Anti-tumor Immune Function Research Articles

Pyroptosis-Inducing Biomaterials Pave the Way for Transformative Antitumor Immunotherapy.

Pyroptosis can effectively overcome immunosuppression and reactivate antitumor immunity. However, pyroptosis initiation is challenging. First, the underlying biological mechanisms of pyroptosis are complex, and a variety of gasdermin family proteins can be targeted to induce pyroptosis. Second, other intracellular death pathways may also interfere with pyroptosis. The rationally designed gasdermin protein-targeting biomaterials are capable of inducing pyroptosis and have the capacity to stimulate antitumor immune function in a safe and effective manner. This review provides a comprehensive overview of the design, function, and antitumor efficacy of pyroptosis-inducing materials and the associated challenges, with a particular focus on the design options for pyroptosis-inducing biomaterials based on the activation of different gasdermin proteins. This review offers a valuable foundation for the further development of pyroptosis-inducing biomaterials for clinical applications.

Non-classical action of Ku70 promotes Treg suppressive function through a FOXP3-dependent mechanism in lung adenocarcinoma.

Ku70, a DNA repair protein, binds to the damaged DNA ends and orchestrates the recruitment of other proteins to facilitate repair of DNA double-strand breaks. Besides its essential role in DNA repair, several studies have highlighted non-classical functions of Ku70 in cellular processes. However, its function in immune homeostasis and anti-tumor immunity remains unknown. Here, we discovered a marked association between elevated Ku70 expression and unfavorable prognosis in lung adenocarcinoma, focusing specifically on increased Ku70 levels in tumor-infiltrated Treg cells. Using a lung-colonizing tumor model of in mice with Treg-specific Ku70 deficiency, we demonstrated that deletion of Ku70 in Treg cells led to a stronger anti-tumor response and slower tumor growth due to impaired immune-suppressive capacity of Treg cells. Furthermore, we confirmed that Ku70 played a critical role in sustaining the suppressive function of human Treg cells. We found that Ku70 bound to FOXP3 and occupied FOXP3-bound genomic sites to support its transcriptional activities. These findings not only unveil a non-homologous end joining (NHEJ)-independent role of Ku70 crucial for Treg suppressive function, but also underscore the potential of targeting Ku70 as an effective strategy in cancer therapy, aiming to both restrain cancer cells and enhance pulmonary anti-tumor immunity.

GLUT1 overexpression in CAR-T cells induces metabolic reprogramming and enhances potency

The intensive nutrient requirements needed to sustain T cell activation and proliferation, combined with competition for nutrients within the tumor microenvironment, raise the prospect that glucose availability may limit CAR-T cell function. Here, we seek to test the hypothesis that stable overexpression (OE) of the glucose transporter GLUT1 in primary human CAR-T cells would improve their function and antitumor potency. We observe that GLUT1OE in CAR-T cells increases glucose consumption, glycolysis, glycolytic reserve, and oxidative phosphorylation, and these effects are associated with decreased T cell exhaustion and increased Th17 differentiation. GLUT1OE also induces broad metabolic reprogramming associated with increased glutathione-mediated resistance to reactive oxygen species, and increased inosine accumulation. When challenged with tumors, GLUT1OE CAR-T cells secrete more proinflammatory cytokines and show enhanced cytotoxicity in vitro, and demonstrate superior tumor control and persistence in mouse models. Our collective findings support a paradigm wherein glucose availability is rate limiting for effector CAR-T cell function and demonstrate that enhancing glucose availability via GLUT1OE could augment antitumor immune function.

Computational dissection of the regulatory mechanisms of aberrant metabolism in remodeling the microenvironment of breast cancer.

