Reprogramming Of Tumor-associated Macrophages Research Articles

RIPK3 Orchestrates Fatty Acid Metabolism in Tumor-Associated Macrophages and Hepatocarcinogenesis.

Metabolic reprogramming is critical for the polarization and function of tumor-associated macrophages (TAM) and hepatocarcinogenesis, but how this reprogramming occurs is unknown. Here, we showed that receptor-interacting protein kinase 3 (RIPK3), a central factor in necroptosis, is downregulated in hepatocellular carcinoma (HCC)-associated macrophages, which correlated with tumorigenesis and enhanced the accumulation and polarization of M2 TAMs. Mechanistically, RIPK3 deficiency in TAMs reduced reactive oxygen species and significantly inhibited caspase1-mediated cleavage of PPAR. These effects enabled PPAR activation and facilitated fatty acid metabolism, including fatty acid oxidation (FAO), and induced M2 polarization in the tumor microenvironment. RIPK3 upregulation or FAO blockade reversed the immunosuppressive activity of TAMs and dampened HCC tumorigenesis. Our findings provide molecular basis for the regulation of RIPK3-mediated, lipid metabolic reprogramming of TAMs, thus highlighting a potential strategy for targeting the immunometabolism of HCC.

Reprogramming Tumor Associated Macrophages toward M1 Phenotypes with Nanomedicine for Anticancer Immunotherapy

AbstractTumor‐associated macrophages (TAMs), one of the most important constituents in tumor immunosuppressive microenvironments, are a potential therapeutic target due to their essential role in promoting tumor progression and metastasis. Macrophages are usually divided into two categories of protumoral M2‐like TAMs and antitumoral M1 phenotypes at the two extremes. Reprogramming M2‐like TAMs toward tumoricidal M1 phenotype is especially intriguing in terms of the restoration of antitumor immunity for anticancer immunotherapy. In this review, the recent advances of nanomedicine‐mediated reprogramming of TAMs from M2 to M1 to elicit the antitumor immunity are discussed. This reprogramming can be achieved via direct re‐education by targeted delivery of various active agents to TAMs and indirect re‐education by modulating the abnormal tumor microenvironment. Perspectives on nanomedicine mediated TAMs‐M1 reprogramming for effective anticancer immunotherapy are also presented.

Self-Propelled Gemini-like LMWH-Scaffold Nanodrugs for Overall Tumor Microenvironment Manipulation via Macrophage Reprogramming and Vessel Normalization.

Angiogenesis is the hallmark of melanoma that nurtures the tumor microenvironment (TME) for rapid tumor progression. Vessel normalization could benefit melanoma treatment through TME reconstruction, while its limited duration and extent are still the drag. Herein, two kinds of look-like nanodrugs, called Gemini-like nanodrugs (GLnano), were constructed separately with the same scaffold of antiangiogenic low molecular weight heparin (LMWH) and mixed upon administration in vivo. For one, doxorubicin (DOX) was encapsulated into LMWH-chrysin nanodrug (LCY) with DSPE-PEG-anisamide decoration (D-LCA nanodrugs) for active targeting and direct cell killing toward melanoma cells. For another, matrix metalloproteinases (MMPs)-sensitive peptide was conjugated to LMWH to encapsulate celecoxib (Cel) (C-Lpep nanodrugs), disassembling in TME by MMPs and releasing Cel for M2-to-M1 reprogramming of tumor-associated macrophages. Our results showed that GLnano could remarkably elongate the vessel normalization window up to 12 days with the highest pericyte coverage of nearly 75%, compared to only 4 days by LCY monotherapy. Furthermore, GLnano could spontaneously form the "treatment-delivery" loop to promote nanodrugs toward deep tumor regions, leading to a potent tumor inhibition, metastasis prevention, and overall TME improvements.

The Remarkable Plasticity of Macrophages: A Chance to Fight Cancer.

