TBAJ-587, a novel diarylquinoline, is active against <i>Mycobacterium abscessus</i>

Nontuberculous mycobacteria (NTM) infections are extremely difficult to treat due to a natural resistance to many antimicrobials. TBAJ-587 is a novel diarylquinoline, which shows higher anti-tuberculosis activity, lower lipophilicity, and weaker inhibition of hERG channels than bedaquiline (BDQ). The susceptibilities of 11 NTM reference strains and 194 clinical Mycobacterium abscessus isolates to TBAJ-587 were determined by the broth microdilution assay. The activity of TBAJ-587 toward the growth of M. abscessus in macrophages was also evaluated. Minimum bactericidal concentration and time-kill kinetic assays were conducted to distinguish between the bactericidal and bacteriostatic activities of TBAJ-587. The synergy between TBAJ-587 and eight clinically important antibiotics was determined using a checkerboard assay. TBAJ-587 was highly effective against M. abscessus by targeting its F-ATP synthase c chain. The antimicrobial activities of TBAJ-587 and BDQ toward intracellular M. abscessus were comparable. The in vivo activities of TBAJ-587 and BDQ in an immunocompromised mouse model were also comparable. TBAJ-587 expressed bactericidal activity and was compatible with eight anti-NTM drugs commonly used in clinical practice; no antagonism was discovered. As such, TBAJ-587 represents a potential candidate for the treatment of NTM infections.