Delamanid: From discovery to its use for pulmonary multidrug-resistant tuberculosis (MDR-TB)

Delamanid and bedaquiline resistance patterns in Mycobacterium tuberculosis in Iran: A cross-sectional analysis

Introduction

The surge of multidrug-resistant TB (MDR-TB) in Iran poses a significant challenge to global healthcare. The introduction of delamanid (DLM) and bedaquiline (BDQ), two potent antimycobacterial drugs, marks a crucial advance. Nevertheless, as resistance in Mycobacterium tuberculosis is on the rise in Iran and resistance to these newer medications is emerging, investigations in this field are of utmost importance.

Methods

In this cross-sectional study, 38 MDR-TB strains were collected from five distinct regional TB laboratories in Iran. The clinical isolates were confirmed as M. tuberculosis using the phenotypic tests and IS6110-based PCR assay. Drug susceptibility testing (DST) for isoniazid, rifampicin, ethambutol, DLM, and BDQ was performed using WHO-approved methods. Sequencing was used to investigate genetic mutations in DLM (ddn, fgd1) and BDQ (Rv0678, atpE, pepQ) genes associated with resistance.

Results

Among the 38 collected MDR-TB isolates, 7 (18.5 %) exhibited resistance to DLM, while all remained susceptible to BDQ. Analysis of the sequencing data revealed that the ddn gene exhibited the highest number of mutations in DLM-resistant isolates, including 18 nonsynonymous mutations and 1 indel leading to frameshift mutations. A common mutation, Gly81Ser, was present in 4 of the DLM-resistant isolates (4/7; 57.1 %). A synonymous mutation, T960C, in the fgd1 gene was uniformly found in DLM-resistant samples. Notably, no significant mutations were observed in the atpE, Rv0678, or pepQ genes in any of the BDQ-susceptible isolates.

Conclusions

Our study underscores the emergence of DLM resistance in a subset of MDR-TB isolates in Iran, primarily associated with mutations in the ddn gene. This emphasizes the ongoing necessity for TB drug resistance surveillance and research. While BDQ remains efficacious, the emergence of DLM resistance is a concerning development, warranting further exploration into resistance mechanisms and the formulation of effective TB control strategies.

Factors associated with acceleration of clinical development for infectious diseases: a cross-sectional analysis of 10-year EMA registration data

Background

Clinical trials feature centrally in the development of drugs and vaccines to determine safety and efficacy. Clinical development can be slow and may have a duration of more than ten years. Global public health threats such as Ebola virus disease (EVD) and COVID-19 have demonstrated that it is possible to accelerate clinical trials while maintaining safety and efficacy. We investigated acceleration in clinical trials over the past decade and identified factors associated with acceleration for drugs targeting infectious diseases.

Methods

A cross-sectional study was performed of all medicinal compounds targeting infectious diseases that received marketing authorisation by the European Medicines Agency (EMA) between 2012 and 2022. We calculated median clinical development time in years between the first phase 1 trial enrolment date and the authorisation date. Multivariable linear regression analysis was performed to identify factors associated with shorter development times.

Findings

Eighty-one trajectories were included. The median clinical development time was 7.3 years (IQR 4.4-12.3). The fastest times belonged to drugs and vaccines targeting COVID-19 (1.3 years, IQR 0.8-1.6), EVD (5.5 years, IQR 5.1-5.8), and Hepatitis A-E (5.5 years, IQR 3.9-8.2). Factors associated with shorter development times were outbreak setting (-5.4 years [95% CI, -8.2 to -2.6]), accelerated assessment status (-4.0 years [95% CI, -7.6 to -0.5]), and drugs with combined compounds (-2.7 years [95% CI, -4.9 to -0.4]).

Interpretation

Clinical development time for infectious disease-related drugs and vaccines was relatively short, and outbreak setting and accelerated EMA assessment were associated with shorter development times.

Funding

Amsterdam Public Health research institute.

The Nitrofuran-Warhead-Equipped Spirocyclic Azetidines Show Excellent Activity against Mycobacterium tuberculosis

A series of 21 new 7'H-spiro[azetidine-3,5'-furo [3,4-d]pyrimidine]s substituted at the pyrimidine ring second position were synthesized. The compounds showed high antibacterial in vitro activity against M. tuberculosis. Two compounds had lower minimum inhibitory concentrations against Mtb (H37Rv strain) compared with isoniazid. The novel spirocyclic scaffold shows excellent properties for anti-tuberculosis drug development.

Real-life use of delamanid: results from the European post-authorisation safety study

BACKGROUND

A post-authorisation safety study (PASS) on delamanid (DLM) was conducted as part of a post-approval commitment to the European Medicines Agency. The aim of this study was to evaluate the use of DLM in a real-life setting, its safety, and treatment outcomes in patients with multidrug-resistant TB (MDR-TB).

