M2-polarized Tumor-associated Macrophages Research Articles

Combined blockade of TGf-β1 and GM-CSF improves chemotherapeutic effects for pancreatic cancer by modulating tumor microenvironment.

The interactions between tumor immune microenvironment (TIME) and pancreatic cancer cells can affect chemotherapeutic efficacy; however, the mechanisms still remain largely unknown. Thirty items in TIME were comprehensively screened by using tissue microarray from pancreatic cancer patients. Their expressions, interconnections and predictive roles for survival were analyzed. Twenty-one of 30 items could stratify the survival of the patients; however, multivariate analysis found that only 5 independent risk factors could predict worse survival (M2-polarized tumor-associated macrophages (TAMs), IgG4 positive cells, TGF-β1, GM-CSF and lymphangiogenesis). They had a much higher expression levels in tumoral tissue, compared to peritumoral tissue. The Spearman analysis showed that M2-polarized TAM, TGF-β1 and GM-CSF were positively correlated with pancreatic cancer stem cells (PCSC), angiogenesis and lymphangiogenesis. Both human and murine pancreatic cancer cells could induce M2-polarized TAM, which showed substantial roles to decease chemotherapeutic effects. After treated by gemcitabine, both human and murine pancreatic cancer cell lines expressed higher level of immune check points, PCSC markers and varieties of immunosuppressive factors; however, TGF-β1 and GM-CSF had the highest increase. Based on the above results, TGF-β1 and GM-CSF were proposed to be the optimal potential targets to improve chemotherapeutic effects. In immunocompetent murine models, we demonstrated that combined blockade of TGF-β1 and GM-CSF improved the chemotherapeutic effects by inhibition of M2-polarized TAM and induction of CD8 positive T cells. This study presents a novel promising combined strategy to improve the chemotherapeutic effects for pancreatic cancer.

Interleukin-37 suppresses hepatocellular carcinoma growth through inhibiting M2 polarization of tumor-associated macrophages

Interleukin (IL)-37 has anti-tumor effects in hepatocellular carcinoma (HCC). Evidence shows that tumor-associated macrophages (TAMs) promote tumor progression. This study was designed to investigate the functional role of IL-37-mediated polarization of TAMs in HCC progression. HCC patient-derived TAMs were transfected with lentiviruses expressing IL-37 (LV-IL-37) and IL-37 siRNA and then the conditioned medium from TAMs were used to culture HCC cells (HepG2 and Huh-7). The phenotype of the macrophages was evaluated by detecting M1- or M2- type specific markers and cytokines. Cell proliferation, migration, and invasion were assessed. A tumor xenograft mouse model was generated with a subcutaneous injection of a mixture of HepG2 cells and TAMs/LV-IL-37. HCC patient-derived PBMCs showed M2 polarization and decreased IL-37 expression. Furthermore, IL-37 promoted TAMs polarization from M2 to M1 subtype through inhibiting the IL‐6/STAT3 signaling. Moreover, IL-6 upregulation by recombinant human IL-6 (rhIL-6) blocked the IL-37 overexpression-mediated inhibition of HCC cell proliferation, migration, and invasion. In addition, IL-37 overexpression in HCC patient-derived TAMs inhibited tumor growth in vivo. Collectively, IL-37 suppresses HCC growth through inhibiting M2 polarization of TAMs via regulating the IL-6/STAT3 pathway.

Nogo-B fosters HCC progression by enhancing Yap/Taz-mediated tumor-associated macrophages M2 polarization

