title: Distribution and dosimetry of I-123-labeled monoclonal antibody 81C6 in patients with anaplastic glioma.
abstract: OBJECTIVE
  Monoclonal antibody 81C6 reacts with the extracellular matrix antigen, tenascin, present on gliomas and other tumors, as well as several normal tissues, including spleen and liver tissue. Single photon emission computed tomography (SPECT) and I-123-labeled 81C6 at various protein doses were used to maximize tumor to normal tissue uptake ratios.
  
  
  METHODS
  The distribution of I-123-labeled monoclonal antibody 81C6 was determined in 16 patients with recurrent gliomas, using SPECT: Between 3.5 and 11.5 mCi of I-123 were administered to each patient, and the antibody doses were between 10.0 and 100.0 mg. Blood was obtained for pharmacokinetic studies, and patients were imaged 1 hour and 18 hours after antibody administration.
  
  
  RESULTS
  All tumors were visualized readily on the SPECT study in areas that corresponded to the contrast, enhancing abnormalities on anatomic neuroimaging studies. The half-life in blood of the I-123 81C6 ranged from 16 to 37 hours. Radiation dosimetry calculations suggest that it might be possible to administer more than 700 cGy to intracranial glioma with I-131 labeled 81C6 under optimal conditions with acceptable non-neurologic organ radiation exposure.
  
  
  CONCLUSIONS
  SPECT imaging with I-123 81C6 identified all tumors and suggests that, with this antibody, more favorable tumor-to-liver and tumor-to-spleen radiation dose ratios are obtained at higher protein doses.
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.
authors.forename: S C
authors.initials: SC
authors.lastname: Schold
authors.forename: M R
authors.initials: MR
authors.lastname: Zalutsky
authors.forename: R E
authors.initials: RE
authors.lastname: Coleman
authors.forename: M J
authors.initials: MJ
authors.lastname: Glantz
authors.forename: A H
authors.initials: AH
authors.lastname: Friedman
authors.forename: R J
authors.initials: RJ
authors.lastname: Jaszczak
authors.forename: S H
authors.initials: SH
authors.lastname: Bigner
authors.forename: D D
authors.initials: DD
authors.lastname: Bigner
mesh_terms: D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D015816:Cell Adhesion Molecules, Neuronal / Q000276:immunology; D004307:Dose-Response Relationship, Radiation; D016326:Extracellular Matrix Proteins / Q000276:immunology; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000276:immunology; D011829:Radiation Dosage; D016499:Radioimmunotherapy; D019063:Tenascin; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D000911:Antibodies, Monoclonal; D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D007457:Iodine Radioisotopes; D009363:Neoplasm Proteins; D019063:Tenascin