title: Denosumab, a fully human monoclonal antibody to RANKL, inhibits bone resorption and increases BMD in knock-in mice that express chimeric (murine/human) RANKL.
abstract: RANKL is a TNF family member that mediates osteoclast formation, activation, and survival by activating RANK. The proresorptive effects of RANKL are prevented by binding to its soluble inhibitor osteoprotegerin (OPG). Recombinant human OPG-Fc recognizes RANKL from multiple species and reduced bone resorption and increased bone volume, density, and strength in a number of rodent models of bone disease. The clinical development of OPG-Fc was discontinued in favor of denosumab, a fully human monoclonal antibody that specifically inhibits primate RANKL. Direct binding assays showed that denosumab bound to human RANKL but not to murine RANKL, human TRAIL, or other human TNF family members. Denosumab did not suppress bone resorption in normal mice or rats but did prevent the resorptive response in mice challenged with a human RANKL fragment encoded primarily by the fifth exon of the RANKL gene. To create mice that were responsive to denosumab, knock-in technology was used to replace exon 5 from murine RANKL with its human ortholog. The resulting "huRANKL" mice exclusively express chimeric (human/murine) RANKL that was measurable with a human RANKL assay and that maintained bone resorption at slightly reduced levels versus wildtype controls. In young huRANKL mice, denosumab and OPG-Fc each reduced trabecular osteoclast surfaces by 95% and increased bone density and volume. In adult huRANKL mice, denosumab reduced bone resorption, increased cortical and cancellous bone mass, and improved trabecular microarchitecture. These huRANKL mice have potential utility for characterizing the activity of denosumab in a variety of murine bone disease models.
authors.affiliation: Metabolic Disorders Research, Amgen, Thousand Oaks, California 91320, USA. paulk@amgen.com
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Kostenuik
authors.forename: Hung Q
authors.initials: HQ
authors.lastname: Nguyen
authors.forename: James
authors.initials: J
authors.lastname: McCabe
authors.forename: Kelly S
authors.initials: KS
authors.lastname: Warmington
authors.forename: Carol
authors.initials: C
authors.lastname: Kurahara
authors.forename: Ning
authors.initials: N
authors.lastname: Sun
authors.forename: Ching
authors.initials: C
authors.lastname: Chen
authors.forename: Luke
authors.initials: L
authors.lastname: Li
authors.forename: Russ C
authors.initials: RC
authors.lastname: Cattley
authors.forename: Gwyneth
authors.initials: G
authors.lastname: Van
authors.forename: Shelia
authors.initials: S
authors.lastname: Scully
authors.forename: Robin
authors.initials: R
authors.lastname: Elliott
authors.forename: Mario
authors.initials: M
authors.lastname: Grisanti
authors.forename: Sean
authors.initials: S
authors.lastname: Morony
authors.forename: Hong Lin
authors.initials: HL
authors.lastname: Tan
authors.forename: Frank
authors.initials: F
authors.lastname: Asuncion
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Li
authors.forename: Michael S
authors.initials: MS
authors.lastname: Ominsky
authors.forename: Marina
authors.initials: M
authors.lastname: Stolina
authors.forename: Denise
authors.initials: D
authors.lastname: Dwyer
authors.forename: William C
authors.initials: WC
authors.lastname: Dougall
authors.forename: Nessa
authors.initials: N
authors.lastname: Hawkins
authors.forename: William J
authors.initials: WJ
authors.lastname: Boyle
authors.forename: William S
authors.initials: WS
authors.lastname: Simonet
authors.forename: John K
authors.initials: JK
authors.lastname: Sullivan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000915:Antibody Affinity / Q000187:drug effects; D000918:Antibody Specificity / Q000187:drug effects; D015519:Bone Density / Q000187:drug effects*; D001862:Bone Resorption / Q000188:drug therapy* / Q000503:physiopathology*; D001842:Bone and Bones / Q000187:drug effects / Q000473:pathology; D000069448:Denosumab; D055879:Gene Knock-In Techniques; D006801:Humans; D006934:Hypercalcemia / Q000188:drug therapy; D051379:Mice; D008969:Molecular Sequence Data; D010010:Osteoclasts / Q000187:drug effects; D010012:Osteogenesis / Q000187:drug effects; D053244:Osteoprotegerin / Q000378:metabolism; D010641:Phenotype; D011485:Protein Binding / Q000187:drug effects; D053245:RANK Ligand / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D055114:X-Ray Microtomography
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D053244:Osteoprotegerin; D053245:RANK Ligand; D000069448:Denosumab