Tumor-associated macrophages (TAMs) and their M2-type extremely promote tumor angiogenesis, invasion and metastasis, including hepatocellular carcinoma (HCC). Nogo-B is expressed in most tissues and participates in macrophage polarization. However, whether Nogo-B is involved in the polarization and the effects of TAMs has been unclear. The expression of Nogo-B in TAMs of HCC patients is significantly increased, which correlated with the poor prognosis of the patients with HCC. Coincidentally, HCC conditioned medium (HCM) facilitated Nogo-B expression and the M2 phenotype of macrophages. Nogo-B knockdown Nogo-B significantly suppressed the M2-type polarization of macrophages and inhibited HCC cells proliferation both in vivo and in vitro. Furthermore, interference of Nogo-B facilitates macrophage-mediated apoptosis of tumor cells. Nogo-B meaningfully enhanced IL4-stimulated the alternative activation of macrophages as well as expression of the transcriptional regulators Yes-associated protein (Yap)/transcriptional coactivator with PDZ-binding motif (Taz). An inhibitor of Yap, Verteporfin, could block Nogo-B-Yap/Taz-mediated macrophages M2 polarization. Nogo-B expression in macrophages facilitates tumor-associated macrophages M2 polarization and protumoral effects of TAMs in HCC. Targeting Nogo-B/Yap/Taz in macrophages could provide a new therapeutic strategy in HCC therapy.

Melanoma-specific bcl-2 promotes a protumoral M2-like phenotype by tumor-associated macrophages

BackgroundA bidirectional crosstalk between tumor cells and the surrounding microenvironment contributes to tumor progression and response to therapy. Our previous studies have demonstrated that bcl-2 affects melanoma progression and regulates...

Wnt5a-induced M2 polarization of tumor-associated macrophages via IL-10 promotes colorectal cancer progression

BackgroundTumor-associated macrophages (TAMs) in the tumor microenvironment influence tumor initiation, invasion and metastasis. Several studies have shown that Wnt5a is mainly expressed in the tumor stroma, especially in TAMs. However, whether Wnt5a regulates the polarization and biological function of TAMs in colorectal cancer (CRC) is incompletely understood.MethodsImmunofluorescence staining was performed to detect CD68 and Wnt5a expression in colorectal tissues from patients (63 CRC specimens VS 20 normal tissues). RT-qPCR, flow cytometry, ELISA and inhibitors were carried out to explore the role of Wnt5a in the polarization of TAMs. Clone formation and transwell assays were performed to determine the effects of Wnt5a–treated macrophages on tumor proliferation, migration and invasion in vitro. Finally, a xenograft model was applied to confirm the effects of Wnt5a+ TAMs on CRC tumorigenesis.ResultsWe found that high Wnt5a+CD68+/CD68+ TAMs ratio was significantly associated with poor prognosis in CRC patients and Wnt5a+ TAM was an M2-like TAM subtype. Subsequently, we found that Wnt5a induced macrophages to secrete IL-10, which then acted as an autocrine cytokine to induce M2 polarization of these macrophages. IL-10 neutralizing antibody completely reversed the pro-M2 effect of Wnt5a. Mechanistically, the CaKMII-ERK1/2-STAT3 pathway was required for Wnt5a-mediated IL-10 expression in macrophages. Furthermore, Wnt5a-induced M2 macrophages promoted CRC cells proliferation, migration and invasion; knockdown of Wnt5a in TAMs significantly impaired the pro-tumor functions of TAMs.ConclusionsOur data indicate that Wnt5a could induce M2 polarization of TAMs by regulating CaKMII-ERK1/2-STAT3 pathway–mediated IL-10 secretion, ultimately promoting tumor growth and metastasis of CRC.

Gemcitabine Recruits M2-Type Tumor-Associated Macrophages into the Stroma of Pancreatic Cancer

