A Novel Platinum(II)–Based Bifunctional ADC Linker Benchmarked Using 89Zr-Desferal and Auristatin F–Conjugated Trastuzumab

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 Zr. Trastuzumab-Lx-DFO-Zr 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. Cancer Res; 77(2); 257-67. ©2016 AACR.

In Vivo Characterization of Platinum(II)-Based Linker Technology for the Development of Antibody–Drug Conjugates: Taking Advantage of Dual Labeling with 195mPt and 89Zr

“…Recently, we introduced Lx as a promising metal-organic ADC linker (20,21). In a first step, Lx is coordinated to diagnostic or therapeutic payloads to provide storable Pt(II) complexes, or semifinal products.…”

“…It has been recognized that these linkers provide suboptimal ADCs; therefore, extensive research on new conjugation technologies has been initiated during the last few years (5,(17)(18)(19). As a pioneering approach in the development of ADCs, we recently described the use of the cationic metal-organic linker [ethylenediamineplatinum(II)] 21 , herein called Lx (LinXis) (20,21). In a first step, Lx can be coordinated to payloads bearing nonconventional functionalities, such as an N-heterocyclic ligand, to provide storable products that we term semifinal.…”

“…On the basis of these characteristics, the Lx linker technology can pave the way to a plugand-play ADC development platform in which antibodies and payloads can easily be varied. The potential of the Lx linker technology was recently demonstrated in the preparation of auristatin F conjugated trastuzumab (trastuzumab-Lx-AF) (21). A single dose of trastuzumab-Lx-AF outperformed its maleimide benchmark trastuzumab-mal-AF and the Food and Drug Administration-approved ado-trastuzumab emtansine in a xenograft mouse model of gastric cancer (NCI-N87) and of ado-trastuzumab emtansine-resistant breast cancer (JIMT-1).…”

Targets for MAbs: innovative approaches for their discovery & validation, LabEx MAbImprove 6thantibody industrial symposium, June 25-26, 2018, Montpellier, France

“…In this way, biodistribution of each component was evaluated. Sijbrandi et al 9 compared the therapeutic efficacy of Kadcyla® in tumor-bearing mice with that of trastuzumab-auristatin F using either the platinum linker or the Seattle Genetics linker technology, and demonstrated that the ADC with the platinum linker outperformed the two other ADCs. A potential explanation for the enhanced efficacy could be the fact that the platinum linker is a charged molecule, and, when coupled to a drug, it cannot enter a normal cell, resulting therefore in decreased toxicity.…”

Mass spectrometric characterization of intact desferal‐conjugated monoclonal antibodies for immuno‐positron emission tomography imaging

“…The attached desferal molecule can then act as a chelator to complex 89 Zr (Figure ). In addition to its diagnostic utility, immuno‐PET approaches that use 89 Zr‐desferal can also be employed to probe pharmacokinetic (PK) properties and assess tumor targeting of novel compounds in oncology …”