Leveraging array-based SPR to profile PROTAC^® cooperativity

Key Highlights

• Directly measure binary and ternary kinetics with no detection labels required

• Evaluate selectivity across a panel of up to hundreds of targets, off-targets, and ligases in parallel

• Develop data-rich profiles of cooperativity

Introduction

Therapeutic strategies around modulating protein degradation present an exciting new opportunity to address previously undruggable targets. Of these approaches, proteolysis targeting chimeras (PROTACs) are a class of molecules that have shown some of the most promise in the clinic. PROTACs are heterobifunctional molecules composed of a small-molecule moiety, which can bind a disease target connected via linker chemistry to an additional small-molecule moiety that binds an E3 ligase. Mechanistically, this design brings the E3 ligase in close proximity to the disease protein enabling ubiquitinylation and subsequent degradation. Depending on the kinetics and reversibility of the binding interaction, PROTACs can be catalytic in nature enabling repeated ubiquitinylation and degradation of disease proteins, provided a powerful mechanism for challenging diseases.

Demonstrated here is a strategy to generate detailed biophysical characterization of PROTACs using the LSA^XT, which provides increased sensitivity and data quality in an HT-SPR format. By creating an array of the disease proteins and closely related mutants/family members along with E3 ligases, up to hundreds of binding interactions can be tested in a single injection. Without the need to label components, robust and quantitative direct measures can be made for selectivity, binary affinity, ternary affinity, and cooperativity. In this approach, a comprehensive view of each PROTAC is obtainable in a truly high-throughput manner amenable to rapid drug discovery and optimization.

Posted by Noah T. Ditto