Myeloid-derived Suppressor Cells Research Articles

A high-fat diet promotes cancer progression by inducing gut microbiota–mediated leucine production and PMN-MDSC differentiation

A high-fat diet (HFD) is a high-risk factor for the malignant progression of cancers through the disruption of the intestinal microbiota. However, the role of the HFD-related gut microbiota in cancer development remains unclear. This study found that obesity and obesity-related gut microbiota were associated with poor prognosis and advanced clinicopathological status in female patients with breast cancer. To investigate the impact of HFD-associated gut microbiota on cancer progression, we established various models, including HFD feeding, fecal microbiota transplantation, antibiotic feeding, and bacterial gavage, in tumor-bearing mice. HFD-related microbiota promotes cancer progression by generating polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). Mechanistically, the HFD microbiota released abundant leucine, which activated the mTORC1 signaling pathway in myeloid progenitors for PMN-MDSC differentiation. Clinically, the elevated leucine level in the peripheral blood induced by the HFD microbiota was correlated with abundant tumoral PMN-MDSC infiltration and poor clinical outcomes in female patients with breast cancer. These findings revealed that the "gut-bone marrow-tumor" axis is involved in HFD-mediated cancer progression and opens a broad avenue for anticancer therapeutic strategies by targeting the aberrant metabolism of the gut microbiota.

Machine-learning and mechanistic modeling of metastatic breast cancer after neoadjuvant treatment.

Clinical trials involving systemic neoadjuvant treatments in breast cancer aim to shrink tumors before surgery while simultaneously allowing for controlled evaluation of biomarkers, toxicity, and suppression of distant (occult) metastatic disease. Yet neoadjuvant clinical trials are rarely preceded by preclinical testing involving neoadjuvant treatment, surgery, and post-surgery monitoring of the disease. Here we used a mouse model of spontaneous metastasis occurring after surgical removal of orthotopically implanted primary tumors to develop a predictive mathematical model of neoadjuvant treatment response to sunitinib, a receptor tyrosine kinase inhibitor (RTKI). Treatment outcomes were used to validate a novel mathematical kinetics-pharmacodynamics model predictive of perioperative disease progression. Longitudinal measurements of presurgical primary tumor size and postsurgical metastatic burden were compiled using 128 mice receiving variable neoadjuvant treatment doses and schedules (released publicly at https://zenodo.org/records/10607753). A non-linear mixed-effects modeling approach quantified inter-animal variabilities in metastatic dynamics and survival, and machine-learning algorithms were applied to investigate the significance of several biomarkers at resection as predictors of individual kinetics. Biomarkers included circulating tumor- and immune-based cells (i.e., circulating tumor cells and myeloid-derived suppressor cells) as well as immunohistochemical tumor proteins (i.e., CD31 and Ki67). Our computational simulations show that neoadjuvant RTKI treatment inhibits primary tumor growth but has little efficacy in preventing (micro)-metastatic disease progression after surgery and treatment cessation. Machine learning algorithms that included support vector machines, random forests, and artificial neural networks, confirmed a lack of definitive biomarkers, which shows the value of preclinical modeling studies to identify potential failures that should be avoided clinically.

Abstract PO3-19-02: White Button Mushroom and Biomarkers of Immune Cell and Inflammatory Responses in Obese Postmenopausal Women at High Risk of Breast Cancer