It is well established that tumor-associated macrophages (TAM) found in most advanced tumors have a pro-tumoral role. In this context, TAM limit the activity of tumor-infiltrating lymphocytes (TIL), and a number of mechanisms have been described including a trapping in the stroma, impeding TIL to reach malignant cells. Based on these results, a number of therapeutic approaches have been designed to deplete TAM. However, during tumor regression induced by immunotherapeutic treatments, recent studies revealed that TAM can switch from pro-tumoral to anti-tumoral and actively cooperate with TIL. Here, we will review the two faces of TAM in their interaction with TIL. We will summarize how they can inhibit T cell activities in growing tumors, and how they may also, together with T cells, successfully contribute to tumor eradication after an appropriate stimulation. Finally, we will discuss current promising therapies combining TAM reprogramming with T cell-based immunotherapy.

Abstract 1513: PI3Kγ inhibition activates T cell memory and relieves T cell exhaustion through the reprogramming of tumor-associated macrophages

Abstract We previously reported that macrophage PI3-kinase γ (PI3Kγ) controls a critical switch between immune stimulation and suppression during inflammation and cancer. PI3Kγ inhibition repolarizes tumor-associated macrophages, leading to downregulation of immune suppressive factors such as Arginase and IL10 and upregulation of IL12 and other pro-inflammatory cytokines. This results in recruitment and activation of intratumoral CD8+ T cells, as well as induction of immunological memory (Kaneda et al 2016). In the present study, we investigated the effect of PI3Kγ inhibition on T cell immune responses, including T cell memory induction and T cell exhaustion, in mouse models of head and neck squamous cell carcinomas (HNSCC). We found that Pik3cg−/− mice cleared implanted HPV+ HNSCC tumors; when re-challenged with tumor cells, these mice rapidly cleared secondary tumors and remained cancer-free. The proportion of T cells, especially CD8+ T cells, significantly increased in primary tumors from Pik3cg−/− mice. These CD8+ T cells expressed significantly more granzyme B and interferon and less T cell exhaustion markers than T cells from WT animals, indicating that PI3Kγ inhibition in macrophages results in T cell activation. We found that anti-tumor activity was transferable, as adoptive transfer of splenic T cells from Pik3cg−/− mice to naive WT mice suppressed tumor growth. Accordingly, Pik3cg−/− mice with primary or secondary tumors exhibited more splenic CD62L-CD44+ CD8+ effector memory T cells than WT mice. In summary, Pik3cg−/− mice exhibit a more activated T cell immune response and T cell memory than WT mice, resulting significant suppression of tumor growth. These results suggest that PI3Kγ-targeted therapy may activate durable T cell immune responses in patients with HNSCC. Citation Format: Hideyuki Takahashi, Paulina Pathria, Ann Shih, Ryan M. Shepard, Marc A. Paradise, Judith A. Varner. PI3Kγ inhibition activates T cell memory and relieves T cell exhaustion through the reprogramming of 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 1513.

Antibody-Fc/FcR Interaction on Macrophages as a Mechanism for Hyperprogressive Disease in Non-small Cell Lung Cancer Subsequent to PD-1/PD-L1 Blockade.

Hyperprogression (HP), a paradoxical boost in tumor growth, was described in a subset of patients treated with immune checkpoint inhibitors (ICI). Neither clinicopathologic features nor biological mechanisms associated with HP have been identified. Among 187 patients with non-small cell lung cancer (NSCLC) treated with ICI at our institute, cases with HP were identified according to clinical and radiologic criteria. Baseline histologic samples from patients treated with ICI were evaluated by IHC for myeloid and lymphoid markers. T-cell-deficient mice, injected with human lung cancer cells and patient-derived xenografts (PDX) belonging to specific mutational subsets, were assessed for tumor growth after treatment with antibodies against mouse and human programmed death receptor-1 (PD-1). The immune microenvironment was evaluated by flow cytometry and IHC. Among 187 patients, 152 were evaluable for clinical response. We identified four categories: 32 cases were defined as responders (21%), 42 patients with stable disease (27.7%), 39 cases were defined as progressors (25.7%), and 39 patients with HP (25.7%). Pretreatment tissue samples from all patients with HP showed tumor infiltration by M2-like CD163+CD33+PD-L1+ clustered epithelioid macrophages. Enrichment by tumor-associated macrophages (TAM) was observed, even in tumor nodules from immunodeficient mice injected with human lung cancer cells and with PDXs. In these models, tumor growth was enhanced by treatment with anti-PD-1 but not anti-PD-1 F(ab)2 fragments. These results suggest a crucial role of TAM reprogramming, upon Fc receptor engagement by ICI, eventually inducing HP and provide clues on a distinctive immunophenotype potentially able to predict HP.See related commentary by Knorr and Ravetch, p. 904.

