Author ORCID Identifier

https://orcid.org/0000-0003-0908-707X

Document Type

Thesis

Date of Award

Spring 2022

Keywords

Antibody-Drug Conjugates, Self-immolative Linkers, Antibodies, Immunosuppression, Immune activation, Oncology, Prodrugs

Degree Name

Biochemistry (BS)

Department

BIOCHEMISTRY

First Advisor

Dr. L. Nathan Tumey

Series

Science and Mathematics

Subject Heading(s)

Antibody-drug conjugates; Immunosuppression; Oncology; Drugs

Abstract

Antibody-drug conjugates (ADCs) are an increasingly popular modality for targeted drug delivery in many oncological and immunological applications. The paratope of a monoclonal antibody (mAb) directs the delivery of a conjugated therapeutic payload to antigen expressing cells, resulting in a controlled transport of payload to a desired cell type. Internalization of the ADC followed by lysosomal degradation results in the release of a payload to perform its biochemical function. A chemical linker between the drug and the antibody is responsible for the stability of the conjugate in circulation alongside mediating the release of an unmodified payload under lysosomal conditions. Currently, the lead linker, ValCit-p-aminobenzyl carbamate (PABC), has demonstrated impressive extracellular integrity while maintaining susceptibility to lysosomal proteases, such as Cathepsin B, for controlled intracellular release.1 However, the well-studied ValCitPABC linker system is largely restricted to amine-containing payloads for immuno-modulating ADCs whereas there are few ADC linkage systems that are able to release alcohol containing payloads, regardless of their functional prevalence across a myriad of biologically active small molecules. We propose that upon cathepsin-mediated cleavage of our ADCs, the ValCit release of a GlyPro ester undergoes rapid cyclization to form a diketopiperazine, thereby releasing the alcohol-containing payload. The efficiency of this linker (ValCitGlyPro) was examined using a model system designed to release dexamethasone, a potent glucocorticoid. Kinetic studies demonstrated that our linker system results in rapid GlyPro-dexamethasone release in lysosomes, which undergoes rapid cyclization to release dexamethasone at neutral pH. After conjugation of the linker payload to targeted and untargeted antibodies, several cell assays show that this system is capable of targeted immune suppression of lipopolysaccharide (LPS) stimulated cells. We also report our efforts to expand the utility of this linker system for the release of anilines, and amines.

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