title: Pre-Clinical Development of a Humanized Anti-CD47 Antibody with Anti-Cancer Therapeutic Potential.
abstract: CD47 is a widely expressed cell surface protein that functions as a regulator of phagocytosis mediated by cells of the innate immune system, such as macrophages and dendritic cells. CD47 serves as the ligand for a receptor on these innate immune cells, SIRP-alpha, which in turn delivers an inhibitory signal for phagocytosis. We previously found increased expression of CD47 on primary human acute myeloid leukemia (AML) stem cells, and demonstrated that blocking monoclonal antibodies directed against CD47 enabled the phagocytosis and elimination of AML, non-Hodgkin's lymphoma (NHL), and many solid tumors in xenograft models. Here, we report the development of a humanized anti-CD47 antibody with potent efficacy and favorable toxicokinetic properties as a candidate therapeutic. A novel monoclonal anti-human CD47 antibody, 5F9, was generated, and antibody humanization was carried out by grafting its complementarity determining regions (CDRs) onto a human IgG4 format. The resulting humanized 5F9 antibody (Hu5F9-G4) bound monomeric human CD47 with an 8 nM affinity. Hu5F9-G4 induced potent macrophage-mediated phagocytosis of primary human AML cells in vitro and completely eradicated human AML in vivo, leading to long-term disease-free survival of patient-derived xenografts. Moreover, Hu5F9-G4 synergized with rituximab to eliminate NHL engraftment and cure xenografted mice. Finally, toxicokinetic studies in non-human primates showed that Hu5F9-G4 could be safely administered intravenously at doses able to achieve potentially therapeutic serum levels. Thus, Hu5F9-G4 is actively being developed for and has been entered into clinical trials in patients with AML and solid tumors (ClinicalTrials.gov identifier: NCT02216409).
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Wang
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Feifei
authors.initials: F
authors.lastname: Zhao
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Serena
authors.initials: S
authors.lastname: Tseng
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Cyndhavi
authors.initials: C
authors.lastname: Narayanan
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Lei
authors.initials: L
authors.lastname: Shura
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Stephen
authors.initials: S
authors.lastname: Willingham
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Maureen
authors.initials: M
authors.lastname: Howard
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Susan
authors.initials: S
authors.lastname: Prohaska
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Jens
authors.initials: J
authors.lastname: Volkmer
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Mark
authors.initials: M
authors.lastname: Chao
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Irving L
authors.initials: IL
authors.lastname: Weissman
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center, Stanford University School of Medicine, Stanford, California, United States of America; Department of Medicine, Division of Hematology, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Ravindra
authors.initials: R
authors.lastname: Majeti
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000493:pharmacokinetics / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized / Q000276:immunology / Q000493:pharmacokinetics / Q000627:therapeutic use*; D000915:Antibody Affinity; D000970:Antineoplastic Agents / Q000276:immunology / Q000493:pharmacokinetics / Q000627:therapeutic use*; D051928:CD47 Antigen / Q000276:immunology*; D005260:Female; D000882:Haplorhini; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy* / Q000276:immunology* / Q000473:pathology; D008252:Macaca fascicularis; D051379:Mice; D008807:Mice, Inbred BALB C; D010587:Phagocytosis / Q000187:drug effects; D000069283:Rituximab / Q000627:therapeutic use; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D051928:CD47 Antigen; D000069283:Rituximab