The composition of T cell subsets and tumor-specific T cell interactions within the tumor microenvironment (TME) contribute to the heterogeneity observed in breast cancer. Moreover, aberrant tumor metabolism is often intimately linked to dysregulated anti-tumor immune function of T cells. Identifying key metabolic genes that affect immune cell interactions thus holds promise for uncovering potential therapeutic targets in the treatment of breast cancer. This study leverages single-cell transcriptomic data from breast cancer to investigate tumor-specific T-cell subsets and their interacting subnetworks in the TME during cancer progression. We further assess the metabolic pathway activities of tumor-specifically activated T-cell subsets. The results reveal that metabolic pathways involved in insulin synthesis, secretion, degradation, as well as fructose catabolism, significantly influence multiple T cell interactions. By integrating the metabolic pathways that significantly up-regulate T cells in tumors and influence their interactions, we identify key abnormal metabolic genes associated with T-cell collaboration and further develop a breast cancer risk assessment model. Additionally, using gene expression profiles of prognosis-related genes significantly associated with aberrant metabolism and drug IC50 values, we predict targeted drugs, yielding potential candidates like GSK-J4 and PX-12. This study integrate the analysis of abnormal T-cell interactions and metabolic pathway abnormalities in the breast cancer TME, elucidating their roles in cancer progression and providing leads for novel breast cancer therapeutic strategies.

JMJD2A promotes the development of castration-resistant prostate cancer by activating androgen receptor enhancer and inhibiting the cGAS-STING pathway.

Exploring targets for inhibiting androgen receptor (AR) activity is an effective strategy for suppressing the development of castration-resistant prostate cancer (CRPC). Upregulation of histone demethylase JMJD2A activity is an important factor in increasing AR expression in CRPC. Based on our research, we found that the binding affinity between JMJD2A and AR increases in CRPC, while the level of AR histone methylation decreases and the H3K27ac level increases in the AR enhancer region. Further investigations revealed that overexpression of the histone demethylase JMJD2A increased the binding affinity between JMJD2A and AR, decreased AR histone methylation levels, upregulated H3K27ac in the AR enhancer region, and increased AR activity. Conversely, knocking down JMJD2A effectively reversed these effects. Additionally, in CRPC, JMJD2A expression was upregulated, the tumor-intrinsic immune cGAS-STING signaling pathway was suppressed, the tumor microenvironment was altered, and AR expression was upregulated. However, both knocking down JMJD2A and inhibiting the cyclic GMP-AMP synthase/stimulator of interferon genes (cGAS-STING) signaling pathway reversed these effects. In summary, our study indicates that in CRPC, JMJD2A can directly bind to AR and activate residual AR enhancers through its demethylation activity, thereby promoting AR expression. Furthermore, upregulation of JMJD2A expression inhibits the innate immune cGAS-STING signaling pathway of the tumor, leading to a decrease in antitumor immune function, and further promoting AR expression.

The current role of dendritic cells in the progression and treatment of colorectal cancer.

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related deaths worldwide. Dendritic cells (DCs) constitute a heterogeneous group of antigen-presenting cells that are important for initiating and regulating both innate and adaptive immune responses. As a crucial component of the immune system, DCs have a pivotal role in the pathogenesis and clinical treatment of CRC. DCs cross-present tumor-related antigens to activate T cells and trigger an antitumor immune response. However, the antitumor immune function of DCs is impaired and immune tolerance is promoted due to the presence of the tumor microenvironment. This review systematically elucidates the specific characteristics and functions of different DC subsets, as well as the role that DCs play in the immune response and tolerance within the CRC microenvironment. Moreover, how DCs contribute to the progression of CRC and potential therapies to enhance antitumor immunity on the basis of existing data are also discussed, which will provide new perspectives and approaches for immunotherapy in patients with CRC.

Tertiary lymphoid structures and their therapeutic implications in cancer.

Tertiary lymphoid structures (TLSs) are ectopic lymphoid aggregates formed by the structured accumulation of immune cells such as B cells and T cells in non-lymphoid tissues induced by infection, inflammation, and tumors. They play a crucial role in the immune response, particularly in association with tumor development, where they primarily exert anti-tumor immune functions during tumorigenesis. Current research suggests that TLSs inhibit tumor growth by facilitating immune cell infiltration and are correlated with favorable prognosis in various solid tumors, serving as an indicator of immunotherapy effectiveness to some extent. Therefore, TLSs hold great promise as a valuable biomarker. Most importantly, immunotherapies aimed to prompting TLSs formation are anticipated to be potent adjuncts to current cancer treatment. This review focuses on the formation process of TLSs and their potential applications in cancer therapy.