METHODS

This was a prospective, multicentric, non-interventional study conducted in the European Union. MDR-TB Regimen selection and patient monitoring were conducted in accordance with existing medical practices. Data on the use of DLM, related adverse events, and treatment outcomes were collected for up to 30 months after the first DLM dose. Descriptive summary statistics were used for continuous and categorical variables.

RESULTS

Out of 86 patients, one had extrapulmonary TB. Two-thirds of the patients were treated with DLM for more than 24 weeks. The most frequent adverse drug reaction to DLM was QT interval prolongation. Resistance to DLM was detected in one patient during treatment. The treatment success rate was 77%.

CONCLUSION

No new safety concerns were revealed, including in patients treated with DLM for more than 24 weeks. QT interval prolongations were well managed and did not lead to any clinically significant cardiac effects. The treatment outcomes were in line with the WHO target for Europe.

Clinical research progress of novel antituberculosis drugs on multidrug-resistant tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) has become a critical challenge to public health, and the prevention and treatment of MDR-TB are of great significance in reducing the global burden of tuberculosis. How to improve the effectiveness and safety of chemotherapy for MDR-TB is a pressing issue that needs to be addressed in tuberculosis control efforts. This article provides a comprehensive review of the clinical application of new antituberculosis drugs in MDR-TB, aiming to provide a scientific basis for the prevention and treatment strategy of MDR-TB.

Evaluating the biomolecular interaction between delamanid/formulations and human serum albumin by fluorescence, CD spectroscopy and SPR: Effects on protein conformation, kinetic and thermodynamic parameters

Delamanid is an anti-tuberculosis drug used for the treatment of drug-resistant tuberculosis. Since delamanid has a high protein bound potential, even patients with low albumin levels should experience high and rapid delamanid clearance. However, the interaction between delamanid and albumin should be better controlled to optimize drug efficacy. This study was designed to evaluate the binding characteristics of delamanid to human serum albumin (HSA) using various methods: fluorescence spectroscopy, circular dichroism (CD), surface plasmon resonance (SPR), and molecular docking simulation. The fluorescence emission band without any shift indicated the interaction was not affected by the polarity of the fluorophore microenvironment. The reduction of fluorescence intensity at 344 nm was proportional to the increment of delamanid concentration as a fluorescence quencher. UV-absorbance measurement at the maximum wavelength (λmax, 280 nm) was evaluated using inner filter effect correction. The HSA conformation change was explained by the intermolecular energy transfer between delamanid and HSA during complex formation. The study, which was conducted at temperatures of 298 K, 303 K, and 310 K, revealed a static quenching mechanism that correlated with a decreased of bimolecular quenching rate constant (kq) and binding constant (Ka) at increased temperatures. The Ka was 1.75-3.16 × 104 M-1 with a specific binding site with stoichiometry 1:1. The negative enthalpy change, negative entropy change, and negative Gibbs free energy change demonstrated an exothermic-spontaneous reaction while van der Waals forces and hydrogen bonds played a vital role in the binding. The molecular displacement approach and molecular docking confirmed that the binding occurred mainly in subdomain IIA, which is a hydrophobic pocket of HSA, with a theoretical binding free energy of -9.33 kcal/mol. SPR exhibited a real time negative sensorgram that resulted from deviation of the reflex angle due to ligand delamanid-HSA complex forming. The binding occurred spontaneously after delamanid was presented to the HSA surface. The SPR mathematical fitting model revealed that the association rate constant (kon) was 2.62 × 108 s-1M-1 and the dissociation rate constant (koff) was 5.65 × 10-3 s-1. The complexes were performed with an association constant (KA) of 4.64 × 1010 M-1 and the dissociation constant (KD) of 2.15 × 10-11 M. The binding constant indicated high binding affinity and high stability of the complex in an equilibrium. Modified CD spectra revealed that conformation of the HSA structure was altered by the presence of delamanid during preparation of the proliposomes that led to the reduction of secondary structure stabilization. This was indicated by the percentage decrease of α-helix. These findings are beneficial to understanding delamanid-HSA binding characteristics as well as the drug administration regimen.

Prevalence and genetic basis of Mycobacterium tuberculosis resistance to pretomanid in China

BACKGROUND

Pretomanid is a key component of new regimens for the treatment of drug-resistant tuberculosis (TB) which are being rolled out globally. However, there is limited information on the prevalence of pre-existing resistance to the drug.

METHODS

To investigate pretomanid resistance rates in China and its underlying genetic basis, as well as to generate additional minimum inhibitory concentration (MIC) data for epidemiological cutoff (ECOFF)/breakpoint setting, we performed MIC determinations in the Mycobacterial Growth Indicator Tube™ (MGIT) system, followed by WGS analysis, on 475 Mycobacterium tuberculosis (MTB) isolated from Chinese TB patients between 2013 and 2020.

