title: Tocilizumab Labeling with 99mTechnetium via HYNIC as a Molecular Diagnostic Agent for Multiple Myeloma.
abstract: BACKGROUND
  Multiple myeloma is the second most common hematological malignancy. Interleukin-6 (IL-6) is one of the key molecules related to growth, survival and proliferation of myeloma cells. Tocilizumab is a humanized monoclonal antibody directed against receptor of IL-6.
  
  
  OBJECTIVE
  To radiolabel Tocilizumab with 99mTechnetium as a potential imaging agents for MM.
  
  
  METHODS
  IL-6R expression was studied by laser confocal microscopy in MM cell lines (U266, NCI-H929 and MM1S). Tocilizumab was derivatized with NHS-HYNIC-Tfa and radiolabeling with 99mTc. Radiochemical stability was determined. In-vitro binding and immunoreactive fraction assays were performed. Biodistribution and SPECT/CT imaging were evaluated in healthy BALB/c and MM-bearing BALB/c nude mice.
  
  
  RESULTS
  LCM studies allowed us to demonstrate that U266, NCI-H929 and MM1S cells present high expression of IL-6R in cell membrane. Radiolabeling was carried out in a fast, reproducible, easy and stable way having high radiochemical purity and did not interfere with epitope recognition. The immunoreactive fraction of 99mTc- HYNIC-Tocilizumab was 86.35%. Biodistribution showed a high uptake in liver, spleen, gastrointestinal tract and kidneys. SPECT/CT imaging of MM-bearing BALB/c nude mice showed liver uptake and a high tumor selective uptake at 24 hours.
  
  
  CONCLUSIONS
  Our results support the potential role of 99mTc-HYNIC-Tocilizumb as a novel MM radiotracer for targeting IL-6 expression in-vivo. We describe the development of a formulation kit to radiolabeling monoclonal antibodies in a clinical setting. We hope that these novel molecular imaging agents will open the path to new diagnostic and therapeutic strategies for MM disease.
authors.affiliation: Departamento de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo. Uruguay.
authors.forename: Ximena
authors.initials: X
authors.lastname: Camacho
authors.affiliation: Nuclear Medicine Medical Investigation Laboratory LIM43-Hospital das Clínicas da Faculdade de Medicina da Universidade de Sao Paulo - HCFMUSP. Brazil.
authors.forename: Camila Longo
authors.initials: CL
authors.lastname: Machado
authors.affiliation: Departamento de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo. Uruguay.
authors.forename: Maria Fernanda
authors.initials: MF
authors.lastname: García
authors.affiliation: Departamento de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo. Uruguay.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Fernández
authors.affiliation: Laboratorio de Señalización Celular y Nanobiología, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo. Uruguay.
authors.forename: Natalia
authors.initials: N
authors.lastname: Oddone
authors.affiliation: Laboratorio de Señalización Celular y Nanobiología, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo. Uruguay.
authors.forename: Juan
authors.initials: J
authors.lastname: Benech
authors.affiliation: Centro de Medicina Nuclear, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, Montevideo. Uruguay.
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Gambini
authors.affiliation: Departamento de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo. Uruguay.
authors.forename: Hugo
authors.initials: H
authors.lastname: Cerecetto
authors.affiliation: Laboratório de Oncologia Experimental, Faculdade de Medicina, Universidade de São Paulo, Av. Dr. Arnaldo Nº 455- Cerqueira César - CEP: 01246903, São Paulo. Brazil.
authors.forename: Roger
authors.initials: R
authors.lastname: Chammas
authors.affiliation: Departamento de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo. Uruguay.
authors.forename: Pablo
authors.initials: P
authors.lastname: Cabral
authors.affiliation: Clínica Hematológica. Hospital de Clínicas. Facultad de Medicina. Universidad de la República, Montevideo, Uruguay, Avenida Italia s/n, P.O. 11800, Montevideo. Uruguay.
authors.forename: Eloisa
authors.initials: E
authors.lastname: Riva
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000737:chemistry*; D006801:Humans; D057054:Molecular Imaging; D009101:Multiple Myeloma / Q000175:diagnosis*; D015609:Organotechnetium Compounds / Q000737:chemistry*; D019275:Radiopharmaceuticals / Q000737:chemistry*; D014407:Tumor Cells, Cultured
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C000623216:technetium 99m HYNIC-tocilizumab
keywords: 99mTc-HYNIC-tocilizumab; IL-6R; Tocilizumab; molecular imaging; multiple myeloma.