitumor immunity. In addition, a TRIM21high/CD73low signature in a subgroup of human breast malignancies was associated with a favorable immune profile. Collectively, our findings uncover a mechanism that governs CD73 proteolysis and point to a new therapeutic strategy by modulating CD73 ubiquitylation.

Immunotherapy in Gastroenteropancreatic Neuroendocrine Neoplasia

The worldwide prevalence and incidence of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) and of NENs, in general, have been increasing recently. While valuing the considerable progress made in the treatment strategies for GEP-NEN in recent years, patients with advanced, metastasized disease still have a poor prognosis, which calls for urgent novel therapies. The immune system plays a dual role: both host-protecting and "tumor-promoting." Hence, immunotherapy is potentially a powerful weapon to help NEN patients. However, although recent successes with checkpoint inhibitors have shown that enhancing antitumor immunity can be effective, the dynamic nature of the immunosuppressive tumor microenvironment presents significant hurdles to the broader application of these therapies. Studies led to their approval in NEN of the lung and Merkel cell carcinoma, whereas results in other settings have not been so encouraging. Oncolytic viruses can selectively infect and destroy cancer cells, acting as an in situ cancer vaccine. Moreover, they can remodel the tumor microenvironment toward a T cell-inflamed phenotype. Oncolytic virotherapy has been proposed as an ablative and immunostimulatory treatment strategy for solid tumors that are resistant to checkpoint inhibitors alone. Future efforts should focus on finding the best way to include immunotherapy in the GEP-NEN treatment scenario. In this context, this study aims at providing a comprehensive generalized review of the immune checkpoint blockade and the oncolytic virotherapy use in GEP-NENs that might improve GEP-NEN treatment strategies.

CD73, a significant protein in liver diseases

Purine adenosine pathway exists widely in the body metabolism, and is involved in regulating various physiological processes. It is one of the important pathways of environmental regulation in human body. CD73 is essentially a protease that catalyzes further dephosphorylation of extracellular adenine nucleotides, hydrolyzing extracellular AMP to adenosine and phosphate. CD73 is an important part of the adenosine signaling pathway. Studies have shown that CD73-mediated adenosine pathway can convert the inflammatory ATP into the immunosuppressant adenosine. This paper aims to summarize the relevant effects of CD73 in the occurrence, development and prognosis of liver diseases such as viral hepatitis, highlight the important role of CD73 in liver diseases, especially in viral hepatitis such as HBV and HCV, and explore new clinical ideas for future treatment targets of liver diseases.

The ubiquitin-specific peptidase 22 is a deubiquitinase of CD73 in breast cancer cells

Cancer cells evade the immune system by expressing inhibitory immune checkpoint receptors such as ecto-5'-nucleotidase (NT5E), also known as CD73, which consequently suppress tumor neoantigen-specific immune response. Blockade of CD73 in mouse models of breast cancer showed a reduction in tumor growth and metastasis. CD73 expression is elevated in a variety of human tumors including breast cancer. While the regulation of CD73 expression at the transcriptional level has been well understood, the factors involved in regulating CD73 expression at the post-transcriptional level have not been identified. Herein, we discovered that the ubiquitin-specific peptidase 22 (USP22), a deubiquitinase associated with poor prognosis and overexpressed in breast cancers, is a positive regulator for CD73. Targeted USP22 deletion resulted in a statistically significant reduction in CD73 protein expression. In contrast, CD73 mRNA expression levels were not reduced, but even slightly increased by USP22 deletion. Further analysis demonstrated that USP22 is a deubiquitinase that specifically interacts with and inhibits CD73 ubiquitination. Consequently, USP22 protects CD73 from ubiquitin-mediated proteasomal degradation in breast cancer cells. Targeted USP22 deletion, inhibits syngeneic breast cancer growth. Collectively, our study reveals USP22 as a positive regulator to promote CD73 expression in breast cancer and provides a rationale to target USP22 in antitumor immune therapy.

Pan-cancer analysis of LINC02535 as a potential biomarker and its oncogenic role in lung adenocarcinoma

Background

LINC02535 has gained much attention for its oncogenicity across several cancers, but the systematic pan-cancer analysis of LINC02535 has not been carried out before.

Methods

Herein, we explored the expression level, prognostic value, and hallmark pathways of LINC02535 across multiple cancers using the Cancer Genome Atlas (TCGA) and Cancer Cell Line Encyclopedia (CCLE) databases. Moreover, the expression and biological features of LINC02535 in lung adenocarcinoma (LUAD) were confirmed by qRT-PCR, in vitro and in vivo experiments.

