21 research outputs found
Immunotherapeutic Blockade of Macrophage Clever-1 Reactivates the CD8(+) T-cell Response against Immunosuppressive Tumors
Purpose: As foremost regulators of cancer-related inflammation and immunotherapeutic resistance, tumor-associated macrophages have garnered major interest as immunotherapeutic drug targets. However, depletory strategies have yielded little benefit in clinical studies to date. An alternative approach is to exploit macrophage plasticity and "reeducate" tumorigenic macrophages toward an immunostimulatory phenotype to activate the host's antitumor immunity.Experimental Design: We investigated the role of the macrophage scavenger receptor common lymphatic endothelial and vascular endothelial receptor-1 (Clever-1) on tumor growth in multiple mouse cancer models with inflammatory and noninflammatory characteristics by using conditional knockouts, bone marrow chimeras, and cell depletion experiments. In addition, the efficacy of immunotherapeutic Clever-1 blockade as monotherapy or in combination with anti-PD-1 was tested.Results: Genetic deficiency of macrophage Clever-1 markedly impaired solid tumor growth. This effect was mediated by macrophages that became immunostimulatory in the absence of Clever-1, skewing the suppressive tumor microenvironment toward inflammation and activating endogenous antitumor CD8 thorn T cells. Comparable effects were achieved with immunotherapeutic blockade of Clever-1. Notably, these effects were similar to those achieved by PD-1 checkpoint inhibition. Moreover, combining anti-Clever-1 with anti-PD-1 provided synergistic benefit in aggressive, nonresponsive tumors.Conclusions: These findings demonstrate the importance of macrophages in mediating antitumor immune responses and support the clinical evaluation of immunotherapeutic Clever-1 blockade as a novel cancer treatment strategy.</div
Clever-1 in cancer – Assessing the efficacy of a novel immunotherapy approach in patient derived explant cultures
The efficacy of oncological treatments has developed significantly in the past few decades but yet various types of cancer still lack curative treatment. In cancer immunotherapies the object is to guide one’s own immune system to detect and desolate the cancerous cells. This method allows reduced use of toxic chemotherapies in oncology. With the use of immunotherapies there have been unprecedented results in treated cancer patients on the depletion of tumor and metastasis. A form of active immunotherapy called immune checkpoint blockade (ICB) targets the key regulators of the immune system and induce inflammatory activation, aiming to re-establish inflammation in the site of the tumor. Targeting of immunosuppressive macrophages with anti-Clever-1 drug is a novel approach in immune-oncological treatments. Humanized anti-Clever-1 antibody is already in phase I/II clinical trials in cancer patients with selected metastatic or inoperable solid tumors and this study is aimed to help to understand the biological effect of this drug in cancer.
With the use of breast cancer patient material that was acquired in collaboration with Turku university hospital we were able to study the expression of Clever-1+ macrophages and CD8+ T cells in the tumor microenvironment with use of immunohistochemistry. In addition, we conducted a novel assay where we co-cultured the patient tumor tissue with peripheral blood mononuclear cells (PBMCs) that are immune cells we extracted from the blood of the test subjects and treated them with anti-Clever-1 antibody. The idea of this assay was to image if the treated cells induce apoptosis in the tumor in relation to control samples.
This unique assay made it possible for us to image the biological response of the tumor tissue more accurately than with the use of basic 2D cell cultures. The results show how these anti-Clever-1 treated PBMCs induce higher amounts of apoptosis in the tumor compared to the controls. This assay thus proved unprecedented results on anti-Clever-1 treatment’s biological effects in the tumor site and is a solid addition to previous studies on the subject. What is more, this novel explant assay is applicable to be used in further studies using different combinations of antibodies and in imaging their biological effects in the tissue, ex vivo.Onkologisten hoitojen tehokkuus on kehittynyt paljon viimeisten vuosikymmenten aikana, mutta lukuisille syöpätyypeille ei edelleenkään ole tehokasta hoitoa. Syövän immuunihoidoissa ohjataan potilaan omaa immuunijärjestelmää tuhoamaan syöpäsolut. Näin voidaan osittain välttää tai vähentää toksisten sytostaattihoitojen käyttöä onkologiassa. Immuunihoidoilla yksin tai yhdistämällä ne perinteisiin syöpähoitoihin on saatu ennennäkemättömiä tuloksia syövän ja sen metastaasien reduktiossa. Eräs aktiivisen immuuniterapian muoto on ICB-hoito (immune checkpoint blockade), jossa elimistön immuunijärjestelmän syöpää vastustavat ominaisuudet pyritään aktivoimaan. Tähän perustuva, immunosuppressiivisiin makrofageihin vaikuttava anti-Clever-1 vasta-aine on uusi mahdollinen immuno-onkologinen hoito. Clever-1 vasta-ainetta on jo käytetty vaiheen I/II kliinisissä kokeissa syöpäpotilailla. Tässä tutkimuksessa selvitettiin Clever-1 vasta-ainehoidon biologisia vaikutuksia ihmisen syöpäkudoksessa ex vivo.
