Membrane Cholesterol Efflux Drives Tumor-Associated Macrophage Reprogramming and Tumor Progression.
Goossens Pieter,Rodriguez-Vita Juan,Etzerodt Anders,Masse Marion,Rastoin Olivia,Gouirand Victoire,Ulas Thomas,Papantonopoulou Olympia,Van Eck Miranda,Auphan-Anezin Nathalie,Bebien Magali,Verthuy Christophe,Vu Manh Thien Phong,Turner Martin,Dalod Marc,Schultze Joachim L,Lawrence Toby
Macrophages possess intrinsic tumoricidal activity, yet tumor-associated macrophages (TAMs) rapidly adopt an alternative phenotype within the tumor microenvironment that is marked by tumor-promoting immunosuppressive and trophic functions. The mechanisms that promote such TAM polarization remain poorly understood, but once identified, they may represent important therapeutic targets to block the tumor-promoting functions of TAMs and restore their anti-tumor potential. Here, we have characterized TAMs in a mouse model of metastatic ovarian cancer. We show that ovarian cancer cells promote membrane-cholesterol efflux and depletion of lipid rafts from macrophages. Increased cholesterol efflux promoted IL-4-mediated reprogramming, including inhibition of IFNγ-induced gene expression. Genetic deletion of ABC transporters, which mediate cholesterol efflux, reverts the tumor-promoting functions of TAMs and reduces tumor progression. These studies reveal an unexpected role for membrane-cholesterol efflux in driving TAM-mediated tumor progression while pointing to a potentially novel anti-tumor therapeutic strategy.
Control of tumor-associated macrophages and T cells in glioblastoma via AHR and CD39.
Takenaka Maisa C,Gabriely Galina,Rothhammer Veit,Mascanfroni Ivan D,Wheeler Michael A,Chao Chun-Cheih,Gutiérrez-Vázquez Cristina,Kenison Jessica,Tjon Emily C,Barroso Andreia,Vandeventer Tyler,de Lima Kalil Alves,Rothweiler Sonja,Mayo Lior,Ghannam Soufiene,Zandee Stephanie,Healy Luke,Sherr David,Farez Mauricio F,Prat Alexandre,Antel Jack,Reardon David A,Zhang Hailei,Robson Simon C,Getz Gad,Weiner Howard L,Quintana Francisco J
Tumor-associated macrophages (TAMs) play an important role in the immune response to cancer, but the mechanisms by which the tumor microenvironment controls TAMs and T cell immunity are not completely understood. Here we report that kynurenine produced by glioblastoma cells activates aryl hydrocarbon receptor (AHR) in TAMs to modulate their function and T cell immunity. AHR promotes CCR2 expression, driving TAM recruitment in response to CCL2. AHR also drives the expression of KLF4 and suppresses NF-κB activation in TAMs. Finally, AHR drives the expression of the ectonucleotidase CD39 in TAMs, which promotes CD8 T cell dysfunction by producing adenosine in cooperation with CD73. In humans, the expression of AHR and CD39 was highest in grade 4 glioma, and high AHR expression was associated with poor prognosis. In summary, AHR and CD39 expressed in TAMs participate in the regulation of the immune response in glioblastoma and constitute potential targets for immunotherapy.
NOD-like receptor C4 Inflammasome Regulates the Growth of Colon Cancer Liver Metastasis in NAFLD.
Ohashi Koichiro,Wang Zhijun,Yang Yoon Mee,Billet Sandrine,Tu Wei,Pimienta Michael,Cassel Suzanne L,Pandol Stephen J,Lu Shelly C,Sutterwala Fayyaz S,Bhowmick Neil,Seki Ekihiro
Hepatology (Baltimore, Md.)
Nonalcoholic fatty liver disease (NAFLD) enhances the growth and recurrence of colorectal cancer (CRC) liver metastasis. With the rising prevalence of NAFLD, a better understanding of the molecular mechanism underlying NAFLD-associated liver metastasis is crucial. Tumor-associated macrophages (TAMs) constitute a large portion of the tumor microenvironment that promotes tumor growth. NOD-like receptor C4 (NLRC4), a component of an inflammasome complex, plays a role in macrophage activation and interleukin (IL)-1β processing. We aimed to investigate whether NLRC4-mediated TAM polarization contributes to metastatic liver tumor growth in NAFLD. Wild-type and NLRC4 mice were fed low-fat or high-fat diet for 6 weeks followed by splenic injection of mouse CRC MC38 cells. The tumors were analyzed 2 weeks after CRC cell injection. High-fat diet-induced NAFLD significantly increased the number and size of CRC liver metastasis. TAMs and CD206-expressing M2 macrophages accumulated markedly in tumors in the presence of NAFLD. NAFLD up-regulated the expression of IL-1β, NLRC4, and M2 markers in tumors. In NAFLD, but not normal livers, deletion of NLRC4 decreased liver tumor growth accompanied by decreased M2 TAMs and IL-1β expression in tumors. Wild-type mice showed increased vascularity and vascular endothelial growth factor (VEGF) expression in tumors with NAFLD, but these were reduced in NLRC4 mice. When IL-1 signaling was blocked by recombinant IL-1 receptor antagonist, liver tumor formation and M2-type macrophages were reduced, suggesting that IL-1 signaling contributes to M2 polarization and tumor growth in NAFLD. Finally, we found that TAMs, but not liver macrophages, produced more IL-1β and VEGF following palmitate challenge. Conclusion: In NAFLD, NLRC4 contributes to M2 polarization, IL-1β, and VEGF production in TAMs, which promote metastatic liver tumor growth.
Treg Cells Promote the SREBP1-Dependent Metabolic Fitness of Tumor-Promoting Macrophages via Repression of CD8 T Cell-Derived Interferon-γ.