RESULTS

We observed a pretomanid MIC distribution with a 99% ECOFF equal to 0.5 mg/L. Of the 15 isolates with MIC values > 0.5 mg/L, one (MIC = 1 mg/L) was identified as MTB lineage 1 (L1), a genotype previously reported to be intrinsically less susceptible to pretomanid, two were borderline resistant (MIC = 2-4 mg/L) and the remaining 12 isolates were highly resistant (MIC ≥ 16 mg/L) to the drug. Five resistant isolates did not harbor mutations in the known pretomanid resistant genes.

CONCLUSIONS

Our results further support a breakpoint of 0.5 mg/L for a non-L1 MTB population, which is characteristic of China. Further, our data point to an unexpected high (14/475, 3%) pre-existing pretomanid resistance rate in the country, as well as to the existence of yet-to-be-discovered pretomanid resistance genes.

A systematic efficacy analysis of tuberculosis treatment with BPaL-containing regimens using a multiscale modeling approach

Tuberculosis (TB) is a life-threatening infectious disease. The standard treatment is up to 90% effective; however, it requires the administration of four antibiotics (isoniazid, rifampicin, pyrazinamide, and ethambutol [HRZE]) over long time periods. This harsh treatment process causes adherence issues for patients because of the long treatment times and a myriad of adverse effects. Therefore, the World Health Organization has focused goals of shortening standard treatment regimens for TB in their End TB Strategy efforts, which aim to reduce TB-related deaths by 95% by 2035. For this purpose, many novel and promising combination antibiotics are being explored that have recently been discovered, such as the bedaquiline, pretomanid, and linezolid (BPaL) regimen. As a result, testing the number of possible combinations with all possible novel regimens is beyond the limit of experimental resources. In this study, we present a unique framework that uses a primate granuloma modeling approach to screen many combination regimens that are currently under clinical and experimental exploration and assesses their efficacies to inform future studies. We tested well-studied regimens such as HRZE and BPaL to evaluate the validity and accuracy of our framework. We also simulated additional promising combination regimens that have not been sufficiently studied clinically or experimentally, and we provide a pipeline for regimen ranking based on their efficacies in granulomas. Furthermore, we showed a correlation between simulation rankings and new marmoset data rankings, providing evidence for the credibility of our framework. This framework can be adapted to any TB regimen and can rank any number of single or combination regimens.

Roadmap for ending TB in China by 2035: The challenges and strategies

Tuberculosis (TB) is one of the top ten causes of death worldwide, taking the lives of over a million people annually. In addition to being a serious health issue, TB is also closely linked to eradicating poverty according to the Sustainable Development Goals (SDGs) of the United Nations (UN). All UN members have committed to ending the TB epidemic by 2030. China has one of the highest TB loads worldwide, ranking third in the world on many TB burden indices. The national strategy for TB control is aimed at creating a collaborative network and integrating TB treatment into the medical system. According to the WHO's global TB report, China is expected to have 748,000 new cases of TB in 2022 and an incidence of 52 cases per 100,000 people. Ending TB remains a huge challenge and requires comprehensive control strategies in China. In this work, we have discussed the challenges of TB prevention and control in China and proposed specific measures to end TB.

Quabodepistat in combination with delamanid and bedaquiline in participants with drug-susceptible pulmonary tuberculosis: protocol for a multicenter, phase 2b/c, open-label, randomized, dose-finding trial to evaluate safety and efficacy

BACKGROUND

Delamanid and bedaquiline are two of the most recently developed antituberculosis (TB) drugs that have been extensively studied in patients with multidrug-resistant TB. There is currently a need for more potent, less-toxic drugs with novel mechanisms of action that can be used in combination with these newer agents to shorten the duration of treatment as well as prevent the development of drug resistance. Quabodepistat (QBS) is a newly discovered inhibitor of decaprenylphosphoryl-β-D-ribose-2'-oxidase, an essential enzyme for Mycobacterium tuberculosis to synthesize key components of its cell wall. The objective of this study is to evaluate the safety, efficacy, and appropriate dosing of a 4-month regimen of QBS in combination with delamanid and bedaquiline in participants with drug-susceptible pulmonary TB in comparison with the 6-month standard treatment (i.e., rifampicin, isoniazid, ethambutol, and pyrazinamide).

METHODS

This phase 2b/c, open-label, randomized, parallel group, dose-finding trial will enroll approximately 120 participants (including no more than 15% with human immunodeficiency virus [HIV] coinfection) aged ≥ 18 to ≤ 65 years at screening with newly diagnosed pulmonary drug-sensitive TB from ~8 sites in South Africa. Following a screening period of up to 14 days, eligible participants will be randomized in a ratio of 1:2:2:1 to one of four arms. Randomization will be stratified by HIV status and the presence of bilateral cavitation on a screening chest x-ray. After the end of the treatment period, participants will be followed until 12 months post randomization. The primary efficacy endpoint is the proportion of participants achieving sputum culture conversion in Mycobacteria Growth Indicator Tube by the end of the treatment period. The safety endpoints consist of adverse events, clinical laboratory tests, vital signs, physical examination findings, and electrocardiographic changes.

