LinXis B.V. / Niels J. Sijbrandi*
Abstract
Greater control is desirable in the stochastic conjugation technology used to synthesize antibody-drug conjugates (ADC). We have shown recently that a fluorescent dye can be stably conjugated to a mAb using a bifunctional platinum(II) linker. Here, we describe the general applicability of this novel linker technology for the preparation of stable and efficacious ADCs. The ethylenediamine platinum(II) moiety, herein called Lx, was coordinated to Desferal (DFO) or auristatin F (AF) to provide storable "semifinal" products, which were directly conjugated to unmodified mAbs. Conjugation resulted in ADCs with unimpaired mAb-binding characteristics, DAR in the range of 2.5 to 2.7 and approximately 85% payload bound to the Fc region, presumably to histidine residues. To evaluate the in vivo stability of Lx and its effect on pharmacokinetics and tumor targeting of an ADC, Lx-DFO was conjugated to the HER2 mAb trastuzumab, followed by radiolabeling with 89Zr. Trastuzumab-Lx-DFO-89Zr was stable in vivo and exhibited pharmacokinetic and tumor-targeting properties similar to parental trastuzumab. In a xenograft mouse model of gastric cancer (NCI-N87) or an ado-trastuzumab emtansine-resistant breast cancer (JIMT-1), a single dose of trastuzumab-Lx-AF outperformed its maleimide benchmark trastuzumab-Mal-AF and FDA-approved ado-trastuzumab emtansine. Overall, our findings show the potential of the Lx technology as a robust conjugation platform for the preparation of anticancer ADCs.
Author information
Sijbrandi NJ1, Merkul E2, Muns JA2, Waalboer DC3, Adamzek K3, Bolijn M3, Montserrat V2, Somsen GW4, Haselberg R4, Steverink PJ2, Houthoff HJ2, van Dongen GA3.
1LinXis B.V., Amsterdam, the Netherlands. sijbrandi@linxispharmaceuticals.com.
2LinXis B.V., Amsterdam, the Netherlands.
3Department of Radiology and Nuclear Medicine, VU Medical Center, Amsterdam, the Netherlands.
4Division of BioAnalytical Chemistry, AIMMS Research Group BioMolecular Analysis, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.