Turun yliopistollisesta keskussairaalasta saatujen rintasyöpänäytteiden avulla pystyimme tutkimaan Clever-1 positiivisten makrofagien ja T-solujen määrää kasvainkudoksessa ja niiden sijoittumista kasvaimen mikroympäristössä käyttäen immunohistokemiallisia menetelmiä. Lisäksi, teimme kokeen, missä käsittelimme potilaiden kasvainkudosta vastaavien potilaiden verestä eristetyillä perifeerisillä mononukleaarisilla soluilla (PBMC, peripheral blood mononuclear cell), joita oli käsitelty anti-Clever-1 vasta-aineella. Tässä tutkimme käsiteltyjen solujen vaikutusta syöpäsoluihin ja kasvainkudoksessa indusoituneen apoptoosin määrää kvalitatiivisesti.
Tämä ainutlaatuinen koe mahdollisti kasvainkudoksen biologisen vasteen kuvantamista paremmin kuin aiemmin yleisesti käytetyllä kaksiulotteisella solukasvatuksella. Koe osoitti, kuinka potilaan käsitellyt PBMC solut infiltroivat kasvainkudokseen ja aiheuttavat apoptoosia kasvainkudoksessa, kun soluja esikäsiteltiin anti-Clever-1 vasta-aineella
Clever-1 positive macrophages in breast cancer
Purpose Common Lymphatic Endothelial and Vascular Endothelial Receptor 1 (Clever-1) is expressed by a subset of immunosuppressive macrophages and targeting the receptor with therapeutic antibodies has been shown to activate T-cell-mediated anti-cancer immunity. The aim of this research was to study Clever-1 expression in breast cancer. Specifically, how Clever-1 + macrophages correlate with clinicopathologic factors, Tumor Infiltrating Lymphocytes (TILs) and prognosis. Methods Tissue microarray blocks were made from 373 primary breast cancer operation specimens. Hematoxylin and Eosin (H&E-staining) and immunohistochemical staining with Clever-1, CD3, CD4 and CD8 antibodies were performed. Differences in quantities of Clever-1 + macrophages and TILs were analyzed. Clever-1 + cell numbers were correlated with 25-year follow-up survival data and with breast cancer clinicopathologic parameters. Results Low numbers of intratumoral Clever-1 + cells were found to be an independent adverse prognostic sign. Increased numbers of Clever-1 + cells were found in high grade tumors and hormone receptor negative tumors. Tumors that had higher amounts of Clever-1 + cells also tended to have higher amounts of TILs. Conclusion The association of intratumoral Clever-1 + macrophages with better prognosis might stem from the function of Clever as a scavenger receptor that modulates tumor stroma. The association of Clever-1 + macrophages with high number of TILs and better prognosis indicates that immunosuppression by M2 macrophages is not necessarily dampening adaptive immune responses but instead keeping them in control to avoid excess inflammation.Peer reviewe
Characterization of Clever-1 expressing extracellular vesicles and their effect on T lymphocyte proliferation
Immune checkpoint inhibitors (ICIs) are the new milestone for the management of advanced solid cancers. Unfortunately, most patients are not responsive to these treatments, since they may develop mechanisms that suppress the quality and quantity of antitumor T-cell responses. The tumor microenvironment (TME) is a key cellular component of tumors. It includes immunomodulatory cells that display important roles in the resistance to ICIs. Among these cells, tumor-associated macrophages (TAMs) from the M2-like phenotype have been described to favor tumor growth and downregulate local and systemic immune responses.
A subpopulation of these TAMs expresses Clever-1 (also known as Stabilin-1), which support the formation of an immunosuppressive TME and T-cell dysfunction. The depletion of Clever-1 both genetically and immunotherapeutically has been shown to activate the adaptive immune system and consequently, reduce tumor growth and metastasis. Recently, Clever-1 expression was detected in body fluids (plasma and lymph). However, how Clever-1 is secreted in the body and its functional consequences in T-cell function is poorly understood.
