Simple and efficient method for producing high radionuclidic purity 111In using enriched 112Cd target.

In this work, a simple and efficient method for producing high radionuclidic purity 111In from an enriched 112Cd target was developed. The enriched 112Cd metal target formed by cyanide-free electroplating was bombarded with protons of 21 MeV in a CS-30 cyclotron. Then, we explored a purification scheme using CL-P204 cation exchange resin wherein 98% of the 111In in the bombarded target could be extracted in less than 1 h. The purified 111In in the form of [111In]In-chloride had a high radionuclidic purity (99.9%) and a low impurity concentration (<1.2 ppm). The yield of 111In via the reaction of 112Cd (p, 2n) 111In was measured to be 222 ± 5 MBq/µA∙h. In addition, a chemical procedure for collecting the unreacted 112Cd at a recovery rate of 96.6% was explored.

Production of 98Tc with high isotopic purity.

In this work, technetium-98 (98Tc) was prepared with high isotopic purity via the nuclear reaction 98Mo (p, n) 98Tc for the first time. An enriched 98Mo metal target formed by spark plasma sintering was bombarded with 9.4 MeV protons in a CS-30 cyclotron. A microgram amount of 98Tc with 99.18% isotopic purity was separated from the irradiated target by anion exchange chromatography. Additionally, a chemical procedure for recovering the enriched 98Mo with a 97% recovery rate was developed.

A radiopharmaceutical [89Zr]Zr-DFO-nimotuzumab for immunoPET with epidermal growth factor receptor expression in vivo.

INTRODUCTION: The potential of the positron-emitting zirconium-89 (89Zr) (t1/2 = 78.4 h) has been recently reported for immune positron emission tomography (immunoPET) radioimmunoconjugates design. In our work, we explored the optimized preparation of [89Zr]Zr-DFO-nimotuzumab, and evaluated 89Zr-labeled monoclonal antibody (mAb) construct for targeted imaging of epidermal growth factor receptor (EGFR) overexpressed in glioma. METHODS: To optimize the radiolabeling efficiency of 89Zr with DFO-nimotuzumab, multiple immunoconjugates and radiolabeling were performed. Radiolabeling yield, radiochemical purity, stability, and activity assay were investigated to characterize [89Zr]Zr-DFO-nimotuzumab for chemical and biological integrity. The in vivo behavior of this tracer was studied in mice bearing subcutaneous U87MG (EGFR-positive) tumors received a 3.5 ±â€¯0.2 MBq/dose using PET/CT imaging. One group mice bearing subcutaneous U87MG (EGFR-positive) tumors received [89Zr]Zr-DFO-nimotuzumab (3.5 ±â€¯0.2 MBq, ~3 µg) (nonblocking) for immunoPET; the other group had 30 µg predose (blocking) of cold nimotuzumab 24 h prior to [89Zr]Zr-DFO-nimotuzumab. RESULTS: [89Zr]Zr-DFO-nimotuzumab was prepared with high radiochemical yield (>90%), radiochemical purity (>99%), and specific activity (115 ±â€¯0.8 MBq/mg). In vitro validation showed that [89Zr]Zr-DFO-nimotuzumab had an initial immunoreactive fraction of 0.99 ±â€¯0.05 and remained active for up to 5 days. A biodistribution study revealed excellent stability of [89Zr]Zr-DFO-nimotuzumab in vivo compared with 89Zr as a bone seeker. High uptake in the liver and heart and modest penetration in the brain were observed, with no significant accumulation of activity in other organs. ImmunoPET studies also indicated prominent image contrast that remarkably high uptake up to ~20%ID/g for nonblocking and ~2%ID/g for blocking in tumor between 12 and 120 h after administration. CONCLUSION: These studies developed a radiopharmaceutical [89Zr]Zr-DFO-nimotuzumab with optimized synthesis. The potential utility of [89Zr]Zr-DFO-nimotuzumab in assessing EGFR status in glioma was demonstrated in this study.