Pooled Safety Analysis and Efficacy of Tenalisib (RP6530), a PI3Kδ/γ Inhibitor, in Patients with Relapsed/Refractory Lymphoid Malignancies

IntroductionTenalisib (RP6530) is a next generation, oral, selective, PI3Kδ/g inhibitor with nanomolar inhibitory potency. Besides its apoptotic and anti-proliferative activity, Tenalisib modulates the tumor microenvironment resulting in reprogramming of tumor associated-macrophages (TAMs) from a protumor M2 phenotype to an antitumor M1 phenotype and a marked reduction of angiogenesis in pre-clinical models. Tenalisib has demonstrated activity in patients with relapsed/refractory lymphoid malignancies (Carmelo, ASH 2016 and Oki, ASCO 2018).Since there are concerns over long-term safety of PI3K δ or PI3K dual δ/g inhibitors with respect to immune-mediated toxicities (e.g. transaminitis, colitis and pneumonitis), cytopenias, and infections, a pooled safety analysis across two Phase I studies in patients treated with Tenalisib was performed.MethodsSafety data was pooled from two Phase I Tenalisib monotherapy trials (NCT02017613 and NCT02567656) with similar key eligibility criteria. Patients had R/R lymphoid malignancies with ≥1 prior therapy. Responses were evaluated in lymphoid malignancies using IWG criteria (Cheson et al., 2007) and in CTCL using the modified Severity Weighted Assessment Tool (mSWAT). Adverse events were graded according to CTCAE v4.03.ResultsA total of 93 patients were included in the analysis. Among these patients, 34% were PTCL, 32% CTCL, 16% HL, 6% DLBCL and 12% were other lymphomas. Patients received a median of 5 prior therapies. 53 % of patients received Tenalisib for ≤ 3 months, 21% for 3-6 months and 26% for > 6 months.The overall incidence of related AEs and ≥G3 AEs were 58% and 29% respectively (Table 1). Very few AEs were seen with exposures >6 months and mainly included single cases of diarrhea, anemia, edema, and abdominal pain. There were no incidences of late onset toxicities such as colitis and pneumonitis and most of the AEs happened during the initial three months of therapy. No treatment discontinuations due to AE's were seen in patients exposed to > 6 months of treatment.Efficacy response assessments of the 66 evaluable patients demonstrated an ORR of 45% in TCL (44% in PTCL (8/18, 3 CR, 4 PR) & 45% in CTCL (9/20, 9 PR)), 29% (4/14; 1CR; 3PR) in HL, and 13% (1/6; 1CR) in DLBCL.ConclusionIn this pooled safety analysis with long term follow-up, Tenalisib exhibited an improved safety profile when compared to other investigational/marketed PI3K inhibitors. The incidence of transaminitis was low and occurred within the first two to three cycles of therapy. In particular, there were no occurrences of pneumonitis or colitis in patients that had been on treatment for > 3 months and beyond. Incidence of neutropenia/thrombocytopenia and infections was limited. Tenalisib can therefore be safely combined with a diverse array of other agents active in lymphoid malignancies. Tenalisib is currently being studied in combination with Pembrolizumab and Romidepsin and as a monotherapy in a Phase II trial in indolent NHL. [Display omitted] DisclosuresHaverkos:Viracta Therapeutics: Membership on an entity's Board of Directors or advisory committees. Ramchandren:Pharmacyclics LLC an AbbVie Company: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy; Merck: Research Funding; Janssen: Consultancy, Research Funding. Devata:Affimed: Research Funding. Routhu:Rhizen Pharmaceuticals SA: Employment. Barde:Rhizen Pharmaceuticals SA: Employment. Nair:Rhizen Pharmaceuticals SA: Employment. Carlo-Stella:Boehringher Ingelheim Italia: Consultancy; Sanofi: Consultancy; MSD Italia: Speakers Bureau; Rhizen Pharmaceuticals: Research Funding; AstraZeneca: Speakers Bureau; ADC Therapeutics: Research Funding, Speakers Bureau; Janssen: Speakers Bureau; Genenta Science: Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Amgen: Speakers Bureau.

