Project Summary
Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is responsible for staggering levels of
morbidity and mortality, with ~1.7 million deaths and ~10 million new cases each year. The current TB
regimens for drug susceptible strains, entailing multidrug cocktails for ≥4 months, leave much to be
desired. The cost and logistics of administering standard of care regimens over many months and the
inability of many patients to tolerate the debilitating side effects further complicate the clinical control of
TB. The lingering negative impacts of the COVID pandemic on TB control efforts and increasing challenge
of multidrug-resistant Mtb strains, which have only a ~50% treatment success rate, further highlight the
urgent need for better antibiotics to tackle this problem. Even our definition of what “better” means has
shifted based on recent appreciation of the heterogeneity of mycobacteria subpopulations that must be
eradicated, including replicating and non-replicating bacilli residing both extracellularly and within host cells
in diverse microenvironments. Thus, effective drug combinations must not only access mycobacteria within
different niches and layers of granulomas but also be able to kill Mtb in many distinct metabolic states while
minimizing the emergence of resistance. In order to meet this urgent need for game-changing new
treatment options for TB, it is imperative to maintain a robust pipeline of new anti-TB drug candidates with
the potential to meet these demanding performance criteria. This project seeks to address this need by
building on our recent discovery of a first-in-class series of compounds that kill Mtb via inhibition of a well-
validated but underexploited target enzyme essential for cell wall synthesis. Thus far, we have
demonstrated sub-micromolar potency, enhanced potency against Mtb within macrophages, high
specificity for Mtb, and high selectivity over mammalian cells. We have strong evidence that these
compounds act via inhibition of an essential enzyme involved in mycolic acid biosynthesis for which there
are currently no viable preclinical candidates. The first major goal of this project is hit-to-lead optimization
and elucidation of structure-activity relationships, using whole cell potency and ADME/PK properties as
key drivers of compound prioritization. Secondly, we will employ orthogonal approaches to further validate
the target and ensure that optimized lead compounds remain on-target. Successful completion of this
project will set the stage for subsequent lead optimization and in vivo efficacy studies of a promising new
class of cell-wall targeting TB antibiotics.