Immunosuppressive Tumor Microenvironment Research Articles

Predictive role of SLC1A5 in neuroblastoma prognosis and immunotherapy

BackgroundNeuroblastoma, a prevalent extracranial solid tumor in pediatric patients, demonstrates significant clinical heterogeneity, ranging from spontaneous regression to aggressive metastatic disease. Despite advances in treatment, high-risk neuroblastoma remains associated with poor survival. SLC1A5, a key glutamine transporter, plays a dual role in promoting tumor growth and immune modulation. However, its contributions to neuroblastoma biology remain largely unexplored.MethodsThis study utilized clinical neuroblastoma samples from 20 patients and 1310 cases from four public datasets to investigate SLC1A5 expression, biological function, and prognostic significance. Differential expression, Kaplan–Meier survival analysis, gene set enrichment analysis, and weighted correlation network analysis were conducted. Functional validation included qPCR, immunohistochemistry, Western blotting, and cell proliferation assays using the SLC1A5 inhibitor V-9302. A prognostic signature, SRPS, was constructed and validated using machine-learning approaches. Immune infiltration analysis was performed to evaluate the tumor immune microenvironment.ResultsSLC1A5 expression was significantly elevated in high-risk neuroblastoma and correlated with advanced stages and poor prognosis. GSEA revealed mTORC1 signaling enrichment in high SLC1A5 expression groups, validated by increased p-p70S6K levels in tumor samples and neuroblastoma cells. V-9302 treatment suppressed mTORC1 signaling and inhibited cell proliferation. Hub-genes were identified to form the SRPS model, which demonstrated superior prognostic performance compared to existing models. Immune infiltration analysis revealed a more immunosuppressive tumor microenvironment associated with high SLC1A5 expression. Additionally, SLC1A5 negatively regulated ST8SIA1, a gene crucial for GD2 biosynthesis, suggesting that SLC1A5 inhibition may enhance GD2-directed immunotherapies.ConclusionSLC1A5 plays a pivotal role in neuroblastoma by promoting tumor progression and shaping an immunosuppressive microenvironment. The SRPS model, incorporating SLC1A5-associated genes, offers robust prognostic utility. Targeting SLC1A5 through advanced drug delivery systems and combined metabolic-immunotherapeutic strategies may enhance treatment specificity and efficacy. These findings provide a foundation for novel therapeutic approaches to improve outcomes in high-risk neuroblastoma patients.

YAP/TEAD4/SP1-induced VISTA expression as a tumor cell-intrinsic mechanism of immunosuppression in colorectal cancer.

Hyperactivation of the YAP/TEAD transcriptional complex in cancers facilitates the development of an immunosuppressive tumor microenvironment. Herein, we observed that the transcription factor SP1 physically interacts with and stabilizes the YAP/TEAD complex at regulatory genomic loci in colorectal cancer (CRC). In response to serum stimulation, PKCζ (protein kinase C ζ) was found to phosphorylate SP1 and enhance its interaction with TEAD4. As a result, SP1 enhanced the transcriptional activity of YAP/TEAD and coregulated the expression of a group of YAP/TEAD target genes. The immune checkpoint V-domain Ig suppressor of T-cell activation (VISTA) was identified as a direct target of the SP1-YAP/TEAD4 complex and found to be widely expressed in CRC cells. Importantly, YAP-induced VISTA upregulation in human CRC cells was found to strongly suppress the antitumor function of CD8+ T cells. Consistently, elevated VISTA expression was found to be correlated with hyperactivation of the SP1-YAP/TEAD axis and associated with poor prognosis of CRC patients. In addition, we found by serendipity that enzymatic deglycosylation significantly improved the anti-VISTA antibody signal intensity, resulting in more accurate detection of VISTA in clinical tumor samples. Overall, our study identified SP1 as a positive modulator of YAP/TEAD for the transcriptional regulation of VISTA and developed a protein deglycosylation strategy to better detect VISTA expression in clinical samples. These findings revealed a new tumor cell-intrinsic mechanism of YAP/TAZ-mediated cancer immune evasion.

Bispecific T-Cell Engagers for the Recruitment of T cells in Solid Tumors: A Literature Review

Abstract In the past decade, T-cell based immunotherapies have grown to become some of the most promising treatments for cancer. Following the success of immune checkpoint inhibitors, other T-cell based therapies emerged including CAR-T cells and bispecific T-cell engagers (BiTEs). BiTEs have the unique ability to crosslink T cells and tumor cells independently of MHC restriction. They do not rely on TCR specificity or the CD4+/CD8+ costimulatory molecules, overcoming tumor MHC downregulation and low-affinity TCR binding. However, like many other immunotherapies, BiTEs have shown limited success beyond the treatment of hematological malignancies. BiTEs for the treatment of solid tumors still face challenges. Studies in gastrointestinal tumors have revealed Fc toxicity, short half-lives, and immunotoxicity, leading to Fc-silenced half-life extended BiTEs with humanized single-chain variable fragments. Studies in prostate tumors, lung tumors, and malignant gliomas have identified promising targets in PSMA, DLL3, and EGFRvIII, respectively, but also highlighted the problems of on-target off-tumor and BiTE-specific toxicities and inaccessible and immunosuppressive tumor microenvironments. Ongoing research to overcome these limitations remains an interesting field to follow, as BiTEs have the potential to be a powerful tool, especially when used in combination with other immunotherapies.

