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Updated: May 12, 2026

Identification of Mediators of T-cell Receptor Signaling via the Screening of Chemical Inhibitor Libraries
Published on: January 22, 2019
Discovery of thiazolobenzoxepin PI3-kinase inhibitors that spare the PI3-kinase β isoform
Steven T Staben1, Chudi Ndubaku, Nicole Blaquiere
1Discovery Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA. stevents@gene.com
Abstract:
A series of suitable five-membered heterocyclic alternatives to thiophenes within a thienobenzoxepin class of PI3-kinase (PI3K) inhibitors was discovered. Specific thiazolobenzoxepin 8-substitution was identified that increased selectivity over PI3Kβ. PI3Kβ-sparing compound 27 (PI3Kβ Ki,app/PI3Kα Ki,app=57) demonstrated dose-dependent knockdown of pAKT, pPRAS40 and pS6RP in vivo as well as differential effects in an in vitro proliferation cell line screen compared to pan PI3K inhibitor GDC-0941. A new structure-based hypothesis for reducing inhibition of the PI3K β isoform while maintaining activity against α, δ and γ isoforms is presented.
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