Reprogramming Tumor-Associated Macrophages by Nanoparticle-Based Reactive Oxygen Species Photogeneration.

Without coordinated strategies to mitigate the immunosuppressive nature of the tumor microenvironment, cancer immunotherapy generally offers limited clinical benefit for established tumors. Tumor-associated macrophages (TAMs) are the critical driver of this immunosuppressive tumor microenvironment, which also promotes tumor metastasis. Here we successfully reprogrammed TAMs to an antitumor M1 phenotype using precision nanoparticle-based reactive oxygen species photogeneration, which demonstrated superior efficiency and efficacy over lipopolysaccharide stimulation. Meanwhile, antigen presentation and T-cell-priming by TAMs were enhanced by inhibiting lysosomal proton pump and proteolytic activity or by promoting tumor associated antigen release in the cytoplasm. The reprogrammed TAMs orchestrate cytotoxic lymphocyte (CTL) recruitment in the tumor and direct memory T-cells toward tumoricidal responses. This strategy could effectively eradicate tumors, inhibit metastasis, and further prevent their recurrence, which holds tremendous promise to realize potent cancer immunotherapy.

Bioinspired tumor-homing nanosystem for precise cancer therapy via reprogramming of tumor-associated macrophages

Rational design of smart nanosystems with high biological safety is a critical milestone for realizing precise imaging-guided cancer theranostics. Herein, a bioinspired nanosystem was designed by camouflaging SPIO@DOX-ICG nanoparticles with cancer cell membrane (CCM) to realize precise cancer treatment through simultaneous chemotherapy, hyperthermia-therapy, and radiotherapy. CCM surface decoration preserves the cancer adhesion molecules and surface antigens in the nanosystem, endowing the nanosystem with tumor-homing ability and high biocompatibility. Guided by dual-modal imaging, the nanosystem specifically accumulated in the tumor region and achieved synergistic anticancer effects after combined treatment, without causing toxic side effects in major organs. Interestingly, the combined treatment also antagonized tumor hypoxia and reprogrammed the polarization of tumor associated macrophages to the antitumor M1 phenotype. Taken together, this study offers a smart strategy for designing a bioinspired tumor-homing nanosystem for precise cancer therapy.

Abstract A31: Reprogramming of tumor-associated macrophages by anti-Program Death Ligand 1 (PDL1)

Abstract Tumor-associated macrophages play a vital role in shaping tumor environment and contribute to the cancer-immune set point. Immunotherapy such as aPD1/aPDL1 has demonstrated remarkable therapeutic efficacy on a variety of cancers through reinvigorating CD8+ T cells. However, its impact on macrophages largely remains unclear. Here by using mouse MC38 cancer model, we show that aPDL1 re-programs macrophages from M2-like to M1-like: it decreases Arginase-I (ARG1), an M2-like marker, and increases iNOS and MHCII, both M1-like markers, on macrophages. Next, we investigate the mechanism behind the reprogramming. We identify that IFNg from CD8+ T cells and NK cells is boosted by aPDL1 and is required for macrophage re-polarization. IFNg blockade abrogates this process. Finally, we examine additional cancer models and observe similar phenotypes in another aPDL1-responsive model, but not in a third, non-responsive model. We conclude that tumor associated macrophage is re-programmed from M2-like to M1-like following aPDL1 treatment, and that it is mediated by enhanced IFNg in the tumor environment. Our findings suggest macrophage reprogramming as a novel mechanism and an independent avenue to promote antitumor activity via modulation of the cancer-immune set point. Citation Format: Huizhong Xiong, Marina Moskalenko, Ryan Rodriguez, Stephanie Mittman, Michelle Yang, Jeong Kim, Rafael Cubas Barcelli. Reprogramming of tumor-associated macrophages by anti-Program Death Ligand 1 (PDL1) [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr A31.