Adenoviral Therapy for Cervical Cancer: From Targeted Modification to Immunotherapy.

Cervical cancer is a significant global health threat, ranking as the fourth most common malignancy among women and resulting in over 300,000 deaths annually. Although screening and vaccination initiatives have led to a decline in incidence rates, treatment options for advanced or recurrent cervical cancer remain inadequate, often proving ineffective and costly. In this context, adenoviral therapy has emerged as a promising strategy to enhance therapeutic outcomes. Adenoviruses are non-enveloped viruses that can efficiently infect a wide range of cells, including tumor cells, while exhibiting a favorable safety profile, making them suitable candidates for clinical applications. Adenoviral vectors possess the unique ability to package large segments of therapeutic genes, allowing for diverse treatment approaches, including oncolytic virotherapy, which selectively targets and destroys tumor cells while stimulating robust immune responses. By engineering adenoviruses to express tumor suppressor genes such as p53, researchers can restore critical apoptotic pathways often disrupted in cervical cancer. Furthermore, genetic modifications to capsid proteins can enhance the targeting of tumor cells and reduce the immunogenicity associated with these viral vectors. Additionally, adenoviral vectors can serve as delivery systems for therapeutic vaccines against HPV oncogenes E6 and E7, promoting effective immune responses and potentially preventing disease progression. The combination of adenoviral therapy with immune checkpoint inhibitors offers a novel approach to overcoming the immunosuppressive tumor microenvironment, enhancing overall antitumor immunity. Overall, this review highlights the significant advancements in adenoviral therapy for cervical cancer, emphasizing the need for further research to optimize these strategies and translate preclinical successes into effective clinical applications. By harnessing the full potential of adenoviral vectors, we can improve treatment options for patients who have cervical cancer, paving the way for more personalized and effective therapeutic interventions.

Targeted editing of CCL5 with CRISPR-Cas9 nanoparticles enhances breast cancer immunotherapy.

Breast cancer remains one of the leading causes of cancer-related mortality among women worldwide. Immunotherapy, a promising therapeutic approach, often faces challenges due to the immunosuppressive tumor microenvironment. This study explores the innovative use of CRISPR-Cas9 technology in conjunction with FCPCV nanoparticles to target and edit the C-C Motif Chemokine Ligand 5 (CCL5) gene, aiming to improve the efficacy of breast cancer immunotherapy. Single-cell RNA sequencing (scRNA-seq) and TCGA-BRCA data identified CCL5 as a key immune-related gene in breast cancer. Using CRISPR-Cas9, sgRNA targeting CCL5 was designed and delivered to breast cancer cells and humanized mouse models via FCPCV nanoparticles. In vitro experiments demonstrated that FCPCV nanoparticles effectively silenced CCL5, enhanced CD8+ T cell activity, and increased the production of cytokines such as IFN-γ, TNF-α, and GZMB. In vivo studies revealed significant tumor suppression, improved immune microenvironment, and increased CD8+/CD4+ ratios in treated mice, without notable toxic side effects. These findings highlight the potential of CRISPR-Cas9 nanoparticle-mediated gene editing as a novel strategy for enhancing breast cancer immunotherapy, providing a new direction for personalized and effective cancer treatment.

CircPRKD3-loaded exosomes concomitantly elicit tumor growth inhibition and glioblastoma microenvironment remodeling via inhibiting STAT3 signaling.