Dual depletion of myeloid-derived suppressor cells and tumor cells with self-assembled gemcitabine-celecoxib nano-twin drug for cancer chemoimmunotherapy

Myeloid-derived suppressor cells (MDSCs) have played a significant role in facilitating tumor immune escape and inducing an immunosuppressive tumor microenvironment. Eliminating MDSCs and tumor cells remains a major challenge in cancer immunotherapy. A novel approach has been developed using gemcitabine-celecoxib twin drug-based nano-assembled carrier-free nanoparticles (GEM-CXB NPs) for dual depletion of MDSCs and tumor cells in breast cancer chemoimmunotherapy. The GEM-CXB NPs exhibit prolonged blood circulation, leading to the preferential accumulation and co-release of GEM and CXB in tumors. This promotes synergistic chemotherapeutic activity by the proliferation inhibition and apoptosis induction against 4T1 tumor cells. In addition, it enhances tumor immunogenicity by immunogenic cell death induction and MDSC-induced immunosuppression alleviation through the depletion of MDSCs. These mechanisms synergistically activate the antitumor immune function of cytotoxic T cells and natural killer cells, inhibit the proliferation of regulatory T cells, and promote the M2 to M1 phenotype repolarization of tumor-associated macrophages, considerably enhancing the overall antitumor and anti-metastasis efficacy in BALB/c mice bearing 4T1 tumors. The simplified engineering of GEM-CXB NPs, with their dual depletion strategy targeting immunosuppressive cells and tumor cells, represents an advanced concept in cancer chemoimmunotherapy.Graphical

Sex as a predictor of progression-free survival in sentinel node-negative stage II melanoma.

e21560 Background: Adjuvant immunotherapy can improve outcomes for resected stage IIB/C melanoma patients, but also poses challenges. Many patients are cured by surgery alone, making them susceptible to unnecessary treatment risks. Additionally, current staging may overlook some high-risk stage IIA patients who could benefit from immunotherapy. Accurate risk assessment is therefore critical to balance benefits and risks of early immunotherapy and optimise patient selection. This study sought to identify clinicopathologic predictors to refine risk stratification for sentinel lymph node-negative (SLN(-)) stage II melanoma patients, with a focus on the role of sex in prognostic accuracy and treatment personalisation. Methods: We retrospectively analysed 565 stage II melanoma patients with negative sentinel lymph node biopsies at four UK hospitals between 2004-2017. The primary outcome was progression-free survival (PFS). Analysed clinicopathologic factors included Breslow thickness, ulceration sex and tumour-infiltrating lymphocytes (TILs). Univariate and multivariate analyses were conducted. Results: Median follow-up was 9.5 years. Melanoma progression occurred in 24% of patients. Sex emerged as a significant PFS predictor. Specifically, stage IIA and IIB males had higher progression risks than females at the same stages. We also observed disparities across stages; for instance, PFS was significantly worse in stage IIA males than stage IIB females (PFS difference: χ2 = 5.629, p = 0.018), revealing gaps in the prognostic accuracy of current staging systems. Stage IIB females—identified as at risk by current standards—had 5-year PFS of 91%. This highlights potential overestimation of their treatment needs and subsequent risk of undue exposure to treatment toxicity. The sex-based discrepancies observed may be partially explained by differences in antitumor immune function, evidenced by the discovery that Non-brisk TILs-an independent predictor of high progression risk in SLN(-) stage II melanoma- were associated with a 20% reduction in PFS in males vs females (p < 0.001). Conclusions: Significant sex-based PFS disparities exist among sentinel lymph node-negative stage II melanoma patients, with implications for treatment decisions. Incorporating sex enables more refined risk assessment than current substaging alone. Specifically, stage IIA males may be under-recognised for progression risks, while many stage IIB females could face overtreatment. Our findings advocate for nuanced, sex-specific approaches to enhance prognostic accuracy and optimise patient care.

Preliminary results from a FIH, open-label phase 1 study with BMC128, a rationally designed live bacterial consortium, in combination with nivolumab.