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is a very lethal disease that can develop therapy resistance over time. The dense stroma in PDAC plays a critical role in tumor progression and resistance. How this stroma interacts with the tumor cells and how this is influenced by chemotherapy remain poorly understood. METHODS: The backbone of this study is the parallel transcriptome analysis of human tumor and mouse stroma in two molecular and clinical representative patient-derived tumor xenografts models. Mice (8 animals per group) were treated for 4 weeks with gemcitabine or control. We studied tumor growth, RNA expression in the stroma, tumor-associated macrophages (TAMs) with immunofluorescence, and cytokines in the serum. RESULTS: A method for parallel transcriptome analysis was optimized. We found that the tumor (differentiation, gene expression) determines the infiltration of macrophages into the stroma. In aggressive PDAC (epithelial-to-mesenchymal transition high), we find more M2 polarized TAMs and the activation of cytokines and growth factors (TNFα, TGFβ1, and IL6). There are increased stromal glycolysis, reduced fatty acid oxidation, and reduced mitochondrial oxidation (tricarboxylic acid cycle and oxidative phosphorylation). Treatment with gemcitabine results in a shift of innate immune cells, especially additional infiltration of protumoral M2 TAMs (P < .001) and metabolic reprogramming. CONCLUSIONS: Gemcitabine treatment of PDAC xenografts stimulates a protumoral macrophage phenotype, and this, in combination with a shift of the tumor cells to a mesenchymal phenotype that we reported previously, contributes to tumor progression and therapeutic resistance. Targeting M2-polarized TAMs may benefit PDAC patients at risk to become refractory to current anticancer regimens.

Correction: All-Trans Retinoic Acid Prevents Osteosarcoma Metastasis by Inhibiting M2 Polarization of Tumor-Associated Macrophages

Correction: All-Trans Retinoic Acid Prevents Osteosarcoma Metastasis by Inhibiting M2 Polarization of Tumor-Associated Macrophages

Effect and Molecular Mechanisms of Traditional Chinese Medicine on Tumor Targeting Tumor-Associated Macrophages.

Traditional Chinese medicine (TCM) has been used as a significant cancer treatment method for many years in China. It has been demonstrated that TCM could assist in inhibiting the growth of tumors and prolonging the survival rates of cancer patients. Although the mechanism of TCM are still not clear, accumulating evidence has shown that they may be related to the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) play a significant role in TME and are polarized to two phenotypes, M1 (classically activated) and M2 (alternatively activated) TAMs. The two different phenotypes of TAMs play converse roles in the TME and M2-polarized tumor-associated macrophages (M2-TAMs) always lead to poor prognosis in cancer patients compared to M1-polarized tumor-associated macrophages (M1-TAMs). In this review, the potential correlation between TCM and TAMs (especially the M2 phenotype) in tumor progression and promising TCM strategies targeting TAMs in cancer are discussed.

TMIC-22. IDENTIFICATION OF CANCER-ASSOCIATED FIBROBLASTS IN GLIOBLASTOMA and Defining Their Protumoral Effects

Abstract While cancer-associated fibroblasts (CAFs) and their pro-tumoral effects have been demonstrated in systemic cancers, CAFs had been presumed absent in glioblastoma given the lack of normal fibroblasts in the healthy brain. Here, we show that 5–26% (mean=12%) of cells in human glioblastomas express CAF markers α-SMA or PDGFR-β, morphologically resemble fibroblasts, and transcriptomically resemble by RNA-seq CAFs from other cancers. Glioblastoma CAFs were chemotactically attracted to glioblastoma-initiating stem cells (P=0.02). While glioblastoma CAFs did not affect differentiated glioblastoma cell proliferation (P=0.4), CAFs increased glioblastoma stem cell proliferation (P=0.002) and expression of glioblastoma stem cell-associated genes (P&lt; 0.001). To identify mediators of CAF/glioblastoma stem cell interactions, we created a resource of inferred crosstalk by mapping the expression of receptors to that of their cognate ligands/agonists, using our RNA-seq results from glioblastoma CAFs and stem cells, revealing PDGF-β/PDGFR and osteopontin/CD44 to mediate stem cell recruitment of CAFs and CAF enrichment of stem cells, as confirmed by blocking antibodies (P=0.02–0.03). CAFs also render the glioblastoma microenvironment more pro-tumoral by promoting M2 polarization of tumor-associated macrophages (P=0.01), an effect we found to arise from unique CAF production of the EDA splice variant of fibronectin binding toll-like receptor 4 (TLR4), a known EDA receptor expressed by macrophages (P=0.02). In patient glioblastomas, CAFs were enriched 3-fold in the subventricular zone (SVZ) (P=0.04) which houses the neural stem cells that generate glioblastoma stem cells. SVZs from epilepsy cases or autopsies of glioblastoma-containing brains without ventricular involvement lacked CAFs. Depleting CAFs in xenografts derived from neurosphere-containing glioblastoma stem cells slowed their growth in vivo (P&lt; 0.001). These findings are among the first to identify and profile glioblastoma CAFs. CAF recruitment by glioblastoma stem cells and creation of a pro-tumoral microenvironment in the perivascular niche housing glioblastoma stem cells, particularly in the SVZ, makes them an intriguing therapeutic target.