Here, we identify by using differential centrifugation process of body fluids and immortalized monocytic conditioned medium that Clever-1 is expressed in both extracellular vesicles (EVs) and non-vesicular (NV) formats. Further, we show using in vitro assays that Clever-1+EVs functionally target T-cells affecting their proliferation status. Future studies are required to prove the process is dependent on Clever-1 and further investigate in the mechanistic routes involved in the inhibition mechanisms of Clever-1+EVs. In conclusion, this study describes the expression of suppressive proteins (e.g., Clever-1) in EV compartments with their inhibitory effects on T-cells in body fluids
Systemic Blockade of Clever-1 Elicits Lymphocyte Activation Alongside Checkpoint Molecule Downregulation in Patients with Solid Tumors : Results from a Phase I/II Clinical Trial
Purpose: Macrophages are critical in driving an immunosuppressive tumor microenvironment that counteracts the efficacy of T-cell-targeting therapies. Thus, agents able to reprogram macrophages toward a proinflammatory state hold promise as novel immunotherapies for solid cancers. Inhibition of the macrophage scavenger receptor Clever-1 has shown benefit in inducing CD8 T-cell-mediated antitumor responses in mouse models of cancer, which supports the clinical development of Clever-1-targeting antibodies for cancer treatment. Patients and Methods: In this study, we analyzed the mode of action of a humanized IgG4 anti-Clever-1 antibody, FP-1305 (bexmarilimab), both in vitro and in patients with heavily pretreated metastatic cancer (n = 30) participating in part 1 (dose-finding) of a phase I/II open-label trial (NCT03733990). We studied the Clever-1 interactome in primary human macrophages in antibody pull-down assays and utilized mass cytometry, RNA sequencing, and cytokine profiling to evaluate FP-1305-induced systemic immune activation in patients with cancer. Results: Our pull-down assays and functional studies indicated that FP-1305 impaired multiprotein vacuolar ATPase-mediated endosomal acidification and improved the ability of macrophages to activate CD8(+)T-cells. In patients with cancer, FP-1305 administration led to suppression of nuclear lipid signaling pathways and a proinflammatory phenotypic switch in blood monocytes. These effects were accompanied by a significant increase and activation of peripheral T-cells with indications of antitumor responses in some patients. Conclusions: Our results reveal a nonredundant role played by the receptor Clever-1 in suppressing adaptive immune cells in humans. We provide evidence that targeting macrophage scavenging activity can promote an immune switch, potentially leading to intratumoral proinflammatory responses in patients with metastatic cancer.Peer reviewe
New tools to prevent cancer growth and spread: a 'Clever' approach
Clever-1 (also known as Stabilin-1 and FEEL-1) is a scavenger receptor expressed on lymphatic endothelial cells, sinusoidal endothelial cells and immunosuppressive monocytes and macrophages. Its role in cancer growth and spread first became evident inStab1(-/-)knockout mice, which have smaller primary tumours and metastases. Subsequent studies in mice and humans have shown that immunotherapeutic blockade of Clever-1 can activate T-cell responses, and that this response is mainly mediated by a phenotypic change in macrophages and monocytes from immunosuppressive to pro-inflammatory following Clever-1 inhibition. Analyses of human cancer cohorts have revealed marked associations between the number of Clever-1-positive macrophages and patient outcome. As hardly any reports to date have addressed the role of Clever-1 in immunotherapy resistance and T-cell dysfunction, we performed data mining using several published cancer cohorts, and observed a remarkable correlation between Clever-1 positivity and resistance to immune checkpoint therapies. This result provides impetus and potential for the ongoing clinical trial targeting Clever-1 in solid tumours, which has so far shown a shift towards immune activation when a particular epitope of Clever-1 is blocked
Clever-1 positive macrophages in breast cancer
Purpose: Common Lymphatic Endothelial and Vascular Endothelial Receptor 1 (Clever-1) is expressed by a subset of immunosuppressive macrophages and targeting the receptor with therapeutic antibodies has been shown to activate T-cell-mediated anti-cancer immunity. The aim of this research was to study Clever-1 expression in breast cancer. Specifically, how Clever-1 + macrophages correlate with clinicopathologic factors, Tumor Infiltrating Lymphocytes (TILs) and prognosis. Methods: Tissue microarray blocks were made from 373 primary breast cancer operation specimens. Hematoxylin and Eosin (H&E-staining) and immunohistochemical staining with Clever-1, CD3, CD4 and CD8 antibodies were performed. Differences in quantities of Clever-1 + macrophages and TILs were analyzed. Clever-1 + cell numbers were correlated with 25-year follow-up survival data and with breast cancer clinicopathologic parameters. Results: Low numbers of intratumoral Clever-1 + cells were found to be an independent adverse prognostic sign. Increased numbers of Clever-1 + cells were found in high grade tumors and hormone receptor negative tumors. Tumors that had higher amounts of Clever-1 + cells also tended to have higher amounts of TILs. Conclusion: The association of intratumoral Clever-1 + macrophages with better prognosis might stem from the function of Clever as a scavenger receptor that modulates tumor stroma. The association of Clever-1 + macrophages with high number of TILs and better prognosis indicates that immunosuppression by M2 macrophages is not necessarily dampening adaptive immune responses but instead keeping them in control to avoid excess inflammation.</p
