6bit | pdb_00006bit
SIRPalpha antibody complex
Structural highlights
Function[SHPS1_HUMAN] Immunoglobulin-like cell surface receptor for CD47. Acts as docking protein and induces translocation of PTPN6, PTPN11 and other binding partners from the cytosol to the plasma membrane. Supports adhesion of cerebellar neurons, neurite outgrowth and glial cell attachment. May play a key role in intracellular signaling during synaptogenesis and in synaptic function (By similarity). Involved in the negative regulation of receptor tyrosine kinase-coupled cellular responses induced by cell adhesion, growth factors or insulin. Mediates negative regulation of phagocytosis, mast cell activation and dendritic cell activation. CD47 binding prevents maturation of immature dendritic cells and inhibits cytokine production by mature dendritic cells.[1] [2] Publication Abstract from PubMedCancer immunotherapy has emerged as a promising therapeutic intervention. However, complete and durable responses are only seen in a fraction of patients who have cancer. A key factor that limits therapeutic success is the infiltration of tumors by cells of the myeloid lineage. The inhibitory receptor signal regulatory protein-alpha (SIRPalpha) is a myeloid-specific immune checkpoint that engages the "don't eat me" signal CD47 expressed on tumors and normal tissues. We therefore developed the monoclonal antibody KWAR23, which binds human SIRPalpha with high affinity and disrupts its binding to CD47. Administered by itself, KWAR23 is inert, but given in combination with tumor-opsonizing monoclonal antibodies, KWAR23 greatly augments myeloid cell-dependent killing of a collection of hematopoietic and nonhematopoietic human tumor-derived cell lines. Following KWAR23 antibody treatment in a human SIRPA knockin mouse model, both neutrophils and macrophages infiltrate a human Burkitt's lymphoma xenograft and inhibit tumor growth, generating complete responses in the majority of treated animals. We further demonstrate that a bispecific anti-CD70/SIRPalpha antibody outperforms individually delivered antibodies in specific types of cancers. These studies demonstrate that SIRPalpha blockade induces potent antitumor activity by targeting multiple myeloid cell subsets that frequently infiltrate tumors. Thus, KWAR23 represents a promising candidate for combination therapy. Anti-SIRPalpha antibody immunotherapy enhances neutrophil and macrophage antitumor activity.,Ring NG, Herndler-Brandstetter D, Weiskopf K, Shan L, Volkmer JP, George BM, Lietzenmayer M, McKenna KM, Naik TJ, McCarty A, Zheng Y, Ring AM, Flavell RA, Weissman IL Proc Natl Acad Sci U S A. 2017 Nov 20. pii: 1710877114. doi:, 10.1073/pnas.1710877114. PMID:29158380[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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