Automated Module Radiolabeling of Peptides and Antibodies with Gallium-68,Lutetium-177 and Iodine-131

Abstract

Our objectives were to automate radiolabeling of therapeutic activities for safe, reliable, cost-effective, practical routine preparation of ¹⁷⁷Lu-radiopeptides, ¹³¹I radioimmunotherapeutic agents, and ⁶⁸Ga-peptide PET diagnostics and, in particular, minimize radiation exposure to the radiopharmaceutical chemist. Reprogramming and adaptation of a commercially available synthetic module (IBA molecular; Synthera^®) allowed high yield, fully automated, in-house radiolabeling of novel therapeutic and diagnostic radiopharmaceuticals under remote shielded sterile conditions. Radiochemical yield and purity was measured by instant thin-layer chromatography and high-performance liquid chromatography. ⁶⁸Ga-octreotate and ¹⁷⁷Lu-octreotate were synthesized, resulting in both radiochemical yield and radiochemical purity greater than 99%. Synthesis of ¹³¹I-rituximab resulted in a yield of 60%, with a radiochemical purity greater than 99%. Using 400 MBq ⁶⁸GaCl₃ per synthesis, the estimated absorbed body and hand dose for a manual synthesis was 2 and 27 μSv, contrasting with automated synthesis exposure of 1.3 and 7.9 μSv. Using 8000 MBq ¹⁷⁷LuCl₃ per synthesis, the estimated absorbed body and hand dose for a manual synthesis was 44.7 and 75 μSv, contrasting with automated synthesis exposure of 2.5 and 20 μSv. Using 6000 MBq ¹³¹I per synthesis, the estimated absorbed body and hand dose for a manual synthesis was 83.7 and 335 μSv, contrasting with automated synthesis exposure of 10.9 and 54.7 μSv. The reduction in radiation exposure by automated synthesis of radiopharmaceuticals in the Synthera^® module was at least five fold. Automated synthesis of therapeutic ¹⁷⁷Lu and ¹³¹I radiopharmaceuticals and ⁶⁸Ga PET agents in the shielded sterile Synthera^® module is simple, practical, and efficient and virtually eliminates radiation exposure to the radiopharmaceutical chemist.