Glioblastoma stem cells (GSCs) and their exosomes (exos) are involved in shaping the immune microenvironment, which is important for tumor invasion and recurrence. However, studies involving GSC-derived exosomal circular RNAs (GDE-circRNAs) in regulating tumor microenvironment (TME) remain unknown. Here, we comprehensively evaluated the significance of a novel immune-related GDE-circRNA in glioma microenvironment. GDE-circPRKD3 was screened out through high-throughput sequencing and verified by RT-PCR, sanger sequencing and RNase R assays. A series of in vitro and in vivo experiments were performed to investigate the function of GDE-circPRKD3. RNA-seq, RNA immunoprecipitation, multicolor flow cytometry and western blotting were used to explore the regulation of GDE-circPRKD3 on STAT3 signaling-mediated TME remodeling. We have characterized a circRNA PRKD3 in GSC exosomes, and lower circPRKD3 expression predicts a worse prognosis for glioblastoma patients. Overexpression of GDE-circPRKD3 significantly impairs the biological competence of glioma and prolongs the survival of xenograft mice. GDE-circPRKD3 binds to HNRNPC in an m6A-dependent manner, accelerates mRNA decay of IL6ST and inhibits downstream target STAT3. Notably, GDE-circPRKD3 promotes CXCL10 secretion by reprogramming tumor-associated macrophages, which in turn recruits CD8+ tumor infiltrating lymphocytes against GBM. Moreover, brain-targeted lipid nanoparticle delivery of circPRKD3 combined with immune checkpoint blockade therapy achieves significant combinatorial benefits. This study provides a novel mechanism by which GDE-circPRKD3 relies on STAT3 signaling to remodel immunosuppressive TME and offers a potential RNA immunotherapy strategy for GBM treatment.

Antitumor Research Based on Drug Delivery Carriers: Reversing the Polarization of Tumor-Associated Macrophages.

The development of malignant tumors is a complex process that involves the tumor microenvironment (TME). An immunosuppressive TME presents significant challenges to current cancer therapies, serving as a key mechanism through which tumor cells evade immune detection and play a crucial role in tumor progression and metastasis. This impedes the optimal effectiveness of immunotherapeutic approaches, including cytokines, immune checkpoint inhibitors, and cancer vaccines. Tumor-associated macrophages (TAMs), a major component of tumor-infiltrating immune cells, exhibit dual functionalities: M1-like TAMs suppress tumorigenesis, while M2-like TAMs promote tumor growth and metastasis. Consequently, the development of various nanocarriers aimed at polarizing M2-like TAMs to M1-like phenotypes through distinct mechanisms has emerged as a promising therapeutic strategy to inhibit tumor immune escape and enhance antitumor responses. This Review covers the origin and types of TAMs, common pathways regulating macrophage polarization, the role of TAMs in tumor progression, and therapeutic strategies targeting TAMs, aiming to provide a comprehensive understanding and guidance for future research and clinical applications.

Patient-Derived Organoid Models for NKT Cell-Based Cancer Immunotherapy

Invariant Natural Killer T (iNKT) cells are a unique subset of T cells that bridge innate and adaptive immunity, displaying potent anti-tumor properties through cytokine secretion, direct cytotoxicity, and recruitment of immune effector cells such as CD8+ T cells and NK cells. Despite their therapeutic potential, the immunosuppressive tumor microenvironment (TME), characterized by regulatory T cells, myeloid-derived suppressor cells (MDSCs), and tumor-associated macrophages (TAMs), limits iNKT cell efficacy. Patient-derived organoid (PDO) platforms provide an innovative model for dissecting these complex interactions and evaluating strategies to reinvigorate iNKT cell functionality within the TME. PDOs closely mimic the genetic, phenotypic, and structural characteristics of primary tumors, enabling the study of tumor–immune dynamics. Integrating iNKT cells into PDOs offers a robust platform for investigating CD1d-mediated interactions, Th1-biased immune responses driven by glycolipid analogs like α-GalCer, and combination therapies such as immune checkpoint inhibitors. Additionally, PDO systems can assess the effects of metabolic modulation, including reducing lactic acid accumulation or targeting glutamine pathways, on enhancing iNKT cell activity. Emerging innovations, such as organoid-on-a-chip systems, CRISPR-Cas9 gene editing, and multi-omics approaches, further expand the potential of PDO–iNKT platforms for personalized immunotherapy research. Although the application of iNKT cells in PDOs is still undeveloped, these systems hold immense promise for bridging preclinical studies and clinical translation. By addressing the challenges of the TME and optimizing therapeutic strategies, PDO–iNKT platforms offer a transformative avenue for advancing cancer immunotherapy and personalized medicine.

The combined immunization of cervical cancer therapeutic vaccine based on Listeria balanced lethal system has a significant therapeutic effect on tumor model mice.

