SIRPa ablation overcomes exhaustion and enhances the antibody- and CAR-mediated antitumor activities of iPSC-derived CAR Macrophages
Ontology highlight
ABSTRACT: SIRPa-CD47 “don’t eat me” checkpoint axis plays a critical role in defining anti-tumor activities of macrophages within the tumor microenvironment. However, targeting this axis with anti-CD47 antibodies to improve anti-tumor responses in clinical trials has proven challenging. Here, we demonstrated that iPSC-derived macrophages (iMacs) with ablated SIRPa yield a superior antitumor effect in conjunction with cancer-targeted antibodies (Ab) or chimeric antigen receptor (CAR) against a variety of CD47-expressing tumors in vitro. Moreover, SIRPA-KO protected macrophages from Ab- or CAR-driven exhaustion, allowing for efficient phagocytosis of tumors after multiple rounds of cancer re-challenges. Ablation of SIRPa in iMacs improved survival of mice grafted ovarian carcinoma and treated with anti-HER2 Abs, while anti-GD2 CAR iMacs with KO SIRPA demonstrated reduction of initial tumor burden in mice with metastatic neuroblastoma xenograft. Overall, our studies support the feasibility of using the iPSC platform to generate SIRPα-ablated iMacs that are resistant to CD47-mediated inhibition for therapeutic applications.
Project description:Chimeric antigen receptor (CAR)-T cell therapies have shown great success in treating hematologic malignancies. Nonetheless, their therapeutic effect on solid tumors remains to be improved. Recently, macrophages have attracted great attention, given their ability to infiltrate solid tumors, phagocytize tumor cells as well as their immunomodulatory capacities. The first generation of CD3ζ-based CAR-macrophages demonstrated that the CAR could stimulate macrophage phagocytosis in a tumor antigen-dependent way. Here, we genetically engineered induced pluripotent stem cell (iPSC)-derived macrophages (iMACs) with TLR4 intracellular TIR domain-containing CARs against EGFRvIII and GPC3, which yielded markedly enhanced antitumor effect in two different solid tumor models including glioblastoma, and hepatocellular carcinoma in which complete remission was achieved with CAR-iMACs alone or in combination with CD47 antibody. Moreover, the tandem CD3ζ-TIR-CAR, or the “second-generation” design of TIR-based dual signaling CAR, endowed iMACs with both target engulfment/efferocytosis capacity against antigen-expressing solid tumor cells, and potency of antigen-dependent M1 state polarization and M2 state resistance in an NF-κB dependent manner. We also illustrated a surprising mechanism of tumor cell elimination by CAR-induced efferocytosis against tumor cell apoptotic bodies. Taken together, we established the next generation CAR-iMACs equipped with orthogonal phagocytosis and polarization capacity for better antitumor functions in treating solid tumors.
Project description:A significant challenge for chimeric antigen receptor (CAR) T cell therapy against glioblastoma (GBM) is its immunosuppressive tumor microenvironment (TME), which is densely populated and supported by protumoral glioma-associated microglia and macrophages (GAMs). Targeting CD47, a don't-eat-me signal overexpressed by tumor cells, disrupts the CD47-SIRPalpha axis and induces GAM phagocytic function. However, antibody-mediated CD47 blockade monotherapy is associated with toxicity and low bioavailability in solid tumors. To overcome these limitations, we combined local CAR T cell therapy with paracrine GAM modulation to effectively eliminate GBM. To this end, we engineered a new CAR T cell against epidermal growth factor receptor variant III (EGFRvIII) that constitutively secretes a signal regulatory protein gamma (SIRPgamma)-related protein (SGRP) with high affinity to CD47. Anti-EGFRvIII-SGRP CAR T cells eliminated EGFRvIII+ GBM in a dose-dependent manner in vitro and eradicated orthotopically xenografted EGFRvIII-mosaic GBM by locoregional application in vivo. This resulted in significant tumor-free long-term survival, followed by partial tumor control upon tumor re-challenge. Combining anti-CD47 antibodies with anti-EGFRvIII CAR T cells failed to achieve a similar therapeutic effect, underscoring the importance of sustained paracrine GAM modulation. Multidimensional brain immunofluorescence microscopy and in-depth spectral flow cytometry on GBM-xenografted brains showed that anti-EGFRvIII-SGRP CAR T cells accelerated GBM clearance, increased CD68+ cell trafficking to tumor scar sites and promoted GAM-mediated tumor cell uptake. In a peripheral lymphoma mouse xenograft model, anti-CD19-SGRP CAR T cells had superior efficacy to conventional anti-CD19 CAR T cells. Validation on human GBM explants revealed that anti-EGFRvIII-SGRP CAR T cells had a similar tumor-killing capacity to anti-EGFRvIII CAR monotherapy but showed a slight improvement in the maintenance of tumor-infiltrated CD14+ cells. Thus, local anti-EGFRvIII-SGRP CAR T cell therapy combines the potent antitumor effect of engineered T cells with the modulation of the surrounding innate immune TME. This results in the additive elimination of bystander EGFRvIII- tumor cells in a manner that overcomes the main mechanisms of CAR T cell therapy resistance, including tumor innate immune suppression and antigen escape.