Abstract 3133: Reprogramming of tumor-associated macrophages by a short synthetic peptide eradicates ovarian cancer

Abstract Purpose: Ovarian cancer is the deadliest gynecologic malignancy with limited treatment options and novel therapies urgently needed. Immunosuppressive microenvironment is critical for tumor progression and immune checkpoint inhibitors, which enable T-cell anticancer immunity revolutionized the outcomes in multiple cancer types. However, this approach had limited success in ovarian cancer. Our small therapeutic peptides, derived from an endogenous type 2 tumor suppressor, Pigment Epithelium-Derived Factor (PEDF), act through an alternative immune mechanism, repolarization of tumor-associated macrophages (TAMs) to the tumor-suppressive phenotype.Experimental Design: Short peptides based on the PEDF's active domain were modified for improved stability and efficacy. Two peptides (PMD-427, PMD-336) were tested in preclinical ovarian cancer models using the human chemoresistant cell line, OvCar-3, and transformed mouse cell line ID8. We also performed mechanistic analysis of the peptides' anti-tumor action, including effects on macrophages cytotoxic, cytokine secretion and migratory activity in vitro and in vivo. Results: PEDF peptide PMD-427 caused > 20-fold reduction in tumor burden. PMD-427 induced selective apoptosis in ovarian cancer cells but not in normal ovarian epithelium. This selectivity was based on context-specific modulation of extrinsic death cascades, Fas and FasL. More importantly, PMD-427 peptides also stimulated macrophage polarization from M2 to M1 phenotype as was evidenced by the shift in cytokine profile (decreased IL-10 and increased IL-12 expression), altered morphology (increased number of dendrite-like-processes) and other changes in M2 markers (attenuated PD-L1 expression). M2/M1 macrophage polarization was also evident by tumor immunostaining. Critically, PMD peptides ovarian cancer cell killing by macrophages as was determined in co-culture studies; this fratricidal activity was reliant on the expression of TRAIL by the macrophages and of its cognate receptor, DR5 by ovarian cancer cells, respectively. Combined with enhanced macrophage motility as observed by time-lapse micropscopy, these changes resulted in increased macrophage recruitment to the tumors and enhance killing of the cancer cells in vivo. The key role of macrophages in the anti-cancer effects of PMD peptides was confirmed by depletion of macrophages in ovarian tumor bearing mice using clodronate liposomes. Conclusions: We have generated a first-in-class multi-targeted peptide drug, which promotes macrophage polarization that results in eradication of ovarian tumors in mice. Citation Format: Reshma Bhowmick, Elena Vinokour, Michael Paul Plebanek, Marisol Villanueva, Victor Shifrin, Jack Henkin, Ignacio Melgar-Asensio, James Petrik, Raghu Kallurie, Olga V. Volpert. Reprogramming of tumor-associated macrophages by a short synthetic peptide eradicates ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3133.

Abstract 69: Chemotherapy-induced cancer cell death diminishes therapeutic efficacy through heme oxygenase-1-mediated inactivation of M1-like tumor associated macrophages

Abstract One of the most common treatment options for cancer is a chemotherapy. After chemotherapy, however, unwanted host effects provoke tumor recurrence and aggressiveness of cancer cells, which often arise as a consequence of disruption in the patient's immune system. Lymphocytes, such as CD8+ cytotoxic T lymphocytes (CTLs), which have capability of suppressing cancer progression, are depleted following chemotherapy. Conventional chemotherapeutic agents kill cancer cells, which boosts recruitment of myeloid cells. Tumor-associated macrophages (TAMs), emerging as abundant tumor-infiltrating myeloid cells in tumor microenvironment, play an important role in immunosuppression caused by conventional chemotherapy. Chemotherapy-induced dying cancer cells could hijack accumulated TAMs, provoking tumor recurrence. Therefore, reprogramming of TAMs to maximize the chemotherapeutic efficacy is considered a promising novel anticancer strategy. In this study, we investigated whether dying cancer cells after chemotherapy could reduce therapeutic efficacy by modulating tumor-infiltrating macrophage activity. In a 4T1 syngeneic mouse breast cancer model, there was a marked decrease in the proportion of M1-like TAMs expressing CD86 with tumor-suppressive activity and reduced tumor infiltration of CTLs following treatment with paclitaxel. Paclitaxel treatment also resulted in an enhancement of heme oxygenase-1 (HO-1) mRNA levels in tumor-infiltrating myeloid cells engulfing dying cancer cells. Consistent with the in vivo profile of TAMs, bone marrow-derived macrophages (BMDMs) phagocytosing dying breast cancer cells exhibited significant upregulation of HO-1 expression. HO-1 induction in BMDMs engulfing dying breast cancer cells facilitated M2 polarization. In contrast, abrogation of HO-1 activity sustained M1 activation of BMDMs co-cultured with dying breast cancer cells. Pharmacologic inhibition of HO-1 activity with zinc protoporphyin IX augmented paclitaxel efficacy by stimulating tumor infiltration of CTLs in a 4T1 breast cancer model. Furthermore, blockade of HO-1 in breast tumor-bearing mice induced increased M1-like TAMs expressing CD86 that plays an important role in stimulating antitumor immune response. Taken together, HO-1 induction by the chemotherapy-derived dying cancer cells in TAMs dampens antitumor effects of chemotherapy by manipulating innate and adaptive immunity. Our results demonstrate that targeting overexpressed HO-1 in the breast tumor microenvironment can control the immune system to potentiate the efficacy of chemotherapy. Citation Format: Seung Hyeon Kim, Xiancai Zhong, Shin-Young Gwak, Ishrat Aklima Muna, Sin-Aye Park, Young-Nam Cha, Young-Joon Surh. Chemotherapy-induced cancer cell death diminishes therapeutic efficacy through heme oxygenase-1-mediated inactivation of M1-like tumor associated macrophages [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 69.

