PMID: 26741947

Authors:

Heffron TP, Heald RA, Ndubaku C, Wei B, Augistin M, Do S, Edgar K, Eigenbrot C, Friedman L, Gancia E, Jackson PS, Jones G, Kolesnikov A, Lee LB, Lesnick JD, Lewis C, McLean N, Mortl M, Nonomiya J, Pang J, Price S, Prior WW, Salphati L, Sideris S, Staben ST, Steinbacher S, Tsui V, Wallin J, Sampath D, Olivero AG

Title:

The Rational Design of Selective Benzoxazepin Inhibitors of the alpha-Isoform of Phosphoinositide 3-Kinase Culminating in the Identification of (S)-2-((2-(1-Isopropyl-1H-1,2,4-triazol-5-yl)-5,6-dihydrobenzo[f]imidazo[1,2-d][1 ,4]oxazepin-9-yl)oxy)propanamide (GDC-0326).

Journal:

J Med Chem. 2016 Jan 20.

Abstract:

Inhibitors of the class I phosphoinositide 3-kinase (PI3K) isoform PI3Kalpha have received substantial attention for their potential use in cancer therapy. Despite the particular attraction of targeting PI3Kalpha, achieving selectivity for the inhibition of this isoform has proved challenging. Herein we report the discovery of inhibitors of PI3Kalpha that have selectivity over the other class I isoforms and all other kinases tested. In GDC-0032 (3, taselisib), we previously minimized inhibition of PI3Kbeta relative to the other class I insoforms. Subsequently, we extended our efforts to identify PI3Kalpha-specific inhibitors using PI3Kalpha crystal structures to inform the design of benzoxazepin inhibitors with selectivity for PI3Kalpha through interactions with a nonconserved residue. Several molecules selective for PI3Kalpha relative to the other class I isoforms, as well as other kinases, were identified. Optimization of properties related to drug metabolism then culminated in the identification of the clinical candidate GDC-0326 (4).