title: In vitro and in vivo toxicity of 5-FdU-alendronate, a novel cytotoxic bone-seeking duplex drug against bone metastasis.
abstract: BACKGROUND
  Bone remains one of the most common anatomic sites for cancer metastases, and the limited therapeutic options aggravate cancer-related morbidity and mortality in multiple malignancies. The covalent conjugation of the amino-bisphosphonate alendronate (ale) with the antimetabolite 5-fluoro-2'-desoxyuridine (5-FdU) results in N(4)-(butyl-(4-hydroxy-4-phosphono)phosphate)-5-fluoro-2'-desoxyuridine (5-FdU-alendronat, 5-FdU-ale), an effective, novel bone-targeting duplex drug directed against skeletal cancer manifestations.
  
  
  METHODS
  In vitro cytotoxicity of ale, 5-FdU or 5-FdU-ale was measured with Alamar Blue and MUH cell viability assays in 14 malignant melanoma, multiple myeloma, bone marrow-derived stromal cell and osteoblast-like cell lines. In vivo toxicity was evaluated using the chicken embryo assay and evaluation of nephrotoxicity and the systemic toxicity in Balb/c nude mice. The effect of 5-FdU-ale on osteoclast was evaluated with Balb/c nude mice in a metastatic breast cancer mouse model.
  
  
  RESULTS
  A cell line-specific, dose-related cytotoxicity was observed for 5-FdU-ale in all cancer cell lines tested, which was significantly less toxic than 5-FdU alone when compared to the benign osteoblasts or stromal cells. The embryotoxicity of 5-FdU-ale was significantly less than that of the parental drugs alendronate or 5-FdU. 5-FdU-ale showed no signs of unwanted side effects, weight loss or nephrotoxicity in mice. In a bone metastasis mouse model, 5-FdU-ale reduced the number of tumor-associated osteoclasts.
  
  
  CONCLUSIONS
  The coupling of an amino-bisphosphonate with an antimetabolite via an N-alkyl-bonding offers a new strategy for the preparation of amino-bisphosphonates conjugates with a cancer cell-specific, efficacious cytotoxic bone-targeting potential along with a reduced systemic toxicity. The innovative duplex drug 5-FdU-ale therefore warrants further clinical investigation.
authors.affiliation: Department of Gynecology and Obstetrics, University of Heidelberg, Im Neuenheimer Feld 440, 69120, Heidelberg, Germany, sarah.schott@med.uni-heidelberg.de.
authors.forename: Sarah
authors.initials: S
authors.lastname: Schott
authors.forename: Sonia
authors.initials: S
authors.lastname: Vallet
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Tower
authors.forename: Seema
authors.initials: S
authors.lastname: Noor
authors.forename: Sanjay
authors.initials: S
authors.lastname: Tiwari
authors.forename: Christian
authors.initials: C
authors.lastname: Schem
authors.forename: Christian
authors.initials: C
authors.lastname: Busch
mesh_terms: D019386:Alendronate / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology / Q000627:therapeutic use; D050071:Bone Density Conservation Agents / Q000494:pharmacology / Q000627:therapeutic use; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000556:secondary; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002642:Chick Embryo; D004338:Drug Combinations; D005260:Female; D005472:Fluorouracil / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006801:Humans; D007668:Kidney / Q000033:anatomy & histology / Q000187:drug effects; D008819:Mice, Nude; D010010:Osteoclasts / Q000187:drug effects
chemical_list: C575868:5-FdU-alendronate; D000964:Antimetabolites, Antineoplastic; D050071:Bone Density Conservation Agents; D004338:Drug Combinations; D005472:Fluorouracil; D019386:Alendronate