Impact of DOTA Conjugation on Pharmacokinetics and Immunoreactivity of [177Lu]Lu-1C1m-Fc, an Anti TEM-1 Fusion Protein Antibody in a TEM-1 Positive Tumor Mouse Model

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

doi:10.3390/pharmaceutics13010096

Impact of DOTA Conjugation on Pharmacokinetics and Immunoreactivity of [¹⁷⁷Lu]Lu-1C1m-Fc, an Anti TEM-1 Fusion Protein Antibody in a TEM-1 Positive Tumor Mouse Model

Pharmaceutics. 2021 Jan 13;13(1):96. doi: 10.3390/pharmaceutics13010096.

Authors

Affiliations

¹ Radiopharmacy Unit, Department of Pharmacy, Lausanne University Hospital and University of Lausanne, CH-1011 Lausanne, Switzerland.
² CRCINA, INSERM 1232-CNRS ERL 6001, University of Angers, University of Nantes, 44000 Nantes, France.
³ Groupement d'Intérêt Public Arronax, F-44800 Saint-Herblain, France.
⁴ LAbCore, Ludwig Institute for Cancer Research, Lausanne University Hospital and University of Lausanne, CH-1066 Epalinges, Switzerland.
⁵ Department of Nuclear Medicine and Molecular Imaging, Lausanne University Hospital and University of Lausanne, CH-1011 Lausanne, Switzerland.
⁶ Ludwig Institute for Cancer Research and Department of Oncology, Lausanne University Hospital and University of Lausanne, CH-1011 Lausanne, Switzerland.
⁷ Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, CH-1011 Lausanne, Switzerland.

Abstract

1C1m-Fc, an anti-tumor endothelial marker 1 (TEM-1) scFv-Fc fusion protein antibody, was previously successfully radiolabeled with ¹⁷⁷Lu. TEM-1 specific tumor uptake was observed together with a non-saturation dependent liver uptake that could be related to the number of dodecane tetraacetic acid (DOTA) chelator per 1C1m-Fc. The objective of this study was to verify this hypothesis and to find the best DOTA per 1C1m-Fc ratio for theranostic applications. 1C1m-Fc was conjugated with six concentrations of DOTA. High-pressure liquid chromatography, mass spectrometry, immunoreactivity assessment, and biodistribution studies in mice bearing TEM-1 positive tumors were performed. A multi-compartment pharmacokinetic model was used to fit the data and a global pharmacokinetic model was developed to illustrate the effect of liver capture and immunoreactivity loss. Organ absorbed doses in mice were calculated from biodistribution results. A loss of immunoreactivity was observed with the highest DOTA per 1C1m-Fc ratio. Except for the spleen and bone, an increase of DOTA per 1C1m-Fc ratio resulted in an increase of liver uptake and absorbed dose and a decrease of uptake in tumor and other tissues. Pharmacokinetic models correlated these results. The number of DOTA per antibody played a determining role in tumor targeting. One DOTA per 1C1m-Fc gave the best pharmacokinetic behavior for a future translation of [¹⁷⁷Lu]Lu-1C1m-Fc in patients.

Keywords: 177Lu radiolabeling; DOTA conjugation; TEM-1; biodistribution; fusion protein antibody; theranostic; tumor/liver ratio.