Project description:Anti-cancer immunotherapy approaches are increasingly coveted. Chimeric antigen receptor (CAR)-T cell therapy has been shown to be an effective treatment for hematological tumors, but the treatment of solid tumors still lacks effectiveness, due to lower intra-tumor infiltration of CAR-T cells and tumor-induced immunosuppression. Macrophages represent a very large proportion of the tumor environment, participate in many aspects to tumor development and therefore represent interesting therapeutic targets. Macrophages can infiltrate solid tumor tissue and interact with almost all cellular components in the tumor microenvironment. In addition, macrophages can also promote a direct anti-tumor response by phagocyting tumor cells. We have developed macrophages expressing a CAR receptor against the HER2 antigen. The CAR receptor possesses an intracellular domain CD3ζ having homology with the protein FcεRI-γ, which once activated by the recognition antibody-antigen, induces the phagocytic activity of macrophages. 72% of macrophages express the CAR after transduction. CAR-M can specifically phagocyte HER2 coated-beads in a much more effective way than WT macrophages. We have then confirmed the capacity of CAR-M to phagocyte HER2+ cancer cell lines. Co-culture of CAR-M with breast cancer tumoroids (HER2+ or HER2-) has also been performed demonstrating their efficacy in a more complex environment. However, in the tumor microenvironment, due to their plasticity, macrophages tend to adopt an anti-inflammatory phenotype losing their anti-tumor activities. We have therefore developed a combined strategy by inhibiting two proprotein convertases, Furin and PC1/3 in CAR-M. The inhibition of furin or PC1/3 induces an increase in pro-inflammatory markers and maintains macrophage activation in the presence of cancer cells. In addition, HER2+ CAR-M with shFurin or shPC1/3 greatly increases the phagocytic activity on Her2+ beads or Her2+ tumors. These enzymes are therefore phenotypic regulators of macrophages. Our strategy is therefore based on a double activation of tumor-infiltrating macrophages. The first one consists in boosting the phagocytic activity of macrophages by having them express a CAR receptor targeting a tumor antigen. The second allows their reprogramming towards a pro- inflammatory phenotype by the inhibition of Furin and/or PC1/3 proprotein convertases
Project description:This dataset is a four-ligand x three-genotype Affymetrix microarray analysis of the regulation of liver genes in the mouse by the constitutive androstane receptor (CAR). 24 female mice of mixed background (C57BL/6x129Sv) were divided into three groups: wild-type (contains only mouse CAR; mCAR), CAR.KO = knockout mice (mice ablated for mCAR gene; mCAR -/-), and CAR.AH= contains human CAR transgene under the control of the mouse albumin promoter in the mCAR -/- background. Each of the three groups underwent four different treatment regimens: CO = corn oil vehicle control, PB = phenobarbitol (100 mg/kg/day), an anti-convulsant agent which can translocate both mCAR and hCAR into the nucleus to turn on target gene expression, TC = TCPOBOP, a potent non-metabolized ligand of mCAR (3 mg/kg), CITCO = a hCAR specific ligand (30 mg/kg/day). Two mice were used per treatment group and each mouse RNA was used for one chip.
Project description:The innate immune system is finely tuned to enable. rapid response to pathogenic stimuli but keep quiescent during tissue homeostasis. Balance of activating and inhibitory signaling sets a threshold for immune activation. Signal regulatory protein (SIRPa) is an immune inhibitory receptor expressed by myeloid cells and interacts with CD47 to inhibit immune cell phagocytosis, migration, and activation. Despite the progress of SIRPa and CD47 antagonist antibodies to promote anti-cancer immunity, it is not yet known whether therapeutic SIRPa receptor agonism could restrain excessive autoimmune inflammation in the context of autoimmunity. Here, we reported that increased neutrophil- and monocyte-associated genes including SIRPA in inflamed tissues biopsies of rheumatoid arthritis and inflammatory bowel diseases, and elevated SIRPA in colonic biopsies is associated with treatment refractory ulcerative colitis patients. We next identified a novel agonistic anti-SIRPa antibody that exhibited potent anti-inflammatory effects in reducing neutrophil and monocytes chemotaxis and tissue infiltration. In preclinical models of arthritis and colitis, anti-SIRPa agonistic antibody ameliorates autoimmune joint inflammation and inflammatory colitis through reducing neutrophils and monocytes in tissues. Our work provides a proof-of-concept for SIRPa receptor agonism for suppressing excessive innate immune activation and autoimmune inflammatory therapeutic treatment