Cervical cancer is the fourth most common cancer and the fourth leading cause of cancer death in women. Effective treatment of cervical cancer is urgently needed. Tumor therapeutic vaccine is a research hotspot in tumor immunotherapy, and the tumor therapeutic vaccine based on attenuated live bacteria carrier has clinical application prospect because of its clear action site and high safety. The bacterial balanced lethal system uses nutritional screening instead of antibiotic screening to avoid the risk of the spread of antibiotic resistance. So it is generally recognized as a green carrier. In our early research, we have constructed two cervical cancer therapeutic vaccine candidates (LM-HPVCW-1 and LI-HPVCW-1) based on Listeria balanced lethal system via transforming the nutrient-deficient strains with nutrition gene complementary plasmid. The complementary plasmid contained the nutrition complementary gene, LM dal gene, and its Amp gene was replaced with asd gene to delete the antibiotic resistance. Besides, it carried the shuffled HPV-16 E6E7 fusion protein gene. In vitro experiments showed that the plasmid carried by the candidate strain could be stably passaged and the target protein could be successfully expressed. In this study, we proved that the two candidate strains were safe in vivo and induced cellular immune response. At the same time, by establishing a tumor-bearing mouse model, it was proved that the two vaccine strains combined immunization could effectively inhibit mouse tumors. The mechanism of tumor suppression may be related to breaking the immunosuppression of tumor microenvironment and inducing CD8+ T cell infiltration. The therapeutic vaccine for cervical cancer constructed in this study is expected to be further applied in clinical practice.

Abstract P015: Targeting SPP1 to enhance CAR T cell therapy in glioblastoma: Implications for integrating radiation therapy in resistant solid tumors

Abstract In the evolving landscape of glioblastoma (GBM) treatment, clinical trials exploring chimeric antigen receptor (CAR) T cell therapies have shown promise; however, their therapeutic efficacy remains constrained, particularly due to the immunosuppressive tumor microenvironment (TME). Emerging evidence highlights that the TME, especially myeloid-driven suppressive networks, plays a central role in resistance to CAR T cell therapy. Despite progress in elucidating these mechanisms, significant ambiguities endure, particularly regarding patient-specific TME heterogeneity and its impact on therapeutic outcomes. Radiation therapy remains a cornerstone in GBM management, known not only for its direct cytotoxic effects but also for its ability to modulate the TME and potentially enhance immune responses. However, the combination of radiation with CAR T cell therapy has not been fully explored, particularly in the context of targeting suppressive myeloid subsets. Recent studies suggest that radiation may induce immunogenic changes within the TME, potentially enhancing CAR T cell infiltration and activity. Our study seeks to investigate how targeting key suppressive mediators, such as SPP1-expressing macrophages, can reshape the TME, setting the stage for combinatorial approaches that leverage the immunomodulatory effects of radiation therapy In this study, we utilized single-cell RNA sequencing to analyze tumors from 41 glioma patients undergoing IL13Rα2-targeted CAR T cell therapy. Our findings revealed heightened suppressive extracellular matrix (ECM) remodeling and immunosuppressive signatures driven by SPP1-expressing myeloid cells, predominantly in non-responsive tumors. Elevated SPP1 expression and increased infiltration of SPP1+ myeloid cells were associated with poor clinical outcomes. Functional transcriptomic analyses demonstrated that SPP1-high macrophages exhibited reduced antigen presentation, impaired phagocytosis, and enhanced ECM biogenesis, coupled with elevated lipid metabolism and non-glycolytic ATP production. These metabolic adaptations were linked to a suppressive immunophenotype that hindered CAR T cell efficacy. To explore therapeutic strategies, we assessed the impact of SPP1 blockade in preclinical syngeneic glioma models. Pre-treatment with anti-SPP1 antibodies prior to CAR T cell infusion significantly reprogrammed the TME, enhancing CAR T cell efficacy and reversing resistance in previously non-responsive models. These results highlight the potential of targeting SPP1 to disrupt suppressive macrophage networks, thereby augmenting CAR T cell responses. Our findings underscore SPP1 as a promising target to overcome resistance in CAR T cell therapies for GBM. This study lays the groundwork for future integration of targeted therapies, such as SPP1 inhibition, with radiation therapy to potentially improve therapeutic outcomes in resistant gliomas, offering new avenues for combinatorial therapeutic innovation. Citation Format: Sharareh Gholamin, Heini Natri, Yuqi Zhao, Shengchao Xu, Maryam Aftabizadeh, Begonya CominAnduix, Supraja Saravanakumar, Christian Masia, Robyn Wong, Lance Peter, Mei-i Chung, Evan D. Mee, Brenda Aguilar, Davis Y. Torrejon, Anusha Kalbasi, Darya Alizadeh, Xiwei Wu, Antoni Ribas, Stephen Forman, Behnam Badie, Terence M. Williams, Nicholas E. Banovich, Christine E. Brown.Targeting SPP1 to enhance CAR T cell therapy in glioblastoma: Implications for integrating radiation therapy in resistant solid tumors.[abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr P015

Abstract B011: Adenosine signaling and immune modulation in the tumor microenvironment: insights from lung cancer murine model of radiation therapy