Abstract Background: White Button Mushroom (WBM), Agaricus bisporus, has anti-tumor and anti-inflammatory effects. Oral WBM mitigated the effects of a high fat diet on hepatic steatosis and insulin resistance in ovariectomized mice. A Phase I trial of WBM in men with prostate cancer demonstrated decreased myeloid derived suppressor cells (MDSC) in those with decreased PSA; MDSC have been linked to different cancers, including breast, and conditions of chronic inflammation. Design: This is a preliminary evidence trail in postmenopausal, obese women at high risk of breast cancer with a single intervention arm of 14g of WBM taken as 28 tablets daily for 3 months to assess effects on inflammation. Participants undergo a physical exam, measuring height, weight, and waist circumference, an optional fine needle aspiration (FNA) of breast tissue, a blood draw, a food frequency questionnaire and a 24-hour food recall at baseline and final visits. Participants are contacted monthly for tolerance and adherence. Blood samples and FNA adipose are used for metabolic measurements and processed for biomarkers of inflammation and immune response. Peripheral blood mononuclear cells (PBMC) will be used for RNA single-cell analysis to assess for immune cell profiles and expression with an interest in evaluating MDSC. Red blood cells will be assessed for fatty acid profiles. Eligibility: Postmenopausal, obese (BMI ≥30, Asian ≥25) women with high risk for breast cancer who can swallow pills are eligible. Patients are high risk if their relative risk of breast cancer is ≥2 times that of the general population; this includes women with a strong family history, a genetic mutation associated with hereditary breast cancer, a high-risk breast histology, Gail model 5-year risk >1.67, or a previous history of stage I-II breast cancer. Participants are excluded for an active malignancy within 5 years, ongoing active or preventative cancer treatment, or lab abnormalities of serum creatinine and total bilirubin >1.5 the upper limit of normal, hemoglobin of < 9.0 g/dL, platelets of < 100,000/mm3, or a total white blood cell count of < 3,500/mm3. Participants cannot be taking mushroom supplements, immunosuppressants, or non-steroidal anti-inflammatories. Specific Aims: This study aims to evaluate the effects of WBM on regulating immune response and inflammation in obese women at high risk for breast cancer. Our primary objective is the assessment of PBMC, specifically MDSC immune profiles before and after treatment. Our secondary objective is to evaluate changes in biomarkers of inflammation, immune cell profiles in breast adipose tissue, BMI, waist circumference, and metabolic biomarkers. Additionally, the study aims to assess tolerability of the WBM dose and effects on diet quality. Statistical Methods: 26 patients will provide 80% power to detect a change in %MDSC of -0.67, assuming a standard deviation of 1.15, and a 2-sided type I error of 5%. We will have similar power to evaluate changes in other immune subsets, inflammatory markers, metabolic markers, anthropometric measurements, and diet quality. FNA adipose tissue analysis will be used as a safety signal to evaluate the potential for unwanted inflammation with taking WBM. 13 patients with FNA will provide 80% power to detect a change of 85% of the standard deviation of the difference in the measure of biomarkers such as Interleukin-6 with a 2-sided type I error of 5%. As a safety signal, the signal will be reported without adjustment for multiple comparisons. Any conclusions based on such secondary endpoints will make note of the multiple comparison issue. Accrual: The accrual target is 26 evaluable patients with an estimated need to enroll 31. The study has enrolled 27 patients, 14 completed the study and 5 are currently on treatment. 8 participants were removed; 3 never started treatment, 1 was diagnosed with breast cancer, and 4 had other medical issues preventing continuation. Contact: Jessica Dzubnar, MD: jdzubnar@coh.org Citation Format: Jessica Dzubnar, Lisa Yee, Shiuan Chen. White Button Mushroom and Biomarkers of Immune Cell and Inflammatory Responses in Obese Postmenopausal Women at High Risk of Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-19-02.

Abstract PO2-15-09: Immune related cell fraction in peripheral blood and outcomes of advanced breast cancer patients treated with Eribulin

Abstract Background: Eribulin prolongs overall survival (OS) of patients with advanced breast cancer, and an ad-hoc analysis of the EMBRACE trial showed that baseline absolute lymphocyte count (ALC) was a predictor of OS prolongation. It has been suggested that eribulin improves the immune response to the tumor by improving the hypoxic environment through remodeling of local tumor vessels and reducing hypoxic stress, leading to OS prolongation. However, the details of the immune response mediated by eribulin remain to be fully elucidated. CD8+ cells attack cancer cells as cytotoxic T cells, while regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) suppress activated T cells that attack cancer cells. In this study, we focused on CD8+ cytotoxic T cells, Tregs, MDSCs, and CD4-CD25-FoxP3+ cells in peripheral blood, analyzed the changes of those immune cells before and after eribulin treatment, and examined the effects on the outcomes of breast cancer patients. Methods: Nineteen patients with advanced or recurrent breast cancer treated with eribulin from April 2021 to May 2023 at our hospital were included. Peripheral blood was collected before drug administration as the first treatment (pre-treatment) and before drug administration in the second course (post-treatment), and the cell fractions, including CD4+ cells, CD8+ cells, CD4+CD25+FoxP3+ Tregs, CD11b+CD14+CD33+ MDSCs, and CD4-CD25-FoxP3+ cells, were analyzed by flow cytometry. The cutoff value for ALC was set at 1000 and NLR at 3.0, and each cell fraction was set to its respective median. Kaplan-Meier plots and logrank tests for progression-free survival (PFS) or OS were applied. Results: CD4+ cells were significantly lower post-treatment compared to pre-treatment (p=0.0140). Further, Tregs were significantly lower post-treatment compared to pre-treatment (p=0.0258). There were no significant changes in the levels of CD8+ cells, MDSCs, and CD4-CD25-FoxP3+ cells between pre- and post-treatment. We examined the association between each cell fraction and ALC or NLR, and found that CD4-CD25-FoxP3+ cells were significantly higher in cases with high NLR (p=0.0110). Analysis of the association between each cell fraction and prognosis at pre-treatment revealed that the high CD8+ cell group had significantly better PFS and OS than the low CD8+ cell group (p=0.0129 and p=0.0077, respectively). Interestingly, the high CD4-CD25-FoxP3+ cell group had significantly worse PFS than the low CD4-CD25-FoxP3+ cell group (p=0.0026). Conclusion: In the current study, Tregs in the peripheral blood of breast cancer patients significantly decreased after eribulin treatment, suggesting that eribulin may improve the immune microenvironment by suppressing immunosuppressive cells in cancer, including Tregs. In addition, the CD4-CD25-FoxP3+ cell fraction may serve as a biomarker for eribulin therapy, and further studies are needed to elucidate the details, including analysis of the constituent cells within the fraction. Citation Format: Masayuki Nagahashi, Ayako Bun, Mamiko Kuroiwa, Miki Komatsu, Sayaka Urano, Yukie Fujimoto, Aoi Oshiro, Ayumu Mitsuyoshi, Haruka Kanaoka, Akira Hattori, Reiko Fukui, Tomoko Higuchi, Arisa Nishimukai, Keiko Murase, Yuichi Takatsuka, Yasuo Miyoshi. Immune related cell fraction in peripheral blood and outcomes of advanced breast cancer patients treated with Eribulin [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-15-09.