8631 Background: Immune-Checkpoint inhibitors (ICI) have transformed the treatment of solid tumors, specifically in cutaneous melanoma, clear cell renal cell carcinoma (ccRCC) and non-small cell lung cancer (NSCLC). Despite these advances, resistance to ICI eventually occurs in many patients. Recent reports have found that patients showing poor response to ICI are characterized by a reduced gut microbiome diversity, suggesting that the gut microbiome might affect immune activation by ICI. BMC128 is a live bacterial consortium of 4 bacterial strains designed to induce anti-tumor immune function when given in conjunction with ICI. These strains were identified by analyzing microbiome data obtained from NSCLC and ccRCC patients presenting varied responses to ICI, using a proprietary computational discovery platform enabling high-resolution functional microbiome analysis. In pre-clinical studies, treatment with BMC128 potentiated the efficacy of ICI in breast cancer and melanoma mouse models, reducing tumor volume, increasing the number of responders, and demonstrating an increase in infiltrating immunocytes: CD4, CD8 and NK cells. The aim of this study was to assess the safety and tolerability of BMC128 in combination with nivolumab. Methods: 12 patients with ccRCC, cutaneous melanoma and NSCLC-adenocarcinoma (EGFR/ALK wild-type) (6, 1 and 5 patients, respectively), who previously progressed on PD1/PDL-1 inhibitors were recruited to this FIH open label phase 1 study. Patients were treated with a daily oral dose of BMC128 4*108 live cells/ strain in combination with nivolumab 480mg q4weeks. The study treatment consisted of 4 stages: depletion with antibiotics, induction with BMC128 monotherapy, combination treatment, and nivolumab monotherapy. Results: No SAEs related to BMC128 were reported throughout the duration of the study. Two patients exhibited minor AEs that were potentially associated with BMC128. At the current time point, 4 out ofthe first 8 patients in the study showed SD and sustained benefit beyond the first imaging timepoint, following the combination treatment. Altogether demonstrating clinical benefit for a total of 16 weeks (2 patients), 24 weeks (1 patient), and 68 weeks (1 patient). Conclusions: BMC128 has demonstrated an excellent safety profile and preliminary beneficial clinical effect. A phase 2 study to investigate the efficacy of BMC128 is planned to be initiated in late 2024. Clinical trial information: NCT05354102 .

Characterization of HIF-1α Knockout Primary Human Natural Killer Cells Including Populations in Allogeneic Glioblastoma.

Enhancing immune cell functions in tumors remains a major challenge in cancer immunotherapy. Natural killer cells (NK) are major innate effector cells with broad cytotoxicity against tumors. Accordingly, NK cells are ideal candidates for cancer immunotherapy, including glioblastoma (GBM). Hypoxia is a common feature of solid tumors, and tumor cells and normal cells adapt to the tumor microenvironment by upregulating the transcription factor hypoxia-inducible factor (HIF)-1α, which can be detrimental to anti-tumor effector immune cell function, including that of NK cells. We knocked out HIF-1α in human primary NK cells using clustered regularly interspaced short palindromic repeat (CRISPR)-associated protein 9 (Cas9). Then, cellular characterizations were conducted in normoxic and hypoxic conditions. Electroporating two HIF-1α-targeting guide RNA-Cas9 protein complexes inhibited HIF-1α expression in expanded NK cells. HIF-1α knockout human NK cells, including populations in hypoxic conditions, enhanced the growth inhibition of allogeneic GBM cells and induced apoptosis in GBM-cell-derived spheroids. RNA-sequencing revealed that the cytotoxicity of HIF-1α knockout NK cells could be related to increased perforin and TNF expression. The results demonstrated that HIF-1α knockout human NK cells, including populations, enhanced cytotoxicity in an environment mimicking the hypoxic conditions of GBM. CRISPR-Cas9-mediated HIF-1α knockout NK cells, including populations, could be a promising immunotherapeutic alternative in patients with GBM.

Synergistic antitumor immune response mediated by paclitaxel-conjugated nanohybrid oncolytic adenovirus with dendritic cell therapy.