Abstract Introduction: Radiation therapy (RT) induces adenosine signaling by releasing ATP in the tumor microenvironment (TME), promoting immune suppression and tumor progression. This study investigates how RT impacts adenosine signaling and immune cell infiltration in a preclinical model of non-small cell lung cancer (NSCLC). Using immunophenotyping of tumor-infiltrating immune cells in LLC1 murine model, we aim to explore the potential of targeting the adenosine pathway in combination with RT to enhance antitumor immunity and clinical outcomes. Methods: LLC1 tumor cells (5 x 105) were implanted subcutaneously in the flanks of C57BL/6 mice. After 12 days, mice received RT (4 Gy x 3 or 8 Gy x 3). Tumor volumes were measured thrice a week and harvested 5- and 10-days post-RT. We performed immunophenotyping of tumor tissue to assess changes in immune (CD45+) and CD45- compartments. The expression of adenosine signaling pathway members was quantified in distinct immune cell populations. Results: RT caused significant inhibition in tumor growth in a dose- and time-dependent manner. 5-days post-RT, CD73 (P< 0.01) and CD39 expressions (P< 0.01) were significantly upregulated in the immune compartment, while A2BR (P< 0.01) and A2AR (P< 0.05) were decreased in the non-immune compartment. RT decreased T cell populations, including CD4+ and CD8+ T cells. Further, CD4+ T cells downregulate adenosine signaling markers, particularly CD73 (P< 0.05) and ENPP1 (P< 0.05), while CD8+ T cells decreased in CD73 expression (P< 0.01). Myeloid subtype abundance was unchanged, but A2AR, A2BR, CD39, and CD73 expressions increased in the M2-like macrophage compartment (F4-80+MHCII-). 10 days post-RT, all adenosine signaling pathway markers significantly increased in the immune compartment and significantly decreased in the non-immune compartment. T cells (TCRb+) and macrophages (F4-80+) increased in abundance, including immuno-suppressive Arg+ macrophages (P< 0.05). Macrophage population that expressed the adenosine signaling markers increased by 10-15% (P< 0.05). While the proportion of CD4+ T cells and Tregs (CD4+FoxP3+) that expressed CD39 and CD73 also increased (P< 0.05). Conclusions: Our study revealed that RT promotes an immunosuppressive TME, in part through adenosine signaling. 5 days post-RT, we observed lymphocyte depletion and upregulation of the adenosine signaling pathway in M2-like macrophages. 10 days post-RT, adenosine signaling significantly increased across the immune compartment and decreased in the non-immune compartment, suggesting that the increase in adenosine signaling post-RT is immunologically mediated and largely driven by the myeloid compartment. These data lead to the hypothesis that inhibition of the adenosine signaling pathway may partially mitigate RT-induced immune suppression and improve RT efficacy. Ongoing work includes quantification of adenosine by LC-MS, extension to a preclinical SCC model of NSCLC, and evaluating adenosine pathway inhibition in combination with RT as a therapeutic strategy to improve antitumor immune responses. Citation Format: Krishan K. Saini, Samanta Sarti, Chelsea L. Rahiman, Brian E. Ragaishis, Patrick J. McCann, Shruti Bansal, Jason Cham, Julia An, Rosa Martin, Ariel Chen, Catherine S. Spina. Adenosine signaling and immune modulation in the tumor microenvironment: insights from lung cancer murine model of radiation therapy. [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr B011.

Accumulation of CD38 in Hybrid Epithelial/Mesenchymal Cells Promotes Immune Remodeling and Metastasis in Breast Cancer.

Triple-negative breast cancer (TNBC) is a highly metastatic subtype of breast cancer. The epithelial-to-mesenchymal transition is a nonbinary process in the metastatic cascade that generates tumor cells with both epithelial and mesenchymal traits known as hybrid EM cells. Recent studies have elucidated the enhanced metastatic potential of cancers featuring the hybrid EM phenotype, highlighting the need to uncover molecular drivers and targetable vulnerabilities of the hybrid EM state. Here, we discovered that hybrid EM breast tumors are enriched in CD38, an immunosuppressive molecule associated with worse clinical outcomes in liquid malignancies. Altering CD38 expression in tumor cell impacted migratory, invasive, and metastatic capabilities of hybrid EM cells. Abrogation of CD38 expression stimulated an antitumor immune response, thereby preventing the generation of an immunosuppressive microenvironment in hybrid EM tumors. CD38 levels positively correlated with PD-L1 expression in samples from patients with TNBC. Moreover, targeting CD38 potentiated the activity of anti-PD-L1, eliciting strong antitumor immunity, with reduced tumor growth in hybrid EM models. Overall, this research exposes upregulation of CD38 as a specific survival strategy utilized by hybrid EM breast tumors to suppress immune cell activity and sustain metastasis, with strong implications in other carcinomas that have hybrid EM properties. Significance: Hybrid cells co-featuring epithelial and mesenchymal traits in triple-negative breast cancer express elevated levels of CD38 to induce immunosuppression and metastasis, indicating CD38 inhibition as potential strategy for treating breast cancer.

