INTRODUCTION: In this study, we optimized the 1,4,7,10-tetraazacyclododecane-N-N'-N"-N"'-tetraacetic acid (DOTA) chelator-to-antibody (c/a) ratio for the aglycosylated variant of the anti-L1-CAM antibody chCE7 (chCE7agl), providing high specific activity and low liver uptake in 177Lu-labeled form. METHODS: chCE7agl was substituted with increasing molar excess of DOTA-NCS. The number of chelators coupled to the antibody and the binding affinities to target tumor cells (IC50 values) of the resulting immunoconjugates were determined. The different immunoconjugates were labeled with 177Lu; specific activity was measured, and metabolic stability was analyzed in human plasma. The effect of different c/a ratios on blood clearance and liver uptake was tested in nude mice. Changes of the protein backbone structure were analyzed by circular dichroism spectroscopy. RESULTS: chCE7agl was substituted with 7, 12 or 15 DOTA ligands. The IC50 concentrations displacing radioiodinated chCE7 antibody increased with the number of chelators (1.5-fold with 7 ligands, 2.5-fold with 12 ligands and a 5-fold increase with 15 ligands). The highest specific activity for 177Lu-DOTA-chCE7agl was obtained with a c/a ratio of 12 (106 MBq/mg). Radioimmunoconjugates were stable in human plasma for at least 24 h. Blood clearance and liver uptake were measured after 24 h (c/a ratios of 12 and 15) or 48 h (c/a ratio of 7). The liver-to-blood ratios were 0.35+/-0.14 (7 ligands), 0.77+/-0.19 (12 ligands) and 17.85+/-3.44 (15 ligands). CONCLUSIONS: DOTA-chCE7agl conjugates with a c/a ratio of 12 combined high specific activity with good in vitro and in vivo properties. The rapid elimination rate from the blood and the high uptake in the liver of chCE7agl substituted with 15 DOTA ligands were found not to be due to conformational changes of the antibody backbone structure.
INTRODUCTION: In this study, we optimized the 1,4,7,10-tetraazacyclododecane-N-N'-N"-N"'-tetraacetic acid (DOTA) chelator-to-antibody (c/a) ratio for the aglycosylated variant of the anti-L1-CAM antibody chCE7 (chCE7agl), providing high specific activity and low liver uptake in 177Lu-labeled form. METHODS: chCE7agl was substituted with increasing molar excess of DOTA-NCS. The number of chelators coupled to the antibody and the binding affinities to target tumor cells (IC50 values) of the resulting immunoconjugates were determined. The different immunoconjugates were labeled with 177Lu; specific activity was measured, and metabolic stability was analyzed in human plasma. The effect of different c/a ratios on blood clearance and liver uptake was tested in nude mice. Changes of the protein backbone structure were analyzed by circular dichroism spectroscopy. RESULTS: chCE7agl was substituted with 7, 12 or 15 DOTA ligands. The IC50 concentrations displacing radioiodinated chCE7 antibody increased with the number of chelators (1.5-fold with 7 ligands, 2.5-fold with 12 ligands and a 5-fold increase with 15 ligands). The highest specific activity for 177Lu-DOTA-chCE7agl was obtained with a c/a ratio of 12 (106 MBq/mg). Radioimmunoconjugates were stable in human plasma for at least 24 h. Blood clearance and liver uptake were measured after 24 h (c/a ratios of 12 and 15) or 48 h (c/a ratio of 7). The liver-to-blood ratios were 0.35+/-0.14 (7 ligands), 0.77+/-0.19 (12 ligands) and 17.85+/-3.44 (15 ligands). CONCLUSIONS: DOTA-chCE7agl conjugates with a c/a ratio of 12 combined high specific activity with good in vitro and in vivo properties. The rapid elimination rate from the blood and the high uptake in the liver of chCE7agl substituted with 15 DOTA ligands were found not to be due to conformational changes of the antibody backbone structure.
Authors: In Soo Shin; Sang-Myung Lee; Hyung Sub Kim; Zhengsheng Yao; Celeste Regino; Noriko Sato; Kenneth T Cheng; Raffit Hassan; Melissa F Campo; Earl F Albone; Peter L Choyke; Ira Pastan; Chang H Paik Journal: Nucl Med Biol Date: 2011-07-07 Impact factor: 2.408
Authors: Romana Meletta; Adrienne Müller Herde; Patrick Dennler; Eliane Fischer; Roger Schibli; Stefanie D Krämer Journal: EJNMMI Res Date: 2016-01-04 Impact factor: 3.138
Authors: Judith Anna Delage; Alain Faivre-Chauvet; Jacques Barbet; Julie Katrin Fierle; Niklaus Schaefer; George Coukos; David Viertl; Steven Mark Dunn; Silvano Gnesin; John O Prior Journal: Pharmaceutics Date: 2021-01-13 Impact factor: 6.321
Authors: Jürgen Grünberg; Simone Jeger; Dikran Sarko; Patrick Dennler; Kurt Zimmermann; Walter Mier; Roger Schibli Journal: PLoS One Date: 2013-04-02 Impact factor: 3.240