Dendritic cell (DC)-based vaccines have emerged as a promising strategy in cancer immunotherapy due to low toxicity. However, the therapeutic efficacy of DC as a monotherapy is insufficient due to highly immunosuppressive tumor environment. To address these limitations of DC as immunotherapeutic agent, we have developed a polymeric nanocomplex incorporating (1) oncolytic adenovirus (oAd) co-expressing interleukin (IL)-12 and granulocyte-macrophage colony-stimulating factor (GM-CSF) and (2) arginine-grafted bioreducible polymer with PEGylated paclitaxel (APP) to restore antitumor immune surveillance function in tumor milieu and potentiate immunostimulatory attributes of DC vaccine. Nanohybrid complex (oAd/APP) in combination with DC (oAd/APP+DC) induced superior expression level of antitumor cytokines (IL-12, GM-CSF, and interferon gamma) than either oAd/APP or DC monotherapy in tumor tissues, thus resulting in superior intratumoral infiltration of both endogenous and exogenous DCs. Furthermore, oAd/APP+DC treatment led superior migration of DC to secondary lymphoid organs, such as draining lymph nodes and spleen, in comparison with either monotherapy. Superior migration profile of DCs in oAd/APP+DC treatment group resulted in more prolific activation of tumor-specific T cells in these lymphoid organs and greater intratumoral infiltration of T cells. Additionally, oAd/APP+DC treatment led to lower subset of tumor infiltrating lymphocytes and splenocytes being immunosuppressive regulatory T cells than any other treatment groups. Collectively, oAd/APP+DC led to superior induction of antitumor immune response and amelioration of immunosuppressive tumor microenvironment to elicit potent tumor growth inhibition than either monotherapy.

Abstract 3191: Chk1/2 inhibition enhances response to lurbinectedin treatment in small cell lung cancer

Abstract Small cell lung cancer (SCLC) remains a significant clinical concern, with only a 7% 5 year survival rate; therefore, there remains an unmet need for efficacious treatments. Lurbinectedin was FDA approved in 2019 to treat platinum-resistant SCLC. Preliminary experiments in SCLC cell lines indicated an increase in intracellular pChk1 when treated with lurbinectedin. Based on these data and our understanding of the role of checkpoint kinases in the DNA damage response (DDR), we hypothesize that the activity of Chk1 is indicative of upregulated DDR activity as a result of double stranded breaks and replicative stress induced by lurbinectedin. In subsequent experiments, we sought to identify the role of Chk1 and Chk2 in the tumor cell response to lurbinectedin by inhibiting their activity using prexasertib (LY2606368, Acrivon Therapeutics). Cell viability experiments indicate decreased tumor cell viability when three SCLC cell lines (H1048, H1105, H1417) are treated with prexasertib as a single agent and in combination with lurbinectedin. Western blot analysis of intracellular proteins from the same SCLC cell lines treated with both drugs demonstrate dose-dependent effects on cell death marker cPARP, DNA damage marker γH2AX, and DDR/cell cycle pathway kinases cdk1 and 2. Ongoing experiments seek to replicate results using alternative Chk1/2 inhibitors, and to explore the effect of lurbinectedin-Chk1/2 inhibitor combination treatment on antitumor immune effector function by in vitro co-culture. Citation Format: Ashley Sanchez Sevilla Uruchurtu, Tyler Roady, Agenxnie Anderson, Wafik S. El-Deiry. Chk1/2 inhibition enhances response to lurbinectedin treatment in small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3191.

Abstract 6531: Anti-tumor immune function of NR2F6, an orphan nuclear receptor, in stromal cells

