QAW039, a slowly dissociating CRTh2 antagonist with potential for improved clinical efficacy

David A. Sykes, Michelle E. Bradley, Darren Riddy, Elizabeth Willard, Ellen Powell-Herlaar, David A. Sandham, Simon J. Watson, Carsten Bauer, Gerald Dubois, Steven J Charlton

Research output: Contribution to conferenceAbstract


QAW039 is an oral, selective, competitive and reversible CRTh2 receptor antagonist currently in clinical development for treatment of asthma. This study describes the detailed investigation of the receptor binding kinetics of QAW039 and compares it to several other known CRTh2 antagonists.

Kinetic binding experiments with [3H3]-QAW039 and CRTh2 receptor were carried out at 37oC, [35S]-GTPγS binding at room temperature1. The ability of compounds to inhibit the whole blood shape change (WBSC) response to PGD2 was monitored using flow cytometry.

The dissociation rate constant for QAW039 was significantly lower than all other clinically relevant CRTh2 antagonists tested (QAV680, OC459 and AZD-1981, Table). QAW039 was the most potent compound tested in the WBSC assay. In the binding assay QAW039 significantly reduced the maximum effect of PGD2 following a 15min incubation.

The slower off-rate of QAW039 from the CRTh2 receptor potentially affords it an improved efficacy, as it can insurmountably block the CRTh2 receptor even in the face of high local concentrations of PGD2.
Original languageEnglish
Number of pages1
Publication statusPublished - 2014
Externally publishedYes
EventEuropean Respiratory Society (ERS) International Congress 2014 - Munich, Germany
Duration: 6 Sep 201410 Sep 2014


ConferenceEuropean Respiratory Society (ERS) International Congress 2014
Internet address

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