M2-polarized tumor-associated macrophages promote epithelial-mesenchymal transition via activation of the AKT3/PRAS40 signaling pathway in intrahepatic cholangiocarcinoma.

Tumor-associated macrophages (TAMs) have been considered as a major component of the tumor microenvironment. However, the crosstalk between M2-polarized tumor-associated macrophages (M2-TAMs) and intrahepatic cholangiocarcinoma (ICC) remains undetermined. In the present study, we aimed to clarify the role of M2-TAMs in ICC and the underlying mechanism. The in vitro assay demonstrated M2-TAMs promoted epithelial-mesenchymal transition (EMT) of ICC cells, resulting in enhanced cell invasion and metastasis ability. Moreover, M2-TAMs modulated the microenvironment of ICC by increasing the secretion of cytokines (GM-CSF, tumor necrosis factor-α [TNF-α], ICAM-1, interleukin-6 [IL-6], etc) and chemokines (CCL1, CCL3, etc). In addition, p-AKT (Ser473) and p-PRAS40 (Thr246) were upregulated in ICC cells when cocultured with M2-TAMs or treated with M2-TAMs secreted core cytokines (GM-CSF, TNF-α, ICAM-1, and IL-6). Consistently, AKT3 silencing (but not AKT1 silencing and AKT2 silencing) markedly inhibited phosphorylation of AKT and PRAS40 of ICC cells and inhibited the EMT process when cocultured with M2-TAMs. Taken together, the current data indicated that M2-TAMs promoted ICC cells EMT, partially through increasing secretion of cytokines and chemokines, thus modulating the microenvironment and activating the AKT3/PRAS40 signaling pathway.

Macrophage transcriptome modification induced by hypoxia and lactate.

The production of lactate under hypoxic conditions or by cancer cells was reported to promote the M2 polarization of tumor-associated macrophages. However, the exact effect of lactate on macrophages, particularly under hypoxic conditions, has remained largely elusive. In the present study, an in-depth bioinformatics analysis of previously published transcriptome data of macrophages was performed. A total of 6, 101 and 764 upregulated genes were identified in the lactate, hypoxia and hypoxia-lactate groups, respectively, whereas 4, 41 and 588 genes were downregulated in the same respective groups. Furthermore, differentially expressed genes (DEGs) of the hypoxia and hypoxia-lactate groups were significantly enriched in the hypoxia-inducible factor 1 (HIF-1) signaling pathway and the Hedgehog pathway. Upregulation of the mTOR and Hedgehog pathways in the hypoxia-lactate group was identified by gene set enrichment analysis. Furthermore, a set of HIF-1 pathway-associated genes was identified to be positively correlated with hypoxia using weighted gene co-expression network analysis. Lactate was indicated to inhibit the cell cycle in a hypoxia-independent manner. The DEGs of the hypoxia and hypoxia-lactate groups, including C-C motif chemokine receptor type 1 and 5, were enriched in the cytokine-cytokine receptor interaction pathway. In conclusion, under normoxic conditions, lactate exerted a weak effect on macrophages, while the combination of lactate and hypoxia markedly promoted the M2-polarization of macrophages via the HIF-1, Hedgehog and mTOR pathways. Lactate and hypoxia may also contribute to the formation of the spatial structure of tumor niches by inhibiting the proliferation of resident macrophages and by regulating the recruitment of peripheral macrophages.

Listeria-based hepatocellular carcinoma vaccine facilitates anti-PD-1 therapy by regulating macrophage polarization.

