Discovery of a Conformationally Constrained Oxazolidinone with Improved Safety and Efficacy Profiles for the Treatment of Multidrug-Resistant Tuberculosis.

Tuberculosis (TB) remains a serious public health challenge, and the research and development of new anti-TB drugs is an essential component of the global strategy to eradicate TB. In this work, we discovered a conformationally constrained oxazolidinone 19c with improved anti-TB activity and safety profile through a focused lead optimization effort. Compound 19c displayed superior in vivo efficacy in a mouse TB infection model compared to linezolid and sutezolid. The druggability of compound 19c was demonstrated in a panel of assays including microsomal stability, cytotoxicity, cytochrome P450 enzyme inhibition, and pharmacokinetics in animals. Compound 19c demonstrated an excellent safety profile in a battery of safety assays, including mitochondrial protein synthesis, hERG K+, hCav1.2, and Nav1.5 channels, monoamine oxidase, and genotoxicity. In a 4 week repeated dose toxicology study in rats, 19c appeared to have less bone marrow suppression than linezolid, which has been a major liability of the oxazolidinone class.