Liu Chang,Chikina Maria,Deshpande Rahul,Menk Ashley V,Wang Ting,Tabib Tracy,Brunazzi Erin A,Vignali Kate M,Sun Ming,Stolz Donna B,Lafyatis Robert A,Chen Wei,Delgoffe Greg M,Workman Creg J,Wendell Stacy G,Vignali Dario A A
Regulatory T (Treg) cells are crucial for immune homeostasis, but they also contribute to tumor immune evasion by promoting a suppressive tumor microenvironment (TME). Mice with Treg cell-restricted Neuropilin-1 deficiency show tumor resistance while maintaining peripheral immune homeostasis, thereby providing a controlled system to interrogate the impact of intratumoral Treg cells on the TME. Using this and other genetic models, we showed that Treg cells shaped the transcriptional landscape across multiple tumor-infiltrating immune cell types. Treg cells suppressed CD8 T cell secretion of interferon-γ (IFNγ), which would otherwise block the activation of sterol regulatory element-binding protein 1 (SREBP1)-mediated fatty acid synthesis in immunosuppressive (M2-like) tumor-associated macrophages (TAMs). Thus, Treg cells indirectly but selectively sustained M2-like TAM metabolic fitness, mitochondrial integrity, and survival. SREBP1 inhibition augmented the efficacy of immune checkpoint blockade, suggesting that targeting Treg cells or their modulation of lipid metabolism in M2-like TAMs could improve cancer immunotherapy.
Specific targeting of CD163 TAMs mobilizes inflammatory monocytes and promotes T cell-mediated tumor regression.
Etzerodt Anders,Tsalkitzi Kyriaki,Maniecki Maciej,Damsky William,Delfini Marcello,Baudoin Elodie,Moulin Morgane,Bosenberg Marcus,Graversen Jonas Heilskov,Auphan-Anezin Nathalie,Moestrup Søren Kragh,Lawrence Toby
The Journal of experimental medicine
Tumor-associated macrophages (TAMs) play critical roles in tumor progression but are also capable of contributing to antitumor immunity. Recent studies have revealed an unprecedented heterogeneity among TAMs in both human cancer and experimental models. Nevertheless, we still understand little about the contribution of different TAM subsets to tumor progression. Here, we demonstrate that CD163-expressing TAMs specifically maintain immune suppression in an experimental model of melanoma that is resistant to anti-PD-1 checkpoint therapy. Specific depletion of the CD163 macrophages results in a massive infiltration of activated T cells and tumor regression. Importantly, the infiltration of cytotoxic T cells was accompanied by the mobilization of inflammatory monocytes that significantly contributed to tumor regression. Thus, the specific targeting of CD163 TAMs reeducates the tumor immune microenvironment and promotes both myeloid and T cell-mediated antitumor immunity, illustrating the importance of selective targeting of tumor-associated myeloid cells in a therapeutic context.
Hedgehog signaling promotes tumor-associated macrophage polarization to suppress intratumoral CD8+ T cell recruitment.
Petty Amy J,Li Ang,Wang Xinyi,Dai Rui,Heyman Benjamin,Hsu David,Huang Xiaopei,Yang Yiping
The Journal of clinical investigation
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.
Loss of p53 drives neuron reprogramming in head and neck cancer.
The solid tumour microenvironment includes nerve fibres that arise from the peripheral nervous system. Recent work indicates that newly formed adrenergic nerve fibres promote tumour growth, but the origin of these nerves and the mechanism of their inception are unknown. Here, by comparing the transcriptomes of cancer-associated trigeminal sensory neurons with those of endogenous neurons in mouse models of oral cancer, we identified an adrenergic differentiation signature. We show that loss of TP53 leads to adrenergic transdifferentiation of tumour-associated sensory nerves through loss of the microRNA miR-34a. Tumour growth was inhibited by sensory denervation or pharmacological blockade of adrenergic receptors, but not by chemical sympathectomy of pre-existing adrenergic nerves. A retrospective analysis of samples from oral cancer revealed that p53 status was associated with nerve density, which was in turn associated with poor clinical outcomes. This crosstalk between cancer cells and neurons represents mechanism by which tumour-associated neurons are reprogrammed towards an adrenergic phenotype that can stimulate tumour progression, and is a potential target for anticancer therapy.
Cancer-Derived Succinate Promotes Macrophage Polarization and Cancer Metastasis via Succinate Receptor.
Wu Jing-Yiing,Huang Tsai-Wang,Hsieh Yi-Ting,Wang Yi-Fu,Yen Chia-Chien,Lee Guan-Lin,Yeh Chang-Ching,Peng Yi-Jen,Kuo Ya-Yi,Wen Hsiu-Ting,Lin Hui-Chen,Hsiao Cheng-Wen,Wu Kenneth K,Kung Hsing-Jien,Hsu Yu-Juei,Kuo Cheng-Chin
Macrophages form a major cell population in the tumor microenvironment. They can be activated and polarized into tumor-associated macrophages (TAM) by the tumor-derived soluble molecules to promote tumor progression and metastasis. Here, we used comparative metabolomics coupled with biochemical and animal studies to show that cancer cells release succinate into their microenvironment and activate succinate receptor (SUCNR1) signaling to polarize macrophages into TAM. Furthermore, the results from in vitro and in vivo studies revealed that succinate promotes not only cancer cell migration and invasion but also cancer metastasis. These effects are mediated by SUCNR1-triggered PI3K-hypoxia-inducible factor 1α (HIF-1α) axis. Compared with healthy subjects and tumor-free lung tissues, serum succinate levels and lung cancer SUCNR1 expression were elevated in lung cancer patients, suggesting an important clinical relevance. Collectively, our findings indicate that the secreted tumor-derived succinate belongs to a novel class of cancer progression factors, controlling TAM polarization and promoting tumorigenic signaling.
Targeting glutamine metabolism enhances tumor-specific immunity by modulating suppressive myeloid cells.
Oh Min-Hee,Sun Im-Hong,Zhao Liang,Leone Robert D,Sun Im-Meng,Xu Wei,Collins Samuel L,Tam Ada J,Blosser Richard L,Patel Chirag H,Englert Judson M,Arwood Matthew L,Wen Jiayu,Chan-Li Yee,Tenora Lukáš,Majer Pavel,Rais Rana,Slusher Barbara S,Horton Maureen R,Powell Jonathan D
The Journal of clinical investigation
Myeloid cells comprise a major component of the tumor microenvironment (TME) that promotes tumor growth and immune evasion. By employing a small-molecule inhibitor of glutamine metabolism, not only were we able to inhibit tumor growth, but we markedly inhibited the generation and recruitment of myeloid-derived suppressor cells (MDSCs). Targeting tumor glutamine metabolism led to a decrease in CSF3 and hence recruitment of MDSCs as well as immunogenic cell death, leading to an increase in inflammatory tumor-associated macrophages (TAMs). Alternatively, inhibiting glutamine metabolism of the MDSCs themselves led to activation-induced cell death and conversion of MDSCs to inflammatory macrophages. Surprisingly, blocking glutamine metabolism also inhibited IDO expression of both the tumor and myeloid-derived cells, leading to a marked decrease in kynurenine levels. This in turn inhibited the development of metastasis and further enhanced antitumor immunity. Indeed, targeting glutamine metabolism rendered checkpoint blockade-resistant tumors susceptible to immunotherapy. Overall, our studies define an intimate interplay between the unique metabolism of tumors and the metabolism of suppressive immune cells.