Abstract PO1-18-04: Neoadjuvant pembrolizumab + decitabine followed by standard neoadjuvant chemotherapy for locally advanced HER2- breast cancer (NCT02957968)

Abstract Background: Higher levels of stromal tumor-infiltrating lymphocytes (sTILs) in breast cancers are associated with increased likelihood of pathologic complete response (pCR) to chemotherapy and improved outcomes. DNA methyltransferase inhibitors (DNMTi) can augment immune responses to cancers by upregulating tumor antigen and MHC expression, decreasing numbers and activity of myeloid derived suppressor cells (MDSC), and increasing responsiveness of T lymphocytes. We have shown that the DNMTi decitabine augments the effectiveness of immunotherapy against murine triple negative breast cancer (TNBC) using murine 4T1 and E0771 mammary carcinoma models. Methods: In a single-arm phase 2 study, patients with HER2-negative breast cancer who were candidates for neoadjuvant chemotherapy (NCT) received decitabine (15 mg/m2 × 4 doses over 5 days) followed by 2 doses of pembrolizumab (pembro) (200 mg, 2 weeks apart) – collectively, window immunotherapy – prior to starting NCT. Two research biopsies were obtained: 1 prior to the window immunotherapy and 1 afterwards, prior to starting NCT. Biopsies were analyzed using established procedures to quantify sTILs and PD-L1 expression. Patients proceeded to NCT and tumor resection per standard of care and were followed up for immune-related adverse events (irAEs) and response. The primary endpoint was change in sTILs. Key secondary endpoints were occurrence of irAEs and pCR following neoadjuvant treatment. After the study was opened, reported results of a phase 3 trial (KEYNOTE 522) led to allowing patients with TNBC to receive additional pembro (200 mg q3w) concurrently with standard NCT and adjuvantly following resection (Cohort A2). Results: 46 patients (median age 54.5 yrs, range 28-72; 71.7% White, 28.3% Black; 100% female) were enrolled and treated on study. 21 patients had TNBC and did not receive neoadjuvant pembro concurrently with NCT nor adjuvant pembro (Cohort A), 7 patients had TNBC and did receive neoadjuvant and/or adjuvant pembro (Cohort A2), and 18 patients were ER+ or PR+ and received neither concurrent nor adjuvant pembro (Cohort B). Blood samples collected after decitabine administration before the first pembro dose showed a 59% decrease (P< 0.01) in monocytic MDSCs compared to baseline; decrease in granulocytic MDSCs was not statistically significant. 37 patients had paired biopsies adequate for sTIL evaluation with a mean change from 23.4% to 30.3% (absolute change 6.9%, P< 0.001). Cohorts A/A2 experienced an absolute sTIL increase of 7.4% (P< 0.01); Cohort B experienced absolute sTIL increase of 6.1% (P=0.01). PD-L1 expression in tumors (H-score using MoAb 22C3 clone) increased by 43% (P< 0.01) across all cohorts. 16 of the 39 patients (41.0%) who proceeded to resection achieved pCR (n=12 of 27 [44.4%] in Cohorts A/A2 and n=4 of 13 [30.8%] in Cohort B). The most frequently reported irAEs were adrenal insufficiency (n=5, 10.9%), maculopapular rash (n=3, 6.5%), and hypothyroidism (n=3, 6.5%). Conclusions: Treatment in the pre-neoadjuvant window with decitabine and pembro could potentially sensitize breast cancers to standard NCT by recruitment of TILs to the tumor tissue. The treatment was well -tolerated at the tested doses. Funding: financial support and drug (pembrolizumab) were provided by Merck Citation Format: Harry Bear, Xiaoyan Deng, Dipankar Bandyopadhyay, Michael Idowu, Maciej Kmieciak, Monique Williams, Giovanni Archer, Lindsey Gwaltney, Patrick Dillon, Daniel Flora, Daniel Stover, Andrew Poklepovic, Mary Hackney, Masey Ross, Hetal Vachhani, Raphael Louie, Kandace McGuire, Amelia Grover, Tasnim Rahman, Amber Hendrix. Neoadjuvant pembrolizumab + decitabine followed by standard neoadjuvant chemotherapy for locally advanced HER2- breast cancer (NCT02957968) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-18-04.

