BACKGROUND: Radioligand therapy using alpha emitters has gained more and more prominence in the last decade. Despite continued efforts to identify new appropriate radionuclides, the combination of 225Ac/213Bi remains among the most promising. Bismuth-213 has been employed in clinical trials in combination with appropriate vectors to treat patients with various forms of cancer, such as leukaemia, bladder cancer, neuroendocrine tumours, melanomas, gliomas, or lymphomas. However, the half-life of 213Bi (T1⁄2 = 46 min) implies that its availability for clinical use is limited to hospitals possessing a 225Ac/213Bi radionuclide generator, which is still predominantly scarce. We investigated a new Ac/Bi generator system based on using the composite sorbent α-ZrP-PAN (zirconium(IV) phosphate as active component and polyacrylonitrile as matrix). The developed 225Ac/213Bi generator was subjected to long-term testing after its development. The elution profile was determined and the elution yield, the contamination of the eluate with the parent 225Ac and the contamination of the eluate with the column material were monitored over time. RESULTS: The high activity (75 MBq of parent 225Ac) generator with a length of 75 mm and a diameter of 4 mm containing the composite sorbent α-ZrP-PAN with a particle size of 0.8 to 1.0 mm as the stationary phase, eluted with a mixture of 10 mM DTPA in 5 mM nitric acid, provided 213Bi with yields ranging from 77 % to 96 % in 2.8 mL of eluate, with parent 225Ac contamination in the order of 10-3 %, up to twenty days of use. CONCLUSION: All the results of the monitored parameters indicate that the composite sorbent α-ZrP-PAN based separation system for the elution of 213Bi is a very promising and functional solution.

Department of Nuclear Chemistry Faculty of Nuclear Sciences and Physical Engineering Czech Technical University Prague Břehová 87 7 115 19 Prague Czech Republic

European Commission Joint Research Centre Karlsruhe Germany

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