Recently, patients with advanced cancers have been benefited greatly from immune checkpoint blockade immunotherapy. However, immune checkpoint blockade is still suboptimal in HCC treatment and more immune modifications are needed to achieve an efficient therapeutic goal. Here, we investigated the combined administration of a Listeria-based HCC vaccine, Lmdd-MPFG, and the anti-PD-1 immune checkpoint blockade antibody. We found that Lmdd-MPFG promoted the expression of PD-L1 in HCC cells but resensitized the tumor local T cell to respond to the anti-PD-1 immunotherapy. Mechanistically, the Lmdd-MPFG vaccine activates the NF-κB pathway in the tumor-associated macrophages (TAMs) through the TLR2 and MyD88 pathway, and recruits p62 to activate the autophagy pathway. The overall effect is skewing the TAMs from M2-polarized TAMs into the M1-polarized TAMs. Most importantly, it skewed the cytokine profiles into antitumor one in the tumor microenvironment (TME). This change restores the T-cell reactivity to the anti-PD-1 blockade. Our results suggested that Lmdd-MPFG combined with PD-1 blockade exerted synergistic antitumor effects through modifying TAMs in the TME and removing T-cell inhibitory signals, thereby providing a new potential strategy for HCC treatment.

Hedgehog signaling promotes tumor-associated macrophage polarization to suppress intratumoral CD8+ T cell recruitment.

Tumor-associated macrophages (TAMs) usually display an antiinflammatory M2-like phenotype to facilitate tumor growth. However, what drives M2 polarization of TAMs and how TAMs suppress antitumor immunity within the tumor microenvironment (TME) remain largely undefined. Using several murine tumor models, we showed that hedgehog (Hh) signaling in myeloid cells is critical for TAM M2 polarization and tumor growth. We also found that tumor cells secrete sonic hedgehog (SHH), an Hh ligand, and that tumor-derived SHH drives TAM M2 polarization. Furthermore, Hh-induced functional polarization in TAMs suppresses CD8+ T cell recruitment to the TME through the inhibition of CXCL9 and CXCL10 production by TAMs. Last, we demonstrated that Krüppel-like factor 4 (Klf4) mediates Hh-dependent TAM M2 polarization and the immunosuppressive function. Collectively, these findings highlight a critical role for tumor-derived SHH in promoting TAM M2 polarization, a mechanism for TAM-mediated immunosuppression, and may provide insights into the design of new cancer immunotherapeutic strategies.

Bexarotene Reduces Production of CCL22 From Tumor-Associated Macrophages in Cutaneous T-Cell Lymphoma.

Bexarotene is a third-generation retinoid X receptor-selective retinoid that has been approved for use in the treatment of both early and advanced cutaneous T-cell lymphoma (CTCL). Although bexarotene has been used for decades in the treatment of CTCL, little is known about the mechanisms underlying its anti-tumor effects in CTCL patients. This study therefore focused on the immunomodulatory effects of bexarotene in vivo using an EL4 mouse T-cell lymphoma model, followed by investigation in CTCL patients treated with bexarotene. Intraperitoneal injection of bexarotene significantly decreased expressions of CCL22, CXCL5, CXCL10, and p19 in the tumor microenvironment. Based on those results, we then evaluated serum levels of CCL22, CXCL5, and CXCL10 in 25 patients with CTCL, revealing that CCL22 was significantly increased in advanced CTCL compared with early CTCL. Next, we evaluated serum levels of CCL22, CXCL5, and CXCL10 in CTCL patients treated with bexarotene. Serum levels of CCL22 were significantly decreased in 80% of CTCL patients who responded to bexarotene therapy. In addition, immunofluorescence staining revealed CD163+ M2 macrophages as the main source of CCL22. Moreover, bexarotene decreased the production of CCL22 by M2 macrophages generated from monocytes in vitro. Our findings suggest that the clinical benefits of bexarotene are partially attributable to suppressive effects on the production of CCL22 by M2-polarized tumor-associated macrophages.