Results

LINC02535 is differentially expressed in 10 of 17 human cancers and serves as a favorable or unfavorable biomarker in distinct cancer types. Gene set enrichment analysis (GSEA) indicated that key oncogenic pathways/phenotypes were remarkably activated in most cancers with intratumoral increased LINC02535, whereas these pathways/phenotypes were suppressed in other cancer types (colon adenocarcinoma, kidney renal clear cell carcinoma, rectal adenocarcinoma) with intratumoral decreased LINC02535. Of note, the epithelial-mesenchymal transition (EMT) phenotype was greatly enriched in LUAD patients with elevated LINC02535. Based on the TCGA and CCLE datasets, LINC02535 was positively correlated with the EMT-related gene CD73 (also named as NT5E, an immunosuppressive gene) in almost all cancer types (Spearman R > 0.5, P < 0.001) including LUAD. Most importantly, qRT-PCR confirmed that LINC02535 was upregulated in lung cancer cells or tissues as opposed to human bronchial epithelial cells or paratumor tissues. Knockdown of LINC02535 inhibited proliferation, migration of LUAD cells and retarded xenografted tumor growth. Moreover, silencing of LINC02535 induced apoptosis and cell cycle arrest at G1 phase.

Conclusions

The findings from our pan-cancer analysis provide a relatively comprehensive understanding of the potential value of LINC02535 across multiple cancers, and the oncogenic role of LINC02535 in LUAD has been confirmed.

Bioscaffold developed with decellularized human amniotic membrane seeded with mesenchymal stromal cells: assessment of efficacy and safety profiles in a second-degree burn preclinical model

Therapies to deep burn injuries remain a global challenge. Human amniotic membrane (hAM) is a biomaterial that has been increasingly explored by the field of regenerative medicine. A decellularized hAM (DhAM) can be used as scaffold for mesenchymal stromal cells (MSCs) to grow without the loss of their stemness potential, allowing its application as cell therapy for wound healing. In this work, we associated DhAM with adipose-derived MSCs (DhAM + AD-MSCs), as a therapy strategy for second-degree burns in a preclinical model. Animals with induced second-degree burns were divided into four groups: control, which consists of a non-adherent gauze; a synthetic commercial dressing as the positive control (Control+); DhAM; and DhAM plus rat AD-MSCs (DhAM + AD-MSCs), followed by detailed and long term analysis (5 weeks). The macroscopical analysis showed the healing improvement in the wound area after the DhAM + AD-MSC treatment. Histological analysis also showed no alteration in the animal organs and a regular epithelial progression in comparison to the control. This observation was also confirmed by the analysis of suprabasal layers in the neoepidermis with CK10, showing a stratified and differentiated epithelium, when compared to Control and Control+. A strong CD73 (ecto-5'-nucleotidase) labeling was observed in the first 2 weeks postburn in dermis and epidermis. The expression in dermis was stronger in the second week in the middle of the wound, when comparing the Control+ with DhAM + AD-MSCs (p= 0.0238). In the epidermis the expression of CD73 was increased in all regions when compared to the control. This data suggests the involvement of this protein on wound healing. A low CD11b labeling was observed in DhAM + AD-MSCs treatment group mainly in the last treatment week, in comparison to Control and Control+ (p< 0.0001), which indicates a reduction in the inflammatory process. MSCs through CD73 can release high concentrations of adenosine, an immunosuppressive molecule, suggesting that this could be the mechanism by which the inflammation was better modulated in the DhAM + AD-MSCs group. The results obtained with this preclinical model confirm the effectiveness and safety of this low-cost and highly available dressing for future clinical application as a therapy for burn treatments.

Integrated multi-omics analysis identifies CD73 as a prognostic biomarker and immunotherapy response predictor in head and neck squamous cell carcinoma

BACKGROUND

Advances in tumor immunotherapy have been developed for patients with advanced recurrent or metastatic (R/M) HNSCC. However, the response of most HNSCC patients to immune checkpoint inhibitors (ICI) remains unsatisfactory. CD73 is a promising target for tumor immunotherapy, but its role in HNSCC remains insufficient. In this study, we aim to explore the function of CD73 in HNSCC.

METHODS

Transcriptomic and clinical data of TCGA-HNSC were downloaded from UCSC Xena for analysis of CD73 mRNA expression and prognosis. Immunohistochemical assay were performed to validate the expression of CD73 in tumor tissues and its relationship with CD8+ T cells. GSEA analysis was performed with the "clusterProfiler" R package. Immune infiltration analysis was calculated with ESTIMATE, CIBERSORT and MCP-counter algorithms. Single-cell transcriptomic data was originated from GSE103322. Cell clustering, annotation and CD73 expression were from the TISCH database. Correlation data between CD73 and tumor signatures were obtained from the CancerSEA database. Somatic mutation data were obtained from TCGA-HNSC and analyzed by "maftools" R package. Immune efficacy prediction was performed using TIDE algorithm and validated with the IMvigor210 cohort.

