CD47–signal regulatory protein-α (SIRPα) interactions form a barrier for antibody-mediated tumor cell destruction

Monoclonal antibodies are among the most promising therapeutic agents for treating cancer. Therapeutic cancer antibodies bind to tumor cells, turning them into targets for immune-mediated destruction. We show here that this antibody-mediated killing of tumor cells is limited by a mechanism involving the interaction between tumor cell-expressed CD47 and the inhibitory receptor signal regulatory protein-α (SIRPα) on myeloid cells. Mice that lack the SIRPα cytoplasmic tail, and hence its inhibitory signaling, display increased antibody-mediated elimination of melanoma cells in vivo. Moreover, interference with CD47–SIRPα interactions by CD47 knockdown or by antagonistic antibodies against CD47 or SIRPα significantly enhances the in vitro killing of trastuzumab-opsonized Her2/Neu-positive breast cancer cells by phagocytes. Finally, the response to trastuzumab therapy in breast cancer patients appears correlated to cancer cell CD47 expression. These findings demonstrate that CD47–SIRPα interactions participate in a homeostatic mechanism that restricts antibody-mediated killing of tumor cells. This provides a rational basis for targeting CD47–SIRPα interactions, using for instance the antagonistic antibodies against human SIRPα described herein, to potentiate the clinical effects of cancer therapeutic antibodies.

[1]  Eric J. Brown,et al.  Bidirectional Negative Regulation of Human T and Dendritic Cells by CD47 and Its Cognate Receptor Signal-Regulator Protein-α: Down-Regulation of IL-12 Responsiveness and Inhibition of Dendritic Cell Activation1 , 2001, The Journal of Immunology.

[2]  A. Ullrich,et al.  Signal-regulatory protein alpha (SIRPalpha) but not SIRPbeta is involved in T-cell activation, binds to CD47 with high affinity, and is expressed on immature CD34(+)CD38(-) hematopoietic cells. , 2001, Blood.

[3]  T. K. van den Berg,et al.  Signal-regulatory protein is selectively expressed by myeloid and neuronal cells. , 1998, Journal of immunology.

[4]  J. Mcwhirter,et al.  CD200 Expression on Tumor Cells Suppresses Antitumor Immunity: New Approaches to Cancer Immunotherapy , 2007, The Journal of Immunology.

[5]  A. Houghton,et al.  Implicating a role for immune recognition of self in tumor rejection: passive immunization against the brown locus protein , 1995, The Journal of experimental medicine.

[6]  E. Vitetta,et al.  A Comparison of the in Vitro and in Vivo Activities of IgG and F(ab′)2 Fragments of a Mixture of Three Monoclonal Anti-Her-2 Antibodies , 2004, Clinical Cancer Research.

[7]  E. Winer,et al.  Predictors of Resistance to Preoperative Trastuzumab and Vinorelbine for HER2-Positive Early Breast Cancer , 2007, Clinical Cancer Research.

[8]  A. Ullrich,et al.  Signal-regulatory protein a ( SIRP a ) but not SIRP b is involved in T-cell activation , binds to CD 47 with high affinity , and is expressed on immature CD 34 1 CD 38 2 hematopoietic cells , 2001 .

[9]  A. Barclay,et al.  CD47 is a ligand for rat macrophage membrane signal regulatory protein SIRP (OX41) and human SIRPα 1 , 2000, European journal of immunology.

[10]  J. Dick,et al.  Polymorphism in Sirpa modulates engraftment of human hematopoietic stem cells , 2007, Nature Immunology.

[11]  D. Stuart,et al.  Structure of Signal-regulatory Protein α , 2009, The Journal of Biological Chemistry.

[12]  Daniel Birnbaum,et al.  Gene expression profiling shows medullary breast cancer is a subgroup of basal breast cancers. , 2006, Cancer research.

[13]  P. Bruhns,et al.  Platelet homeostasis is regulated by platelet expression of CD47 under normal conditions and in passive immune thrombocytopenia. , 2005, Blood.

[14]  Ash A. Alizadeh,et al.  Anti-CD47 Antibody Synergizes with Rituximab to Promote Phagocytosis and Eradicate Non-Hodgkin Lymphoma , 2010, Cell.

