title: RANK ligand inhibition plus docetaxel improves survival and reduces tumor burden in a murine model of prostate cancer bone metastasis.
abstract: Tumor cells induce excessive osteoclastogenesis, mediating pathologic bone resorption and subsequent release of growth factors and calcium from bone matrix, resulting in a "vicious cycle" of bone breakdown and tumor proliferation. RANK ligand (RANKL) is an essential mediator of osteoclast formation, function, and survival. In metastatic prostate cancer models, RANKL inhibition directly prevents osteolysis via blockade of osteoclastogenesis and indirectly reduces progression of skeletal tumor burden by reducing local growth factor and calcium concentrations. Docetaxel, a well-established chemotherapy for metastatic hormone-refractory prostate cancer, arrests the cell cycle and induces apoptosis of tumor cells. Suppression of osteoclastogenesis through RANKL inhibition may enhance the effects of docetaxel on skeletal tumors. We evaluated the combination of the RANKL inhibitor osteoprotegerin-Fc (OPG-Fc) with docetaxel in a murine model of prostate cancer bone metastasis. Tumor progression, tumor area, and tumor proliferation and apoptosis were assessed. OPG-Fc alone reduced bone resorption (P < 0.001 versus PBS), inhibited progression of established osteolytic lesions, and reduced tumor area (P < 0.0001 versus PBS). Docetaxel alone reduced tumor burden (P < 0.0001 versus PBS) and delayed the development of osteolytic lesions. OPG-Fc in combination with docetaxel suppressed skeletal tumor burden (P = 0.0005) and increased median survival time by 16.7% (P = 0.0385) compared with docetaxel alone. RANKL inhibition may enhance docetaxel effects by increasing tumor cell apoptosis as evident by increased active caspase-3. These studies show that inhibition of RANKL provides an additive benefit to docetaxel treatment in a murine model of prostate cancer bone metastasis and supports clinical evaluation of this treatment option in patients.
authors.affiliation: Department of Hematology/Oncology Research, Amgen Washington, Seattle, Washington 98119-3105, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Miller
authors.forename: Martine
authors.initials: M
authors.lastname: Roudier
authors.forename: Jon
authors.initials: J
authors.lastname: Jones
authors.forename: Allison
authors.initials: A
authors.lastname: Armstrong
authors.forename: Jude
authors.initials: J
authors.lastname: Canon
authors.forename: William C
authors.initials: WC
authors.lastname: Dougall
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001859:Bone Neoplasms / Q000150:complications / Q000473:pathology / Q000556:secondary*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D000077143:Docetaxel; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D010014:Osteolysis / Q000150:complications; D053244:Osteoprotegerin / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000473:pathology*; D053245:RANK Ligand / Q000037:antagonists & inhibitors*; D011961:Receptors, Fc; D016019:Survival Analysis; D043823:Taxoids / Q000494:pharmacology*; D047368:Tumor Burden / Q000187:drug effects*; D051598:Whole Body Imaging; D023041:Xenograft Model Antitumor Assays
chemical_list: D053244:Osteoprotegerin; D053245:RANK Ligand; D011961:Receptors, Fc; D043823:Taxoids; D000077143:Docetaxel