Discovery of Highly Selective Inhibitors of p38α

Author(s): Ioana Popa-Burke, Steve Birkos, Leonard Blackwell, Lynn Cheatham, Jennifer Clark, John K. Dickson, Jr., Scott Galasinski, William P. Janzen, Jose Mendoza, Jennifer L. Miller, Robert P. Mohney, Paul M. Steed, C. N. Hodge.

Journal Name: Current Topics in Medicinal Chemistry

Volume 5 , Issue 10 , 2005

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Abstract:

The p38 MAP kinases are a family of serine/threonine protein kinases that play a key role in cellular pathways leading to pro-inflammatory responses. We have developed and implemented a method for rapidly identifying and optimizing potent and selective p38α inhibitors, which is amenable to other targets and target classes. A diverse library of druggable, purified and quantitated molecules was assembled and standardized enzymatic assays were performed in a microfluidic format that provided very accurate and precise inhibition data allowing for development of SAR directly from the primary HTS. All compounds were screened against a collection of more than 60 enzymes (kinases, proteases and phosphatases), allowing for removal of promiscuous and non-selective inhibitors very early in the discovery process. Follow-up enzymological studies included measurement of concentration of compound in buffer, yielding accurate determination of Ki and IC50 values, as well as mechanism of action. In addition, active compounds were screened against less desirable properties such as inhibition of the enzyme activity by aggregation, irreversible binding, and timedependence. Screening of an 88,634-compound library through the above-described process led to the rapid identification of multiple scaffolds ( > 5 active compounds per scaffold) of potential drug leads for p38α that are highly selective against all other enzymes tested, including the three other p38 isoforms. Potency and selectivity data allowed prioritization of the identified scaffolds for optimization. Herein we present results around our 3-thio-1,2,4-triazole lead series of p38α selective inhibitors, including identification, SAR, synthesis, selectivity profile, enzymatic and cellular data in their progression towards drug candidates.

Keywords: serine/threonine protein kinases, drug discovery, anti-cytokine biotherapeutics, sar, high throughput screening, library design, thio- triazole

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Article Details

VOLUME: 5
ISSUE: 10
Year: 2005
Page: [941 - 951]
Pages: 11
DOI: 10.2174/1568026054985867
Price: $58

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