title: Improved efficacy of alpha-particle-targeted radiation therapy: dual targeting of human epidermal growth factor receptor-2 and tumor-associated glycoprotein 72.
abstract: BACKGROUND
  Human epidermal growth factor receptor-2 (HER-2) and tumor-associated glycoprotein 72 (TAG-72) have proven to be excellent molecular targets for cancer imaging and therapy. Trastuzumab, which binds to HER-2, is effective in the treatment of disseminated intraperitoneal disease when labeled with (213)Bi or (212)Pb. (213)Bi-humanized CC49 monoclonal antibody (HuCC49DeltaCH2), which binds to TAG-72, inhibits the growth of subcutaneous xenografts. A next logical step to improve therapeutic benefit would be to target tumors with both molecules simultaneously.
  
  
  METHODS
  Athymic mice bearing intraperitoneal human colon carcinoma xenografts were treated with a combination of trastuzumab and HuCC49DeltaCH2 labeled with (213)Bi administered through an intraperitoneal route. The sequence of administration also was examined.
  
  
  RESULTS
  Before combining the 2 monoclonal antibodies, the effective doses of (213)Bi-CC49DeltaCH2 and (213)Bi-trastuzumab for the treatment of peritoneal disease were determined to be 500 muCi for each labeled antibody. Treatment with (213)Bi-HuCC49DeltaCH2 resulted in a median survival of 45 days and was comparable to the median survival achieved with (213)Bi-trastuzumab. Each combination provided greater therapeutic efficacy than either of the agents given alone. However, the greatest therapeutic benefit was achieved when (213)Bi-HuCC49DeltaCH2 and (213)Bi-trastuzumab were coinjected, and a median survival of 147 days was obtained.
  
  
  CONCLUSIONS
  Dual targeting of 2 distinct molecules in tumors such as TAG-72 and HER-2 with alpha-particle radiation resulted in an enhanced, additive, therapeutic benefit. The authors also observed that this radioimmunotherapeutic strategy was well tolerated.
authors.affiliation: Radioimmune and Inorganic Chemistry Section, Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Diane E
authors.initials: DE
authors.lastname: Milenic
authors.forename: Erik D
authors.initials: ED
authors.lastname: Brady
authors.forename: Kayhan
authors.initials: K
authors.lastname: Garmestani
authors.forename: Paul S
authors.initials: PS
authors.lastname: Albert
authors.forename: Alia
authors.initials: A
authors.lastname: Abdulla
authors.forename: Martin W
authors.initials: MW
authors.lastname: Brechbiel
mesh_terms: D000512:Alpha Particles / Q000627:therapeutic use*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D000912:Antibodies, Neoplasm / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology* / Q000528:radiation effects; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000628:therapy*; D005260:Female; D006023:Glycoproteins / Q000276:immunology* / Q000528:radiation effects; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D016499:Radioimmunotherapy / Q000379:methods*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology* / Q000528:radiation effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D000951:Antigens, Neoplasm; D006023:Glycoproteins; D018719:Erb-b2 Receptor Tyrosine Kinases; C091202:B72.3 antibody; C047052:tumor-associated antigen 72; C508053:ERBB2 protein, human