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      Potent immunomodulatory effects of an anti-CEA-IL-2 immunocytokine on tumor therapy and effects of stereotactic radiation


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          While anti-CEA antibodies have no direct effect on CEA-positive tumors, they can be used to direct potent anti-tumor effects as an antibody-IL-2 fusion protein (immunocytokine, ICK), and at the same time reduce the toxicity of IL-2 as a single agent. Using a fusion protein of humanized anti-CEA with human IL-2 (M5A-IL-2) in a transgenic murine model expressing human CEA, we show high tumor uptake of the ICK to CEA-positive tumors with additional lymph node targeting. ICK treated CEA-positive tumors exhibit significant tumor eradication. Analysis of tumor-infiltrating lymphocytes shows a high frequency of both CD8 + and CD4 + T cells along with CD11b positive myeloid cells in ICK treated mice. The frequency of tumor-infiltrating FoxP3 + CD4 + T cells (Tregs) is significantly reduced vs anti-CEA antibody-treated controls, indicating that ICK did not preferentially stimulate migration or proliferation of Tregs to the tumor. Combination therapy with anti-PD-1 antibody did not improve tumor reduction over ICK therapy alone. Since stereotactic tumor irradiation (SRT), commonly used in cancer therapy has immunomodulatory effects, we tested combination SRT+ICK therapy in two tumor model systems. Use of fractionated vs single high dose SRT in combination with ICK resulted in greater tumor inhibition and immunity to tumor rechallenge. In particular, tumor microenvironment and myeloid cell composition appear to play a significant role in the response rate to ICK+SRT combination therapy.

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          Most cited references 36

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          The biology of interleukin-2 and interleukin-15: implications for cancer therapy and vaccine design.

          Interleukin-2 and interleukin-15 have pivotal roles in the control of the life and death of lymphocytes. Although their heterotrimeric receptors have two receptor subunits in common, these two cytokines have contrasting roles in adaptive immune responses. The unique role of interleukin-2 is in the elimination of self-reactive T cells to prevent autoimmunity. By contrast, interleukin-15 is dedicated to the prolonged maintenance of memory T-cell responses to invading pathogens. As discussed in this Review, the biology of these cytokines will affect the development of novel therapies for malignancy and autoimmune diseases, as well as the design of vaccines against infectious diseases.
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            Inhibition of vasculogenesis, but not angiogenesis, prevents the recurrence of glioblastoma after irradiation in mice.

            Despite the high doses of radiation delivered in the treatment of patients with glioblastoma multiforme (GBM), the tumors invariably recur within the irradiation field, resulting in a low cure rate. Understanding the mechanism of such recurrence is therefore important. Here we have shown in an intracranial GBM xenograft model that irradiation induces recruitment of bone marrow-derived cells (BMDCs) into the tumors, restoring the radiation-damaged vasculature by vasculogenesis and thereby allowing the growth of surviving tumor cells. BMDC influx was initiated by induction of HIF-1 in the irradiated tumors, and blocking this influx prevented tumor recurrence. Previous studies have indicated that BMDCs are recruited to tumors in part through the interaction between the HIF-1-dependent stromal cell-derived factor-1 (SDF-1) and its receptor, CXCR4. Pharmacologic inhibition of HIF-1 or of the SDF-1/CXCR4 interaction prevented the influx of BMDCs, primarily CD11b+ myelomonocytes, and the postirradiation development of functional tumor vasculature, resulting in abrogation of tumor regrowth. Similar results were found using neutralizing antibodies against CXCR4. Our data therefore suggest a novel approach for the treatment of GBM: in addition to radiotherapy, the vasculogenesis pathway needs to be blocked, and this can be accomplished using the clinically approved drug AMD3100, a small molecule inhibitor of SDF-1/CXCR4 interactions.
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              Stat3 mediates myeloid cell-dependent tumor angiogenesis in mice.

              The underlying molecular mechanisms that cause immune cells, mediators of our defense system, to promote tumor invasion and angiogenesis remain incompletely understood. Constitutively activated Stat3 in tumor cells has been shown to promote tumor invasion and angiogenesis. Therefore, we sought to determine whether Stat3 activation in tumor-associated inflammatory cells has a similar function. We found that Stat3 signaling mediates multidirectional crosstalk among tumor cells, myeloid cells in the tumor stroma, and ECs that contributes to tumor angiogenesis in mice. Myeloid-derived suppressor cells and macrophages isolated from mouse tumors displayed activated Stat3 and induced angiogenesis in an in vitro tube formation assay via Stat3 induction of angiogenic factors, including VEGF and bFGF. Stat3-regulated factors produced by both tumor cells and tumor-derived myeloid cells also induced constitutive activation of Stat3 in tumor endothelium, and inhibiting Stat3 in ECs substantially reduced in vitro tumor factor-induced endothelial migration and tube formation. In vivo assays demonstrated the requirement for Stat3 signaling in tumor-associated myeloid cells for tumor angiogenesis. Our results indicate that, by virtue of the ability of Stat3 in tumor cells and tumor-derived myeloid cells to upregulate expression of factors that activate Stat3 in ECs, Stat3 mediates multidirectional crosstalk among tumor cells, tumor-associated myeloid cells, and ECs that contributes to tumor angiogenesis.

                Author and article information

                Taylor & Francis
                14 February 2020
                14 February 2020
                : 9
                : 1
                [a ]Department of Molecular Imaging and Therapy, City of Hope , Duarte, CA, USA
                [b ]School of Pharmacy, West Coast University , Los Angeles, CA, USA
                [c ]Department of Radiation Oncology, City of Hope , Duarte, CA, USA
                [d ]Radiopharmacy, City of Hope , Duarte, CA, USA
                Author notes
                CONTACT John E. Shively jshively@ 123456coh.org Department of Molecular Imaging and Therapy, City of Hope , 1500 East Duarte Rd, Duarte, CA 91010, USA
                © 2020 The Author(s). Published with license by Taylor & Francis Group, LLC.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License ( http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

                Page count
                Figures: 7, References: 49, Pages: 15
                Funded by: National Institutes of Health 10.13039/100000054
                Award ID: P01 CA43904
                This work was supported by National Institutes of Health grant [P01 CA43904].
                Original Research


                il-2, immunocytokine, cea, antibody, stereotactic radiation, breast cancer


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