Abstract Growing evidence points to the importance of the tumor microenvironment (TME) in tumor growth control, progression, and therapy response. Among those is the greater understanding of immune system components within the TME as mediators of tumor growth control. NR2F6 is an orphan nuclear receptor, which was shown to serve as an immune intrinsic checkpoint component and has been suggested to elicit tumor-intrinsic suppression of anti-tumor immunity. Correspondingly, genetic depletion of NR2F6 in CD8 T cells abrogates the immune-activating cytokines (e.g., IL-2, IFNg). In addition, genetic ablation of NR2F6 in melanoma cells activates CD8 T cell-mediated anti-tumor immunity partly by suppressing the expression of tumor-intrinsic immune repressors NACC1 and FKBP10. Notably, combined genetic ablation of tumor cells (NR2F6 KO melanoma) and stroma cells (NR2F6 KO mouse) resulted in a more pronounced inhibition of tumor growth compared with ablation of either tumor cells or TME. The latter provides the foundation for screening NR2F6 inhibitors, which are expected to have a strong systemic (tumor inhibition and immune cell activation) effect on tumor growth. Interestingly, single-cell transcriptomic data from human tumors identified high expression of NR2F6 in stroma cells, cancer-associated fibroblasts (CAFs), and tumor-associated endothelial cells (TAEs). Consistent with these, scRNAseq analysis of mouse melanoma revealed higher expression of NR2F6 in SMA+ immune suppressive myo-CAFs than in immune activating CAFs. Studies that directly reveal the role of stromal NR2F6 in anti-tumor immunity and tumor growth and the state of NR2F6 inhibitors will be discussed. Citation Format: Hyungsoo Kim, Yongmei Feng, Marria Radaeva, Eduard Sergienko, Artem Cherkasov, Ze'ev A. Ronai. Anti-tumor immune function of NR2F6, an orphan nuclear receptor, in stromal cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6531.

Abstract 3720: Utility of oncolytic virus as an immunostimulants and potential for combination therapy with ICIs

Abstract Background: Anti-PD-1 antibodies have been approved for a variety of carcinomas, but their efficacy in gastrointestinal cancers is limited. CD8-positive T cells (CD8) of tumor-infiltrating lymphocytes (TILs) and resident memory T cells (TRMs) with long-term anti-tumor immune function have been reported to be associated with the therapeutic efficacy of anti-PD-1 antibodies. Among our oncolytic adenoviruses (OVs), OBP-301, in which the human telomerase reverse transcriptase (hTERT) promoter element drives the expression of the viral E1A and E1B genes, is currently undergoing clinical trials. In the present study, we investigated the usefulness of OVs as immunostimulants and their potential efficacy in combination with anti-PD-1 antibodies. Methods: The cell lines used were the mouse colon cancer cell line CT26 and the mouse pancreatic cancer cell line PAN02. In vitro, the cytotoxic activity of the OVs and extracellular ATP in the culture supernatant were determined. OBP-502, an OBP-301 variant with the gene cassette of the RGD peptide, and anti-PD-1 antibody were used to examine the antitumor effect on subcutaneous tumors. OBP-702, another OBP-301 variant with the gene cassette of the wild-type p53 tumor suppressor gene, was used to examine the effect of long-term anti-tumor immunity. The effects on memory T-precursor cells (MPEC), CD8 and TRM were immunologically assessed in a rechallenge study. Results: OBP-502 and OBP-702 showed cytotoxic activity against CT26 and PAN02 cells in vitro, and significantly increased ATP in the culture supernatant. In vivo, the anti-PD-1 antibody/OBP-502 combination therapy significantly increased intratumor CD8 in CT26 and PAN02 subcutaneous tumors compared to each monotherapy. Complete response was achieved in 4 out of 12 mice by the combination therapy against CT26 tumors. When CT26 cells was re-seeded into tumor-free mice cured by the combination therapy, 2 out of 4 mice remained tumor-free. In the CT26 and PAN02 subcutaneous tumor model, OBP-702 increased CD44-positive CD62L-negative MPECs that differentiated into TRMs in the spleen, and this effect was blocked by ATP receptor inhibition. In CT26 and PAN02 bilateral subcutaneous tumor models, OBP-702 had a significant antitumor effect on both OBP-702-treated and -non-treated sides, and TIL analysis showed a significant increase in CD8 and TRM. In a rechallenge study, OBP-702-pretreatment showed significant growth inhibition of re-inoculated tumors. Conclusion: The OVs showed potent and long-term immune activation by inducing CD8 and TRM in tumors as well as direct anti-tumor effects, and synergistic effects with ICI. Citation Format: Daisuke Kadowaki, Shinji Kuroda, Masashi Hashimoto, Nobuhiko Kanaya, Yoshihiko Kakiuchi, Satoru Kikuchi, Kazuhiro Noma, Hiroshi Tazawa, Shunsuke Kagawa, Yasuo Urata, Toshiyoshi Fujiwara. Utility of oncolytic virus as an immunostimulants and potential for combination therapy with ICIs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3720.