An miR-340-5p-macrophage feedback loop modulates the progression and tumor microenvironment of glioblastoma multiforme.

MicroRNAs (miRNAs) have been shown to be involved in the progression and tumor microenvironment of glioblastoma multiforme (GBM). Our previous research has indicated that miR-340-5p has an antitumor effect in vitro. However, the role of miR-340-5p in GBM has not been fully elucidated. Here, we show that downregulation of miR-340-5p in GBM is correlated with tumor size, recurrence, and poor survival. Moreover, we found that miR-340-5p levels are correlated with the density of tumor-associated macrophages (TAMs) and M2-polarized TAMs in GBM. Biofunctional investigations revealed that downregulation of miR-340-5p promoted TAM recruitment and M2-TAMs polarization in vitro and in vivo. In addition, we found that upregulation of miR-340-5p inhibited tumor growth and was associated with good prognosis in vivo. Through gene expression profiles and bioinformatics analysis, we showed that miR-340-5p directly targets POSTN, which recruited TAMs through integrin αvβ3. Downregulation of miR-340-5p in GBM did not induce the differentiation of TAMs into polarized M2 cells but was able to promote the M2 polarization of TAMs through directly targeting LTBP-1. Furthermore, we found that M2-TAMs promoted tumorigenesis and were associated with a poor prognosis in vivo. In an in vitro study, we demonstrated that M2-TAMs inhibited miR-340-5p expression in GBM cells by upregulation of TGFβ-1, which increased HMGA-2 expression in GBM. A ChIP assay confirmed that HMGA-2 transcriptionally suppressed miR-340-5p expression. Patients with low-miR-340-5p expression, high CD163, high POSTN, high LIBP1 levels, and high HMGA-2 had a poor prognosis with shorter overall survival, confirming data from the TCGA database. These findings suggest that an miR-340-5p-macrophage feedback loop modulates the progression and tumor microenvironment of GBM and may represent a prognostic biomarker and therapeutic strategy for GBM.

Inhibition of M2-like macrophages by all-trans retinoic acid prevents cancer initiation and stemness in osteosarcoma cells.

Emerging evidence indicates that M2-polarized tumor-associated macrophages (TAMs) directly participate in tumor initiation, progression and metastasis. However, to date, few studies have investigated novel strategies for inhibiting TAMs in order to overcome osteosarcoma. In this study, we reported that M2 macrophages were enriched in osteosarcoma tissues from patients, and M2-polarized TAMs enhanced cancer initiation and stemness of osteosarcoma cells, thereby establishing M2-polarized TAMs as a therapeutic target for blocking osteosarcoma formation. We also found that all-trans retinoic acid (ATRA) weakened TAM-induced osteosarcoma tumor formation by inhibiting M2 polarization of TAMs in vivo, and inhibited the colony formation, as well as sphere-formation capacity of osteosarcoma cells promoted by M2-type macrophages in vitro. Furthermore, M2-type macrophages enhanced cancer stem cells (CSCs) properties as assessed by increasing the numbers of CD117+Stro-1+ cells accompanied by the upregulation of CSC markers (CD133, CXCR4, Nanog, and Oct4), which could clearly be reduced by ATRA. Taken together, the results of this study demonstrated the role of M2-polarized TAMs in osteosarcoma initiation and stemness by activating CSCs, and indicated that ATRA treatment is a promising approach for treating osteosarcoma by preventing M2 polarization of TAMs.

Abstract LB-059: Hyperglycemia enhances cancer immune evasion by inducing alternative macrophage polarization through increased O-GlcNAcylation