DISCUSSION

QBS's potent bactericidal activity and distinct mechanism of action (compared with other TB drugs currently available for human use) may make it an ideal candidate for inclusion in a novel treatment regimen to improve efficacy and potentially prevent resistance to concomitant TB drugs. This trial will assess the effectiveness, safety, and dosing of a new, shorter, QBS-based, combination anti-TB treatment regimen.

TRIAL STATUS

ClinicalTrials.gov NCT05221502. Registered on February 3, 2022.

Cutaneous tuberculosis. Part II: Complications, diagnostic workup, histopathologic features, and treatment

Despite the availability of effective treatment regimens for cutaneous tuberculosis, challenges to disease control result from delayed diagnosis, infection with multidrug-resistant mycobacterial strains, and coinfection with HIV. Delayed diagnosis can be mitigated when dermatologists are sensitized to the clinical signs and symptoms of infection and by the incorporation of appropriate diagnostic tests. All cases of cutaneous tuberculosis should be confirmed with histopathology and culture with or without molecular testing. In each case, a thorough evaluation for systemic involvement is necessary. Mycobacteria may not be isolated from cutaneous tuberculosis lesions and therefore, a trial of antituberculosis treatment may be required to confirm the diagnosis. The second article in this 2-part continuing medical education series describes the sequelae, histopathology, and treatment of tuberculosis.

Advanced drug delivery and therapeutic strategies for tuberculosis treatment

Tuberculosis (TB) remains a significant global health challenge, necessitating innovative approaches for effective treatment. Conventional TB therapy encounters several limitations, including extended treatment duration, drug resistance, patient noncompliance, poor bioavailability, and suboptimal targeting. Advanced drug delivery strategies have emerged as a promising approach to address these challenges. They have the potential to enhance therapeutic outcomes and improve TB patient compliance by providing benefits such as multiple drug encapsulation, sustained release, targeted delivery, reduced dosing frequency, and minimal side effects. This review examines the current landscape of drug delivery strategies for effective TB management, specifically highlighting lipid nanoparticles, polymer nanoparticles, inorganic nanoparticles, emulsion-based systems, carbon nanotubes, graphene, and hydrogels as promising approaches. Furthermore, emerging therapeutic strategies like targeted therapy, long-acting therapeutics, extrapulmonary therapy, phototherapy, and immunotherapy are emphasized. The review also discusses the future trajectory and challenges of developing drug delivery systems for TB. In conclusion, nanomedicine has made substantial progress in addressing the challenges posed by conventional TB drugs. Moreover, by harnessing the unique targeting abilities, extended duration of action, and specificity of advanced therapeutics, innovative solutions are offered that have the potential to revolutionize TB therapy, thereby enhancing treatment outcomes and patient compliance.

Baseline and acquired resistance to bedaquiline, linezolid and pretomanid, and impact on treatment outcomes in four tuberculosis clinical trials containing pretomanid

Bedaquiline (B), pretomanid (Pa) and linezolid (L) are key components of new regimens for treating rifampicin-resistant tuberculosis (TB). However, there is limited information on the global prevalence of resistance to these drugs and the impact of resistance on treatment outcomes. Mycobacterium tuberculosis (MTB) phenotypic drug susceptibility and whole-genome sequence (WGS) data, as well as patient profiles from 4 pretomanid-containing trials-STAND, Nix-TB, ZeNix and SimpliciTB-were used to investigate the rates of baseline resistance (BR) and acquired resistance (AR) to BPaL drugs, as well as their genetic basis, risk factors and impact on treatment outcomes. Data from >1,000 TB patients enrolled from 2015 to 2020 in 12 countries was assessed. We identified 2 (0.3%) participants with linezolid BR. Pretomanid BR was also rare, with similar rates across TB drug resistance types (0-2.1%). In contrast, bedaquiline BR was more prevalent among participants with highly resistant TB or longer prior treatment histories than those with newly diagnosed disease (5.2-6.3% vs. 0-0.3%). Bedaquiline BR was a risk factor for bacteriological failure or relapse in Nix-TB/ZeNix; 3/12 (25%, 95% CI 5-57%) participants with vs. 6/185 (3.2%, 1.2-6.9%) without bedaquiline BR. Across trials, we observed no linezolid AR, and only 3 cases of bedaquiline AR, including 2 participants with poor adherence. Overall, pretomanid AR was also rare, except in ZeNix patients with bedaquiline BR. WGS analyses revealed novel mutations in canonical resistant genes and, in 7 MTB isolates, the genetic determinants could not be identified. The overall low rates of BR to linezolid and pretomanid, and to a lesser extent to bedaquiline, observed in the pretomanid trials are in support of the worldwide implementation of BPaL-based regimens. Similarly, the overall low AR rates observed suggest BPaL drugs are better protected in the regimens trialed here than in other regimens combining bedaquiline with more, but less effective drugs.