Abstract PO1-18-03: Chemokine-modulating regimen (rintatolimod, IFN-α2b, celecoxib): New strategy to drive CD8+T-cells into triple negative breast cancer

Abstract BACKGROUND: Pathologic complete response (pCR) is critical for positive long-term outcomes after neoadjuvant chemotherapy (NAC) in triple negative breast cancer (TNBC) but is achieved only in 40-50% of patients. Combination of NAC with pembrolizumab, the new standard of care in TNBC, increases the pCR rate to 65% but is associated with significant and often permanent immune-related toxicities. Higher levels of CD8+ cytotoxic T-lymphocytes (CTLs) and low levels of regulatory T-cells (Treg) and myeloid derived suppressor cells (MDSC) in the tumor microenvironment (TME) predict improved relapse-free survival (RFS), overall survival (OS) and pCR, a surrogate marker for RFS. Locally produced chemokines CCL5, CXCL9, CXCL10 and CXCL11 are critical for CTL infiltration, while CCL22 is responsible for Treg attraction, with high CXCL9 being associated with a 3-fold higher rate of pCR after NAC. Our preclinical data show that Chemokine-modulatory (CKM) regimen, combining rintatolimod (TLR3 agonist), interferon (IFN)α2b and celecoxib (COX-2 inhibitor), eliminates the suppressive aspects of paclitaxel-induced inflammation and induces CTL-attractants but decreases MDSC- and Treg-attractants in the TME. We hypothesized that the combination of CKM with paclitaxel-based NAC will promote selective CTL infiltration into TNBC, and along with doxorubicin/cyclophosphamide (AC), will result in higher rate of pCR, translating into improved RFS and OS. METHODS: In this phase I study NCT04081389, 9 pts with stage I-III TNBC and median age of 47 (37-55) years received 3 weeks of paclitaxel with CKM, followed by 9 weeks of paclitaxel alone, followed by standard dose-dense AC and surgery. Paclitaxel was given weekly IV at 80 mg/m2 for 12 weeks, rintatolimod 200 mg IV, IFN-α2b and celecoxib 200 mg oral twice daily on days 1-3 of each of the initial 3 weeks. IFN-α2b was administered in an accelerated titration design at doses 0 or 5 million units (MU)/m2 [Dose Level (DL) 1 and 2, respectively] in the first 2 pts (no intra-patient dose escalation), then 10 MU/m2 [DL3] in 4 pts and then 20 MU/m2 [DL4] in 3 pts. Day 1 pre- and post-treatment blood samples were drawn. Pre- and post-treatment (at 3 weeks) biopsies were obtained from 5 pts at DL3 and DL4. Dose-limiting toxicity (DLT) was defined as grade 3 or higher within the first 3 weeks of treatment. Primary endpoint was safety and tolerability, to determine the recommended phase II dose (RP2D) of CKM for extended efficacy study. Secondary endpoints included efficacy (pCR), along with RFS and OS. Biomarkers were analyzed in exploratory studies. RESULTS: Treatment was well-tolerated with mostly grade 1 or 2 treatment-related adverse events (TRAEs) and no DLTs. Grade 3 TRAE were neutropenia (3/9), attributed to CKM (1/9) or paclitaxel (3/9), pneumonia (1/9) and anemia (1/9) attributed to AC. Paclitaxel- or AC-related toxicities were not higher than expected. There were no delayed or immune-related toxicities beyond treatment. 5/9 (56%) pts attained pCR, and 1 additional pt had ypTmic at the time of surgery. There was consistent (p=0.07) selective increase in CD8α (CTL marker) in post-treatment tumor biopsies with concomitant decrease in CD8α in the blood (p=0.04) measured by RT-PCR. RNA sequencing on the blood samples (7 pre- and post-treatment) showed that higher M2 macrophages and naïve B cells in the pre-treatment samples were associated with higher probability of non pCR (adjusted p=0.02 and 0.05, respectively). CKM treatment decreased CD8α and CD8β post-treatment in the blood samples. Higher CD8+ T cells and NK cells in the post-treatment blood samples, were associated with higher likelihood of pCR, although this trend did not reach statistical significance. CONCLUSIONS: We have observed preliminary indications of safety and good tolerability of the combination of CKM regimen with paclitaxel, with promising pCR + ypTmic of 66%. RNA sequencing indicates that CKM may drive CD8+ T cells from the blood into the tumor. Citation Format: Shipra Gandhi, Cayla Jones, Mateusz Opyrchal, Ronald Slomba, Kristopher Attwood, Jianmin Wang, Eduardo Cortes Gomez, Tracey O'Connor, Ellis Levine, Pawel Kalinski. Chemokine-modulating regimen (rintatolimod, IFN-α2b, celecoxib): New strategy to drive CD8+T-cells into triple negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-18-03.

Abstract PO1-24-12: Investigating the immunological function of alpha-2-glycoprotein 1, zinc-binding in regulating tumor response in the breast cancer microenvironment