Chidamide enhances T-cell-mediated anti-tumor immune function by inhibiting NOTCH1/NFATC1 signaling pathway in ABC-type diffuse large B-cell lymphoma

Chidamide (CS055/HBI-8000, tucidinostat) has shown promising effects in the clinical treatment of various hematologic tumors. Diffuse large B-cell lymphoma (DLBCL) has shown highly heterogeneous biological characteristics. There are complex mechanisms of the role of chidamide in DLBCL for in-depth study. It is essential to probe further into the mechanism of drug-tumor interactions as a guide to clinical application and to understand the occurrence and progression of DLBCL. In vitro and in vivo models were utilized to determine the effects of chidamide on signaling pathways involved in the DLBCL tumor microenvironment. The experimental results show that chidamide inhibited the proliferation of DLBCL cell lines in a dose- and time-dependent manner, and down-regulated the expression of NOTCH1 and NFATC1 in DLBCL cells as well as decreased the concentration of IL-10 in the supernatant. In addition, chidamide significantly lowered the expression of PD1 or TIM3 on CD4+T cells and CD8+T cells and elevated the levels of IL-2, IFN-γ, and TNF-α in the serum of animal models, which augmented the function of circulating T cells and tumor-infiltrating T cells and ultimately significantly repressed the growth of tumors. These findings prove that chidamide can effectively inhibit the cell activity of DLBCL cell lines by inhibiting the activation of NOTCH1 and NFATC1 signaling pathways. It can also improve the abnormal DLBCL microenvironment in which immune escape occurs, and inhibit immune escape. This study provides a new therapeutic idea for the exploration of individualized precision therapy for patients with malignant lymphoma.

A Bioinspired Immunostimulatory System for Inducing Powerful Antitumor Immune Function by Directly Causing Plasma Membrane Rupture.

The Gasdermin protein is a membrane disruptor that can mediate immunogenic pyroptosis and elicit anti-tumor immune function. However, cancer cells downregulate Gasdermin and develop membrane repair mechanisms to resist pyroptosis. Therefore, an artificial membrane disruptor (AMD) that can directly mediate membrane rupture in pyroptosis-deficient cells and induce antitumor immune responses in a controllable manner will be valuable in preclinical and clinical research. A micron-scale Ce6-based AMD that can directly induce plasma membrane rupture (PMR) in gasdermin-deficient tumor cells is established. Micron-scale AMDs localize Ce6 specifically to the plasma membrane without labeling other organelles. Compared to free Ce6 molecules, the use of AMDs results in a higher degree of specificity for the plasma membrane. Due to this specificity, AMDs mediate fast and irreversible PMR under 660 nm red light. Furthermore, the AMDs are capable of inducing programmed cell death and lytic cell death in a catalytic manner, demonstrating that the amount of Ce6 used by AMDs is only one-fifth of that used by Ce6 alone when inducing 80% of cancer cell death. In vivo, the AMDs show specificity for tumor targeting and penetration, suggesting that light-driven programmed cell death is specific to tumors. AMDs are applied to antitumor therapy in gasdermin-deficient tumors, resulting in efficient tumor elimination with minimal damage to major organs when combined with anti-PD-1 therapy. Tumor regression is correlated with PMR-mediated inflammation and T-cell-based immune responses. This study provides new insights for designing bioinspired membrane disruptors for PMR and mediating anti-tumor immunotherapy. Additionally, AMD is a dependable tool for examining the immunogenicity of PMR both in vitro and in vivo.

