A Series of Pyrazolo-Quinazoline Amines Inhibits the CytochromeOxidase in.

Thecytochrome(cyt-) oxidase is a validated drug target for tuberculosis treatment. In addition to telacebec (Q203), a clinical-stage drug candidate, several preclinical cyt-:inhibitors have been reported. However, the bactericidal potency of cyt-:inhibitors is limited by cytochrome bd oxidase (cyt-), an alternative terminal oxidase. We developed a high-throughput whole-mycobacteria assay to identify new cyt-inhibitors. Screening 115,398 small molecules identified several new chemical series, including a pyrazolo-quinazoline amine series. Chemical optimization yielded the potent derivative ETX1975-3, which, in combination with Q203, is bactericidal against, retains activity against a panel of M/XDRclinical isolates, and also shows efficacy against nontuberculous mycobacteria (NTM). Mode of action studies validated the cyt-target as the molecular target. While further chemical optimization is required, favorable microbiological, ADMET, and in vivo potency of ETX1975-3 makes it a promising preclinical candidate for tuberculosis and NTM infections.