Abstract Purpose: Tumor immunology has attracted considerable attention as an innovative therapeutic strategy for various types of cancer. Elucidating the unique immunoregulatory mechanisms in the breast cancer microenvironment will assist in the development of novel treatment strategies. Recently, we and other researchers have found that androgen receptor (AR) expression is associated with the immunosuppressive phenotype in the breast cancer microenvironment, suggesting some immunoregulatory function in breast cancer; however, the mechanism remains unclear. Here, we focused on AR-dependent secreted protein, alpha-2-glycoprotein 1, zinc-binding (ZAG) encoded by the AZGP1 gene in breast cancer, which is structurally similar to HLA class I and is implicated in immune regulation. In this study, we investigated the immunological function of AZGP1/ZAG in the breast cancer microenvironment. Methods: We performed a gene set enrichment analysis (GSEA) to screen the biological processes associated with AZGP1 expression using a gene expression profile dataset of the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC). Subsequently, we analyzed the correlation between AZGP1 expression and the immune cell composition in breast cancer tissues estimated with the CIBERSORTx using METABRIC and another dataset of The Sweden Cancerome Analysis Network-Breast. In our previous study of 45 breast cancer tissue samples, we evaluated the infiltration of 11 types of immune cells using flow cytometry (FCM). ZAG expression was further evaluated by immunohistochemistry, and the relationship between ZAG expression and the immune cell composition in breast cancer tissue was analyzed. Based on the results of this analysis (shown in the results section) we hypothesized that ZAG has some effect on the macrophage (Mφ). The action of ZAG in M1/M2 polarization models constructed using primary culture of human peripheral blood mononuclear cells (PBMC)-derived Mφ was assessed based on the expression of M1/M2 differentiation markers (CD86, CD80/CD163, MRC1) and HLA class I/II expression evaluated by FCM (n=15 each). Results: GSEA demonstrated that AZGP1 expression was negatively correlated with multiple gene sets representing immunological processes, including inflammatory response, allograft rejection, interferon gamma response, IL6/JAK/STAT3 signaling, complement, and IL2/STAT5 signaling. Analysis by CIBERSORTx showed that AZGP1 expression was negatively correlated with the absolute score (the absolute abundance of total immune cell infiltration), Mφ M1, NK cells activated, CD4+ T memory activated, and CD8+ T (r<-3 and p< 0.05). Analyses of our in-house dataset using breast cancer tissue showed that ZAG expression was associated with decreased infiltration of monocytes/macrophages, non-classical monocytes, and myeloid-derived suppressor cells in breast cancer tissues assessed by FCM. In the in vitro analyses, ZAG decreased the expression of CD80, CD163, MRC1, and HLA classes I and II in the M1 polarization model and the expression of CD163 and MRC1 in the M2 polarization model. Conclusion: AZGP1/ZAG was associated with an immunosuppressive phenotype and reduced infiltration of specific immune cell subsets, particularly Mφ, into breast cancer tissues. In the in vitro analysis, ZAG demonstrated some regulatory effects on the phenotypic change of Mφ. Our findings strongly suggest ZAG is a novel mediator of AR-dependent immunomodulation in the breast cancer microenvironment, laying the foundation for future studies to elucidate the immunological role of ZAG in breast cancer. Citation Format: Toru Hanamura, Kozue Yokoyama, Shigehisa Kitano, Hiroshi Kagamu, Makiko Yamashita, Mayako Terao, Takuho Okamura, Nobue Kumaki, Katsuto Hozumi, Takayuki Iwamoto, Chikako Honda, Sasagu Kurozumi, Jennifer Richer, Naoki Niikura. Investigating the immunological function of alpha-2-glycoprotein 1, zinc-binding in regulating tumor response in the breast cancer microenvironment [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-24-12.

Abstract PO3-24-10: Losartan enhances the radiosensitivity of triple-negative breast cancer by reshaping the tumor immune microenvironment

Abstract Triple-negative breast cancer (TNBC) represents the most aggressive subtype of breast cancer, and the therapeutic options available for TNBC are limited. In addition to surgery and chemotherapy, radiotherapy (RT) is a primary treatment modality for TNBC. However, radio-resistance poses significant challenges to TNBC treatment. Prior research has shown that losartan, an angiotensin receptor blocker, can improve vessel perfusion and drug delivery, thereby enhancing the efficacy of chemotherapy or radiotherapy in cancer. However, in our study, we found that losartan could enhance the radiosensitivity of TNBC in immunocompetent mice model, but not in immunodeficient mice model and TNBC cells. It suggested that losartan might enhance the radiosensitivity of TNBC in an immune system dependent way. Previous studies had noted that tumor immune microenvironment (TIME) played an important role in radio-resistance. Therefore, we focused on the TIME in our further study. For immune cells, it had reported that the recruitment and activation of immunosuppressive cells such as M2 phenotype tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs), could lead to the establishment of and immunosuppressive TIME and decreased the radiosensitivity. In this study, we found losartan facilitated the polarization of TAMs towards the M1 phenotype, and impeded the immunosuppressive function of MDSCs after RT in 4T1 TNBC mice model. Additionally, losartan also caused a significant increase of CD8+ T lymphocytes in the TIME, and also markedly enhanced the activity of infiltrated T cell. When the CD8+ T cells were eliminated by anti-CD8α antibody, the radiosensitization effect of losartan was significantly decreased. Therefore, T-cell mediated tumor suppression is essential for the radiosensitization caused by losartan in TNBC. For immune factors, we found that TNBC exhibited an increase in the expression of programmed death-ligand (PD-L1) and indoleamine-2,3-dioxygenase (IDO) upon exposure to irradiation, and the combination of losartan resulted in a significant reduction in their expression in vitro and in vivo. At the same time, the 4T1 TNBC transplantation tumors were significantly inhibited by losartan combined with PD-1 inhibitor after RT, which indicated that losartan might amplify the efficacy of radio-immunotherapy. Collectively, these findings suggest that losartan could reshape the TIME of TNBC through regulating immune cells (TAMs, MDCSs and CD8+ T cells) and immune factors (PD-L1 and IDO), which result in the enhancement of radiosensitivity of TNBC. In our investigation, losartan was innovatively found to increase the radiosensitivity of TNBC by reshaping the TIME rather than on the tumor stroma. As one of the most commonly prescribed drugs for hypertension, the safety and affordability of losartan have been extensively confirmed. In the future, losartan combined with radiotherapy might be a promising strategy for TNBC treatment. Citation Format: Cuiwei Liu, Xu Wang, Zihan Xia, Yuxi Ma, Yanxia Zhao. Losartan enhances the radiosensitivity of triple-negative breast cancer by reshaping the tumor immune microenvironment [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-24-10.

