Biology subjects

Dartois, V. A.

Publications and source records attributed to Dartois, V. A..

7 recordsLinked to original sources

bioRxiv2022

Mycobacterium tuberculosis DprE1 inhibitor OPC-167832 is active against Mycobacterium abscessus in vitro

The anti-tuberculosis candidate OPC-167832, an inhibitor of DprE1, was active against Mycobacterium abscessus. Resistance mapped to M. abscessus dprE1, suggesting target retention. OPC-167832 was bactericidal and did not antagonize activity of clinical anti-M. abscessus antibiotics. Due to its moderate potency compared to Mycobacterium tuberculosis, the compound lacked efficacy in a mouse model and is thus not a repurposing candidate. These results identify OPC-167832 - DprE1 as a lead-target couple for a M. abscessus-specific optimization program.

microbiology↗

bioRxiv2022

Strongly bactericidal all-oral β-lactam combinations for the treatment of Mycobacterium abscessus lung disease

Bioactive forms of oral {beta}-lactams were screened in vitro against Mycobacterium abscessus with and without the bioactive form of the oral {beta}-lactamase inhibitor avibactam-ARX1796. Sulopenem was equally active without avibactam, while tebipenem, cefuroxime and amoxicillin required avibactam for optimal activity. Systematic pairwise combination of the four {beta}-lactams revealed strong bactericidal synergy for each of sulopenem, tebipenem and cefuroxime combined with amoxicillin in the presence of avibactam. These all-oral {beta}-lactam combinations warrant clinical evaluation.

microbiology↗

bioRxiv2022

Activity of Tricyclic Pyrrolopyrimidine Gyrase B Inhibitor against Mycobacterium abscessus

Tricyclic pyrrolopyrimidines (TPPs) are a new class of antibacterials inhibiting the ATPase of DNA gyrase. TPP8, a representative of this class, is active against Mycobacterium abscessus in vitro. Spontaneous TPP8 resistance mutations mapped to the ATPase domain of M. abscessus DNA gyrase and the compound inhibited DNA supercoiling activity of recombinant M. abscessus enzyme. Further profiling of TPP8 in macrophage and mouse infection studies demonstrated proof-of-concept activity against M. abscessus ex vivo and in vivo.

microbiology↗

bioRxiv2022

A novel oral GyrB/ParE dual binding inhibitor effective against multidrug resistant Neisseria gonorrhoeae and other high-threat pathogens

Drug resistant Neisseria gonorrhoeae is a serious global health concern. New drugs are needed that can overcome existing drug resistance, as well as limit development of new resistance. We describe the small molecule tricyclic pyrimidoindole JSF-2414 [8-(6- fluoro-8-(methylamino)-2-((2-methylpyrimidin-5-yl)oxy)-9H-pyrimido[4,5-b]indol-4-yl)-2- oxa-8-azaspiro[4.5]decan-3-yl)methanol], which simultaneously binds to ATP binding regions of DNA gyrase (GyrB) and topoisomerase (ParE). JSF-2414 displays potent activity against N. gonorrhoeae including drug-resistant strains. A phosphate prodrug JSF-2659 was developed to facilitate oral dosing. In two different animal models of Neisseria gonorrhoeae vaginal infection, JSF-2659 was highly efficacious in reducing microbial burdens to the limit of detection. The parent molecule also showed potent in vitro activity against high-threat Gram positive organisms, and JSF-2659 was shown in a deep tissue model of VRSA and a model of C. difficile-induced colitis to be highly efficacious and protective. JSF-2659 is a novel drug candidate against high-threat multidrug resistant organisms with low potential to develop new resistance.

microbiology↗

bioRxiv2021

Novel regimens of bedaquiline-pyrazinamide combined with moxifloxacin, rifabutin, delamanid and/or OPC-167832 in murine tuberculosis models