[15]  H. Gresham,et al.  Cd47-Signal Regulatory Protein α (Sirpα) Regulates Fcγ and Complement Receptor–Mediated Phagocytosis , 2001, The Journal of experimental medicine.

[16]  A. Barclay,et al.  The SIRP family of receptors and immune regulation , 2006, Nature Reviews Immunology.

[17]  Ash A. Alizadeh,et al.  Therapeutic antibody targeting of CD47 eliminates human acute lymphoblastic leukemia. , 2011, Cancer research.

[18]  C. Lagenaur,et al.  Role of CD47 as a marker of self on red blood cells. , 2000, Science.

[19]  T. Berg,et al.  Innate immune ‘self’ recognition: a role for CD47–SIRPα interactions in hematopoietic stem cell transplantation , 2008 .

[20]  E. Sausville,et al.  A mechanistic perspective of monoclonal antibodies in cancer therapy beyond target-related effects. , 2007, The oncologist.

[21]  S. Akira,et al.  Negative Regulation of Platelet Clearance and of the Macrophage Phagocytic Response by the Transmembrane Glycoprotein SHPS-1* , 2002, The Journal of Biological Chemistry.

[22]  C. Lagenaur,et al.  Integrin-associated Protein Is a Ligand for the P84 Neural Adhesion Molecule* , 1999, The Journal of Biological Chemistry.

[23]  T. Matozaki,et al.  SHPS-1 promotes the survival of circulating erythrocytes through inhibition of phagocytosis by splenic macrophages. , 2006, Blood.

[24]  L. Presta,et al.  Inhibitory Fc receptors modulate in vivo cytoxicity against tumor targets , 2000, Nature Medicine.

[25]  M. Kasuga,et al.  A novel membrane glycoprotein, SHPS-1, that binds the SH2-domain-containing protein tyrosine phosphatase SHP-2 in response to mitogens and cell adhesion , 1996, Molecular and cellular biology.

[26]  A. Musolino,et al.  Immunoglobulin G fragment C receptor polymorphisms and clinical efficacy of trastuzumab-based therapy in patients with HER-2/neu-positive metastatic breast cancer. , 2008, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[27]  M. Glennie,et al.  Renaissance of cancer therapeutic antibodies. , 2003, Drug discovery today.

[28]  T. K. van den Berg,et al.  Signal Regulatory Proteins in the Immune System , 2005, The Journal of Immunology.

[29]  R. Dillman,et al.  Monoclonal antibodies in cancer therapy: 25 years of progress. , 2008, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[30]  Daniel Birnbaum,et al.  A gene expression signature identifies two prognostic subgroups of basal breast cancer , 2011, Breast Cancer Research and Treatment.

[31]  T. Matozaki,et al.  Negative Regulation of Phagocytosis in Macrophages by the CD47-SHPS-1 System1 , 2005, The Journal of Immunology.

[32]  A. Saven,et al.  Antibodies selected from combinatorial libraries block a tumor antigen that plays a key role in immunomodulation. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[33]  A. Kretz-Rommel,et al.  Blockade of CD200 in the Presence or Absence of Antibody Effector Function: Implications for Anti-CD200 Therapy , 2008, The Journal of Immunology.

[34]  A. Ullrich,et al.  A family of proteins that inhibit signalling through tyrosine kinase receptors , 1997, Nature.

[35]  J. Isola,et al.  Trastuzumab causes antibody-dependent cellular cytotoxicity–mediated growth inhibition of submacroscopic JIMT-1 breast cancer xenografts despite intrinsic drug resistance , 2007, Molecular Cancer Therapeutics.

[36]  B. Neel,et al.  Identification of Major Binding Proteins and Substrates for the SH2-Containing Protein Tyrosine Phosphatase SHP-1 in Macrophages , 1998, Molecular and Cellular Biology.

[37]  Lewis L Lanier,et al.  NK cell recognition. , 2005, Annual review of immunology.

[38]  J. V. D. van de Winkel,et al.  Mac-1 (CD11b/CD18) is crucial for effective Fc receptor-mediated immunity to melanoma. , 2003, Blood.