Antibody drug conjugates (ADCs) present a unique opportunity to increase the safety of highly toxic drugs by utilizing the specificity of antibodies to obtain targeted delivery of potent drugs to specific tissues. Classically, this is achieved by linking an amine-containing payload to an antibody using the well-studied mcValCitPABC linker. Yet, there are surprisingly few technologies for attaching alcohol containing payloads to an antibody. Theoretically, the simplest way to achieve this would be through an ester linkage. However, very little is known about the lysosomal and plasma stability of ester linkages on ADCs. Herein, we describe a number of experiments to evaluate this stability in both human/mouse plasma and in lysosomes. Furthermore, we describe the design of a peptide-linked ester that is rapidly cleaved in the lysosome.<br/><br/>The stability of ester linked payloads was evaluated by examining an anti-HER2 antibody bound to an ester linked dexamethasone payload. In the presence of lysosomes, the ester remained intact while the antibody backbone was proteolytically degraded. Upon incubation with SKBR3 cells, the major product released from the ADC was an ester-containing metabolite, cys-mc-Dex, thus confirming the lysosomal stability of this linkage in a cell-based system. Having demonstrated that simple esters are stable upon lysosomal uptake, we next undertook the design of a novel linker that undergoes an immolation that results in spontaneous ester-cleavage. In a model system designed to release dexamethasone, we have shown that this linker is rapidly cleaved by cathepsin B, thus resulting in the release of free dexamethasone. Furthermore, we show that the ester is stable in mouse plasma and only cleaved upon lysosomal uptake. With this research we hope to further our knowledge of ester linkages in ADCs as well as to develop a feasible way to release an unmodified alcohol-containing drug into a chosen cell type via lysosomally-induced ester linkage.

Esters in ADC linkers: Optimization of stability and lysosomal cleavage

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.