Key players of immunosuppression in epithelial malignancies: Tumor-infiltrating myeloid cells and γδ T cells.

The tumor microenvironment of solid tumors governs the differentiation of otherwise non-immunosuppressive macrophages and gamma delta (γδ) T cells into strong immunosuppressors while promoting suppressive abilities of known immunosuppressors such as myeloid-derived suppressor cells (MDSCs) upon infiltration into the tumor beds. In epithelial malignancies, tumor-associated macrophages (TAMs), precursor monocytic MDSCs (M-MDSCs), and gamma delta (γδ) T cells often acquire strong immunosuppressive abilities that dampen spontaneous immune responses by tumor-infiltrating T cells and B lymphocytes against cancer. Both M-MDSCs and γδ T cells have been associated with worse prognosis for multiple epithelial cancers. Here we discuss recent discoveries on how tumor-associated macrophages and precursor M-MDSCs as well as tumor associated-γδ T cells acquire immunosuppressive abilities in the tumor beds, promote cancer metastasis, and perspectives on how possible novel interventions could restore the effective adaptive immune responses in epithelial cancers.

Strategies to reprogram anti-inflammatory macrophages towards pro-inflammatory macrophages to support cancer immunotherapies.

Tumor-associated myeloid cells, including macrophages and myeloid-derived suppressor cells, can be highly prevalent in solid tumors and play a significant role in the development of the tumor. Therefore, myeloid cells are being considered potential targets for cancer immunotherapies. In this review, we focused on strategies aimed at targeting tumor-associated macrophages (TAMs). Most strategies were studied preclinically but we also included a limited number of clinical studies based on these strategies. We describe possible underlying mechanisms and discuss future challenges and prospects.

Tumor suppressor function of RBMS3 overexpression in EOC associated with immune cell infiltration

ObjectivesEpithelial ovarian cancer (EOC) is considered to be a prevalent female malignancy with both high incidence and mortality. It is reported that RNA-binding protein 3 (RBMS3) executives a tumor suppressor function in different cancers. This investigation was designed to examine the expression of RBMS3 in epithelial ovarian cancer, the effects on EOC cells, and its connection to immune cells that infiltrate tumors in the EOC microenvironment. MethodsThe expression levels of RBMS3 in EOC tissues as well as their correlations with immune cell infiltration and clinical outcome were examined using bioinformatics approaches. Western blotting as well as immunohistochemistry were carried out to determine the protein levels in EOC tissues. In addition, qRT-PCR was employed to look at the expression of the mRNA. The role of RBMS3 in EOC cells was investigated, and an RBMS3 lentiviral vector was developed. The effects of RBMS3 on subcutaneous tumor development, the proliferation protein Ki-67, the tumor angiogenesis indicator CD31, and its function in controlling the tumor immune microenvironment were evaluated by in vivo tests. ResultsThere was a considerable decrease in RBMS3 expression in EOC tissues, which was linked to a poor prognosis for patients and the infiltration of multiple immune cell. Given immunohistochemical studies, tissues with increased RBMS3 expression had decreased markers of myeloid-derived suppressor cells, regulatory T cells, and M2 macrophages, whereas M1 macrophage markers were elevated. RBMS3 appears to suppress the capabilities of proliferating, invading, and migrating in EOC cells according to in vitro tests, whereas tumors overexpressing RBMS3 developed more slowly in syngeneic mouse models. The overexpression of RBMS3 led to a decline in the levels of Ki-67 protein and CD31. Additionally, it showed a negatively correlation with markers of regulatory T cell, myeloid-derived suppressor cell, and M2 macrophage but a positive correlation with markers of M1 macrophage. ConclusionsThe findings revealed that elevated RBMS3 expression plays a tumor suppressor role in EOC and was connected to patient survival in EOC. The studies conducted in vitro and in vivo demonstrated a link between RBMS3 expression and the infiltration of certain immune cells, indicating a function for RBMS3 in the immunosuppressive tumor microenvironment and its promising efficiency as a novel target for immunotherapy against EOC.

CHMP2A regulates broad immune cell-mediated antitumor activity in an immunocompetent in vivo head and neck squamous cell carcinoma model

BackgroundNatural killer (NK) cells are key effector cells of antitumor immunity. However, tumors can acquire resistance programs to escape NK cell-mediated immunosurveillance. Identifying mechanisms that mediate this resistance enables us...

17β-estradiol promotes myeloid-derived suppressor cells functions and alleviates inflammatory bowel disease by activation of Stat3 and NF-κB signalings

17β-estradiol promotes myeloid-derived suppressor cells functions and alleviates inflammatory bowel disease by activation of Stat3 and NF-κB signalings

The Influence of Exercise on Cancer Risk, the Tumor Microenvironment and the Treatment of Cancer.

