Radiolabelling of monoclonal antibodies for radiotherapy

Preparation of beta emitting radioisotope and development of labelling techniques with antibodies, peptides and their conjugates was investigated. Samarium-153 was labelled to DTPA - antibody conjugate giving low yields due to instability of labelled products and low specific activity of 153Sm produced. Rhenium-188 was labelled to antibodies and lanreotide peptides by direct method and indirect method via MAG3-conjugate giving maximum yields of 86.1% and 79.5% labelling for 188Re-labelled antibody and 99.3% and 85.0% labelling for 188Re-labelled lanreotide, respectively. Synthesis of DOTA and DOTA-lanreotide was performed and the products were characterized by instrumental analysis and compared with standard sample. Yttrium-90 was produced by 90Sr/90Y generator system and was labelled to DOTA-lanreotide with more than 97% labelling yields. All radiolabelled products were determined for radiochemical purity by ITLC and HPLC, in vitro and serum stability, immunoreactivity or receptor binding affinity and some of them were evaluated for in vivo biodistribution in model animals. (author)