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Background: 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 99m Technetium 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°C, derivatized with NHS-HYNIC-Tfa and radiolabeled with 99m Tc. 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 99mTc 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., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

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., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

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.

We described herein a simple and efficient microwave assisted synthesis of HYNIC analogues. Two different activated esters of HYNIC, the hydrazine protected with a trifluoroacetyl group (5) and the free hydrazine (6) were conjugated to the monoclonal antibody Nimotuzumab. Technetium-99m radiolabeling of Nimotuzumab was achieved with high efficiency using 5 and 6 derivates. The NHS-HYNIC-Tfa derivate allowed better labeling yields during longer times of preservation of the conjugated antibody.

Vascular endothelial growth factor (VEGF) is one of the classic factors involved in tumor-induced angiognesis in several solid tumors. Bevacizumab, a monoclonal antibody against VEGF, can be used as an imaging tool in preclinical studies. The aim of this study was to radiolabel Bevacizumab with (99m)Tc and to evaluate in vivo its imaging properties in an adenocarcinoma animal model. For this purpose, Bevacizumab was derivatized with Suc-HYNIC as a bifunctional coupling agent. A mixture of Tricine/SnCl(2).2H(2)O was added to Bevacizumab-HYNIC and radiolabeled with (99m)TcO(4)(-). The radiochemical stability of the radiolabeled antibody was assessed. Biodistribution and scintigraphy imaging were performed in normal CD1 female mice and in spontaneous adenocarcinoma tumor bearing CD1 mice (n = 5). We demonstrated that 99mTc-HYNIC-Bevacizumab was stable. In vivo biodistribution studies revealed that tumor uptake of (99m)Tc-HYNIC-Bevacizumab was 1.37 ± 0.51% and 5.33 ± 2.13% at 4 and 24 h postinjection, respectively. Scintigraphy image studies showed tumor selective uptake of (99m)Tc-HYNIC-Bevacizumab in the tumor-bearing mice. We conclude that (99m)Tc-HYNIC-Bevacizumb has the potential to be used as a tracer for tumor imaging in preclinical studies.

Introduction: Vascular endothelial growth factor (VEGF) is one of the classic factors to tumor-induced angiogenesis in several tumor types, including melanoma. Bevacizumab, a monoclonal antibody against VEGF, could be used as an imaging tool in preclinical studies., Objective: To radiolabel bevacizumab with [(99m)Tc(CO)3(OH2)3](+) and evaluate it in vivo and in vitro for melanoma imaging properties., Methods: Bevacizumab was radiolabeled with [(99m)Tc(CO)3(OH2)3](+) ion in saline. The radiochemical stability of the labeled antibody was assessed. The biodistribution and scintigraphy imaging of the radiolabeled antibody were evaluated in normal C57BL/6J mice and in C57BL/6J mice bearing murine B16F1 melanoma tumors. Immunoreactivity of bevacizumab to murine tumors was determined from direct immunofluorescence and immunoblotting assays., Results: We demonstrate that (99m)Tc(CO)3-bevacizumab was stable. In vivo biodistribution studies revealed that tumor uptake of (99m)Tc(CO)3-bevacizumab was 2.64 and 2.51 %ID/g at 4 and 24 h postinjection. Scintigraphy image studies showed tumor selective uptake of (99m)Tc(CO)3-bevacizumab in the tumor-bearing mice. This affinity was confirmed by immunoassays performed on B16F10 tumor samples., Conclusions: (99m)Tc(CO)3-bevacizumab could be used as an approach for tumor nuclear imaging in preclinical studies. This should be useful to provide insights into the angiogenic stimulus before and after chemotherapy, which might help improve current antitumor therapy., (Copyright © 2013 S. Karger AG, Basel.)