The highly selective and oral phosphoinositide 3-kinase delta (PI3K-δ) inhibitor roginolisib induces apoptosis in mesothelioma cells and increases immune effector cell composition

Targeting aberrantly expressed kinases in malignant pleural mesothelioma (MPM) is a promising therapeutic strategy. We here investigated the effect of the novel and highly selective Phosphoinositide 3-kinase delta (PI3K-δ) inhibitor roginolisib (IOA-244) on MPM cells and on the immune cells in MPM microenvironment.To this aim, we analyzed the expression of PI3K-δ by immunohistochemistry in specimens from primary MPM, cell viability and death in three different MPM cell lines treated with roginolisib alone and in combination with ipatasertib (AKT inhibitor) and sapanisertib (mTOR inhibitor). In a co-culture model of patient-derived MPM cells, autologous peripheral blood mononuclear cells and fibroblasts, the tumor cell viability and changes in immune cell composition were investigated after treatment of roginolisib with nivolumab and cisplatin. PI3K-δ was detected in 66/89 (74%) MPM tumors and was associated with reduced overall survival (12 vs. 25 months, P=0.0452). Roginolisib induced apoptosis in MPM cells and enhanced the anti-tumor efficacy of AKT and mTOR kinase inhibitors by suppressing PI3K-δ/AKT/mTOR and ERK1/2 signaling. Furthermore, the combination of roginolisib with chemotherapy and immunotherapy re-balanced the immune cell composition, increasing effector T-cells and reducing immune suppressive cells. Overall, roginolisib induces apoptosis in MPM cells and increases the antitumor immune cell effector function when combined with nivolumab and cisplatin.These results provide first insights on the potential of roginolisib as a therapeutic agent in patients with MPM and its potential in combination with established immunotherapy regimen.

Endothelial cells in tumor microenvironment: insights and perspectives.

The tumor microenvironment is a highly complex and dynamic mixture of cell types, including tumor, immune and endothelial cells (ECs), soluble factors (cytokines, chemokines, and growth factors), blood vessels and extracellular matrix. Within this complex network, ECs are not only relevant for controlling blood fluidity and permeability, and orchestrating tumor angiogenesis but also for regulating the antitumor immune response. Lining the luminal side of vessels, ECs check the passage of molecules into the tumor compartment, regulate cellular transmigration, and interact with both circulating pathogens and innate and adaptive immune cells. Thus, they represent a first-line defense system that participates in immune responses. Tumor-associated ECs are involved in T cell priming, activation, and proliferation by acting as semi-professional antigen presenting cells. Thus, targeting ECs may assist in improving antitumor immune cell functions. Moreover, tumor-associated ECs contribute to the development at the tumor site of tertiary lymphoid structures, which have recently been associated with enhanced response to immune checkpoint inhibitors (ICI). When compared to normal ECs, tumor-associated ECs are abnormal in terms of phenotype, genetic expression profile, and functions. They are characterized by high proliferative potential and the ability to activate immunosuppressive mechanisms that support tumor progression and metastatic dissemination. A complete phenotypic and functional characterization of tumor-associated ECs could be helpful to clarify their complex role within the tumor microenvironment and to identify EC specific drug targets to improve cancer therapy. The emerging therapeutic strategies based on the combination of anti-angiogenic treatments with immunotherapy strategies, including ICI, CAR T cells and bispecific antibodies aim to impact both ECs and immune cells to block angiogenesis and at the same time to increase recruitment and activation of effector cells within the tumor.

Does oncolytic viruses-mediated metabolic reprogramming benefit or harm the immune microenvironment?

Oncolytic virus immunotherapy as a new tumor therapy has made remarkable achievements in clinical practice. And metabolic reprogramming mediated by oncolytic virus has a significant impact on the immune microenvironment. This review summarized the reprogramming of host cell glucose metabolism, lipid metabolism, oxidative phosphorylation, and glutamine metabolism by oncolytic virus and illustrated the effects of metabolic reprogramming on the immune microenvironment. It was found that oncolytic virus-induced reprogramming of glucose metabolism in tumor cells has both beneficial and detrimental effects on the immune microenvironment. In addition, oncolytic virus can promote fatty acid synthesis in tumor cells, inhibit oxidative phosphorylation, and promote glutamine catabolism, which facilitates the anti-tumor immune function of immune cells. Therefore, targeted metabolic reprogramming is a new direction to improve the efficacy of oncolytic virus immunotherapy.