MIC: 1 ng/ml (2.3 nM) for M. tuberculosis H37Rv and 4 ng/ml (9.2 nM) for Mycobacterium smegmatis

The loss of human lives to tuberculosis (TB) continues unabated as a result of poverty, synergy with the HIV/AIDS pandemic, and the emergence of multidrug- and extensively drug-resistant strains of Mycobacterium tuberculosis. BTZ043 is the most advanced candidate for inclusion in combination therapies for both drug-sensitive and extensively drug-resistant TB.

In vitro: BTZ043 displayed similar activity against all clinical isolates of M. tuberculosis that were tested, including extensively drug-resistant and multidrug-resistant strains, indicating that it targets a previously unknown biological function. BTZ043 is bactericidal, reducing viability in vitro by more than 1000-fold in under 72 hours, which is comparable to the INH killing effect [1].

In vivo: The in vivo efficacy of BTZ043 was assessed 4 weeks after a low-dose aerosol infection of in the chronic BALB/c mice model of TB. Four weeks of treatment with BTZ043 reduced the bacterial load in the lungs and spleens by 1 and 2 logs, respectively, at the concentrations used. Additional findings suggest that BTZ efficacy is time- rather than dose-dependent [1].

Clinical trial: Up to now, BTZ043 is still in the preclinical development stage.

Reference:
[1] Makarov V, Manina G, Mikusova K, et al.  Benzothiazinones kill Mycobacterium tuberculosis by blocking arabinan synthesis. Science. 2009 May 8;324(5928):801-4.