Microglia promote glioblastoma via mTOR-mediated immunosuppression of the tumour microenvironment.
Dumas Anaelle A,Pomella Nicola,Rosser Gabriel,Guglielmi Loredana,Vinel Claire,Millner Thomas O,Rees Jeremy,Aley Natasha,Sheer Denise,Wei Jun,Marisetty Anantha,Heimberger Amy B,Bowman Robert L,Brandner Sebastian,Joyce Johanna A,Marino Silvia
The EMBO journal
Tumour-associated microglia/macrophages (TAM) are the most numerous non-neoplastic populations in the tumour microenvironment in glioblastoma multiforme (GBM), the most common malignant brain tumour in adulthood. The mTOR pathway, an important regulator of cell survival/proliferation, is upregulated in GBM, but little is known about the potential role of this pathway in TAM. Here, we show that GBM-initiating cells induce mTOR signalling in the microglia but not bone marrow-derived macrophages in both in vitro and in vivo GBM mouse models. mTOR-dependent regulation of STAT3 and NF-κB activity promotes an immunosuppressive microglial phenotype. This hinders effector T-cell infiltration, proliferation and immune reactivity, thereby contributing to tumour immune evasion and promoting tumour growth in mouse models. The translational value of our results is demonstrated in whole transcriptome datasets of human GBM and in a novel in vitro model, whereby expanded-potential stem cells (EPSC)-derived microglia-like cells are conditioned by syngeneic patient-derived GBM-initiating cells. These results raise the possibility that microglia could be the primary target of mTOR inhibition, rather than the intrinsic tumour cells in GBM.
Targeting tumor-associated macrophages and granulocytic myeloid-derived suppressor cells augments PD-1 blockade in cholangiocarcinoma.
Loeuillard Emilien,Yang Jingchun,Buckarma EeeLN,Wang Juan,Liu Yuanhang,Conboy Caitlin,Pavelko Kevin D,Li Ying,O'Brien Daniel,Wang Chen,Graham Rondell P,Smoot Rory L,Dong Haidong,Ilyas Sumera
The Journal of clinical investigation
Immune checkpoint blockade (ICB) has revolutionized cancer therapeutics. Desmoplastic malignancies, such as cholangiocarcinoma (CCA), have an abundant tumor immune microenvironment (TIME). However, to date, ICB monotherapy in such malignancies has been ineffective. Herein, we identify tumor-associated macrophages (TAMs) as the primary source of programmed death-ligand 1 (PD-L1) in human and murine CCA. In a murine model of CCA, recruited PD-L1+ TAMs facilitated CCA progression. However, TAM blockade failed to decrease tumor progression due to a compensatory emergence of granulocytic myeloid-derived suppressor cells (G-MDSCs) that mediated immune escape by impairing T cell response. Single-cell RNA sequencing (scRNA-Seq) of murine tumor G-MDSCs highlighted a unique ApoE G-MDSC subset enriched with TAM blockade; further analysis of a human scRNA-Seq data set demonstrated the presence of a similar G-MDSC subset in human CCA. Finally, dual inhibition of TAMs and G-MDSCs potentiated ICB. In summary, our findings highlight the therapeutic potential of coupling ICB with immunotherapies targeting immunosuppressive myeloid cells in CCA.
Dynamic changes in glioma macrophage populations after radiotherapy reveal CSF-1R inhibition as a strategy to overcome resistance.
Akkari Leila,Bowman Robert L,Tessier Jeremy,Klemm Florian,Handgraaf Shanna M,de Groot Marnix,Quail Daniela F,Tillard Lucie,Gadiot Jules,Huse Jason T,Brandsma Dieta,Westerga Johan,Watts Colin,Joyce Johanna A
Science translational medicine
Tumor-associated macrophages (TAMs) and microglia (MG) are potent regulators of glioma development and progression. However, the dynamic alterations of distinct TAM populations during the course of therapeutic intervention, response, and recurrence have not yet been fully explored. Here, we investigated how radiotherapy changes the relative abundance and phenotypes of brain-resident MG and peripherally recruited monocyte-derived macrophages (MDMs) in glioblastoma. We identified radiation-specific, stage-dependent MG and MDM gene expression signatures in murine gliomas and confirmed altered expression of several genes and proteins in recurrent human glioblastoma. We found that targeting these TAM populations using a colony-stimulating factor-1 receptor (CSF-1R) inhibitor combined with radiotherapy substantially enhanced survival in preclinical models. Our findings reveal the dynamics and plasticity of distinct macrophage populations in the irradiated tumor microenvironment, which has translational relevance for enhancing the efficacy of standard-of-care treatment in gliomas.
FGF2 alters macrophage polarization, tumour immunity and growth and can be targeted during radiotherapy.
Regulation of the programming of tumour-associated macrophages (TAMs) controls tumour growth and anti-tumour immunity. We examined the role of FGF2 in that regulation. Tumours in mice genetically deficient in low-molecular weight FGF2 (FGF2) regress dependent on T cells. Yet, TAMS not T cells express FGF receptors. Bone marrow derived-macrophages from Fgf2 mice co-injected with cancer cells reduce tumour growth and express more inflammatory cytokines. FGF2 is induced in the tumour microenvironment following fractionated radiation in murine tumours consistent with clinical reports. Combination treatment of in vivo tumours with fractionated radiation and a blocking antibody to FGF2 prolongs tumour growth delay, increases long-term survival and leads to a higher iNOS/CD206 TAM ratio compared to irradiation alone. These studies show for the first time that FGF2 affects macrophage programming and is a critical regulator of immunity in the tumour microenvironment.
Transcriptional regulatory networks of tumor-associated macrophages that drive malignancy in mesenchymal glioblastoma.