There are several modifiable factors that can be targeted to prevent and manage the occurrence and progression of cancer, and maintaining adequate exercise is a crucial one. Regular physical exercise has been shown to be a beneficial strategy in preventing cancer, potentially amplifying the effectiveness of established cancer therapies, alleviating certain cancer-related symptoms, and possibly mitigating side effects resulting from treatment. Nevertheless, the exact mechanisms by which exercise affects tumors, especially its impact on the tumor microenvironment (TME), remain uncertain. This review aims to present an overview of the beneficial effects of exercise in the context of cancer management, followed by a summary of the exercise parameters, especially exercise intensity, that need to be considered when prescribing exercise for cancer patients. Finally, we discuss the influence of exercise on the TME, including its effects on crucial immune cells (e.g., T cells, macrophages, neutrophils, natural killer cells, myeloid-derived suppressor cells, B cells), intratumor angiogenesis, and cancer metabolism. This comprehensive review provides up-to-date scientific evidence on the effects of exercise training on cancer and offers guidance to clinicians for the development of safe and feasible exercise training programs for cancer patients in clinical practice.

Myeloid-derived suppressor cells in pleural effusion as a diagnostic marker for early discrimination of pulmonary tuberculosis from pneumonia

IntroductionTuberculous pleural effusion (TPE) stands as one of the primary forms of extrapulmonary tuberculosis (TB) and frequently manifests in regions with a high prevalence of TB, consequently being a notable cause of pleural effusion in such areas. However, the differentiation between TPE and parapneumonic pleural effusion (PPE) presents diagnostic complexities. This study aimed to evaluate the potential of myeloid-derived suppressor cells (MDSCs) in the pleural fluid as a potential diagnostic marker for distinguishing between TPE and PPE.MethodsAdult patients, aged 18 years or older, who presented to the emergency room of a tertiary referral hospital and received a first-time diagnosis of pleural effusion, were prospectively enrolled in the study. Various immune cell populations, including T cells, B cells, natural killer (NK) cells, and MDSCs, were analyzed in both pleural fluid and peripheral blood samples.ResultsIn pleural fluid, the frequency of lymphocytes, including T, B, and NK cells, was notably higher in TPE compared to PPE. Conversely, the frequency of polymorphonuclear (PMN)-MDSCs was significantly higher in PPE. Notably, compared to traditional markers such as the neutrophil-to-lymphocyte ratio and adenosine deaminase level, the frequency of PMN-MDSCs emerged as a more effective discriminator between PPE and TPE. PMN-MDSCs demonstrated superior positive and negative predictive values and exhibited a higher area under the curve in the receiver operating characteristic curve analysis. PMN-MDSCs in pleural effusion increased the levels of reactive oxygen species and suppressed the production of interferon-gamma from T cells following nonspecific stimulation. These findings suggest that MDSC-mediated immune suppression may contribute to the pathology of both TPE and PPE.DiscussionThe frequency of PMN-MDSCs in pleural fluid is a clinically useful indicator for distinguishing between TPE and PPE.

Dexamethasone promotes renal fibrosis by upregulating ILT4 expression in myeloid-derived suppressor cells.

Studies have shown that adoptive transfer of myeloid-derived suppressor cells (MDSCs) can alleviate various inflammatory diseases, including glomerulonephritis, but the long-term effects of the transferred MDSCs are still unclear. In addition, although glucocorticoids exert immunosuppressive effects on inflammatory diseases by inducing the expansion of MDSCs, the impact of glucocorticoids on the immunosuppressive function of MDSCs and their molecular mechanisms are unclear. In this study, we found that adoptive transfer of MDSCs to doxorubicin-induced focal segmental glomerulosclerosis (FSGS) mice for eight consecutive weeks led to an increase in serum creatinine and proteinuria and aggravation of renal interstitial fibrosis. Similarly, 8 weeks of high-dose dexamethasone administration exacerbated renal interstitial injury and interstitial fibrosis in doxorubicin-induced mice, manifested as an increase in serum creatinine and proteinuria, collagen deposition and α-SMA expression. On this basis, we found that dexamethasone could enhance MDSC expression and secretion of the fibrosis-related cytokines TGF-β and IL-10. Mechanistically, we revealed that dexamethasone promotes the expression of immunoglobulin-like transcription factor 4 (ILT4), which enhances the T-cell inhibitory function of MDSCs and promotes the activation of STAT6, thereby strengthening the expression and secretion of TGF-β and IL-10. Knocking down ILT4 alleviated renal fibrosis caused by adoptive transfer of MDSCs. Therefore, our findings demonstrate that the role and mechanism of dexamethasone mediate the expression and secretion of TGF-β and IL-10 in MDSCs by promoting the expression of ILT4, thereby leading to renal fibrosis.