Timing Anti-PD-L1 Checkpoint Blockade Immunotherapy to Enhance Tumor Irradiation

Background: The ability of radiotherapy (RT) to drive anti-tumor immunity is limited by adaptive resistance. While RT induces inflammation and recruits activated tumor-infiltrating lymphocytes (TILs), including cytotoxic T lymphocytes (CTLs), the resulting radiation- and IFNγ-dependent PD-L1 expression restores an immunosuppressed tumor microenvironment. Unleashing an effective anti-tumor response may require the precise sequencing of RT and checkpoint blockade immunotherapy (CBI) to block PD-L1 signaling before it can mediate its suppressive effects. Methods: Flank tumors formed in BALB/c mice with syngeneic CT26 colon or 4T1 mammary carcinoma cells were treated with otherwise ineffective doses of ionizing radiation (10 Gy) followed by CBI (0.2 mg anti-PD-L1, i.v.) after 0, 1, 3, 5, or 7 days, comparing tumor response. Anti-PD-L1 delivery was measured by fluorescence, TILs by flow cytometry and immunofluorescence, PD-L1 expression by immunohistochemistry, and tumor size by calipers. Results: In both CT26 and 4T1 tumors, 10 Gy alone resulted in a transient growth delay associated with infiltrating CTLs peaking at 3 days and PD-L1 at 5 days. CTLs returned to baseline after 7 days, consistent with adaptive resistance. Anti-PD-L1 failed to potentiate radiation except when injected 5 days after 10 Gy, which prevented CTL depletion and led to tumor elimination. Potentially contributing to compound effects, anti-PD-L1 penetrated tumors and bound PD-L1 more efficiently after irradiation. Conclusions: Optimal timing to exploit radiation-induced permeability to enhance CBI delivery and interrupt adaptive resistance by blocking PD-L1 as it peaks may offer a general strategy to enhance external beam radiotherapy by protecting activated TILs and potentiating anti-tumor immune response.

A Second Near-Infrared Window-Responsive Metal-Organic-Framework-Based Photosensitizer for Tumor Immunotherapy via Synergistic Ferroptosis and STING Activation.

Photodynamic therapy (PDT) holds promise as a cancer treatment modality due to its potential for enhanced therapy precision and safety. To enhance deep tissue penetration and minimize tissue adsorption and phototoxicity, developing photosensitizers activated by second near-infrared window (NIR-II) light shows significant potential. However, the efficacy of PDT is often impeded by tumor microenvironment hypoxia, primarily caused by irregular tumor vasculature. Fortunately, the stimulator of interferon genes (STING) pathway, known for immune activation, has been linked to vasculature normalization. In this study, we developed a nanoplatform (Fe-THBQ/SR) by loading a STING agonist (SR-717) into an iron-tetrahydroxy-1,4-benzoquinone (Fe-THBQ) metal-organic framework. Fe-THBQ was proven to be an effective NIR-II photosensitizer, generating numerous reactive oxygen species (ROS) under 1064 nm laser irradiation. These ROS downregulated heat shock protein expression, consequently promoting mild-photothermal therapy (mild-PTT), and facilitated ferroptosis by depleting glutathione (GSH)/glutathione peroxidase 4. Moreover, Fe-THBQ/SR released SR-717 upon GSH stimulation, synergizing with the ROS-mediated double-stranded DNA leakage to enhance STING activation. This process contributed to tumor vasculature normalization and hypoxia alleviation, thereby enhancing the PDT efficacy. Overall, we presented a versatile single-laser-triggered nanoplatform (Fe-THBQ/SR) for NIR-II PDT and NIR-II mild-PTT and simultaneously coupled it with the effective activation of STING to form a reinforcing cycle. These synergistic enhancements increased the immunogenicity of tumor cells, remodeled the immunosuppressive tumor microenvironment, increased T lymphocyte infiltration, and improved therapeutic outcomes.

Galectin-1-Induced Tumor Associated Macrophages Repress Antitumor Immunity in Hepatocellular Carcinoma Through Recruitment of Tregs.