Sa Jason K,Chang Nakho,Lee Hye Won,Cho Hee Jin,Ceccarelli Michele,Cerulo Luigi,Yin Jinlong,Kim Sung Soo,Caruso Francesca P,Lee Mijeong,Kim Donggeon,Oh Young Taek,Lee Yeri,Her Nam-Gu,Min Byeongkwi,Kim Hye-Jin,Jeong Da Eun,Kim Hye-Mi,Kim Hyunho,Chung Seok,Woo Hyun Goo,Lee Jeongwu,Kong Doo-Sik,Seol Ho Jun,Lee Jung-Il,Kim Jinho,Park Woong-Yang,Wang Qianghu,Sulman Erik P,Heimberger Amy B,Lim Michael,Park Jong Bae,Iavarone Antonio,Verhaak Roel G W,Nam Do-Hyun
BACKGROUND:Glioblastoma (GBM) is a complex disease with extensive molecular and transcriptional heterogeneity. GBM can be subcategorized into four distinct subtypes; tumors that shift towards the mesenchymal phenotype upon recurrence are generally associated with treatment resistance, unfavorable prognosis, and the infiltration of pro-tumorigenic macrophages. RESULTS:We explore the transcriptional regulatory networks of mesenchymal-associated tumor-associated macrophages (MA-TAMs), which drive the malignant phenotypic state of GBM, and identify macrophage receptor with collagenous structure (MARCO) as the most highly differentially expressed gene. MARCO TAMs induce a phenotypic shift towards mesenchymal cellular state of glioma stem cells, promoting both invasive and proliferative activities, as well as therapeutic resistance to irradiation. MARCO TAMs also significantly accelerate tumor engraftment and growth in vivo. Moreover, both MA-TAM master regulators and their target genes are significantly correlated with poor clinical outcomes and are often associated with genomic aberrations in neurofibromin 1 (NF1) and phosphoinositide 3-kinases/mammalian target of rapamycin/Akt pathway (PI3K-mTOR-AKT)-related genes. We further demonstrate the origination of MA-TAMs from peripheral blood, as well as their potential association with tumor-induced polarization states and immunosuppressive environments. CONCLUSIONS:Collectively, our study characterizes the global transcriptional profile of TAMs driving mesenchymal GBM pathogenesis, providing potential therapeutic targets for improving the effectiveness of GBM immunotherapy.
Platelet-derived growth factor beta is a potent inflammatory driver in paediatric high-grade glioma.
Ross James L,Chen Zhihong,Herting Cameron J,Grabovska Yura,Szulzewsky Frank,Puigdelloses Montserrat,Monterroza Lenore,Switchenko Jeffrey,Wadhwani Nitin R,Cimino Patrick J,Mackay Alan,Jones Chris,Read Renee D,MacDonald Tobey J,Schniederjan Matthew,Becher Oren J,Hambardzumyan Dolores
Brain : a journal of neurology
Paediatric high-grade gliomas (HGGs) account for the most brain tumour-related deaths in children and have a median survival of 12-15 months. One promising avenue of research is the development of novel therapies targeting the properties of non-neoplastic cell-types within the tumour such as tumour associated macrophages (TAMs). TAMs are immunosuppressive and promote tumour malignancy in adult HGG; however, in paediatric medulloblastoma, TAMs exhibit anti-tumour properties. Much is known about TAMs in adult HGG, yet little is known about them in the paediatric setting. This raises the question of whether paediatric HGGs possess a distinct constituency of TAMs because of their unique genetic landscapes. Using human paediatric HGG tissue samples and murine models of paediatric HGG, we demonstrate diffuse midline gliomas possess a greater inflammatory gene expression profile compared to hemispheric paediatric HGGs. We also show despite possessing sparse T-cell infiltration, human paediatric HGGs possess high infiltration of IBA1+ TAMs. CD31, PDGFRβ, and PDGFB all strongly correlate with IBA1+ TAM infiltration. To investigate the TAM population, we used the RCAS/tv-a system to recapitulate paediatric HGG in newborn immunocompetent mice. Tumours are induced in Nestin-positive brain cells by PDGFA or PDGFB overexpression with Cdkn2a or Tp53 co-mutations. Tumours driven by PDGFB have a significantly lower median survival compared to PDGFA-driven tumours and have increased TAM infiltration. NanoString and quantitative PCR analysis indicates PDGFB-driven tumours have a highly inflammatory microenvironment characterized by high chemokine expression. In vitro bone marrow-derived monocyte and microglial cultures demonstrate bone marrow-derived monocytes are most responsible for the production of inflammatory signals in the tumour microenvironment in response to PDGFB stimulation. Lastly, using knockout mice deficient for individual chemokines, we demonstrate the feasibility of reducing TAM infiltration and prolonging survival in both PDGFA and PDGFB-driven tumours. We identify CCL3 as a potential key chemokine in these processes in both humans and mice. Together, these studies provide evidence for the potent inflammatory effects PDGFB has in paediatric HGGs.
Cyclodextrin-based host-guest complexes loaded with regorafenib for colorectal cancer treatment.
Bai Hongzhen,Wang Jianwei,Phan Chi Uyen,Chen Qi,Hu Xiurong,Shao Guoqiang,Zhou Jun,Lai Lihua,Tang Guping
The malignancy of colorectal cancer (CRC) is connected with inflammation and tumor-associated macrophages (TAMs), but effective therapeutics for CRC are limited. To integrate therapeutic targeting with tumor microenvironment (TME) reprogramming, here we develop biocompatible, non-covalent channel-type nanoparticles (CNPs) that are fabricated through host-guest complexation and self-assemble of mannose-modified γ-cyclodextrin (M-γ-CD) with Regorafenib (RG), RG@M-γ-CD CNPs. In addition to its carrier role, M-γ-CD serves as a targeting device and participates in TME regulation. RG@M-γ-CD CNPs attenuate inflammation and inhibit TAM activation by targeting macrophages. They also improve RG's anti-tumor effect by potentiating kinase suppression. In vivo application shows that the channel-type formulation optimizes the pharmacokinetics and bio-distribution of RG. In colitis-associated cancer and CT26 mouse models, RG@M-γ-CD is proven to be a targeted, safe and effective anti-tumor nanomedicine that suppresses tumor cell proliferation, lesions neovascularization, and remodels TME. These findings indicate RG@M-γ-CD CNPs as a potential strategy for CRC treatment.
