A Novel Inhibitor against the Biofilms of Non-Tuberculous Mycobacteria.

Non-tuberculous Mycobacteria (NTM), previously classified as environmental microbes, have emerged as opportunistic pathogens causing pulmonary infections in immunocompromised hosts. The formation of the biofilm empowers NTM pathogens to escape from the immune response and antibiotic action, leading to treatment failures. NF1001 is a novel thiopeptide antibiotic first-in-class compound with potent activity against planktonic/replicating and biofilm forms of various NTM species. It is potent against both drug-sensitive and -resistant NTM. It has demonstrated a concentration-dependent killing of replicating and intracellularly growing NTM, and has inhibited and reduced the viability of NTM in biofilms. Combination studies using standard-of-care (SoC) drugs for NTM exhibited synergetic/additive effects, but no antagonism against both planktonic and biofilm populations of Mycobacterium abscessus and Mycobacterium avium. In summary, the activity of NF1001 alone or in combination with SoC drugs projects NF1001 as a promising candidate for the treatment of difficult-to-treat NTM pulmonary diseases (NTM-PD) and cystic fibrosis (CF) in patients.

A multi-targeting pre-clinical candidate against drug-resistant tuberculosis.

FNDR-20081 [4-{4-[5-(4-Isopropyl-phenyl)- [1,2,4]oxadiazol-3-ylmethyl]-piperazin-1-yl}-7-pyridin-3-yl-quinoline] is a novel, first in class anti-tubercular pre-clinical candidate against sensitive and drug-resistant Mycobacterium tuberculosis (Mtb). In-vitro combination studies of FNDR-20081 with first- and second-line drugs exhibited no antagonism, suggesting its compatibility for developing new combination-regimens. FNDR-20081, which is non-toxic with no CYP3A4 liability, demonstrated exposure-dependent killing of replicating-Mtb, as well as the non-replicating-Mtb, and efficacy in a mouse model of infection. Whole genome sequencing (WGS) of FNDR-20081 resistant mutants revealed the identification of pleotropic targets: marR (Rv0678), a regulator of MmpL5, a transporter/efflux pump mechanism for drug resistance; and Rv3683, a putative metalloprotease potentially involved in peptidoglycan biosynthesis. In summary, FNDR-20081 is a promising first in class compound with the potential to form a new combination regimen for MDR-TB treatment.

A high-throughput cidality screen for Mycobacterium tuberculosis.

Exposure to Mycobacterium tuberculosis (Mtb) aerosols is a major threat to tuberculosis (TB) researchers, even in bio-safety level-3 (BSL-3) facilities. Automation and high-throughput screens (HTS) in BSL3 facilities are essential for minimizing manual aerosol-generating interventions and facilitating TB research. In the present study, we report the development and validation of a high-throughput, 24-well 'spot-assay' for selecting bactericidal compounds against Mtb. The bactericidal screen concept was first validated in the fast-growing surrogate Mycobacterium smegmatis (Msm) and subsequently confirmed in Mtb using the following reference anti-tubercular drugs: rifampicin, isoniazid, ofloxacin and ethambutol (RIOE, acting on different targets). The potential use of the spot-assay to select bactericidal compounds from a large library was confirmed by screening on Mtb, with parallel plating by the conventional gold standard method (correlation, r2 = 0.808). An automated spot-assay further enabled an MBC90 determination on resistant and sensitive Mtb clinical isolates. The implementation of the spot-assay in kinetic screens to enumerate residual Mtb after either genetic silencing (anti-sense RNA, AS-RNA) or chemical inhibition corroborated its ability to detect cidality. This relatively simple, economical and quantitative HTS considerably minimized the bio-hazard risk and enabled the selection of novel vulnerable Mtb targets and mycobactericidal compounds. Thus, spot-assays have great potential to impact the TB drug discovery process.