Tumor-associated macrophages (TAMs) are commonly considered accomplices in tumorigenesis and tumor development. However, the precise mechanism by which tumor cells prompt TAMs to aid in evading immune surveillance remains to be further investigated. Here, it is elucidated that tumor-secreted galectin-1 (Gal1) conferred immunosuppressive properties to TAMs. Specifically, patient specimens and a public database is first used to analyze the clinical relevance of Gal1 in hepatocellular carcinoma (HCC). Then, it is demonstrated that TAMs functioned as a critical mediator in the Gal1-induced progression of HCC and the establishment of an immunosuppressive tumor microenvironment. Furthermore, RNA-sequencing determined that Gal1 promoted the upregulation of chemokine (C-C motif) ligand 20 (CCL20) in TAMs via activating the PI3K/AKT/NF-κB pathway. Employing an anti-CCL20 neutralizing antibody and Foxp3DTR mice, it is demonstrated that CCR6+Foxp3+ regulatory T cells (Tregs) recruited by Gal1-induced TAMs contributed to reduced infiltration and dysfunctional state of CD8+ T cells, subsequently facilitating tumor progression. Targeting Gal1 dampened the secretion of CCL20 and inhibits the recruitment of Tregs, thereby activating anti-tumor immunity and ameliorating anti-PD-1 resistance. Together, this findings revealed that Gal1-induced TAMs recruited Tregs through the CCL20-CCR6 axis. Inhibition of Gal1 improves the effectiveness of anti-PD1 therapy, shedding important new light on the combination immunotherapy of HCC.

CXCR4 antagonist-loaded nanoparticles reprogram the tumor microenvironment and enhance immunotherapy in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a leading cause of cancer death that has limited treatment options for advanced stages. Although PD-1 inhibitors such as nivolumab and pembrolizumab have been approved for advanced HCC treatment, their effectiveness is often hampered by the immunosuppressive tumor microenvironment (TME), which is due to hypoxia-driven CXCL12/CXCR4 axis activation. In this study, we developed 807-NPs, lipid-coated tannic acid (TA) nanoparticles that encapsulate BPRCX807, a potent CXCR4 antagonist to target HCC. 807-NPs enhance the pharmacokinetics and improve the tumor availability of BPRCX807 without causing systemic toxicity. Our findings show that 807-NPs block the CXCR4/CXCL12 pathway, inhibiting Akt and mTOR activation in HCC cells and M2 macrophages and promoting their repolarization toward the antitumor M1 phenotype. In orthotopic murine HCC models, systemic administration of 807-NPs significantly remodeled the immunosuppressive TME by reprogramming tumor-associated macrophages (TAMs) toward an immunostimulatory phenotype and promoting cytotoxic T-cell infiltration into tumors. This led to suppressed primary tumor growth and metastasis, while enhancing the efficacy of cancer immunotherapies, including PD-1 blockade and whole-cancer cell vaccines, by promoting T-cell activation. Our work demonstrates the potential of using nanotechnology to deliver CXCR4 antagonists for cancer immunotherapy.

A Self-Amplifying Photodynamic Biomedicine for Cascade Immune Activation Against Triple-Negative Breast Cancer.

The efficacy of immunotherapy in triple-negative breast cancer (TNBC) is significantly hindered by its low immunogenicity and immunosuppressive tumor microenvironment. Non-invasive photodynamic therapy (PDT) is increasingly recognized as a potential immunotherapeutic stimulant in the treatment of TNBC. However, photodynamic immunotherapy is constrained by tumor hypoxia and excessive inflammation suppression during the course of treatment. Herein, a simple and efficacious biomedicine is formulated to overcome adverse influences by amplifying photodynamic immunotherapy, thereby stimulating the systemic immune response. Specifically, the approach targeted tumor delivery by employing specific agents such as the photosensitizer (verteporfin), the hypoxic ameliorator (atovaquone), and the cyclooxygenase-2/prostaglandin E2 (COX-2/PGE2) signaling blocker (celecoxib). More importantly, the biomedicine effectively ameliorated hypoxia and inhibited COX-2/PGE2 signaling, thereby amplifying PDT-induced immunogenic cell death. This, in turn, enhanced the efficacy of photodynamic immunotherapy and triggered a robust immune response cascade. Notably, the self-amplifying photodynamic biomedicine significantly inhibited primary tumors, distal tumors, lung metastases, and post-operative recurrence while maintaining high biocompatibility. To sum up, the work provides a viable cascade stimulation approach and an efficient biomedical nanoplatform, offering a novel strategy for photodynamic immunotherapy of TNBC in the clinic.

Complement C3 of tumor-derived extracellular vesicles promotes metastasis of RCC via recruitment of immunosuppressive myeloid cells

Heterogeneous roles of complement C3 have been implicated in tumor metastasis and are highly context dependent. However, the underlying mechanisms linking C3 to tumor metastasis remain elusive in renal cell carcinoma (RCC). Here, we demonstrate that C3 of RCC cell-derived extracellular vesicles (EVs) contributes to metastasis via polarizing tumor-associated macrophages (TAMs) into the immunosuppressive phenotype and recruiting polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). Mechanistically, EV C3 induces the secretion of CCL2 and CXCL1 by lung macrophages and subsequently enhances TAM polarization and PMN-MDSC recruitment. Notably, targeting the CCL2/CCR2 or CXCL1/CXCR2 axis with the inhibitors RS504393 or Navarixin, respectively, effectively suppresses lung metastasis induced by RCC-derived C3 in a mouse model. Clinically, RCC patients with high expression of C3 demonstrate poor prognosis. Collectively, our findings reveal that tumor-derived EV C3 induces an immunosuppressive tumor microenvironment via TAMs, and thus promoting RCC metastasis.

