SarAr - a new ligand for radiolabeling with 64Cu: its potential for therapy

Full text: High specific activity 64Cu is routinely produced at the National Medical Cyclotron, Australia. Cu-64 decays by β+ (0.655 MeV; 19%) and β- (0.573 MeV; 40%), which enables both imaging by PET and potential for radiotherapy. SarAr (amino-benzyl-cryptate) is a new ligand for use in radiolabelling protein and peptides. SarAr rapidly complexes with Cu(II), and is stable in serum for >160 hr. The radioimmunoconjugate 64Cu-SarAr-B72.3 was prepared and its biodistribution in LS174t tumour-bearing nude mice showed good (38.4 + 4.8 %ID/g at 48 hr) tumour localisation. Its pharmacokinetics was compared with the analogous 131I and 111In labelled B72.3. MIRDOSE 3 calculations show dose to the tumour verses non-target organs is higher than the analogous products. A therapeutic study involving the injection of varying activities (10/40 MBq) of 64Cu-SarAr-B72.3 into tumour bearing mice resulted in the extension of survival times of the mice of up to 200 %. Copyright (2000) American Chemical Society