Turning anecdotal irradiation-induced anticancer immune responses into reproducible in situ cancer vaccines via disulfiram/copper-mediated enhanced immunogenic cell death of breast cancer cells

Irradiation (IR) induces immunogenic cell death (ICD) in tumors, but it rarely leads to the abscopal effect (AE); even combining IR with immune checkpoint inhibitors has shown only anecdotal success in inducing AEs. In this study, we aimed to enhance the IR-induced immune response and generate reproducible AEs using the anti-alcoholism drug, disulfiram (DSF), complexed with copper (DSF/Cu) to induce tumor ICD. We measured ICD in vitro and in vivo. In mouse tumor models, DSF/Cu was injected intratumorally followed by localized tumor IR, creating an in situ cancer vaccine. We determined the anticancer response by primary tumor rejection and assessed systemic immune responses by tumor rechallenge and the occurrence of AEs relative to spontaneous lung metastasis. In addition, we analyzed immune cell subsets and quantified proinflammatory and immunosuppressive chemokines/cytokines in the tumor microenvironment (TME) and blood of the vaccinated mice. Immune cell depletion was investigated for its effects on the vaccine-induced anticancer response. The results showed that DSF/Cu and IR induced more potent ICD under hypoxia than normoxia in vitro. Low-dose intratumoral (i.t.) injection of DSF/Cu and IR(12Gy) demonstrated strong anti-primary and -rechallenged tumor effects and robust AEs in mouse models. These vaccinations also increased CD8+ and CD4+ cell numbers while decreasing Tregs and myeloid-derived suppressor cells in the 4T1 model, and increased CD8+, dendritic cells (DC), and decreased Treg cell numbers in the MCa-M3C model. Depleting both CD8+ and CD4+ cells abolished the vaccine’s anticancer response. Moreover, vaccinated tumor-bearing mice exhibited increased TNFα levels and reduced levels of immunosuppressive chemokines/cytokines. In conclusion, our novel approach generated an anticancer immune response that results in a lack of or low tumor incidence post-rechallenge and robust AEs, i.e., absence of or decreased spontaneous lung metastasis in tumor-bearing mice. This approach is readily translatable to clinical settings and may increase IR-induced AEs in cancer patients.

Immune System Disorder and Cancer-Associated Cachexia

Cancer-associated cachexia (CAC) is a debilitating condition marked by muscle and fat loss, that is unresponsive to nutritional support and contributes significantly to morbidity and mortality in patients with cancer. Immune dysfunction, driven by cytokine imbalance, contributes to CAC progression. This review explores the potential relationship between CAC and anti-cancer immune response in pre-clinical and clinical studies. Pre-clinical studies showcase the involvement of cytokines like IL-1β, IL-6, IL-8, IFN-γ, TNF-α, and TGF-β, in CAC. IL-6 and TNF-α, interacting with muscle and adipose tissues, induce wasting through JAK/STAT and NF-κB pathways. Myeloid-derived suppressor cells (MDSCs) exacerbate CAC by promoting inflammation. Clinical studies confirm elevated pro-inflammatory cytokines (IL-6, IL-8, TNFα) and immune markers like the neutrophil-to-lymphocyte ratio (NLR) in patients with CAC. Thus, immunomodulatory mechanisms involved in CAC may impact the anti-neoplastic immune response. Inhibiting CAC mechanisms could enhance anti-cancer therapies, notably immunotherapy. R-ketorolac, a new immunomodulator, reversed the weight loss and increased survival in mice. Combining these agents with immunotherapy may benefit patients with cancer experiencing CAC. Further research is vital to understand the complex interplay between tumor-induced immune dysregulation and CAC during immunotherapy.

Impact of Surgery-Induced Myeloid-derived Suppressor Cells and the NOX2/ROS Axis on Postoperative Survival in Human Pancreatic Cancer.

Pancreatic cancer surgery triggered pronounced accumulation of NOX2+ myeloid-derived suppressor cells that inhibited NK cell function and negatively prognosticated postoperative patient survival. We propose the targeting of M-MDSC as a conceivable strategy to reduce postoperative immunosuppression in pancreatic cancer.

Loss of TRIM29 mitigates viral myocarditis by attenuating PERK-driven ER stress response in male mice

Viral myocarditis, an inflammatory disease of the myocardium, is a significant cause of sudden death in children and young adults. The current coronavirus disease 19 pandemic emphasizes the need to understand the pathogenesis mechanisms and potential treatment strategies for viral myocarditis. Here, we found that TRIM29 was highly induced by cardiotropic viruses and promoted protein kinase RNA-like endoplasmic reticulum kinase (PERK)-mediated endoplasmic reticulum (ER) stress, apoptosis, and reactive oxygen species (ROS) responses that promote viral replication in cardiomyocytes in vitro. TRIM29 deficiency protected mice from viral myocarditis by promoting cardiac antiviral functions and reducing PERK-mediated inflammation and immunosuppressive monocytic myeloid-derived suppressor cells (mMDSC) in vivo. Mechanistically, TRIM29 interacted with PERK to promote SUMOylation of PERK to maintain its stability, thereby promoting PERK-mediated signaling pathways. Finally, we demonstrated that the PERK inhibitor GSK2656157 mitigated viral myocarditis by disrupting the TRIM29-PERK connection, thereby bolstering cardiac function, enhancing cardiac antiviral responses, and curbing inflammation and immunosuppressive mMDSC in vivo. Our findings offer insight into how cardiotropic viruses exploit TRIM29-regulated PERK signaling pathways to instigate viral myocarditis, suggesting that targeting the TRIM29-PERK axis could mitigate disease severity.