Abstract 4730: Targeting glutamine metabolism enhances tumor specific immunity by inhibiting the generation and function of suppressive myeloid cells

Abstract In order to sustain their inexorable growth, tumors have specialized reprogrammed metabolism. This metabolism creates an acidic, hypoxic and nutrient-depleted tumor microenvironment (TME). Such an environment inhibits antitumor effector cells while promoting the differentiation and function of inhibitory cells such as T regulatory cells, myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAM). We hypothesized that by targeting tumor metabolism we could alter the TME and “condition” tumors to be more susceptible to immunotherapy. To this end, along with the Johns Hopkins Drug Discovery Program we developed a novel prodrug of 6-diazo-5-oxo-l-norleucine, inhibitor of glutamine metabolism (JHU-083). Recently, it has been shown that M2 macrophages require glutamine metabolism for differentiation and function. In light of the similarities between M2 macrophages and suppressive myeloid cells, we hypothesized that JHU-083 might inhibit the generation and function of MDSCs and TAMs. We tested this hypothesis in the 4T1 breast cancer model and 3LL lung carcinoma model. These tumors are relatively resistant to immunotherapy and are characterized by increased generation of MDSCs and distant spontaneous metastasis. JHU-083 treated mice suppressed tumor growth compared to the vehicle treated group. Immunologically, we observed markedly reduced numbers of MDSCs in circulating blood within 3 days of drug treatment compared to vehicle group, leading to favorable CD8 to MDSCs ratios. Consistently, JHU083-treated group displayed significantly decreased percentages and numbers of MDSCs in the tumor, and increased tumor infiltrating CD8 cells. Interestingly, JHU-083 treatment induced TAM reprogramming. While the TAM from the vehicle treated group displayed increased M2 markers and arginase; the JHU-083 treated tumor-infiltrating cells showed increased TNF-a producing M1-like macrophage phenotypes compared to vehicle group. These TNF-a producing cells were negatively correlated with tumor sizes. Notably, JHU083 treatment not only controlled primary tumor growth but also drastically reduced spontaneous lung metastasis. The decrease of MDSCs infiltration in the lung were also observed in JHU083-treated group. Mechanistically, our data suggest that JHU-083 inhibits CSF2/CSF3 production and survival of the tumor itself as well as directly affects macrophage metabolism and signaling. Also, LC-MS based metabolites analysis from JHU-083 treated tumors revealed reduced kynurenine:tryptophan ratios compared to the control group, indicating the metabolic modulation of the tumor microenvironment. Overall, our data support a novel role for glutamine inhibitor, JHU-083, in enhancing tumor-specific Immunity by targeting suppressive myeloid cells. Citation Format: Min-Hee Oh, Im-Hong Sun, Liang Zhao, Im-Meng Sun, Wei Xu, Chirag Patel, Robert Leone, Ada J. Tam, Judd Englert, Pavel Majer, Rana Rais, Barbara Slusher, Maureen R. Horton, Jonathan D. Powell. Targeting glutamine metabolism enhances tumor specific immunity by inhibiting the generation and function of suppressive myeloid cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4730.