A recent landmark trial showed a 4-month regimen of rifapentine, pyrazinamide, moxifloxacin and isoniazid (PZMH) to be non-inferior to the 6-month standard of care. Here, two murine models of tuberculosis were used to test whether novel regimens replacing rifapentine and isoniazid with bedaquiline and another drug would maintain or increase the sterilizing activity of the regimen. In BALB/c mice, replacing rifapentine in the PZM backbone with bedaquiline (i.e., BZM) significantly reduced both lung CFU counts after 1 month and the proportion of mice relapsing within 3 months after completing 1.5 months of treatment. Addition of rifabutin to BZM (BZMRb) further increased the sterilizing activity. In the C3HeB/FeJ mouse model characterized by caseating lung lesions, treatment with BZMRb resulted in significantly fewer relapses than PZMH after 2 months of treatment. A regimen combining the new DprE1 inhibitor OPC-167832 and delamanid (BZOD) also had superior bactericidal and sterilizing activity compared to PZM in BALB/c mice and was similar in efficacy to PZMH in C3HeB/FeJ mice. Thus, BZM represents a promising backbone for treatment-shortening regimens. Given the prohibitive drug-drug interactions between bedaquiline and rifampin or rifapentine, the BZMRb regimen represents the best opportunity to combine, in one regimen, the treatment-shortening potential of the rifamycin class with that of BZM and deserves high priority for evaluation in clinical trials. Other 4-drug BZM-based regimens and BZOD represent promising opportunities for extending the spectrum of treatment-shortening regimens to rifamycin- and fluoroquinolone-resistant tuberculosis.

microbiology↗

bioRxiv2021

A chemical-genetic map of the pathways controlling drug potency in Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) infection is notoriously difficult to treat. Treatment efficacy is limited by Mtbs intrinsic drug resistance, as well as its ability to evolve acquired resistance to all antituberculars in clinical use. A deeper understanding of the bacterial pathways that govern drug efficacy could facilitate the development of more effective therapies to overcome resistance, identify new mechanisms of acquired resistance, and reveal overlooked therapeutic opportunities. To define these pathways, we developed a CRISPR interference chemical-genetics platform to titrate the expression of Mtb genes and quantify bacterial fitness in the presence of different drugs. Mining this dataset, we discovered diverse and novel mechanisms of intrinsic drug resistance, unveiling hundreds of potential targets for synergistic drug combinations. Combining chemical-genetics with comparative genomics of Mtb clinical isolates, we further identified numerous new potential mechanisms of acquired drug resistance, one of which is associated with the emergence of a multidrug-resistant tuberculosis (TB) outbreak in South America. Lastly, we make the unexpected discovery of an "acquired drug sensitivity." We found that the intrinsic resistance factor whiB7 was inactivated in an entire Mtb sublineage endemic to Southeast Asia, presenting an opportunity to potentially repurpose the macrolide antibiotic clarithromycin to treat TB. This chemical-genetic map provides a rich resource to understand drug efficacy in Mtb and guide future TB drug development and treatment.

microbiology↗

bioRxiv2021

Chemical-genetic interaction mapping links carbon metabolism and cell wall structure to tuberculosis drug efficacy

Current chemotherapy against Mycobacterium tuberculosis (Mtb), an important human pathogen, requires a multidrug regimen lasting several months. While efforts have been made to optimize therapy by exploiting drug-drug synergies, testing new drug combinations in relevant host environments remains arduous. In particular, host environments profoundly affect the bacterial metabolic state and drug efficacy, limiting the accuracy of predictions based on in vitro assays alone. In this study, we utilize conditional Mtb knockdown mutants of essential genes as an experimentally-tractable surrogate for drug treatment, and probe the relationship between Mtb carbon metabolism and chemical-genetic interactions (CGI). We examined the anti-tubercular drugs isoniazid, rifampicin and moxifloxacin, and found that CGI are differentially responsive to the metabolic state, defining both environment-independent and -dependent interactions. Specifically, growth on the in vivo-relevant carbon source, cholesterol, reduced rifampicin efficacy by altering mycobacterial cell surface lipid composition. We report that a variety of perturbations in cell wall synthesis pathways restore rifampicin efficacy during growth on cholesterol, and that both environment-independent and cholesterol-dependent in vitro CGI could be leveraged to enhance bacterial clearance in the mouse infection model. Our findings present an atlas of novel chemical-genetic-environmental interactions that can be used to optimize drug-drug interactions as well as provide a framework for understanding in vitro correlates of in vivo efficacy. SignificanceEfforts to improve tuberculosis therapy include optimizing multi-drug regimens to take advantage of drug-drug synergies. However, the complex host environment has a profound effect on bacterial metabolic state and drug activity, making predictions of optimal drug combinations difficult. In this study, we leverage a newly developed library of conditional knockdown Mycobacterium tuberculosis mutants in which genetic depletion of essential genes mimics the effect of drug therapy. This tractable system allowed us to assess the effect of growth condition on predicted drug-drug interactions. We found that these interactions can be differentially sensitive to the metabolic state and select in vitro-defined interactions can be leveraged to accelerate bacterial killing during infection. These findings suggest new strategies for optimizing tuberculosis therapy.

microbiology↗