Evaluation of 2,3-dihydroimidazo[2,1-b]oxazole and imidazo[2,1-b]oxazole derivatives as chemotherapeutic agents

Imidazo[2,1-b]oxazole and 2,3-dihydroimidazo[2,1-b]oxazole ring systems are commonly employed in therapeutically active molecules. In this article, the authors review the utilization of these core scaffolds as chemotherapeutic agents from 2018 to 2022. These scaffolds possess many important biological activities including antimicrobial and anticancer, among others. This review covers their biological activities and structure-activity relationships. One of the most important drugs in this class of compounds is the antitubercular agent delamanid. In this paper, the compounds structure-activity relationship and preclinical and clinical trial data are thoroughly presented.

The effect of anti-tuberculosis drug pharmacokinetics on QTc prolongation

BACKGROUND

Implementation of newer anti-tuberculosis (TB) drugs may prolong the QT interval, increasing the risk of arrythmias and sudden cardiac death. The potential for cardiac adverse events has prompted recommendations for frequent cardiac monitoring during treatment. However, unknowns remain, including the association between drug concentrations and QT interval.

METHODS

An observational prospective cohort study design was used. Patients undergoing treatment for drug-resistant TB in Georgia were assessed. Serial blood samples were collected at 4-6 weeks for pharmacokinetics. Electrocardiograms were recommended to be performed monthly. A generalized estimating equation spline model was used to investigate (1) the effect difference between bedaquiline and delamanid, (2) the cumulative effect of number of anti-TB drugs, and (3) the relationship between serum drug concentrations on QTc interval.

RESULTS

Among 94 patients receiving either bedaquiline (n = 64) or delamanid (n = 30)-based treatment, most were male (82%), and the mean age was 39 years. The mean maximum QTc increase during the first six months was 37.5 ms (IQR: 17.8-56.8). Bedaquiline- and delamanid-based regimens displayed similar increased mean QTc change from baseline during drug administration (P = 0.12). Increasing number of anti-TB drugs was associated with an increased QTc (P = 0.01), but participants trended back towards baseline after drug discontinuation (P = 0.25). A significant association between AUC, Cmin, Cmax, and increased QTc interval was found for bedaquiline (months 1-6) and levofloxacin (months 1-12).

CONCLUSION

Bedaquiline- and delamanid-based regimens and increasing number of QT prolonging agents led to modest increases in the QTc interval with minimal clinical effect.

Advances in Diagnostics and Drug Discovery against Resistant and Latent Tuberculosis Infection

Latent tuberculosis infection (LTBI) represents a subclinical, asymptomatic mycobacterial state affecting approximately 25% of the global population. The substantial prevalence of LTBI, combined with the risk of progressing to active tuberculosis, underscores its central role in the increasing incidence of tuberculosis (TB). Accurate identification and timely treatment are vital to contain and reduce the spread of the disease, forming a critical component of the global strategy known as "End TB." This review aims to examine and highlight the most recent scientific evidence related to new diagnostic approaches and emerging therapeutic treatments for LTBI. While prevalent diagnostic methods include the tuberculin skin test (TST) and interferon gamma release assay (IGRA), WHO's approval of two specific IGRAs for Mycobacterium tuberculosis (MTB) marked a significant advancement. However, the need for a specific test with global application viability has propelled research into diagnostic tests based on molecular diagnostics, pulmonary immunity, epigenetics, metabolomics, and a current focus on next-generation MTB antigen-based skin test (TBST). It is within these emerging methods that the potential for accurate distinction between LTBI and active TB has been demonstrated. Therapeutically, in addition to traditional first-line therapies, anti-LTBI drugs, anti-resistant TB drugs, and innovative candidates in preclinical and clinical stages are being explored. Although the advancements are promising, it is crucial to recognize that further research and clinical evidence are needed to solidify the effectiveness and safety of these new approaches, in addition to ensuring access to new drugs and diagnostic methods across all health centers. The fight against TB is evolving with the development of more precise diagnostic tools that differentiate the various stages of the infection and with more effective and targeted treatments. Once consolidated, current advancements have the potential to transform the prevention and treatment landscape of TB, reinforcing the global mission to eradicate this disease.

SK-03-92 Drug Kills Intracellular Mycobacterium tuberculosis

BACKGROUND

Tuberculosis affects millions of people worldwide. The emergence of drug-resistant Mycobacterium tuberculosis strains has made treatment more difficult. A drug discovery project initiated to screen natural products identified a lead stilbene compound, and structure function analysis of hundreds of analogs led to the discovery of the SK-03-92 stilbene lead compound with activity against several non-tuberculoid mycobacteria.

METHODS

For this study, an MIC analysis and intracellular killing assay were performed to test SK-03-92 against M. tuberculosis grown in vitro as well as within murine macrophage cells.

RESULTS

The MIC analysis showed that SK-03-92 had activity against M. tuberculosis in the range of 0.39 to 6.25 μg/mL, including activity against single-drug-resistant strains. Further, an intracellular kill assay demonstrated that the SK-03-92 lead compound killed M. tuberculosis cells within murine macrophage cells.

