Synthesis and stability test of radioimmunoconjugate 177Lu-DOTA-F(ab ′)2-trastuzumab for theranostic agent of HER2 positive breast cancer

Publication date: Available online 27 July 2016 Source:Journal of Radiation Research and Applied Sciences Author(s): Sandra Hermanto, Ratna Dini Haryuni, Martalena Ramli, Abdul Mutalib, Sumi Hudiyono The use of trastuzumab as intact IgG labeling radionuclide for HER2 positive breast cancer theranostic agent is not ideal because it is slowly eliminated from the blood and normal tissues resulting in low tumor/blood (T/B) and tumor/normal tissue (T/NT) ratios. To overcome this limitation, we developed the trastuzumab F(ab′)2 fragments and radiolabeling of the fragments by β and γ-particle of Lutetium-177. F(ab)2 fragments were produced by digestion of trastuzumab IgG (Herceptin) with pepsin for 18 h at 37 °C. The F(ab′)2 fragment fractionated in PD-10 column, followed by the conjugation with 2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (p-SCN-Bn-DOTA) as a metal chelator and radiolabeling with 177LuCl3. Molecular weight of fragments was calculated by LCMS (Liquid Chromatography Mass Spectroscopy) and the radiochemical purity was evaluated by ITLC-SG (Instan Thin Layer Chromatography). Our study showed that the purity of F(ab′)2 fragment generated by PD-10 fractions was >98% and the molecular weight of F(ab′)2 was 98.35 kDa. The average numbers of pSCN-Bn-DOTA chelates per antibody fragment were 5.03 ± 1.5 and the optimum conjugation reactions was performed at molar ratio 20:1 (chelator to antibody). The...
Source: Journal of Radiation Research and Applied Sciences - Category: Physics Source Type: research