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Efficient preparation of site-specific antibody-drug conjugates using phosphopantetheinyl transferases

Grunewald, Jan and Klock, Heath and Cellitti, Susan and Bursulaya, Badry and Mcmullan, Daniel and Jones, David and Chiu, Hsien-Po and Patterson, Paula and Zhou, Huanfang and Vance, Julie and Nigoghossian, Edward and Tong, Hung and Daniel, Dylan and Mallet, William and Ou, Weijia and Uno, Tetsuo and Brock, Ansgar and Lesley, Scott and Geierstanger, Bernhard (2015) Efficient preparation of site-specific antibody-drug conjugates using phosphopantetheinyl transferases. Bioconjugate Chemistry, 26 (12). pp. 2554-2562. ISSN 1520-4812

Abstract

Post-translational modification catalyzed by phosphopantetheinyl transferases (PPTases) has previously been used to site-specifically label proteins with structurally diverse molecules. PPTase catalysis results in covalent modification of a serine residue in acyl/peptidyl carrier proteins and their surrogate substrates which are typically fused to the N- or C-terminus. To test the utility of PPTases for preparing antibody-drug conjugates (ADCs), we inserted 11 and 12-mer PPTase substrate sequences at 110 constant region loop positions of trastuzumab. Using Sfp-PPTase, 63 sites could be efficiently labeled with an auristatin toxin, resulting in 95 homogeneous ADCs. ADCs labeled in the CH1 domain displayed in general excellent pharmacokinetic profiles and negligible drug loss. A subset of CH2 domain conjugates underwent rapid clearance in mouse pharmacokinetic studies. Rapid clearance correlated with lower thermal stability of the particular antibodies. Independent of conjugation site, almost all ADCs exhibited subnanomolar in vitro cytotoxicity against HER2-positive cell lines. One selected ADC was shown to induce tumor regression in a xenograft model at a single dose of 3 mg/kg, demonstrating that PPTase-mediated conjugation is suitable for the production of highly efficacious and homogeneous ADCs.

Item Type: Article
Date Deposited: 26 Apr 2016 23:45
Last Modified: 26 Apr 2016 23:45
URI: https://oak.novartis.com/id/eprint/26602

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