Tumor and intratumoral pathogen cascade-targeting photothermal nanotherapeutics for boosted immunotherapy of colorectal cancer.

Clinical benefits of immunotherapy in colorectal cancer (CRC) are limited due to the low immunogenicity and immunosuppressive tumor microenvironment. Fusobacterium nucleatum (Fn) is discovered to colonize CRC tumors and dampen immunotherapy by fostering an immunosuppressive TME. Herein, a controllable "Shielding-deshielding" N-acetylgalactosamine (GalNAc)-derived photothermal nanotherapeutic is developed to mediate cascade targeting toward tumor and intratumoral Fn for enhanced photothermal-immunotherapy. This nanotherapeutic can in situ generate near infrared-II laser-activatable photothermal agent by reacting with endogenous hydrogen sulfide in CRC. The Schiff bond-tethered hyaluronic acid coating not only facilitates precise localization within CRC but shieldes GalNAc-mediated liver targeting, which can be deshielded upon a slightly acidic TME to anchor Fn by binding to its lectin Fap2. This cascade-targeting nanotherapeutic enables efficacious tumor accumulation and reinforces photothermal therapy (PTT) efficacy. Notably, PTT efficiently induces immunogenic cell death in CRC cells, leading to augmented immunogenicity and CD8+ T cell activation. Meanwhile, synchronous eradication of Fn facilitates M1 macrophage polarization, and promotes intratumoral infiltration of CD8+ T cell by reducing succinic acid level, thereby further boosting antitumor immunity against both primary and distant tumors. Overall, this study involving cascade targeting-reinforced PTT and intratumoral microorganism modulation offers new insight into effective CRC immunotherapy.

DOP029 SPP1 in colitis-associated colon cancer

Abstract Background Colitis-associated carcinoma (CAC) is a major complication that arises in patients with a long-standing ulcerative colitis (UC) and Crohn’s disease (CD). Albeit numerous studies report mutational landscape of CAC, its transcriptomic landscape is poorly understood. Thus, to interrogate the tumour ecology & mechanisms behind CAC development, we adopted a muti-modal approach utilizing FFPE tissues from human CAC patients and colon organoids. We leveraged immunology bulk gene expression and spatial gene expression to derive a robust gene signature of CAC at a single cell resolution. Methods To comprehensively profile the CAC immune microenvironment, we created a comprehensive dataset (Nanostring) covering relevant clinical FFPE samples encompassing 40 patients suffering from either IBD or CAC, alongside inflammation-free healthy controls (10 patients/group). We observed a robust upregulation of the SPP1 (Secreted Phosphoprotein 1) gene encoding osteopontin (OPN) in CAC. Subsequently, we extended our methodology to spatially resolved transcriptomics (Xenium) using 5μm FFPE sections from CAC & UC patients (3 patients/group). This provided insights into the spatial and single cell expression of SPP1 and its target receptors at a subcellular resolution. Furthermore, we mapped the ligand-receptor pairs onto cell types to uncover SPP1 signalling in CAC. These findings were validated at a protein level by whole FFPE section confocal microscopy. Results Immunology gene expression (Nanostring) dataset revealed a strong upregulation of SPP1 gene encoding OPN in CAC as compared to UC and CD. Spatially resolved transcriptomics (Xenium) unveiled the spatial heterogeneity of SPP1 expression in CAC, that is primarily arising from CD68+ CD163+ macrophages in CAC (Fig 1B), validated through OPN/CD68 immunostainings. Ligand-receptor (LR) analysis revealed a distinct LR pairing focusing on SPP1, that is secreted (outgoing signal) macrophages to T cells (as incoming signal) via upregulated integrin and CD44-receptors (Fig 1D/E). Furthermore, CAC tumour cells surrounding the SPP1+ macrophages exhibited a distinct gene expression signature associated with T cell exclusion and immunosuppression in CAC (Fig 1C/FG). Conclusion We identified a CAC specific upregulation of SPP1 at both RNA and protein levels, expressed by CD68+ CD163+ macrophages. Mutually exclusive spatial location of SPP1/OPN+ macrophages and CD8+ T cells suggests a crucial indirect role of SPP1/OPN in mediating an immunosuppressive tumour microenvironment. We further uncovered CAC specific, single cell gene expression signature that has the potential to identify pre-malignant stages of CAC.