CONCLUSION

Together, the data show the SK-03-92 lead compound can kill M. tuberculosis bacteria within mammalian macrophages.

Mapping Research Trends of Medications for Multidrug-Resistant Pulmonary Tuberculosis Based on the Co-Occurrence of Specific Semantic Types in the MeSH Tree: A Bibliometric and Visualization-Based Analysis of PubMed Literature (1966-2020)

Background

Before the COVID-19 pandemic, tuberculosis is the leading cause of death from a single infectious agent worldwide for the past 30 years. Progress in the control of tuberculosis has been undermined by the emergence of multidrug-resistant tuberculosis. The aim of the study is to reveal the trends of research on medications for multidrug-resistant pulmonary tuberculosis (MDR-PTB) through a novel method of bibliometrics that co-occurs specific semantic Medical Subject Headings (MeSH).

Methods

PubMed was used to identify the original publications related to medications for MDR-PTB. An R package for text mining of PubMed, pubMR, was adopted to extract data and construct the co-occurrence matrix-specific semantic types. Biclustering analysis of high-frequency MeSH term co-occurrence matrix was performed by gCLUTO. Scientific knowledge maps were constructed by VOSviewer to create overlay visualization and density visualization. Burst detection was performed by CiteSpace to identify the future research hotspots.

Results

Two hundred and eight substances (chemical, drug, protein) and 147 diseases related to MDR-PTB were extracted to form a specific semantic co-occurrence matrix. MeSH terms with frequency greater than or equal to six were selected to construct high-frequency co-occurrence matrix (42 × 20) of specific semantic types contains 42 substances and 20 diseases. Biclustering analysis divided the medications for MDR-PTB into five clusters and reflected the characteristics of drug composition. The overlay map indicated the average age gradients of 42 high-frequency drugs. Fifteen top keywords and 37 top terms with the strongest citation bursts were detected.

Conclusion

This study evaluated the literatures related to MDR-PTB drug therapy, providing a co-occurrence matrix model based on the specific semantic types and a new attempt for text knowledge mining. Compared with the macro knowledge structure or hot spot analysis, this method may have a wider scope of application and a more in-depth degree of analysis.

Advances of new drugs bedaquiline and delamanid in the treatment of multi-drug resistant tuberculosis in children

Tuberculosis (TB) is a major public health problem, with nearly 10 million new cases and millions of deaths each year. Around 10% of these cases are in children, but only a fraction receive proper diagnosis and treatment. The spread of drug-resistant (DR) strain of TB has made it difficult to control, with only 60% of patients responding to treatment. Multi-drug resistant TB (MDR-TB) is often undiagnosed in children due to lack of awareness or under-diagnosis, and the target for children's DR-TB treatment has only been met in 15% of goals. New medications such as bedaquiline and delamanid have been approved for treating DR-TB. However, due to age and weight differences, adults and children require different dosages. The availability of child-friendly formulations is limited by a lack of clinical data in children. This paper reviews the development history of these drugs, their mechanism of action, efficacy, safety potential problems and current use in treating DR-TB in children.

Design, synthesis and antitubercular activity of novel N-(amino)piperazinyl benzothiazinones with improved safety

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB) remains a major global health problem and new therapeutic antitubercular agents are urgent needed. Among the novel antituberculosis drugs in the pipeline, Benzothiazinones (BTZs) are among the most potent antituberculosis agents against both drug-susceptible and multidrug-resistant (MDR) tuberculosis. Our group has focused on structural modifications of the side chain at C-2 position of the BTZ core and WAP-2101/2102 with excellent in vitro activity were discovered in our lab. However, the severe in vivo toxicity was observed during subsequent acute toxicity evaluation. Herein, a series of novel N-(amino)piperazinyl benzothiazinone derivatives were designed and synthesized as new anti-TB agents to reduce the in vivo toxicity. Our results show that majority of them exhibit the same potent or comparable activity against both MTB H₃₇Rv and MDR-MTB strains (MIC: 4.00 - <1 ng/mL) as PBTZ169. Especially, compound 2c with low cardiac toxicity, low cell cytotoxicity and acceptable oral pharmacokinetic (PK) profiles have low acute toxicity in mice (LD₅₀ > 500 mg/kg), suggesting it may serve as a promising lead compound for further antitubercular drug discovery.

Isoflavonoid and Furanochromone Natural Products as Potential DNA Gyrase Inhibitors: Computational, Spectral, and Antimycobacterial Studies

In pursuit of new antitubercular agents, we here report the antimycobacterial (H₃₇Rv) and DNA gyrase inhibitory potential of daidzein and khellin natural products (NPs). We procured a total of 16 NPs based on their pharmacophoric similarities with known antimycobacterial compounds. The H₃₇Rv strain of M. tuberculosis was found to be susceptible to only two out of the 16 NPs procured; specifically, daidzein and khellin each exhibited an MIC of 25 μg/mL. Moreover, daidzein and khellin inhibited the DNA gyrase enzyme with IC₅₀ values of 0.042 and 0.822 μg/mL, respectively, compared to ciprofloxacin with an IC₅₀ value of 0.018 μg/mL. Daidzein and khellin were found to have lower toxicity toward the vero cell line, with IC₅₀ values of 160.81 and 300.23 μg/mL, respectively. Further, molecular docking study and MD simulation of daidzein indicated that it remained stable inside the cavity of DNA GyrB domain for 100 ns.