Project description:The innate immune system is finely tuned to enable rapid response to pathogenic stimuli but keep quiescent during tissue homeostasis.Balance of activating and inhibitory signaling sets a threshold for immune activation. Signal regulatory protein (SIRPa) is an immune inhibitory receptor expressed by myeloid cells and interacts with CD47 to inhibit immune cell phagocytosis, migration, and activation. Despite the progress of SIRPa and CD47 antagonist antibodies to promote anti-cancer immunity, it is not yet known whether therapeutic SIRPa receptor agonism could restrain excessive autoimmune inflammation in the context of autoimmunity. Here, we reported that increased neutrophil- and monocyte-associated genes including SIRPA in inflamed tissues biopsies of rheumatoid arthritis and inflammatory bowel diseases, and elevated SIRPA in colonic biopsies is associated with treatment refractory ulcerative colitis patients. We next identified a novel agonistic anti-SIRPa antibody that exhibited potent anti-inflammatory effects in reducing neutrophil and monocytes chemotaxis and tissue infiltration. In preclinical models of arthritis and colitis, anti-SIRPa agonistic antibody ameliorates autoimmune joint inflammation and inflammatory colitis through reducing neutrophils and monocytes in tissues. Our work provides a proof-of-concept for SIRPa receptor agonism for suppressing excessive innate immune activation and autoimmune inflammatory therapeutic treatment
Project description:Adoptively transferred T cells and agents designed to block the CD47/SIRPalpha axis are promising cancer therapeutics that activate distinct arms of the immune system. We administered anti-CD47 with adoptively transferred T cells with the goal of enhancing antitumor efficacy but observed rapid macrophage-mediated clearance of T cells expressing chimeric antigen receptors (CARs) or engineered T cell receptors, which abrogated therapeutic benefit. anti-CD47 mediated CAR T clearance was potent and rapid enough to serve as an effective safety switch. To overcome this challenge, we engineered a CD47 variant (47E) that engaged SIRPalpha and provided a “don’t-eat-me” signal that was not blocked by anti-CD47 antibodies. TCR or CAR T cells expressing 47E were resistant to clearance by macrophages following anti-CD47, and mediated significant, sustained macrophage recruitment into the TME. Although many of the recruited macrophages manifested an M2-like profile, the combined therapy synergistically enhanced antitumor efficacy. This work identifies macrophages as major regulators of T cell persistence and illustrates the fundamental challenge of combining T cell directed therapeutics with those designed to activate macrophages. It further delivers a therapeutic approach capable of simultaneously harnessing the antitumor effects of T cells and macrophages that manifests enhanced potency against solid tumors.
Project description:We previously developed human CAR macrophages (CAR-M) and demonstrated redirection of macrophage anti-tumor function leading to tumor control in immunodeficient xenograft models. Here, we developed clinically relevant fully immunocompetent syngeneic models to evaluate the potential for CAR-M to remodel the tumor microenvironment (TME), induce T cell anti-tumor immunity, and sensitize solid tumors to PD1/PDL1 checkpoint inhibition. In vivo, anti-HER2 CAR-M significantly reduced tumor burden, prolonged survival, remodeled the TME, increased intratumoral T cell and natural killer (NK) cell infiltration, and induced epitope spreading. CAR-M therapy protected against antigen-negative relapse in a T cell dependent fashion, confirming long-term anti-tumor immunity. In HER2+ solid tumors resistant to anti-PD1(aPD1) monotherapy, the combination of CAR-M and aPD1 significantly improved tumor growth control, survival, and remodeling of the TME. These results demonstrate synergy between CAR-M and T cell checkpoint blockade and provide a strategy to enhance response to aPD1 therapy for patients with non-responsive tumors.
Project description:We previously developed human CAR macrophages (CAR-M) and demonstrated redirection of macrophage anti-tumor function leading to tumor control in immunodeficient xenograft models. Here, we developed clinically relevant fully immunocompetent syngeneic models to evaluate the potential for CAR-M to remodel the tumor microenvironment (TME), induce T cell anti-tumor immunity, and sensitize solid tumors to PD1/PDL1 checkpoint inhibition. In vivo, anti-HER2 CAR-M significantly reduced tumor burden, prolonged survival, remodeled the TME, increased intratumoral T cell and natural killer (NK) cell infiltration, and induced epitope spreading. CAR-M therapy protected against antigen-negative relapse in a T cell dependent fashion, confirming long-term anti-tumor immunity. In HER2+ solid tumors resistant to anti-PD1(aPD1) monotherapy, the combination of CAR-M and aPD1 significantly improved tumor growth control, survival, and remodeling of the TME. These results demonstrate synergy between CAR-M and T cell checkpoint blockade and provide a strategy to enhance response to aPD1 therapy for patients with non-responsive tumors.
Project description:Chimeric antigen receptor (CAR) T cell therapy is a promising immunotherapy against cancer. Although there is a growing interest in other cell types, a comparison of CAR immune effector cells in challenging solid tumor contexts is lacking. Here, we compare mouse and human NKG2D-CAR expressing T cells, NK cells and macrophages against glioblastoma, the most aggressive primary brain tumor. In vitro we show that T cell cancer killing is CAR-dependent, whereas intrinsic cytotoxicity overrules CAR-dependence for NK cells and CAR macrophages reduce glioma cells in co-culture assays. In orthotopic immunocompetent glioma mouse models, systemically administered CAR T cells demonstrate superior accumulation in the tumor and each immune cell type induces distinct changes in the tumor microenvironment. An otherwise low therapeutic efficacy is significantly enhanced by co-expression of pro-inflammatory cytokines in all CAR immune effector cells, underscoring the necessity for multifaceted cell engineering strategies to overcome the immunosuppressive solid tumor microenvironment.