CAR-T cell-mediated depletion of immunosuppressive tumor-associated macrophages promotes endogenous antitumor immunity and augments adoptive immunotherapy.
Rodriguez-Garcia Alba,Lynn Rachel C,Poussin Mathilde,Eiva Monika A,Shaw Lauren C,O'Connor Roddy S,Minutolo Nicholas G,Casado-Medrano Victoria,Lopez Gonzalo,Matsuyama Takami,Powell Daniel J
The immunosuppressive tumor microenvironment (TME) represents a major barrier for effective immunotherapy. Tumor-associated macrophages (TAMs) are highly heterogeneous and plastic cell components of the TME which can either promote tumor progression (M2-like) or boost antitumor immunity (M1-like). Here, we demonstrate that a subset of TAMs that express folate receptor β (FRβ) possess an immunosuppressive M2-like profile. In syngeneic tumor mouse models, chimeric antigen receptor (CAR)-T cell-mediated selective elimination of FRβ TAMs in the TME results in an enrichment of pro-inflammatory monocytes, an influx of endogenous tumor-specific CD8 T cells, delayed tumor progression, and prolonged survival. Preconditioning of the TME with FRβ-specific CAR-T cells also improves the effectiveness of tumor-directed anti-mesothelin CAR-T cells, while simultaneous co-administration of both CAR products does not. These results highlight the pro-tumor role of FRβ TAMs in the TME and the therapeutic implications of TAM-depleting agents as preparative adjuncts to conventional immunotherapies that directly target tumor antigens.
Heme catabolism by tumor-associated macrophages controls metastasis formation.
Consonni Francesca Maria,Bleve Augusto,Totaro Maria Grazia,Storto Mariangela,Kunderfranco Paolo,Termanini Alberto,Pasqualini Fabio,Alì Chiara,Pandolfo Chiara,Sgambelluri Francesco,Grazia Giulia,Santinami Mario,Maurichi Andrea,Milione Massimo,Erreni Marco,Doni Andrea,Fabbri Marco,Gribaldo Laura,Rulli Eliana,Soares Miguel Parreira,Torri Valter,Mortarini Roberta,Anichini Andrea,Sica Antonio
Although the pathological significance of tumor-associated macrophage (TAM) heterogeneity is still poorly understood, TAM reprogramming is viewed as a promising anticancer therapy. Here we show that a distinct subset of TAMs (F4/80CD115C3aRCD88), endowed with high rates of heme catabolism by the stress-responsive enzyme heme oxygenase-1 (HO-1), plays a critical role in shaping a prometastatic tumor microenvironment favoring immunosuppression, angiogenesis and epithelial-to-mesenchymal transition. This population originates from F4/80HO-1 bone marrow (BM) precursors, accumulates in the blood of tumor bearers and preferentially localizes at the invasive margin through a mechanism dependent on the activation of Nrf2 and coordinated by the NF-κB1-CSF1R-C3aR axis. Inhibition of F4/80HO-1 TAM recruitment or myeloid-specific deletion of HO-1 blocks metastasis formation and improves anticancer immunotherapy. Relative expression of HO-1 in peripheral monocyte subsets, as well as in tumor lesions, discriminates survival among metastatic melanoma patients. Overall, these results identify a distinct cancer-induced HO-1 myeloid subgroup as a new antimetastatic target and prognostic blood marker.
mRNA Delivery of a Bispecific Single-Domain Antibody to Polarize Tumor-Associated Macrophages and Synergize Immunotherapy against Liver Malignancies.
Advanced materials (Deerfield Beach, Fla.)
Liver malignancies are among the tumor types that are resistant to immune checkpoint inhibition therapy. Tumor-associated macrophages (TAMs) are highly enriched and play a major role in inducing immunosuppression in liver malignancies. Herein, CCL2 and CCL5 are screened as two major chemokines responsible for attracting TAM infiltration and inducing their polarization toward cancer-promoting M2-phenotype. To reverse this immunosuppressive process, an innovative single-domain antibody that bispecifically binds and neutralizes CCL2 and CCL5 (BisCCL2/5i) with high potency and specificity is directly evolved. mRNA encoding BisCCL2/5i is encapsulated in a clinically approved lipid nanoparticle platform, resulting in a liver-homing biomaterial that allows transient yet efficient expression of BisCCL2/5i in the diseased organ in a multiple dosage manner. This BisCCL2/5i mRNA nanoplatform significantly induces the polarization of TAMs toward the antitumoral M1 phenotype and reduces immunosuppression in the tumor microenvironment. The combination of BisCCL2/5i with PD-1 ligand inhibitor (PD-Li) achieves long-term survival in mouse models of primary liver cancer and liver metastasis of colorectal and pancreatic cancers. The work provides an effective bispecific targeting strategy that could broaden the PD-Li therapy to multiple types of malignancies in the human liver.
Targeting monoamine oxidase A-regulated tumor-associated macrophage polarization for cancer immunotherapy.
Wang Yu-Chen,Wang Xi,Yu Jiaji,Ma Feiyang,Li Zhe,Zhou Yang,Zeng Samuel,Ma Xiaoya,Li Yan-Ruide,Neal Adam,Huang Jie,To Angela,Clarke Nicole,Memarzadeh Sanaz,Pellegrini Matteo,Yang Lili
Targeting tumor-associated macrophages (TAMs) is a promising strategy to modify the immunosuppressive tumor microenvironment and improve cancer immunotherapy. Monoamine oxidase A (MAO-A) is an enzyme best known for its function in the brain; small molecule MAO inhibitors (MAOIs) are clinically used for treating neurological disorders. Here we observe MAO-A induction in mouse and human TAMs. MAO-A-deficient mice exhibit decreased TAM immunosuppressive functions corresponding with enhanced antitumor immunity. MAOI treatment induces TAM reprogramming and suppresses tumor growth in preclinical mouse syngeneic and human xenograft tumor models. Combining MAOI and anti-PD-1 treatments results in synergistic tumor suppression. Clinical data correlation studies associate high intratumoral MAOA expression with poor patient survival in a broad range of cancers. We further demonstrate that MAO-A promotes TAM immunosuppressive polarization via upregulating oxidative stress. Together, these data identify MAO-A as a critical regulator of TAMs and support repurposing MAOIs for TAM reprogramming to improve cancer immunotherapy.