RESULTS

Compared with normal tissues, both mRNA and protein expressions of CD73 were elevated in tumor tissues (P = 9.7×10-10, P = 7.6×10-5, respectively). Kaplan-Meier analysis revealed that patients with high expression of CD73 had worse overall survival (log-rank P = 0.0094), and CD73 could be used as a diagnostic factor for HNSCC (AUC = 0.778). Both bulk RNA-seq and single-cell RNA-seq analysis showed that high CD73 expression can promote EMT and metastasis, samples with high CD73 expression had reduced CD8+ T cells. Furthermore, it was found that CD73-high group was more prone to have mutations in TP53, HRAS and CDKN2A, and were negatively correlated with TMB (P = 0.0055) and MSI (P = 0.00034). Mutational signature analysis found that CD73 was associated with APOBEC signature. Immunotherapy efficacy analysis showed that CD73-high group was less sensitive to immune efficacy.

CONCLUSIONS

Our results demonstrate that CD73 has an inhibitory effect on the tumor microenvironment, and is more likely to be unresponsive to ICI therapy. Collectively, targeting CD73 may provide new insights for tumor targeted therapy and/or immunotherapy.

Nanobiotherapeutic strategies to target immune microenvironment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the subtype with the least favourable outcomes in breast cancer. Besides chemotherapy, there is a chronic lack of other effective treatments. Advances in omic technologies have liberated us from the ambiguity of TNBC heterogeneity in terms of cancer cell and immune microenvironment in recent years. This new understanding of TNBC pathology has already led to the exploitation of novel nanoparticulate systems, including tumor vaccines, oncolytic viruses, and antibody derivatives. The revolutionary ideas in the therapeutic landscape provide new opportunities for TNBC patients. Translating these experimental medicines into clinical benefit is both appreciated and challenging. In this review, we describe the prospective nanobiotherapy of TNBC that has been developed to overcome clinical obstacles, and provide our vision for this booming field at the overlap of cancer biotherapy and nanomaterial design.

Adenosinergic axis and immune checkpoint combination therapy in tumor: A new perspective for immunotherapy strategy

There are two figures and one table in this review, the review consists of 5823 words, without the description of figures and table, but including references.

Tumor cells escape anti-tumor immune responses in various ways, including functionally shaping the microenvironment through the secretion of various chemokines and, cytokines. Adenosine is a powerful immunosuppressive metabolite, that is frequently elevated in the extracellular tumor microenvironment (TME). Thus, it has recently been proposed as a novel antitumor immunoassay for targeting adenosine- generating enzymes, such as CD39, CD73, and adenosine receptors. In recent years, the discovery of the immune checkpoints, such as programmed cell death 1(PD-1) and cytotoxic T lymphocyte antigen 4 (CTLA-4), has also greatly changed treatment methods and ideas for malignant tumors. Malignant tumor immunotherapy has been developed from point-to-point therapy targeting immune checkpoints, combining different points of different pathways to create a therapy based on the macroscopic immune regulatory system network. This article reviews the theoretical basis of the adenosine energy axis and immune checkpoint combined therapy for malignant tumors and the latest advances in malignant tumors.

Therapeutic efficacy and mechanism of CD73-TGFβ dual-blockade in a mouse model of triple-negative breast cancer

Although chemotherapy and recently approved immunotherapies have improved treatment of triple-negative breast cancer (TNBC), the clinical outcome for this deadly disease remains unsatisfactory. We found that both cluster of differentiation 73 (CD73) and transforming growth factor (TGF)β were elevated in TNBC and correlated with the epithelial-mesenchymal transition (EMT), fibrotic stroma, an immune-tolerant tumor environment, and poor prognosis. To explore the efficacy of CD73-TGFβ dual-blockade, we generated a bifunctional anti-CD73-TGFβ construct consisting of the CD73 antibody MEDI9447 fused with the TGFβRII extracellular-domain (termed MEDI-TGFβR). MEDI-TGFβR retained full and simultaneous blocking efficiency for CD73 and TGFβ. Compared with MEDI9447 activity alone, MEDI-TGFβR demonstrated superior inhibitory activity against CD73-dependent cell migration and the EMT in CD73-high TNBC cells and effectively reduced lung metastasis in a syngeneic mouse model of TNBC. Mechanistically, the CD73-TGFβ dual-blockade reverted the EMT and stromal fibrosis and induced tumor cell death, which was accompanied by the accumulation of M1-macrophages and production of tumor necrosis factor α (TNFα). The CD73-TGFβ dual-blockade promoted a multifaceted inflammatory tumor microenvironment, as shown by the diminished levels of myeloid-derived suppressor cells (MDSCs) and M2-macrophages, and substantially increased levels of activated dendritic cells, cytotoxic T cells, and B cells. Collectively, our results have highlighted a novel strategy for TNBC treatment.