Feasibility studies for radiolabeling: Using clinical grade (⁶⁴Cu)CuCl₂ produced by (p,n), (n,p) and (n,γ) routes

Copper-64, by virtue of its simultaneous emission of β+ and β- particles was considered to be an important diagnostic radiotracers and radiotherapeutic agents. This prompted us to evaluate the effectiveness of (⁶⁴Cu)CuCl₂ produced by alternate route namely ⁶³Cu(n,γ)⁶⁴Cu and ⁶⁴Zn(n,p)⁶⁴Cu for radiolabeling of various Copper-64 based radiopharmaceuticals, further compare to that of (⁶⁴Cu)CuCl₂ produced by conventional route via ⁶⁴Ni(p,n)⁶⁴Cu. Finally the (⁶⁴Cu)Cu-ATSM was filtered using sterile 0.20 μm PES membrane syringe filter. RCP was assessed by radio-TLC (⁶⁰AoSG, 100% CH₃COOC₂H₅) and radio- HPLC (RP18, 280 nm and 1.0 mL/min). The observed radiochemical yield (RCY) of the produced (⁶⁴Cu)Cu-ATSM was ~85% using nca (⁶⁴Cu)CuCl₂ produced from two different routes, while RCY of produced (⁶⁴Cu)Cu-ATSM using ca (⁶⁴Cu)CuCl₂ was ~15%. However the RCP for each of the (⁶⁴Cu)Cu-ATSM formulations were >99%. In stand-alone NMCs with in-house cyclotron, it is feasible to use nca (⁶⁴Cu)CuCl₂ (produced from enriched Nickel-64 target) for radiolabeling various Copper-64 based radiopharmaceuticals. However nca (⁶⁴Cu)CuCl₂ produced from fast neutron flux reactor is a preferred choice for centralized radiopharmacies involved in production of various Copper-64 based radiopharmaceuticals and supply to various NMCs across the length and breadth of country like India