IL-1β-Induced Elevation of Solute Carrier Family 7 Member 11 Promotes Hepatocellular Carcinoma Metastasis Through Up-regulating Programmed Death Ligand 1 and Colony-Stimulating Factor 1.
He Qin,Liu Mei,Huang Wenjie,Chen Xiaoping,Zhang Bixiang,Zhang Tongyue,Wang Yijun,Liu Danfei,Xie Meng,Ji Xiaoyu,Sun Mengyu,Tian Dean,Xia Limin
Hepatology (Baltimore, Md.)
BACKGROUND AND AIMS:Because of a paucity of effective treatment options, metastasis is still a major cause for HCC-associated mortality. The molecular mechanism of inflammation-induced HCC metastasis is open for study. Here, we characterized the function of solute carrier family 7 member 11 (SLC7A11) in inflammation-related HCC metastasis and probed therapy strategies for this subpopulation of patients. APPROACH AND RESULTS:Elevated expression of SLC7A11 was positively correlated with poor tumor differentiation, and higher tumor-nodule-metastasis stage, and indicated poor prognosis in human HCC. SLC7A11 increased HIF1α expression through reducing α-ketoglutarate (αKG) level by exporting glutamate. SLC7A11 up-regulated programmed death ligand 1 (PD-L1) and colony-stimulating factor 1 (CSF1) expression through αKG-HIF1α cascade. SLC7A11 overexpression in HCC cells promoted intratumoral tumor-associated macrophage (TAM) and myeloid-derived suppressor cell (MDSC) infiltration through the CSF1/colony-stimulating factor 1 receptor (CSF1R) axis, whereas knockdown of CSF1 attenuated SLC7A11-mediated intratumoral TAM and MDSC infiltration and HCC metastasis. Depletion of either TAMs or MDSCs decreased SLC7A11-mediated HCC metastasis. Furthermore, the combination of CSF1R inhibitor BZL945 and anti-PD-L1 antibody blocked SLC7A11-induced HCC metastasis. In addition, IL-1β up-regulated SLC7A11 expression through the interleukin-1 receptor type 1 (IL-1R1)/extracellular signal-regulated kinase/specificity protein 1 pathway. SLC7A11 knockdown impaired IL-1β-promoted HCC metastasis. Anakinra, an IL-1R1 antagonist, reversed IL-1β-promoted HCC metastasis. In human HCC tissues, SLC7A11 expression was positively associated with HIF1α, PD-L1, and CSF1 expression and intratumoral TAM and MDSC infiltration. CONCLUSIONS:IL-1β-induced SLC7A11 overexpression up-regulated PD-L1 and CSF1 through the αKG/HIF1α axis, which promoted TAM and MDSC infiltration. Interruption of this oncogenic loop may provide a promising therapy strategy for the inhibition of SLC7A11-mediated HCC metastasis.
Overcoming microenvironmental resistance to PD-1 blockade in genetically engineered lung cancer models.
Martinez-Usatorre Amaia,Kadioglu Ece,Boivin Gael,Cianciaruso Chiara,Guichard Alan,Torchia Bruno,Zangger Nadine,Nassiri Sina,Keklikoglou Ioanna,Schmittnaegel Martina,Ries Carola H,Meylan Etienne,De Palma Michele
Science translational medicine
Immune checkpoint blockade (ICB) with PD-1 or PD-L1 antibodies has been approved for the treatment of non-small cell lung cancer (NSCLC). However, only a minority of patients respond, and sustained remissions are rare. Both chemotherapy and antiangiogenic drugs may improve the efficacy of ICB in mouse tumor models and patients with cancer. Here, we used genetically engineered mouse models of ; NSCLC, including a mismatch repair-deficient variant ( ; ; ) with higher mutational burden, and longitudinal imaging to study tumor response and resistance to combinations of ICB, antiangiogenic therapy, and chemotherapy. Antiangiogenic blockade of vascular endothelial growth factor A and angiopoietin-2 markedly slowed progression of autochthonous lung tumors, but contrary to findings in other cancer types, addition of a PD-1 or PD-L1 antibody was not beneficial and even accelerated progression of a fraction of the tumors. We found that antiangiogenic treatment facilitated tumor infiltration by PD-1 regulatory T cells (T), which were more efficiently targeted by the PD-1 antibody than CD8 T cells. Both tumor-associated macrophages (TAMs) of monocyte origin, which are colony-stimulating factor 1 receptor (CSF1R) dependent, and TAMs of alveolar origin, which are sensitive to cisplatin, contributed to establish a transforming growth factor-β-rich tumor microenvironment that supported PD-1 T Dual TAM targeting with a combination of a CSF1R inhibitor and cisplatin abated T, redirected the PD-1 antibody to CD8 T cells, and improved the efficacy of antiangiogenic immunotherapy, achieving regression of most tumors.
Engineering Endogenous Tumor-Associated Macrophage-Targeted Biomimetic Nano-RBC to Reprogram Tumor Immunosuppressive Microenvironment for Enhanced Chemo-Immunotherapy.
Wang Yupeng,Yu Jie,Luo Zhijian,Shi Qiankun,Liu Guanglong,Wu Fan,Wang Zhizhang,Huang Yubin,Zhou Dongfang
Advanced materials (Deerfield Beach, Fla.)
Immunotherapy has shown encouraging results in various cancers, but the response rates are relatively low due to the complex tumor immunosuppressive microenvironment (TIME). The presence of tumor-associated macrophages (TAMs) and tumor hypoxia correlates significantly with potent immunosuppressive activity. Here, a hemoglobin-poly(ε-caprolactone) (Hb-PCL) conjugate self-assembled biomimetic nano red blood cell (nano-RBC) system (V(Hb)) is engineered to deliver chemotherapeutic doxorubicin (DOX) and oxygen for reprogramming TIME. The Hb moiety of V(Hb)@DOX can bind to endogenous plasma haptoglobin (Hp) and specifically target the M2-type TAMs via the CD163 surface receptor, and effectively kill the cells. In addition, the O released by the Hb alleviates tumor hypoxia, which further augments the antitumor immune response by recruiting fewer M2-type macrophages. TAM-targeting depletion and hypoxia alleviation synergistically reprogram the TIME, which concurrently downregulate PD-L1 expression of tumor cells, decrease the levels of immunosuppressive cytokines such as IL-10 and TGF-β, elevate the immunostimulatory IFN-γ, enhance cytotoxic T lymphocyte (CTL) response, and boost a strong memory response. The ensuing TAM-targeted chemo-immunotherapeutic effects markedly inhibit tumor metastasis and recurrence. Taken together, the engineered endogenous TAM-targeted biomimetic nano-RBC system is a highly promising tool to reprogram TIME for cancer chemo-immunotherapy.
