title: Fab(nimotuzumab)-HYNIC-99mTc: Antibody Fragmentation for Molecular Imaging Agents.
abstract: Finally, fast blood clearance nimotuzumab is a humanized monoclonal antibody that recognise, with high specific affinity, the epidermal growth factor receptor (EGF-R) which play an important role in the growth process associated with many solid tumors. In this work, the whole antibody was digested with papain in order to generate a Fab fragment, derivatized with NHS-HYNIC-Tfa and radiolabel with technetium-99m (99mTc) as a potential agent of molecular imaging of cancer. Both, whole and fragment radiolabels were in-vivo and in-vitro characterized. Radiolabeling conditions with Tricine as coligand and quality controls were assessed to confirm the integrity of the labeled fragment. Biodistribution and imaging studies in normal and spontaneous adenocarcinoma mice were performed at different times to determine the in-vivo characteristics of the radiolabel fragment. Tumor localization was visualized by conventional gamma camera imaging studies, and the results were compared with the whole antibody. Also, an immunoreactivity assay was carried out for both. The results showed clearly the integrity of the nimotuzumab fragment and the affinity by the receptor was verified. Fab(nimotuzumab)-HYNIC was obtained with high purity and a simple strategy of radiolabeling was performed. Finally, a fast blood clearance was observed in the biodistribution studies increasing the tumor uptake of Fab(nimotuzumab)- HYNIC-99mTc over time, with tumor/muscle ratios of 3.81 ± 0.50, 5.16 ± 1.97 and 6.32 ± 1.98 at 1 h, 4 h and 24 h post injection. Urinary excretion resulted in 32.89 ± 3.91 %ID eliminated at 24 h. Scintigraphy images showed uptake in the tumor and the activity in non-target organs was consistent with the biodistribution data at the same time points. Hence, these preliminary results showed important further characteristic of Fab(nimotuzumab)-HYNIC-99mTc as a molecular imaging agent of cancer.
authors.affiliation: Departamento de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Uruguay. vcalzada@cin.edu.uy.
authors.forename: Victoria
authors.initials: V
authors.lastname: Calzada
authors.forename: María Fernanda
authors.initials: MF
authors.lastname: García
authors.forename: Luis Michel
authors.initials: LM
authors.lastname: Alonso-Martínez
authors.forename: Ximena
authors.initials: X
authors.lastname: Camachoc
authors.forename: Enzo
authors.initials: E
authors.lastname: Goicochea
authors.forename: Marcelo
authors.initials: M
authors.lastname: Fernández
authors.forename: Abmel Xiques
authors.initials: AX
authors.lastname: Castillo
authors.forename: Arlhee
authors.initials: A
authors.lastname: Díaz-Miqueli
authors.forename: Normando
authors.initials: N
authors.lastname: Iznaga-Escobar
authors.forename: René Leyva
authors.initials: RL
authors.lastname: Montaña
authors.forename: Omar
authors.initials: O
authors.lastname: Alonso
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Gambini
authors.forename: Pablo
authors.initials: P
authors.lastname: Cabral
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging*; D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000032:analysis* / Q000378:metabolism / Q000493:pharmacokinetics; D066246:ErbB Receptors / Q000032:analysis* / Q000378:metabolism; D006801:Humans; D006834:Hydrazines / Q000032:analysis* / Q000378:metabolism / Q000493:pharmacokinetics; D051379:Mice; D057054:Molecular Imaging / Q000379:methods*; D009539:Nicotinic Acids / Q000032:analysis* / Q000378:metabolism / Q000493:pharmacokinetics; D010206:Papain / Q000378:metabolism; D011877:Radionuclide Imaging / Q000379:methods; D013667:Technetium / Q000032:analysis* / Q000378:metabolism / Q000493:pharmacokinetics; D014018:Tissue Distribution
chemical_list: C120392:6-hydrazinopyridine-3-carboxylic acid; D061067:Antibodies, Monoclonal, Humanized; D006834:Hydrazines; D009539:Nicotinic Acids; C501466:nimotuzumab; D013667:Technetium; D066246:ErbB Receptors; D010206:Papain