Enhanced Cellular Ablation by Attenuating Hypoxia Status and Reprogramming Tumor-Associated Macrophages via NIR Light-Responsive Upconversion Nanocrystals.

Near-infrared (NIR) light-mediated photodynamic therapy (PDT), especially based on lanthanide-doped upconversion nanocrystals (UCNs), have been extensively investigated as a promising strategy for effective cellular ablation owing to their unique optical properties to convert NIR light excitation into multiple short-wavelength emissions. Despite the deep tissue penetration of NIR light in living systems, the therapeutic efficiency is greatly restricted by insufficient oxygen supply in hypoxic tumor microenvironment. Moreover, the coexistent tumor-associated macrophages (TAMs) play critical roles in tumor recurrence during the post-PDT period. Herein, we developed a unique photosensitizer-loaded UCNs nanoconjugate (PUN) by integrating manganese dioxide (MnO2) nanosheets and hyaluronic acid (HA) biopolymer to improve NIR light-mediated PDT efficacy through attenuating hypoxia status and synergistically reprogramming TAMs populations. After the reaction with overproduced H2O2 in acidic tumor microenvironment, the MnO2 nanosheets were degraded for the production of massive oxygen to greatly enhance the oxygen-dependent PDT efficiency upon 808 nm NIR light irradiation. More importantly, the bioinspired polymer HA could effectively reprogram the polarization of pro-tumor M2-type TAMs to anti-tumor M1-type macrophages to prevent tumor relapse after PDT treatment. Such promising results provided the great opportunities to achieve enhanced cellular ablation upon NIR light-mediated PDT treatment by attenuating hypoxic tumor microenvironment, and thus facilitated the rational design of new generations of nanoplatforms toward immunotherapy to inhibit tumor recurrence during post-PDT period.

CYP4X1 Inhibition by Flavonoid CH625 Normalizes Glioma Vasculature through Reprogramming TAMs via CB2 and EGFR-STAT3 Axis.

Tumor-associated macrophages (TAMs) are pivotal effector cells in angiogenesis. Here, we tested whether CYP4X1 inhibition in TAMs by flavonoid CH625 prolongs survival and normalizes glioma vasculature. CH625 was selected against the CYP4X1 3D model by virtual screening and showed inhibitory activity on the CYP4X1 catalytic production of 14,15-EET-EA in the M2-polarized human peripheral blood mononuclear cells (IC50 = 16.5 μM). CH625 improved survival and reduced tumor burden in the C6 and GL261 glioma intracranial and subcutaneous model. In addition, CH625 normalized vasculature (evidenced by a decrease in microvessel density and HIF-1α expression and an increase in tumor perfusion, pericyte coverage, and efficacy of temozolomide therapy) accompanied with the decreased secretion of 14,15-EET-EA, VEGF, and TGF-β in the TAMs. Furthermore, CH625 attenuated vascular abnormalization and immunosuppression induced by coimplantation of GL261 cells with CYP4X1high macrophages. In vitro TAM polarization away from the M2 phenotype by CH625 inhibited proliferation and migration of endothelial cells, enhanced pericyte migration and T cell proliferation, and decreased VEGF and TGF-β production accompanied with the downregulation of CB2 and EGFR-dependent downstream STAT3 expression. These effects were reversed by overexpression of CYP4X1 and STAT3 or exogenous addition of 14,15-EET-EA, VEGF, TGF-β, EGF, and CB2 inhibitor AM630. These results suggest that CYP4X1 inhibition in TAMs by CH625 prolongs survival and normalizes tumor vasculature in glioma via CB2 and EGFR-STAT3 axis and may serve as a novel therapeutic strategy for human glioma.

Metabolic changes in tumor cells and tumor-associated macrophages: A mutual relationship

In order to adapt to the reduced availability of nutrients and oxygen in the tumor microenvironment and the increased requirements of energy and building blocks necessary for maintaining their high proliferation rate, malignant cells undergo metabolic changes that result in an increased production of lactate, nitric oxide, reactive oxygen species, prostaglandins and other byproducts of arachidonic acid metabolism that influence both the composition of the inflammatory microenvironment and the function of the tumor-associated macrophages (TAMs). In response to cues present in the TME, among which products of altered tumor cell metabolism, TAMs are also required to reprogram their metabolism, with activation of glycolysis, fatty acid synthesis and altered nitrogen cycle metabolism. These changes result in functional reprogramming of TAMs which includes changes in the production of cytokines and angiogenetic factors, and contribute to the tumor progression and metastasis. Understanding the metabolic changes governing the intricate relationship between the tumor cells and the TAMs represents an essential step towards developing novel therapeutic approaches targeting the metabolic reprogramming of the immune cells to potentiate their tumoricidal potential and to circumvent therapy resistance.

