X-ray Crystal Structure-Guided Design and Optimization of 7 H -Pyrrolo[2,3- d ]pyrimidine-5-carbonitrile Scaffold as a Potent and Orally Active Monopolar Spindle 1 Inhibitor

Triple-negative breast cancer (TNBC) is an aggressive breast-cancer subtype associated with poor prognosis and high relapse rates. Monopolar spindle 1 kinase (MPS1) is an apical dual-specificity protein kinase that is over-expressed in TNBC. We herein report a highly selective MPS1 inhibitor based on a 7 -pyrrolo[2,3- ]pyrimidine-5-carbonitrile scaffold. Our lead optimization was guided by key X-ray crystal structure analysis. evaluation of candidate ( ) is shown to effectively mitigate human TNBC cell proliferation.