A cell-free, high-throughput screening service for accelerated GPCR ligand discovery

PROJECT SUMMARY
The proposed Phase I STTR project is a partnership between a biotechnology company KXTbioIncand the
University of North Carolina at Chapel Hill to develop an innovative high throughput screening service for
identifying new drug candidates that act via G protein coupled receptorsGPCRsThis large protein superfamily
has been the most successful source of therapeutic targetsaccounting forof all prescription
pharmaceuticals in such diverse areas as cancercardiac dysfunctiondiabetescentral nervous system
disordersobesityinflammationand painHoweverwith much of the low hanging fruit already pickedthe pace
of GPCR drug discovery and development has slowed due to the challenges associated with obtainingD
structures of GPCRs and performing structure activity studiesConcurrentlynew findings in GPCR
pharmacology research have uncovered previously unknown intricacies of GPCR signaling that expanded their
potential as targets for therapeutic interventions even furtherConsidering the decreasing productivity in the
pharmaceutical industry and rising development costsmore effective methods of identifying GPCR drug
candidates would be highly valuableAlthough crystal structures of GPCRs are now being generatedtheir utility
will remain limited for the foreseeable futureVarious functional assays are currently the mainstay of GPCR
screening effortsand rely on detecting downstream cellular signaling events initiated by changes in GPCR
activityChosen for their strong and easy to measure signalsthese techniques are performed in live cell culturesmaking them prone to off target effects resulting in both false positives and false negativesintroducing higher
variability and costsas well as reduced throughputKXTbio and UNC Chapel Hill aim to develop a new screening technology that would eliminate many of the
drawbacks of the existing methodsThe new high throughput screeningHTSplatform will use purified GPCRs
and G proteinsthus avoiding cell culturesGPCR activity will be monitored by the immediately ensuing G protein
activation involving an exchange of the bound GDP molecule for a GTPThe fluorescent analog of GTP whose
fluorescent yield increases upon G protein binding will be used in the assay as the signal sourceThis proposed
real time HTS system can differentiate between agonistsantagonists and allosteric modulatorsusing a minimal
number of componentsthus reducing artefacts and cell dependent effectsIn contrast to related G protein
activation assays it does not require filtration and washing steps or radiolabelsIn this Phase I project KXTbio
aims to deliver a proof of concept of the proposed HTS GPCR platformand if successfula Phase II project will
followwhere the platform will be fully implementedtestedand optimized in a multi well plate formatKXTbio
plans to commercialize it is as a service with a possibility of licensing the technology to drug discovery
companies PROJECT NARRATIVE
The goal of the proposed Phase I STTR project is to develop a new high throughput screening platform to greatly
accelerate the discovery of drug candidates acting via G protein coupled receptorswhich are the targets ofof marketed pharmaceuticalsThe platform was designed expressly to eliminate the shortcomings of the existing
methods to increase productivityand will be marketed to drug discovery companies