Reprogramming of Tumor-Associated Macrophages with Anticancer Therapies: Radiotherapy versus Chemo- and Immunotherapies.

Tumor-associated macrophages (TAMs) play a central role in tumor progression, metastasis, and recurrence after treatment. Macrophage plasticity and diversity allow their classification along a M1–M2 polarization axis. Tumor-associated macrophages usually display a M2-like phenotype, associated with pro-tumoral features whereas M1 macrophages exert antitumor functions. Targeting the reprogramming of TAMs toward M1-like macrophages would thus be an efficient way to promote tumor regression. This can be achieved through therapies including chemotherapy, immunotherapy, and radiotherapy (RT). In this review, we first describe how chemo- and immunotherapies can target TAMs and, second, we detail how RT modifies macrophage phenotype and present the molecular pathways that may be involved. The identification of irradiation dose inducing macrophage reprogramming and of the underlying mechanisms could lead to the design of novel therapeutic strategies and improve synergy in combined treatments.

Abstract SY06-01: Tumor-associated myelomonocytic cells as therapeutic targets

Abstract SY06-01: Tumor-associated myelomonocytic cells as therapeutic targets

Reprogramming Tumor-Associated Macrophages by Antibody Targeting Inhibits Cancer Progression and Metastasis.

Tumors are composed of multiple cell types besides the tumor cells themselves, including innate immune cells such as macrophages. Tumor-associated macrophages (TAMs) are a heterogeneous population of myeloid cells present in the tumor microenvironment (TME). Here, they contribute to immunosuppression, enabling the establishment and persistence of solid tumors as well as metastatic dissemination. We have found that the pattern recognition scavenger receptor MARCO defines a subtype of suppressive TAMs and is linked to clinical outcome. An anti-MARCO monoclonal antibody was developed, which induces anti-tumor activity in breast and colon carcinoma, as well as in melanoma models through reprogramming TAM populations to a pro-inflammatory phenotype and increasing tumor immunogenicity. This anti-tumor activity is dependent on the inhibitory Fc-receptor, FcγRIIB, and also enhances the efficacy of checkpoint therapy. These results demonstrate that immunotherapies using antibodies designed to modify myeloid cells of the TME represent a promising mode of cancer treatment.

A novel copper chelate modulates tumor associated macrophages to promote anti-tumor response of T cells.

BackgroundAt the early stages of carcinogenesis, the induction of tumor specific T cell mediated immunity seems to block the tumor growth and give protective anti-tumor immune response. However, tumor associated macrophages (TAMs) might play an immunosuppressive role and subvert this anti tumor immunity leading to tumor progression and metastasis.Methodology/Principal FindingsThe Cu (II) complex, (chelate), copper N-(2-hydroxy acetophenone) glycinate (CuNG), synthesized by us, has previously been shown to have a potential usefulness in immunotherapy of multiple drug resistant cancers. The current study demonstrates that CuNG treatment of TAMs modulates their status from immunosuppressive to proimmunogenic nature. Interestingly, these activated TAMs produced high levels of IL-12 along with low levels of IL-10 that not only allowed strong Th1 response marked by generation of high levels of IFN-γ but also reduced activation induced T cell death. Similarly, CuNG treatment of peripheral blood monocytes from chemotherapy and/or radiotherapy refractory cancer patients also modulated their cytokine status. Most intriguingly, CuNG treated TAMs could influence reprogramming of TGF-β producing CD4+CD25+ T cells toward IFN-γ producing T cells.Conclusion/SignificanceOur results show the potential usefulness of CuNG in immunotherapy of drug-resistant cancers through reprogramming of TAMs that in turn reprogram the T cells and reeducate the T helper function to elicit proper anti-tumorogenic Th1 response leading to effective reduction in tumor growth.