title: Preliminary biological evaluation of ¹²⁵I-labeled anti-carbonic anhydrase IX monoclonal antibody in the mice bearing HT-29 tumors.
abstract: OBJECTIVE
  To evaluate ¹²⁵I-labeled anti-carbonic anhydrase IX monoclonal antibody (¹²⁵I-MAb) as a novel single-photon emission computed tomography tracer for imaging carbonic anhydrase IX in the mice bearing HT-29 tumors.
  
  
  METHODS
  Anti-carbonic anhydrase IX monoclonal antibody was labeled with iodine-125 by the iodogen method. The radiochemical purity of ¹²⁵I-MAb was measured by radio-thin-layer chromatography. The in-vitro stability of ¹²⁵I-MAb was determined in PBS (0.05 mol/l, pH 7.4) or new-born calf serum at 37°C, and analyzed by radio-thin-layer chromatography. A biodistribution study and planar imaging were carried out in the mice bearing HT-29 tumors. The expression of CA IX in HT-29 tumors was analyzed by immunohistochemistry.
  
  
  RESULTS
  ¹²⁵I-MAb was obtained with a radiolabeling efficiency of 98%, and showed high stability in PBS and new-born calf serum. Furthermore, the biodistribution study showed specific tumor uptake in the mice bearing HT-29 tumors, and planar imaging with ¹²⁵I-MAb 48 h post injection showed a high concentration of radioactivity in tumors and a much decreased concentration in tumors in the blocking group. An immunohistochemical analysis showed the expression of CA IX in HT-29 tumors.
  
  
  CONCLUSIONS
  The preliminary biodistribution study and results from planar imaging showed the potential of ¹²⁵I-MAb as an agent for tumor diagnosis and encouraged further investigation.
authors.affiliation: Centre of Radiopharmaceutical Research, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, People's Republic of China.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Li
authors.forename: Lingli
authors.initials: L
authors.lastname: Shi
authors.forename: Cheng
authors.initials: C
authors.lastname: Wang
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Zhang
authors.forename: Lina
authors.initials: L
authors.lastname: Jia
authors.forename: Xiao
authors.initials: X
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.forename: Yujin
authors.initials: Y
authors.lastname: Qi
authors.forename: Lan
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000493:pharmacokinetics; D000951:Antigens, Neoplasm / Q000276:immunology*; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000276:immunology* / Q000493:pharmacokinetics; D019073:HT29 Cells; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D008297:Male; D051379:Mice; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D007457:Iodine Radioisotopes; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases