Repolarization Of Tumor-associated Macrophages Research Articles

Antiglioma via regulating oxidative stress and remodeling tumor-associated macrophage using lactoferrin-mediated biomimetic codelivery of simvastatin/fenretinide

Effective treatment of malignant glioma still remains a formidable challenge due to lack of the effective BBB-permeable drugs and efficient brain delivery methods, and the pharmacotherapy options are very limited. Therefore, to develop an effective therapeutic strategy is a pressing need. In this work, a noncytotoxic drug combination (i.e., simvastatin and fenretinide) was revealed to be potent for treating glioma, which was co-encapsulated into a TPGS-TAT-embedded lactoferrin nanoparticle system for achieving brain-targeted biomimetic delivery via the LRP-1 receptor. It was shown that the lactoferrin nanoparticle repolarized the tumor-associated macrophages from the M2 phenotype to M1 via regulating the STAT6 pathway, as well as induced the ROS-mediated mitochondrial apoptosis by inhibiting the Ras/Raf/p-Erk pathway in the glioma cells. The antiglioma efficacy was further demonstrated in both the subcutaneous and orthotopic glioma models. The repolarization of tumor-associated macrophages not only prompted the ROS generation but also induced the innate immunity (e.g., antitumor cytokine release). This delivery and therapeutic strategy provides a novel modality for the glioma treatment.

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.

Repolarization of Tumor-Associated Macrophages in a Genetically Engineered Nonsmall Cell Lung Cancer Model by Intraperitoneal Administration of Hyaluronic Acid-Based Nanoparticles Encapsulating MicroRNA-125b.

Tumor-associated macrophages (TAMs) acquire a pro-tumor (M2) phenotype, which promotes tumor growth, angiogenesis, and metastasis. Certain microRNAs (miRs), such as miR-125b, can reprogram TAMs into an antitumor/pro-inflammatory (M1) phenotype. Using CD44 targeting hyaluronic acid-poly(ethylenimine) (HA-PEI)-based nanoparticles encapsulating miR-125b, we have herein shown macrophage-specific delivery and transfection upon intraperitoneal (i.p.) administration. We have exploited the inherent ability of peritoneal macrophages to migrate toward the inflammation/injury and demonstrated that following intraperitoneal administration of HA-PEI nanoparticles, there is an accumulation of HA-PEI nanoparticles in the macrophage-ablated lung tissues of both naïve and KRAS/p53 double mutant genetically engineered (KP-GEM) nonsmall cell lung cancer (NSCLC) mouse model. Additionally, upon transfection with miR-125b, we observed a >6-fold increase in the M1 to M2 macrophage ratio and 300-fold increase in the iNOS (M1 marker)/Arg-1 (M2 marker) ratio in TAMs as compared to the untreated control group. The results of these studies show that i.p. administered macrophage-specific HA-PEI nanoparticles can successfully transfect TAMs in lung tissues of both naïve mice and a KP-GEM NSCLC mouse model. Successful TAM repolarization toward the M1 phenotype has significant implication in anticancer immunotherapy.

ROS-Inducing Micelles Sensitize Tumor-Associated Macrophages to TLR3 Stimulation for Potent Immunotherapy

One approach to cancer immunotherapy is the repolarization of immunosuppressive tumor-associated macrophages (TAMs) to antitumor M1 macrophages. The present study developed galactose-functionalized zinc protoporphyrin IX (ZnPP) grafted poly(l-lysine)- b-poly(ethylene glycol) polypeptide micelles (ZnPP PM) for TAM-targeted immunopotentiator delivery, which aimed at in vivo repolarization of TAMs to antitumor M1 macrophages. The outcomes revealed that ROS-inducing ZnPP PM demonstrated specificity for the in vitro and in vivo targeting of macrophages, elevated the level of ROS, and lowered STAT3 expression in BM-TAMs. Poly I:C (PIC, a TLR3 agonist)-loaded ZnPP PM (ZnPP PM/PIC) efficiently repolarized TAMs to M1 macrophages, which were reliant on ROS generation. Further, ZnPP PM/PIC substantially elevated the activated NK cells and T lymphocytes in B16-F10 melanoma tumors, which caused vigorous tumor regression. Therefore, the TAM-targeted transport of an immunologic adjuvant with ZnPP-grafted nanovectors may be a potential strategy to repolarize TAMs to M1 macrophages in situ for effective cancer immunotherapy.

