title: Evaluation of anti-podoplanin rat monoclonal antibody NZ-1 for targeting malignant gliomas.
abstract: BACKGROUND
  Podoplanin/aggrus is a mucin-like sialoglycoprotein that is highly expressed in malignant gliomas. Podoplanin has been reported to be a novel marker to enrich tumor-initiating cells, which are thought to resist conventional therapies and to be responsible for cancer relapse. The purpose of this study was to determine whether an anti-podoplanin antibody is suitable to target radionuclides to malignant gliomas.
  
  
  METHODS
  The binding affinity of an anti-podoplanin antibody, NZ-1 (rat IgG(2a)), was determined by surface plasmon resonance and Scatchard analysis. NZ-1 was radioiodinated with (125)I using Iodogen [(125)I-NZ-1(Iodogen)] or N-succinimidyl 4-guanidinomethyl 3-[(131)I]iodobenzoate ([(131)I]SGMIB-NZ-1), and paired-label internalization assays of NZ-1 were performed. The tissue distribution of (125)I-NZ-1(Iodogen) and that of [(131)I]SGMIB-NZ-1 were then compared in athymic mice bearing glioblastoma xenografts.
  
  
  RESULTS
  The dissociation constant (K(D)) of NZ-1 was determined to be 1.2 × 10(-10) M by surface plasmon resonance and 9.8 × 10(-10) M for D397MG glioblastoma cells by Scatchard analysis. Paired-label internalization assays in LN319 glioblastoma cells indicated that [(131)I]SGMIB-NZ-1 resulted in higher intracellular retention of radioactivity (26.3 ± 0.8% of initially bound radioactivity at 8 h) compared to that from the (125)I-NZ-1(Iodogen) (10.0 ± 0.1% of initially bound radioactivity at 8 h). Likewise, tumor uptake of [(131)I]SGMIB-NZ-1 (39.9 ± 8.8 %ID/g at 24 h) in athymic mice bearing D2159MG xenografts in vivo was significantly higher than that of (125)I-NZ-1(Iodogen) (29.7 ± 6.1 %ID/g at 24 h).
  
  
  CONCLUSIONS
  The overall results suggest that an anti-podoplanin antibody NZ-1 warrants further evaluation for antibody-based therapy against glioblastoma.
authors.affiliation: Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA. yukinari-k@bea.hi-ho.ne.jp
authors.forename: Yukinari
authors.initials: Y
authors.lastname: Kato
authors.forename: Ganesan
authors.initials: G
authors.lastname: Vaidyanathan
authors.forename: Mika Kato
authors.initials: MK
authors.lastname: Kaneko
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Mishima
authors.forename: Nidhi
authors.initials: N
authors.lastname: Srivastava
authors.forename: Vidyalakshmi
authors.initials: V
authors.lastname: Chandramohan
authors.forename: Charles
authors.initials: C
authors.lastname: Pegram
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Keir
authors.forename: Chien-Tsun
authors.initials: CT
authors.lastname: Kuan
authors.forename: Darell D
authors.initials: DD
authors.lastname: Bigner
authors.forename: Michael R
authors.initials: MR
authors.lastname: Zalutsky
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000627:therapeutic use*; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001932:Brain Neoplasms / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D045744:Cell Line, Tumor; D005260:Female; D005434:Flow Cytometry; D005909:Glioblastoma / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D016499:Radioimmunotherapy; D019275:Radiopharmaceuticals / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020349:Surface Plasmon Resonance; D014018:Tissue Distribution; D000098853:Podoplanin
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D007457:Iodine Radioisotopes; D008562:Membrane Glycoproteins; D019275:Radiopharmaceuticals; C092025:Pdpn protein, rat; D000098853:Podoplanin