title: A (90)Y-labelled anti-ROBO1 monoclonal antibody exhibits antitumour activity against hepatocellular carcinoma xenografts during ROBO1-targeted radioimmunotherapy.
abstract: BACKGROUND
  ROBO1 is a membrane protein that functions in axon guidance. ROBO1 contributes to tumour metastasis and angiogenesis and may have potential as a target protein of immunotherapy because ROBO1 is specifically expressed at high levels in hepatocellular carcinoma. In this study, we examined biodistribution and radioimmunotherapy (RIT) using a radioisotope-labelled anti-ROBO1 monoclonal antibody (MAb) against hepatocellular carcinoma models.
  
  
  METHODS
  ROBO1-positive HepG2 human hepatocellular carcinoma xenograft nude mice were used in this study. We conjugated anti-ROBO1 MAb with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), and the conjugates were labelled with (111)In and (90)Y. To study biodistribution, the (111)In-DOTA-anti-ROBO1 MAb was injected into HepG2 xenograft mice via the tail vein. To evaluate any antitumour effect, a RIT study was performed, and the (90)Y-DOTA-anti-ROBO1 MAb was injected via the tail vein. Tumour volume, mouse weight, and blood cell count were periodically measured throughout the experiments. The tumours and organs of mice were collected, and a histopathological analysis was carried out.
  
  
  RESULTS
  The tumour uptake of (111)In-anti-ROBO1 MAb in HepG2 xenograft mice was 15.0% ± 0.69% injected dose per gram at 48 h after injection. Immunotherapy with cold-anti-ROBO1 MAb (70 μg) did not cause a significant antitumour effect. RIT with 6.7 MBq of (90)Y-anti-ROBO1 MAb caused significant tumour growth suppression. Transient body weight loss and bone-marrow suppression were observed. Histopathological analyses of tumours revealed the fatal degeneration of tumour cells, significant reduction of the Ki-67 index, and an increase of the apoptosis index. Normal organs showed no significant injury, but a transient reduction of hematopoietic cells was observed in the spleen and in the sternal bone marrow.
  
  
  CONCLUSIONS
  These results suggest that RIT with (90)Y-anti-ROBO1 MAb is a promising treatment for ROBO1-positive hepatocellular carcinoma.
authors.affiliation: Department of Radiology, Graduate School of Medicine, The University of Tokyo, 3-1, Hongo 7-Chome, Bunkyo-ku 113-8655, Tokyo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Fujiwara
authors.affiliation: Department of Radiology, Graduate School of Medicine, The University of Tokyo, 3-1, Hongo 7-Chome, Bunkyo-ku 113-8655, Tokyo, Japan.
authors.forename: Keitaro
authors.initials: K
authors.lastname: Koyama
authors.affiliation: SANKYO LABO SERVICE Co., Ltd., 2-13-16, Nishiichinoe, Edogawaku 132-0023, Tokyo, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Suga
authors.affiliation: Department of Pathology, Graduate School of Medicine, The University of Tokyo, 3-1, Hongo 7-Chome, Bunkyo-ku 113-8655, Tokyo, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Ikemura
authors.affiliation: FUJIFILM RI Pharma Co., Ltd., 453-1, Shimo-Okura, Matsuo-Machi, Sammu-City 289-1592, Chiba, Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Saito
authors.affiliation: FUJIFILM RI Pharma Co., Ltd., 453-1, Shimo-Okura, Matsuo-Machi, Sammu-City 289-1592, Chiba, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hino
authors.affiliation: Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku 153-8904, Tokyo, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Iwanari
authors.affiliation: Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku 153-8904, Tokyo, Japan ; Institute of Immunology Co., Ltd., 1-1-1 Koraku, Bunkyo 112-0004, Tokyo, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Kusano-Arai
authors.affiliation: Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku 153-8904, Tokyo, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Mitsui
authors.affiliation: FUJIFILM RI Pharma Co., Ltd., 453-1, Shimo-Okura, Matsuo-Machi, Sammu-City 289-1592, Chiba, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kasahara
authors.affiliation: Department of Pathology, Graduate School of Medicine, The University of Tokyo, 3-1, Hongo 7-Chome, Bunkyo-ku 113-8655, Tokyo, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Fukayama
authors.affiliation: Department of Systems Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku 153-8904, Tokyo, Japan.
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Kodama
authors.affiliation: Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku 153-8904, Tokyo, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Hamakubo
authors.affiliation: Department of Radiology, Graduate School of Medicine, The University of Tokyo, 3-1, Hongo 7-Chome, Bunkyo-ku 113-8655, Tokyo, Japan.
authors.forename: Toshimitsu
authors.initials: T
authors.lastname: Momose
keywords: 90Y; Biodistribution; Hepatocellular carcinoma; ROBO1; Radioimmunotherapy