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Ponce LP, Fenn NC, Moritz N, Krupka C, Kozik JH, Lauber K, Subklewe M, Hopfner KP. SIRPα-antibody fusion proteins stimulate phagocytosis and promote elimination of acute myeloid leukemia cells. Oncotarget 2017; 8:11284-11301. [PMID: 28061465 PMCID: PMC5355265 DOI: 10.18632/oncotarget.14500] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 12/12/2016] [Indexed: 01/13/2023] Open
Abstract
CD47, expressed on a variety of tumor cells, confers immune resistance by delivering an inhibitory "don't eat me" signal to phagocytic cells via its myeloid-specific receptor SIRPα. Recent studies have shown that blocking the CD47-SIRPα axis with CD47-directed antibodies or antibody-derivatives enhances phagocytosis and increases antitumor immune effects. However, CD47 expression on healthy cells creates an antigen sink and potential sites of toxicity, limiting the efficacy of CD47-directed therapies. In this study, we first characterized CD47 expression in Acute Myeloid Leukemia (AML) patients (n = 213) and found that CD47 is highly expressed on both AML bulk and stem cells irrespective of the disease state. Furthermore, to inhibit the CD47-SIRPα signaling pathway at the tumor site, we developed a so-called local inhibitory checkpoint monoclonal antibody (licMAB) by grafting the endogenous SIRPα domain to the N-terminus of the light chain of an antibody targeting CD33, a surface antigen expressed in AML. LicMABs selectively bind CD33-expressing cells even in the presence of a large CD33-negative CD47-positive antigen sink, stimulate phagocytosis of AML cells and eliminate AML cell lines and primary, patient-derived AML cells. Our findings qualify licMABs as a promising therapeutic approach to confine the benefit of disrupting the CD47-SIRPα axis to tumor antigen-expressing cells.
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Affiliation(s)
- Laia Pascual Ponce
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
- Graduate School of Quantitative Biosciences Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Nadja C. Fenn
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Nadine Moritz
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Christina Krupka
- Department of Internal Medicine III, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany
- Gene Center and Clinical Co-operation Group Immunotherapy at the Helmholtz Zentrum München, Munich, Germany
| | - Jan-Hendrik Kozik
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Kirsten Lauber
- Department of Radiation Oncology, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Marion Subklewe
- Department of Internal Medicine III, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany
- Gene Center and Clinical Co-operation Group Immunotherapy at the Helmholtz Zentrum München, Munich, Germany
| | - Karl-Peter Hopfner
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
- Graduate School of Quantitative Biosciences Munich, Ludwig-Maximilians-Universität München, Munich, Germany
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