title: Feasibility of 186Re-radioimmunotherapy for treatment in an adjuvant setting of colon cancer.
abstract: OBJECTIVE
  (186)Re displays abundant intermediate energy beta emission, and possesses an appropriate physical half-life of 3.7 days. We compared the efficacy of radioimmunotherapy (RIT) with an anti-colorectal cancer monoclonal IgG1, (186)Re-A7, with that of RIT employing (131)I in a mouse liver metastasis model.
  
  
  METHODS
  Liver metastases were established by intrasplenic injection of LS180 human colon cancer cells. Based on the results of toxicity assessment with escalated administration doses, 21 MBq (186)Re-A7 and 7 MBq (131)I-A7 were chosen as maximum tolerated doses. In the first experiment, mice underwent RIT at 2 weeks when metastases attain a diameter of several millimeters, and were killed 2 weeks later to assess metastatic burden in the liver. In the second experiment, RIT was conducted at 1 week when metastases of several hundred micrometers in diameter were observed, and survival of mice was examined.
  
  
  RESULTS
  (186)Re-A7 RIT inhibited the growth of liver metastases better than (131)I-A7 RIT ( P<0.02). Furthermore, (186)Re-A7 RIT induced better improvement in survival of mice than (131)I-A7 RIT ( P<0.002). (186)Re-A7 RIT caused slightly more severe myelotoxicity in mice, but they eventually recovered. Radiation dose estimation demonstrated a significant advantage of (186)Re-A7 RIT over (131)I-A7 RIT.
  
  
  CONCLUSIONS
  These results support the use of RIT with (186)Re-MAb in an adjuvant setting in cases involving minimal disease.
authors: Department of Biotracer Medicine, Kanazawa University Graduate School of Medical Sciences, 13-1 Takaramachi, 920-8640, Kanazawa, Ishikawa, Japan.
authors: Seigo
authors: S
authors: Kinuya
authors: Kunihiko
authors: K
authors: Yokoyama
authors: Mishiroku
authors: M
authors: Izumo
authors: Takami
authors: T
authors: Sorita
authors: Takashi
authors: T
authors: Obata
authors: Hirofumi
authors: H
authors: Mori
authors: Kazuhiro
authors: K
authors: Shiba
authors: Naoto
authors: N
authors: Watanabe
authors: Noriyuki
authors: N
authors: Shuke
authors: Takatoshi
authors: T
authors: Michigishi
authors: Norihisa
authors: N
authors: Tonami
mesh_terms: D000818:Animals; D003110:Colonic Neoplasms / Q000473:pathology*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D018796:Immunoconjugates / Q000627:therapeutic use*; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008113:Liver Neoplasms / Q000556:secondary* / Q000628:therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D016499:Radioimmunotherapy; D011868:Radioisotopes / Q000008:administration & dosage / Q000627:therapeutic use*; D011879:Radiotherapy Dosage; D012211:Rhenium / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D018796:Immunoconjugates; D007457:Iodine Radioisotopes; D011868:Radioisotopes; D012211:Rhenium