Targeting tumour-reprogrammed myeloid cells: the new battleground in cancer immunotherapy
Tumour microenvironment is a complex ecosystem in which myeloid cells are the most abundant immune elements. This cell compartment is composed by different cell types, including neutrophils, macrophages, dendritic cells, and monocytes but also unexpected cell populations with immunosuppressive and pro-tumour roles. Indeed, the release of tumour-derived factors influences physiological haematopoiesis producing unconventional cells with immunosuppressive and tolerogenic functions such as myeloid-derived suppressor cells. These pro-tumour myeloid cell populations not only support immune escape directly but also assist tumour invasion trough non-immunological activities. It is therefore not surprising that these cell subsets considerably impact in tumour progression and cancer therapy resistance, including immunotherapy, and are being investigated as potential targets for developing a new era of cancer therapy. In this review, we discuss emerging strategies able to modulate the functional activity of these tumour-supporting myeloid cells subverting their accumulation, recruitment, survival, and functions. These innovative approaches will help develop innovative, or improve existing, cancer treatments
Systemic Blockade of Clever-1 Elicits Lymphocyte Activation Alongside Checkpoint Molecule Downregulation in Patients with Solid Tumors: Results from a Phase I/II Clinical Trial
Purpose:Macrophages are critical in driving an immunosuppressive tumor microenvironment that counteracts the efficacy of T-cell–targeting therapies. Thus, agents able to reprogram macrophages toward a proinflammatory state hold promise as novel immunotherapies for solid cancers. Inhibition of the macrophage scavenger receptor Clever-1 has shown benefit in inducing CD8+ T-cell–mediated antitumor responses in mouse models of cancer, which supports the clinical development of Clever-1–targeting antibodies for cancer treatment.Patients and Methods:In this study, we analyzed the mode of action of a humanized IgG4 anti–Clever-1 antibody, FP-1305 (bexmarilimab), both in vitro and in patients with heavily pretreated metastatic cancer (n = 30) participating in part 1 (dose-finding) of a phase I/II open-label trial (NCT03733990). We studied the Clever-1 interactome in primary human macrophages in antibody pull-down assays and utilized mass cytometry, RNA sequencing, and cytokine profiling to evaluate FP-1305–induced systemic immune activation in patients with cancer.Results:Our pull-down assays and functional studies indicated that FP-1305 impaired multiprotein vacuolar ATPase–mediated endosomal acidification and improved the ability of macrophages to activate CD8+ T-cells. In patients with cancer, FP-1305 administration led to suppression of nuclear lipid signaling pathways and a proinflammatory phenotypic switch in blood monocytes. These effects were accompanied by a significant increase and activation of peripheral T-cells with indications of antitumor responses in some patients.Conclusions:Our results reveal a nonredundant role played by the receptor Clever-1 in suppressing adaptive immune cells in humans. We provide evidence that targeting macrophage scavenging activity can promote an immune switch, potentially leading to intratumoral</p
A Novel Immunostimulatory Platform for Amplifying the Abscopal Response Rates of Radiation Therapy
Radiation therapy (RT) is one of the primary treatment modalities for head and neck squamous cell carcinoma (HNSCC). At the time of diagnosis two-thirds of HNSCC patients have local-advanced disease and 50-60% of these patients will experience a local-regional or metastatic relapse within three years. Improving the immunogenic response of RT may help address this clinical problem. However, current RT regimens have failed to reliably generate robust antitumor immunity as evidenced by the rarity of clinical abscopal responses. Recently we engineered a chimeric fusion molecule called Flagrp170, a novel immunostimulatory agent highly capable of promoting antigen presentation and T-cell activation. We hypothesize that the combination of RT and Flagrp170 provides superior immunogenic signals producing effective and durable antitumor immunity against HNSCC. We report that administration of Flagrp170 to the tumor sites upon RT using a small animal radiation research platform (SARPP) results in potent activation of antigen-presenting cells, increased functionality of tumor-infiltrating T-cells, and systemic immune augmentation. Additionally, the combination treatment is able to reduce the dose of RT required for tumor control and protects previously cured animals from subsequent tumor re-challenge. Finally, the combination treatment can successfully control the contralateral untreated tumors, supporting the superior activity of Flagrp170 in potentiating abscopal responses of RT. Our data suggest that the Flagrp170 may be used to enhance immunogenic cancer cell death in RT and resultant protective antitumor immunity can potentially help reduce post-RT recurrence of HNSCC