Imaging and Treatment of Primary Tumors and Metastases by Targeted Macrophage Therapy, Using Radiation Therapy-Directed Encapsulated Nanoparticles

Liposome-protamine-hyaluronic acid nanoparticles (LPH-NPs; 173 ± 7.2 nm in diameter) encapsulated in oxygen-rich microcapsules (3.6 ± 0.8 μm in diameter) that release their contents upon exposure to radiation were used in two radiotherapy sessions. We investigated primary tumor and metastasis imaging and macrophage-based therapy through silencing of “don’t eat me” signals and an increase in tumor-associated macrophages (TAMs) of M1 phenotype. For the first radiotherapy session, LPH-NPs, containing 5% iopamiron, and 250 nmol anti-CD47 small interfering RNA (siRNA) were mixed with 1.0 mL oxygen-rich solution (2200 ppm O2) containing 4.0% alginate, 3.0% hyaluronate, 1 mg ascorbate, and 1 μg/mL CD-40 and sprayed into 0.5 mmol/L FeCl2 supplemented with 1 μg/mL anti-vascular endothelial growth factor receptor (VEGFR)-1/2 antibody (Ab). The resultant microcapsules (1 × 1010) were intravenously (i.v.) administered into C57BL/6 mice with a primary MC38 tumor in the left hind leg and lung metastases, and their accumulation in the tumor was monitored by computed tomography (CT). Subsequently, the primary tumors and metastases were treated with 10 or 20 Gy 60Co γ-radiation. For the second session, microcapsules were generated by mixing LPH-NPs containing 200 μg anti-CD40 monoclonal Ab (moAb) and 900,000 IU interleukin (IL)-2, with the same oxygen-rich cocktail used in session one, and were sprayed into 0.5 mmol/L FeCl2 supplemented with 1 μg/mL anti-P-selectin Ab. They were then i.v. administered into the mice and allowed to interact with P-selectin for 9 h prior to a second radiotherapy with 10 or 20 Gy 60Co γ-radiation. In session one, the anti-VEGFR-1/2 microcapsules accumulated around the primary and metastatic tumors as detected by CT, and in response to the irradiation, they released anti-CD 47 siRNA LPH-NPs and oxygen-rich water, which silenced “don’t eat me” signals and increased tumor oxygen concentration, respectively. In session two, the microcapsules accumulated around the primary tumor through a P-selectin antigen-antibody reaction, and in response to the irradiation, they released anti-CD 40 moAb/IL-2 LPH-NPs and oxygen-rich water. Additionally, the radiation recruited TAMs in the tumors. The released anti-CD 40 moAb/IL-2 switched the phenotype of the recruited TAMs from M2 to M1, and the increased oxygen concentration due to the repeatedly released oxygen-rich water inhibited TAM repolarization from M1 to M2, leading to an increase in TAMs of M1 phenotype, which then attacked the tumors for which the “don’t eat me” signals were already silenced in session one. These treatments significantly increased the antitumor effect (EF 1.8) and reduced metastasis by 82.6%. Our CT-detectable microcapsules exhibited targeted macrophage therapy, improving tumor diagnosis and treatment.

Beyond the M-CSF receptor - novel therapeutic targets in tumor-associated macrophages.

Tumor-associated macrophages (TAM) are by now established as important regulators of tumor progression by impacting on tumor immunity, angiogenesis, and metastasis. Hence, a multitude of approaches are currently pursued to intervene with TAM's protumor activities, the most advanced of which being a blockade of macrophage-colony stimulating factor (M-CSF)/M-CSF receptor (M-CSFR) signaling. M-CSFR signaling largely impacts on the differentiation of macrophages, including TAM, and hence strongly influences the numbers of these cells in tumors. However, a repolarization of TAM toward a more antitumor phenotype may be more elegant and may yield stronger effects on tumor growth. In this respect, several aspects of TAM behavior could be altered, such as their intratumoral localization, metabolism and regulatory pathways. Intervention strategies could include the use of small molecules but also new generations of biologicals which may complement the current success of immune checkpoint blockers. This review highlights current work on the search for new therapeutic targets in TAM.

