Sistema FMUSP-HC: Faculdade de Medicina da Universidade de São Paulo (FMUSP) e Hospital das Clínicas da FMUSPCAMACHO, XimenaPERRONI, CarolinaMACHADO, Camila L.CARNEIRO, Camila de GodoiJUNQUEIRA, Mara de SouzaFARIA, DanieleGARCIA, Maria F.FERNANDEZ, MarceloODDONE, NataliaBENECH, JuanBUCHPIGUEL, Carlos A.CERECETTO, HugoCHAMMAS, RogerRIVA, EloisaCABRAL, PabloGAMBINI, Juan P.2021-08-132021-08-132021ANTI-CANCER AGENTS IN MEDICINAL CHEMISTRY, v.21, n.14, p.1883-1893, 20211871-5206https://observatorio.fm.usp.br/handle/OPI/41377Background: Multiple Myeloma (MM) is a malignant hematologic disorder and the second most common blood cancer. Interleukin-6 (IL-6) has been identified as a crucial factor for the proliferation and survival of MM cells and the overexpression of IL-6 receptor is being studied as a molecular target for therapeutic and diagnostic use in myelomas and other comorbidities. Tocilizumab is a humanized monoclonal antibody that binds IL-6R. Objective: We aim to label and evaluate Fab(Tocilizumab) with 99mTechnetium or Cy7 as potential MM imaging agents. Methods: IL-6R distribution was analyzed by Laser Confocal Microscopy (LCM) in MM cell lines. Fab(Tocilizumab) was produced by the digestion of Tocilizumab with papain for 24h at 37 degrees C, derivatized with NHS-HYNIC-Tfa and radiolabeled with Tc-99m. Radiochemical stability and in vitro cell assays were evaluated. Biodistribution and SPECT/CT were performed. Also, Fab(Tocilizumab) was labeled with Cy7 for in vivo fluorescence imaging up to 72h. Results: LCM analysis demonstrates IL-6R distribution on MM cell lines. Incubation with papain resulted in complete digestion of Tocilizumab and exhibited a good purity and homogeneity. Radiolabeling with Tc-99m via NHS-HYNIC-Tfa was found to be fast, easy, reproducible and stable, revealing high radiochemical purity and without interfering with IL-6R recognition. Biodistribution and SPECT/CT studies showed a quick blood clearance and significant kidney and MM engrafted tumor uptake. Cy7-Fab(Tocilizumab) fluorescent imaging allowed MM1S tumor identification up to 72h p.i. Conclusion: These new molecular imaging agents could potentially be used in the clinical setting for staging and follow-up of MM through radioactive whole-body IL-6R expression visualization in vivo. The fluorescent version could be used for tissue sample evaluation and to guide surgical excision, if necessary.engrestrictedAccessFab(Tocilizumab)molecular imagingIL-6Rmultiple myeloma(99m)Technetium- or Cy7-lableled Fab(Tocilizumab)breast-cancer xenograftsextramedullary plasmacytomamonoclonal-antibodiesinterleukin-6 il-6bonetocilizumabreceptortherapytc-99mpathogenesisarticleCopyright BENTHAM SCIENCE PUBL LTD10.2174/1871520621999210104181238OncologyChemistry, Medicinal1875-5992