Abstract Epidemiological studies have shown diabetes mellitus (DM) to significantly increase the risk for cancer and cancer progression. Hyperglycemia is the most important characteristic of DM and directly correlates with a poor prognosis in cancer patients. While enhanced availability of glucose can directly fuel tumor cell proliferation, the effect on the tumor immune microenvironment is less well known. Here, we demonstrate in vitro and in different murine tumor models that hyperglycemia induces an increased flux through the hexosamine biosynthetic pathway (HBP) in tumor-associated macrophages (TAMs) resulting in an upregulation of O-GlcNAcylation. Increased O-GlcNAcylation was associated with alternative M2 polarization of TAMs and reduced anti-tumor immunity. The effect of hyperglycemia on tumor growth was dependent on an intact adaptive immunity. Furthermore, inhibition of M2 polarization by the addition of anti-CSF1R antibodies abrogated the effect of hyperglycemia on tumor growth. Similarly, treatment of mice with inhibitors of the HBP or O-GlcNAcylation reduced M2 polarization of TAMs and reversed immune evasion of growing tumors. Finally, we find enhanced M2 polarization in chronically hyperglycemic patients with colorectal cancer compared to non-diabetic normoglycemic patients. Our findings provide a new and targetable mechanism of cancer immune evasion, advocating for strict control of hyperglycemia in cancer patients. Citation Format: Natalia Rodrigues Mantuano, Michal Stanczak, Isadora Oliveira, Alessandra Filardy, Ronan Silva, Alfred Zippelius, Adriane Regina Todeschini, Heinz Laubli. Hyperglycemia enhances cancer immune evasion by inducing alternative macrophage polarization through increased O-GlcNAcylation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-059.

Abstract 3099: Characterization of bone marrow tumor associated macrophages in patients with chronic lymphocytic leukemia treated with Ibrutinib

Abstract Introduction. Complete remission (CR) is observed in 9-26% of patients with chronic lymphocytic leukemia (CLL), with virtually no patient converting to CR beyond 2 years of treatment. Residual bone marrow (BM) disease is typically observed in patients not achieving CR, increasing interest about the specific effects of ibrutinib on the CLL BM microenvironment. Ibrutinib markedly increases the number and function of T cells, and suppresses regulatory B-cell function. However, it may induce M2 polarization of tumor-associated macrophages (TAM), as suggested by limited studies conducted on peripheral blood. Methods. In order to characterize the specific effect of ibrutinib on the CLL BM microenvironment, we identified patients with previously untreated CLL, receiving frontline single agent ibrutinib for more than 2 years, for whom BM biopsy samples were available at baseline and after 1 and 2 years of treatment. All samples were analyzed by immunohistochemistry and the number of positive cells per high power field (HPF)(200X) was assessed; CD68 was used as a general TAM marker, and CD163, PD-L1 and arginase-1 as M2 markers. Negative BM samples, collected as part of lymphoma staging, were used as normal controls. Results. Thirteen patients were included in the study; 85% had unfavorable FISH abnormalities (including deletion 11q and deletion 17p) and 77% had unmutated IGHV. After &amp;gt; 2 years of treatment, 3 (23%) patients had achieved CR, and 10 (77%) partial remission (PR), characterized by residual BM disease. BM samples were available for 11 patients at baseline, 12 patients at 1 year of treatment, and 9 patients at 2 years of treatment. PD-L1 and arginase-1 were negative in BM samples from all patients at all time points and in all 3 normal BMs. The median number of CD68-positive cells/HPF was 3 (range, 3-5) at baseline, 5 (range, 3-20) at 1 year, and 5 (range, 3-10) at 2 years; no differences in CD68 expression was observed between patients who achieved PR and those who achieved CR. All patients with normal BM had five CD68-positive cells/HPF. The median number of CD163-positive cells/HPF was 5 (range, 5-15) at baseline, 15 (range, 10-30) at 1 year, and 20 (range, 15-20) at 2 years; a more pronounced increase in CD163-positive cells was observed among patients who achieved PR as compared to patients who achieved CR. All patients with normal BM had approximatively ten CD163-positive cells/HPF. Conclusions. Ibrutinib increases BM CD68 (TAM) in patients with CLL, reaching a plateau after 1 year of treatment, and BM CD163 (TAM M2), with no plateau observed at 2 years of treatment. The increase in TAM M2 is more pronounced in patients who do not achieve CR after &amp;gt; 2 years of treatment, representing a potential therapeutic target for consolidation strategies. Additional M2 markers, including CSF1R, and digital analysis are being applied, and results will be presented at the meeting. Citation Format: Paolo Strati, Ellen Schlette, Luisa Solis Soto, Daniela Duenas, Ignacio Wistuba, Jan Burger. Characterization of bone marrow tumor associated macrophages in patients with chronic lymphocytic leukemia treated with Ibrutinib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3099.

