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Nanoparticle enhanced MRI can monitor macrophage response to CD47 mAb immunotherapy in osteosarcoma.

ABSTRACT: CD47 monoclonal antibodies (mAbs) activate tumor-associated macrophages (TAMs) in sarcomas to phagocytose and eliminate cancer cells. Though CD47 mAbs have entered clinical trials, diagnostic tests for monitoring therapy response in vivo are currently lacking. Ferumoxytol is an FDA-approved iron supplement which can be used "off label" as a contrast agent: the nanoparticle-based drug is phagocytosed by TAM and can be detected with magnetic resonance imaging (MRI). We evaluated if ferumoxytol-enhanced MRI can monitor TAM response to CD47 mAb therapy in osteosarcomas. Forty-eight osteosarcoma-bearing mice were treated with CD47 mAb or control IgG and underwent pre- and post-treatment ferumoxytol-MRI scans. Tumor enhancement, quantified as T2 relaxation times, was compared with the quantity of TAMs as determined by immunofluorescence microscopy and flow cytometry. Quantitative data were compared between experimental groups using exact two-sided Wilcoxon rank-sum tests. Compared to IgG-treated controls, CD47 mAb-treated tumors demonstrated significantly shortened T2 relaxation times on ferumoxytol-MRI scans (p?

SUBMITTER: Mohanty S

PROVIDER: S-EPMC6367456 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Nanoparticle enhanced MRI can monitor macrophage response to CD47 mAb immunotherapy in osteosarcoma.

Mohanty Suchismita S Yerneni Ketan K Theruvath Johanna Lena JL Graef Claus Moritz CM Nejadnik Hossein H Lenkov Olga O Pisani Laura L Rosenberg Jarrett J Mitra Siddhartha S Cordero Alejandro Sweet AS Cheshier Samuel S Daldrup-Link Heike E HE

Cell death & disease 20190115 2

CD47 monoclonal antibodies (mAbs) activate tumor-associated macrophages (TAMs) in sarcomas to phagocytose and eliminate cancer cells. Though CD47 mAbs have entered clinical trials, diagnostic tests for monitoring therapy response in vivo are currently lacking. Ferumoxytol is an FDA-approved iron supplement which can be used "off label" as a contrast agent: the nanoparticle-based drug is phagocytosed by TAM and can be detected with magnetic resonance imaging (MRI). We evaluated if ferumoxytol-enh ...[more]

PMID: 30674867

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Project description:BackgroundCancer cells can overexpress CD47, an innate immune checkpoint that prevents phagocytosis upon interaction with signal regulatory protein alpha (SIRPα) expressed in macrophages and other myeloid cells. Several clinical trials have reported that CD47 blockade reduces tumor growth in hematological malignancies. However, CD47 blockade has shown modest results in solid tumors, including melanoma. Our group has demonstrated that histone deacetylase 6 inhibitors (HDAC6is) have immunomodulatory properties, such as controlling macrophage phenotype and inflammatory properties. However, the molecular and cellular mechanisms controlling these processes are not fully understood. In this study, we evaluated the role of HDAC6 in regulating the CD47/SIRPα axis and phagocytosis in macrophages.MethodsWe tested the role of HDAC6is, especially Nexturastat A, in regulating macrophage phenotype and phagocytic function using bone marrow-derived macrophages and macrophage cell lines. The modulation of the CD47/SIRPα axis and phagocytosis by HDAC6is was investigated using murine and human melanoma cell lines and macrophages. Phagocytosis was evaluated via coculture assays of macrophages and melanoma cells by flow cytometry and immunofluorescence. Lastly, to evaluate the antitumor activity of Nexturastat A in combination with anti-CD47 or anti-SIRPα antibodies, we performed in vivo studies using the SM1 and/or B16F10 melanoma mouse models.ResultsWe observed that HDAC6is enhanced the phenotype of antitumoral M1 macrophages while decreasing the protumoral M2 phenotype. In addition, HDAC6 inhibition diminished the expression of SIRPα, increased the expression of other pro-phagocytic signals in macrophages, and downregulated CD47 expression in mouse and human melanoma cells. This regulatory role on the CD47/SIRPα axis translated into enhanced antitumoral phagocytic capacity of macrophages treated with Nexturastat A and anti-CD47. We also observed that the systemic administration of HDAC6i enhanced the in vivo antitumor activity of anti-CD47 blockade in melanoma by modulating macrophage and natural killer cells in the tumor microenvironment. However, Nexturastat A did not enhance the antitumor activity of anti-SIRPα despite its modulation of macrophage populations in the SM1 tumor microenvironment.ConclusionsOur results demonstrate the critical regulatory role of HDAC6 in phagocytosis and innate immunity for the first time, further underscoring the use of these inhibitors to potentiate CD47 immune checkpoint blockade therapeutic strategies.

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Nanoparticle enhanced MRI can monitor macrophage response to CD47 mAb immunotherapy in osteosarcoma.

Publications

Nanoparticle enhanced MRI can monitor macrophage response to CD47 mAb immunotherapy in osteosarcoma.

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