Optimization of the preparation of 99mTc-labeled Hynic-derivatized Annexin V for human use

Abstract Hydrazino nicotinate (Hynic) is one of the most attractive bifunctional agents designed for the labeling of proteins with 99m Tc. Recently, a 99m Tc-labeled Hynic-Annexin V derivative has been described and successfully evaluated in animal models of apoptosis. Prior to a phase I human study, the preparation of 99m Tc-Hynic-Annexin V has been optimized. The influence of the Hynic-load of Annexin V, amount of protein, nature and amount of reducing agent, activity and co-ligand on the labeling yield were evaluated using ITLC and size-exclusion FPLC. Optimal labeling yields were obtained when 60-90 μg Hynic-Annexin V was labeled with up to 1.11 GBq (30 mCi) 99m TcO 4 -using 10-20 μg SnCl 2 .2H 2 O as reducing agent and 1.5 mg tricine as the co-ligand. Biodistribution in normal mice was comparable to literature data.