Abstract 343: A potent and selective cfms inhibitor EI-1071 inhibits CSF1R signaling and regulates the tumor-associated macrophages

Abstract We have found that tumor-associated macrophages (TAMs) isolated from metastatic tumors displayed a predominant M2 phenotype. Preclinical studies show that M2-polarized TAMs forge an immunosuppressive microenvironment at metastatic niches to facilitate colonization. Colony-stimulating factor 1 receptor (CSF-1R) signaling is known to regulate the survival and maintenance of M2 TAMs, suggesting targeting CSF-1R might have therapeutic potential in halting cancer progression. To this end, we developed an orally active and selective small-molecule CSF-1R inhibitor EI-1071. Experimental procedures: EI-1071 was evaluated in kinase and cell-based bioassays, including macrophage proliferation and osteoclast differentiation. In vivo activity was verified using murine syngeneic models of colorectal cancer and breast cancer. EI-1071 was administered individually or in combination with an anti-PD1 antibody. Tumor infiltrating leucocytes were profiled using flow cytometric analysis. Results: EI-1071 exhibited nanomolar potency for inhibition of CSF-1R but not other 453 kinases tested. In cell-based bioassays, EI-1071 inhibited CSF-1R activity in human monocytes/macrophages, AML-5 leukemia, MNFS-60 leukemia, and human osteoclasts. In preclinical studies, EI-1071 displayed a favorable ADME properties, including hepatocyte stability, high Caco-2 permeability, and pharmacokinetic profiles. Oral administration of EI-1071 reduced TAM infiltration in the MC38 colorectal cancer and EMT6 breast cancer models. Moreover, EI-1071 dosed with an anti-PD-1 antibody showed further enhanced antitumor activity in vivo . Conclusions: Preclinical characterization of EI-1071 demonstrated that it is a potent and selective CSF-1R inhibitor and has a favorable drug like properties for further clinical evaluation. Therefore, EI-1071 is undergoing IND-enabling activities for the First-In-Human (FIH) Phase 1 study. Citation Format: Hung-Kai Chen, Huey-Wen Hsiao, Li-Ming Lu, Chih-Lun Hsiao, Yin-Ping Wang, Jing-Yi Huang, Chu-Bin Liao, Shao-Zheng Peng, Daw-Tsun Shih. A potent and selective cfms inhibitor EI-1071 inhibits CSF1R signaling and regulates the tumor-associated macrophages [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 343.

Role of Cancer-Associated Fibroblast in Gastric Cancer Progression and Resistance to Treatments.

Although the survival of gastric cancer (GC) patients has gradually improved, the outcomes of advanced GC patients remain unsatisfactory despite standard treatment with conventional chemotherapy or targeted agents. Several studies have shown that cancer-associated fibroblasts (CAFs), a major component of tumor stroma in GC, may have significant roles in GC progression and resistance to treatments. CAFs are a major source of various secreted molecules in the tumor microenvironment, which stimulate cancer cells and other noncancerous components of GC. Surprisingly, these factors could be involved in gastric carcinogenesis. Cytokines, including interleukin-6 and interleukin-11, or growth factors, such as fibroblast growth factor produced from CAFs, can directly activate GC cells and consequently lead to the development of an aggressive phenotype. Galectin-1 or hepatocyte growth factor can be involved in CAF-derived neovascularization in GC. In addition, recent studies showed that CAFs can affect tumor immunity through M2 polarization of tumor-associated macrophages. Finally, the current study aimed to introduce several inhibitory agents and evaluate their suppressive effects on CAFs in patients with GC progression. However, further studies are required to evaluate their safety and select appropriate patients for application in clinical settings.