Abstract SY06-02: Macrophage-targeted cancer immunotherapy

Abstract Combining immunotherapies that harness cytotoxic T cells to fight cancer has become a major effort in treating metastatic cancer patients. We present data on an example of cancer immunotherapy combination targeting innate immune cells, in particular tumor-associated macrophages (TAMs), that is currently being tested in the clinic. Combination of a TAM-depleting anti-CSF-1R antibody with an activating anti-CD40 agonist demonstrated synergistic antitumoral efficacy resulting in complete tumor remission in preclinical mouse cancer models. Ex vivo RNA sequencing of sorted TAM revealed that only the combination treatment induced a transient, profound repolarization of TAMs towards an immunostimulatory M1 phenotype. However, these TAM populations are ultimately eliminated. The central role of macrophages was further substantiated by complete loss of therapeutic benefit when TAMs were depleted prior to combinational treatment. Furthermore, rechallenge and depletion experiments demonstrated that tumor rejection is finally mediated by an antitumoral T-cell response. In colorectal cancer patients coexpression of human CSF1R and CD40 on TAMs was detected, providing the basis to explore this combination in the clinic. Citation Format: Carola Ries. Macrophage-targeted cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr SY06-02. doi:10.1158/1538-7445.AM2017-SY06-02

Attenuated listeria monocytogenes reprograms M2-polarized tumor-associated macrophages in ovarian cancer leading to iNOS-mediated tumor cell lysis (TUM4P.908)

Abstract A principal mechanism by which tumors evade immune-mediated elimination is through immunosuppression. Previous approaches to tumor immunotherapy have focused on modifying the immunosuppressive environment with immune checkpoint inhibitors, cytokine therapy, and other modalities with the intent to generate T-cell based anti-tumor immunity. We hypothesized that transformation of the suppressive ovarian cancer microenvironment could be achieved by introduction of the attenuated ΔactA/ΔinlB strain of Listeria monocytogenes. ΔactA/ΔinlB introduced into the microenvironment of the aggressive ID8-Defb29/Vegf-A murine ovarian carcinoma is preferentially phagocytosed by tumor-associated macrophages (TAMs) and reprograms that population from one of suppression to immunostimulation. TAMs in the peritoneum upregulated their co-stimulatory molecules CD80 and CD86, increased transcription of inflammatory cytokines, and downregulated transcription of suppressive effector molecules. Surprisingly, therapeutic benefit was not mediated by T- or NK-cell activity. ΔactA/ΔinlB-induced repolarization of TAMs activated direct tumor cell lysis via Nos2 production of nitric oxide. Modulation of the immunosuppressive nature of the ID8-Defb29/Vegf-A microenvironment, specifically by reprogramming of the TAM suppressive population from M2 to M1 polarization, is critical for our observed immune-mediated survival benefit.

Novel antitumor mechanism-of-action of an IL-2 fusion protein mediated by tumor associated macrophage repolarization and innate-like CD8+ memory T cells

Meeting abstracts ALT-801, a fusion of interleukin-2 and a single-chain T cell receptor domain specific to a p53 peptide/HLA-A*0201 complex, has shown immune cell-mediated activity in human xenograft tumor SCID mouse models and in patients with metastatic malignancies. To further investigate the

Re-polarization of tumor-associated macrophages to pro-inflammatory M1 macrophages by microRNA-155

Re-polarization of tumor-associated macrophages to pro-inflammatory M1 macrophages by microRNA-155

569 POSTER Preclinical studies and characterization of BMS-777607, a small molecule inhibitor of Met receptor tyrosine kinase

Pancreatic cancer (PAC) is one of the most lethal malignant neoplasms with poor prognosis and high mortality. Emerging evidence has revealed that abnormal tumor lipid metabolism and tumor-associated macrophages (TAMs) significantly contribute to PAC development and progression. Therefore, concurrently reprogramming tumor lipid metabolism and regulating TAMs function could be a promising strategy for effective PAC therapy. Herein, we identified an important enzyme catabolizing lipids (monoacylglycerol lipase, MGLL) and a key receptor regulating macrophage phenotype (endocannabinoid receptor-2, CB-2) that are over-expressed in PAC cells and on TAMs, respectively. Based on this finding, we developed a reduction-responsive poly (disulfide amide) (PDSA)-based nanoplatform for systemic co-delivery of MGLL siRNA (siMGLL) and CB-2 siRNA (siCB-2). This nanoplatform could utilize its reduction-responsive characteristic to rapidly release siRNA for efficient silencing of MGLL and CB-2, inducing concurrent suppression of free fatty acids (FFAs) generation in PAC cells and repolarization of TAMs into tumor-inhibiting M1-like phenotype. With this suppressed FFAs generation to inhibit nutrient supply for tumor cells and repolarized TAMs to secrete tumoricidal cytokines such as TNF-α and IL-12, a combinational anticancer effect could be achieved in both xenograft and orthotopic PAC tumor models.