Current Therapeutic Delivery Approaches Using Nanocarriers for the Treatment of Tuberculosis Disease

Tuberculosis is a major health issue globally and a leading cause of death due to the infective microorganism Mycobacterium tuberculosis. Treatment of drug resistance tuberculosis requires longer treatment with multiple daily doses of drugs. Unfortunately, these drugs are often associated with poor patient compliance. In this situation, a need has been felt for the less toxic, shorter, and more effective treatment of the infected tuberculosis patients. Current research to develop novel anti-tubercular drugs shows hope for better management of the disease. Research on drug targeting and precise delivery of the old anti-tubercular drugs with the help of nanotechnology is promising for effective treatment. This review has discussed the status currently available treatments for tuberculosis patients infected with Mycobacterium alone or in comorbid conditions like diabetes, HIV and cancer. This review also highlighted the challenges in the current treatment and research on the novel anti-tubercular drugs to prevent multi-drug-resistant tuberculosis. It presents the research highlights on the targeted delivery of anti-tubercular drugs using different nanocarriers for preventing multi-drug resistant tuberculosis. Report has shown the importance and development of the research on nanocarriers mediated anti-tubercular delivery of the drugs to overcome the current challenges in tuberculosis treatment.

QcrB inhibition as a potential approach for the treatment of tuberculosis: A review of recent developments, patents, and future directions

The unmet medical need for drug-resistant tuberculosis (DRTB) is a significant concern. Accordingly, identifying new drug targets for tuberculosis (TB) treatment and developing new therapies based on these drug targets is one of the strategies to tackle DRTB. QcrB is an innovative drug target to create treatments for DRTB. This article highlights QcrB inhibitors and their therapeutic compositions for treating TB. The literature for this article was gathered from PubMed and free patent databases utilizing different keywords related to QcrB inhibitor-based inventions. The data was collected from the conceptualization of telacebec (2010) QcrB to December 2022. A little interesting and encouraging research has been performed on QcrB inhibitors. Telacebec and TB47 are established QcrB inhibitors in the clinical trial. The inventive QcrB inhibitor-based drug combinations can potentially handle DRTB and reduce the TB therapy duration. The authors anticipate great opportunities in fostering QcrB inhibitor-based patentable pharmaceutical inventions against TB. Drug repurposing can be a promising strategy to get safe and effective QcrB inhibitors. However, developing drug resistance, drug tolerance, and selectivity of QcrB inhibitors for Mtb will be the main challenges in developing effective QcrB inhibitors. In conclusion, QcrB is a promising drug target for developing effective treatments for active, latent, and drug-resistant TB. Many inventive and patentable combinations and compositions of QcrB inhibitors with other anti-TB drugs are anticipated as future treatments for TB.

Designing New Magic Bullets to Penetrate the Mycobacterial Shield: An Arduous Quest for Promising Therapeutic Candidates

Mycobacterium spp. intimidated mankind since time immemorial. The triumph over this organism was anticipated with the introduction of potent antimicrobials in the mid-20th century. However, the emergence of drug resistance in mycobacteria, Mycobacterium tuberculosis, in particular, caused great concern for the treatment. With the enemy growing stronger, there is an immediate need to equip the therapeutic arsenal with novel and potent chemotherapeutic agents. The task seems intricating as our understanding of the dynamic nature of the mycobacteria requires intense experimentation and research. Targeting the mycobacterial cell envelope appears promising, but its versatility allows it to escape the lethal effect of the molecules acting on it. The unique ability of hiding (inactivity during latency) also assists the bacterium to survive in a drug-rich environment. The drug delivery systems also require upgradation to allow better bioavailability and tolerance in patients. Although the resistance to the novel drugs is inevitable, our commitment to the research in this area will ensure the discovery of effective weapons against this formidable opponent.

Advances in computational frameworks in the fight against TB: The way forward

Around 1.6 million people lost their life to Tuberculosis in 2021 according to WHO estimates. Although an intensive treatment plan exists against the causal agent, Mycobacterium Tuberculosis, evolution of multi-drug resistant strains of the pathogen puts a large number of global populations at risk. Vaccine which can induce long-term protection is still in the making with many candidates currently in different phases of clinical trials. The COVID-19 pandemic has further aggravated the adversities by affecting early TB diagnosis and treatment. Yet, WHO remains adamant on its "End TB" strategy and aims to substantially reduce TB incidence and deaths by the year 2035. Such an ambitious goal would require a multi-sectoral approach which would greatly benefit from the latest computational advancements. To highlight the progress of these tools against TB, through this review, we summarize recent studies which have used advanced computational tools and algorithms for-early TB diagnosis, anti-mycobacterium drug discovery and in the designing of the next-generation of TB vaccines. At the end, we give an insight on other computational tools and Machine Learning approaches which have successfully been applied in biomedical research and discuss their prospects and applications against TB.

