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This work describes the production of high-specific activity 55Co and the evaluation of the stability of 55Co-metal-chelate-peptide complexes in vivo. 55Co was produced via the 58Ni(p,α)55Co reaction and purified using anion exchange chromatography with an average recovery of 92% and an average specific activity of 1.96 GBq/mmol. 55Co-DO3A and 55Co-NO2A peptide complexes were radiolabeled at 3.7 MBq/mg and injected into HCT-116 tumor xenografted mice. Positron emission tomography (PET) and biodistribution studies were performed at 24 and 48 hours postinjection and compared to those of 55CoCl2. Both 55Co-metal-chelate complexes demonstrated good in vivo stability by reducing the radiotracers' uptake in the liver by sixfold at 24 hours with ~ 1%ID/g and at 48 hours with ~ 0.5% ID/g and reducing uptake in the heart by fourfold at 24 hours with ~ 0.7% ID/g and sevenfold at 48 hours with ~ 0.35% ID/g. These results support the use of 55Co as a promising new radiotracer for PET imaging of cancer and other diseases. [ABSTRACT FROM AUTHOR]

The epidermal growth factor receptor (EGFR) is overexpressed in the majority of malignancies and has been associated with poor outcomes. Panitumumab, an anti-EGFR monoclonal antibody that binds to the extracellular binding domain of EGFR, is increasingly used with radiotherapy and chemotherapy but has associated toxicities. The purpose of this study was to develop and characterize a novel targeted imaging agent for the EGFR using radiolabeled panitumumab. Flow cytometry studies were performed to evaluate EGFR expression in several cell lines. Desferrioxamine-Bz-NCS (DFO) was conjugated to panitumumab and labeled with 89Zr. Cell uptake studies were performed in four cell lines. For biodistribution studies and micro--positron emission tomography/computed tomography (PET/CT), mouse xenograft models were generated using the same cell lines. PET was performed, and tumors and select organs were harvested for biodistribution studies. Panitumumab was radiolabeled with 89Zr with high radiochemical purity and specific activity and was found to be stable in serum. Cell binding studies demonstrated that radiotracer uptake in cells correlated with the degree of EGFR expression. MicroPET/CT imaging studies demonstrated a high intensity of 89Zr-panitumumab in A431 and HCT 116 tumors in comparison with the EGFR-negative tumors. Biodistribution studies confirmed the results from the imaging studies. 89Zr-panitumumab imaging of EGFR-positive tumors demonstrated levels of radiotracer uptake associated with EGFR expression. [ABSTRACT FROM AUTHOR]

This work describes the production of high-specific activity 55Co and the evaluation of the stability of 55Co-metal-chelate-peptide complexes in vivo. 55Co was produced via the 58Ni(p,α)55Co reaction and purified using anion exchange chromatography with an average recovery of 92% and an average specific activity of 1.96 GBq/μmol. 55Co-DO3A and 55Co-NO2A peptide complexes were radiolabeled at 3.7 MBq/μg and injected into HCT-116 tumor xenografted mice. Positron emission tomography (PET) and biodistribution studies were performed at 24 and 48 hours postinjection and compared to those of 55CoCl2. Both 55Co-metal-chelate complexes demonstrated good in vivo stability by reducing the radiotracers' uptake in the liver by sixfold at 24 hours with ~ 1% ID/g and at 48 hours with ~ 0.5% ID/g and reducing uptake in the heart by fourfold at 24 hours with ~ 0.7% ID/g and sevenfold at 48 hours with ~ 0.35% ID/g. These results support the use of 55Co as a promising new radiotracer for PET imaging of cancer and other diseases.

The epidermal growth factor receptor (EGFR) is overexpressed in the majority of malignancies and has been associated with poor outcomes. Panitumumab, an anti-EGFR monoclonal antibody that binds to the extracellular binding domain of EGFR, is increasingly used with radiotherapy and chemotherapy but has associated toxicities. The purpose of this study was to develop and characterize a novel targeted imaging agent for the EGFR using radiolabeled panitumumab. Flow cytometry studies were performed to evaluate EGFR expression in several cell lines. Desferrioxamine-Bz-NCS (DFO) was conjugated to panitumumab and labeled with (89)Zr. Cell uptake studies were performed in four cell lines. For biodistribution studies and micro-positron emission tomography/computed tomography (PET/CT), mouse xenograft models were generated using the same cell lines. PET was performed, and tumors and select organs were harvested for biodistribution studies. Panitumumab was radiolabeled with (89)Zr with high radiochemical purity and specific activity and was found to be stable in serum. Cell binding studies demonstrated that radiotracer uptake in cells correlated with the degree of EGFR expression. MicroPET/CT imaging studies demonstrated a high intensity of (89)Zr-panitumumab in A431 and HCT 116 tumors in comparison with the EGFR-negative tumors. Biodistribution studies confirmed the results from the imaging studies. (89)Zr-panitumumab imaging of EGFR-positive tumors demonstrated levels of radiotracer uptake associated with EGFR expression.