Tumor-induced reshuffling of lipid composition on the endoplasmic reticulum membrane sustains macrophage survival and pro-tumorigenic activity.
Di Conza Giusy,Tsai Chin-Hsien,Gallart-Ayala Hector,Yu Yi-Ru,Franco Fabien,Zaffalon Lea,Xie Xin,Li Xiaoyun,Xiao Zhengtao,Raines Lydia N,Falquet Maryline,Jalil Antoine,Locasale Jason W,Percipalle Piergiorgio,Masson David,Huang Stanley Ching-Cheng,Martinon Fabio,Ivanisevic Julijana,Ho Ping-Chih
Tumor-associated macrophages (TAMs) display pro-tumorigenic phenotypes for supporting tumor progression in response to microenvironmental cues imposed by tumor and stromal cells. However, the underlying mechanisms by which tumor cells instruct TAM behavior remain elusive. Here, we uncover that tumor-cell-derived glucosylceramide stimulated unconventional endoplasmic reticulum (ER) stress responses by inducing reshuffling of lipid composition and saturation on the ER membrane in macrophages, which induced IRE1-mediated spliced XBP1 production and STAT3 activation. The cooperation of spliced XBP1 and STAT3 reinforced the pro-tumorigenic phenotype and expression of immunosuppressive genes. Ablation of XBP1 expression with genetic manipulation or ameliorating ER stress responses by facilitating LPCAT3-mediated incorporation of unsaturated lipids to the phosphatidylcholine hampered pro-tumorigenic phenotype and survival in TAMs. Together, we uncover the unexpected roles of tumor-cell-produced lipids that simultaneously orchestrate macrophage polarization and survival in tumors via induction of ER stress responses and reveal therapeutic targets for sustaining host antitumor immunity.
Tryptophan-derived microbial metabolites activate the aryl hydrocarbon receptor in tumor-associated macrophages to suppress anti-tumor immunity.
Hezaveh Kebria,Shinde Rahul S,Klötgen Andreas,Halaby Marie Jo,Lamorte Sara,Ciudad M Teresa,Quevedo Rene,Neufeld Luke,Liu Zhe Qi,Jin Robbie,Grünwald Barbara T,Foerster Elisabeth G,Chaharlangi Danica,Guo Mengdi,Makhijani Priya,Zhang Xin,Pugh Trevor J,Pinto Devanand M,Co Ileana L,McGuigan Alison P,Jang Gun Ho,Khokha Rama,Ohashi Pamela S,O'Kane Grainne M,Gallinger Steven,Navarre William W,Maughan Heather,Philpott Dana J,Brooks David G,McGaha Tracy L
The aryl hydrocarbon receptor (AhR) is a sensor of products of tryptophan metabolism and a potent modulator of immunity. Here, we examined the impact of AhR in tumor-associated macrophage (TAM) function in pancreatic ductal adenocarcinoma (PDAC). TAMs exhibited high AhR activity and Ahr-deficient macrophages developed an inflammatory phenotype. Deletion of Ahr in myeloid cells or pharmacologic inhibition of AhR reduced PDAC growth, improved efficacy of immune checkpoint blockade, and increased intra-tumoral frequencies of IFNγCD8 T cells. Macrophage tryptophan metabolism was not required for this effect. Rather, macrophage AhR activity was dependent on Lactobacillus metabolization of dietary tryptophan to indoles. Removal of dietary tryptophan reduced TAM AhR activity and promoted intra-tumoral accumulation of TNFαIFNγCD8 T cells; provision of dietary indoles blocked this effect. In patients with PDAC, high AHR expression associated with rapid disease progression and mortality, as well as with an immune-suppressive TAM phenotype, suggesting conservation of this regulatory axis in human disease.
The microbiome-derived metabolite TMAO drives immune activation and boosts responses to immune checkpoint blockade in pancreatic cancer.
Mirji Gauri, Worth Alison, Bhat Sajad Ahmad, El Sayed Mohamed, Kannan Toshitha, Goldman Aaron R, Tang Hsin-Yao, Liu Qin, Auslander Noam, Dang Chi V, Abdel-Mohsen Mohamed, Kossenkov Andrew, Stanger Ben Z, Shinde Rahul S
The composition of the gut microbiome can control innate and adaptive immunity and has emerged as a key regulator of tumor growth, especially in the context of immune checkpoint blockade (ICB) therapy. However, the underlying mechanisms for how the microbiome affects tumor growth remain unclear. Pancreatic ductal adenocarcinoma (PDAC) tends to be refractory to therapy, including ICB. Using a nontargeted, liquid chromatography-tandem mass spectrometry-based metabolomic screen, we identified the gut microbe-derived metabolite trimethylamine -oxide (TMAO), which enhanced antitumor immunity to PDAC. Delivery of TMAO intraperitoneally or via a dietary choline supplement to orthotopic PDAC-bearing mice reduced tumor growth, associated with an immunostimulatory tumor-associated macrophage (TAM) phenotype, and activated effector T cell response in the tumor microenvironment. Mechanistically, TMAO potentiated the type I interferon (IFN) pathway and conferred antitumor effects in a type I IFN-dependent manner. Delivering TMAO-primed macrophages intravenously produced similar antitumor effects. Combining TMAO with ICB (anti-PD1 and/or anti-Tim3) in a mouse model of PDAC significantly reduced tumor burden and improved survival beyond TMAO or ICB alone. Last, the levels of bacteria containing CutC (an enzyme that generates trimethylamine, the TMAO precursor) correlated with long-term survival in patients with PDAC and improved response to anti-PD1 in patients with melanoma. Together, our study identifies the gut microbial metabolite TMAO as a driver of antitumor immunity and lays the groundwork for potential therapeutic strategies targeting TMAO.
Neuregulin 4 suppresses NASH-HCC development by restraining tumor-prone liver microenvironment.
The mammalian liver comprises heterogeneous cell types within its tissue microenvironment that undergo pathophysiological reprogramming in disease states, such as non-alcoholic steatohepatitis (NASH). Patients with NASH are at an increased risk for the development of hepatocellular carcinoma (HCC). However, the molecular and cellular nature of liver microenvironment remodeling that links NASH to liver carcinogenesis remains obscure. Here, we show that diet-induced NASH is characterized by the induction of tumor-associated macrophage (TAM)-like macrophages and exhaustion of cytotoxic CD8+ T cells in the liver. The adipocyte-derived endocrine factor Neuregulin 4 (NRG4) serves as a hormonal checkpoint that restrains this pathological reprogramming during NASH. NRG4 deficiency exacerbated the induction of tumor-prone liver immune microenvironment and NASH-related HCC, whereas transgenic NRG4 overexpression elicited protective effects in mice. In a therapeutic setting, recombinant NRG4-Fc fusion protein exhibited remarkable potency in suppressing HCC and prolonged survival in the treated mice. These findings pave the way for therapeutic intervention of liver cancer by targeting the NRG4 hormonal checkpoint.
Intratumoural immune heterogeneity as a hallmark of tumour evolution and progression in hepatocellular carcinoma.
Nguyen Phuong H D,Ma Siming,Phua Cheryl Z J,Kaya Neslihan A,Lai Hannah L H,Lim Chun Jye,Lim Jia Qi,Wasser Martin,Lai Liyun,Tam Wai Leong,Lim Tony K H,Wan Wei Keat,Loh Tracy,Leow Wei Qiang,Pang Yin Huei,Chan Chung Yip,Lee Ser Yee,Cheow Peng Chung,Toh Han Chong,Ginhoux Florent,Iyer Shridhar,Kow Alfred W C,Young Dan Yock,Chung Alexander,Bonney Glen K,Goh Brian K P,Albani Salvatore,Chow Pierce K H,Zhai Weiwei,Chew Valerie
The clinical relevance of immune landscape intratumoural heterogeneity (immune-ITH) and its role in tumour evolution remain largely unexplored. Here, we uncover significant spatial and phenotypic immune-ITH from multiple tumour sectors and decipher its relationship with tumour evolution and disease progression in hepatocellular carcinomas (HCC). Immune-ITH is associated with tumour transcriptomic-ITH, mutational burden and distinct immune microenvironments. Tumours with low immune-ITH experience higher immunoselective pressure and escape via loss of heterozygosity in human leukocyte antigens and immunoediting. Instead, the tumours with high immune-ITH evolve to a more immunosuppressive/exhausted microenvironment. This gradient of immune pressure along with immune-ITH represents a hallmark of tumour evolution, which is closely linked to the transcriptome-immune networks contributing to disease progression and immune inactivation. Remarkably, high immune-ITH and its transcriptomic signature are predictive for worse clinical outcome in HCC patients. This in-depth investigation of ITH provides evidence on tumour-immune co-evolution along HCC progression.
Pilot study of Tremelimumab with and without cryoablation in patients with metastatic renal cell carcinoma.
Campbell Matthew T,Matin Surena F,Tam Alda L,Sheth Rahul A,Ahrar Kamran,Tidwell Rebecca S,Rao Priya,Karam Jose A,Wood Christopher G,Tannir Nizar M,Jonasch Eric,Gao Jianjun,Zurita Amado J,Shah Amishi Y,Jindal Sonali,Duan Fei,Basu Sreyashi,Chen Hong,Espejo Alexsandra B,Allison James P,Yadav Shalini S,Sharma Padmanee
Cryoablation in combination with immune checkpoint therapy was previously reported to improve anti-tumor immune responses in pre-clinical studies. Here we report a pilot study of anti-CTLA-4 (tremelimumab) with (n = 15) or without (n = 14) cryoablation in patients with metastatic renal cell carcinoma (NCT02626130), 18 patients with clear cell and 11 patients with non-clear cell histologies. The primary endpoint is safety, secondary endpoints include objective response rate, progression-free survival, and immune monitoring studies. Safety data indicate ≥ grade 3 treatment-related adverse events in 16 of 29 patients (55%) including 6 diarrhea/colitis, 3 hepatitis, 1 pneumonitis, and 1 glomerulonephritis. Toxicity leading to treatment discontinuation occurs in 5 patients in each arm. 3 patients with clear cell histology experience durable responses. One patient in the tremelimumab arm experiences an objective response, the median progression-free survival for all patients is 3.3 months (95% CI: 2.0, 5.3 months). Exploratory immune monitoring analysis of baseline and post-treatment tumor tissue samples shows that treatment increases immune cell infiltration and tertiary lymphoid structures in clear cell but not in non-clear cell. In clear cell, cryoablation plus tremelimumab leads to a significant increase in immune cell infiltration. These data highlight that treatment with tremelimumab plus cryotherapy is feasible and modulates the immune microenvironment in patients with metastatic clear cell histology.
A phase 1-2 trial of sitravatinib and nivolumab in clear cell renal cell carcinoma following progression on antiangiogenic therapy.
Science translational medicine
The accumulation of immune-suppressive myeloid cells is a critical determinant of resistance to anti-programmed death-1 (PD-1) therapy in advanced clear cell renal cell carcinoma (ccRCC). In preclinical models, the tyrosine kinase inhibitor sitravatinib enhanced responses to anti-PD-1 therapy by modulating immune-suppressive myeloid cells. We conducted a phase 1-2 trial to choose an optimal sitravatinib dose combined with a fixed dose of nivolumab in 42 immunotherapy-naïve patients with ccRCC refractory to prior antiangiogenic therapies. The combination demonstrated no unexpected toxicities and achieved an objective response rate of 35.7% and a median progression-free survival of 11.7 months, with 80.1% of patients alive after a median follow-up of 18.7 months. Baseline peripheral blood neutrophil-to-lymphocyte ratio correlated with response to sitravatinib and nivolumab. Patients with liver metastases showed durable responses comparable to patients without liver metastases. In addition, correlative studies demonstrated reduction of immune-suppressive myeloid cells in the periphery and tumor microenvironment following sitravatinib treatment. This study provides a rationally designed combinatorial strategy to improve outcomes of anti-PD-1 therapy in advanced ccRCC.