Liquid chromatography-tandem mass spectrometry analysis of delamanid and its metabolite in human cerebrospinal fluid using protein precipitation and on-line solid-phase extraction

The penetration of the antituberculosis drug delamanid into the central nervous system is not established. The distribution of delamanid and its major metabolite, DM-6705, into the cerebrospinal fluid requires investigation. A liquid chromatography-tandem mass spectrometry method for the quantification of delamanid and DM-6705 in human cerebrospinal fluid was developed and validated. The calibration range for both analytes was 0.300 - 30.0 ng/mL. The deuterium-labelled analogue of delamanid (delamanid-d4) and OPC-14714 were used as internal standards for delamanid and DM-6705, respectively. Samples were processed by protein precipitation followed by on-line solid-phase extraction and high-performance liquid chromatography on an Agilent 1260 HPLC system. A Phenomenex Gemini-NX C18 (5.0 µm, 50 mm × 2.0 mm) analytical column was used for on-line solid-phase extraction, and a Waters Xterra MS C18 (5.0 µm, 100 mm × 2.1 mm) analytical column for chromatographic separation using gradient elution, at a flow rate of 300 µL/min. The total run time was 7.5 min. Analytes were detected by multiple reaction monitoring on an AB Sciex 5500 triple quadrupole mass spectrometer at unit mass resolution, with electrospray ionization in the positive mode. Accuracy and precision were assessed over three independent validation batches. Extraction recoveries were more than 98% and were consistent across the analytical range. Both analytes in CSF exhibited non-specific adsorption to polypropylene tubes. The method was used to analyse cerebrospinal fluid samples from patients with pulmonary tuberculosis in an exploratory pharmacokinetic study.

Latent tuberculosis and computational biology: A less-talked affair

Tuberculosis (TB) is a pervasive and devastating air-borne disease caused by the organisms belonging to the Mycobacterium tuberculosis (Mtb) complex. Currently, it is the global leader in infectious disease-related death in adults. The proclivity of TB to enter the latent state has become a significant impediment to the global effort to eradicate TB. Despite decades of research, latent tuberculosis (LTB) mechanisms remain poorly understood, making it difficult to develop efficient treatment methods. In this review, we seek to shed light on the current understanding of the mechanism of LTB, with an accentuation on the insights gained through computational biology. We have outlined various well-established computational biology components, such as omics, network-based techniques, mathematical modelling, artificial intelligence, and molecular docking, to disclose the crucial facets of LTB. Additionally, we highlighted important tools and software that may be used to conduct a variety of systems biology assessments. Finally, we conclude the article by addressing the possible future directions in this field, which might help a better understanding of LTB progression.

Early experience of delamanid in extensively drug-resistant pulmonary tuberculosis

Tuberculosis is a leading cause of death in our country. Multidrug-resistant tuberculosis increases the morbidity and mortality due to severe manifestations and difficult and prolonged medications. Newer antitubercular drugs like delamanid have been approved by WHO in management of these cases, but the real-world experience of this drug is lacking in our country. We present our early experience of use of delamanid in extensively drug-resistant pulmonary tuberculosis.

Treatment options for children with multi-drug resistant tuberculosis

INTRODUCTION

According to the latest report from the World Health Organization (WHO), approximately 10.0 million people fell ill with tuberculosis (TB) in 2020, 12% of which were children aged under 15 years. There is very few experience on treatment of multi-drug resistant (MDR)-TB in pediatrics.

AREAS COVERED

The aim of this review is to analyze and summarize therapeutic options available for children experiencing MDR-TB. We also focused on management of MDR-TB prophylaxis.

EXPERT OPINION

The therapeutic management of children with MDR-TB or MDR-TB contacts is complicated by a lack of knowledge, and the fact that many potentially useful drugs are not registered for pediatric use and there are no formulations suitable for children in the first years of life. Furthermore, most of the available drugs are burdened by major adverse events that need to be taken into account, particularly in the case of prolonged therapy. A close follow-up with a standardized timeline and a comprehensive assessment of clinical, laboratory, microbiologic and radiologic data is extremely important in these patients. Due to the complexity of their management, pediatric patients with confirmed or suspected MDR-TB should always be referred to a specialized center.

The Struggle to End a Millennia-Long Pandemic: Novel Candidate and Repurposed Drugs for the Treatment of Tuberculosis

This article provides an encompassing review of the current pipeline of putative and developed treatments for tuberculosis, including multidrug-resistant strains. The review has organized each compound according to its site of activity. To provide context, mention of drugs within current recommended treatment regimens is made, thereafter followed by discussion on recently developed and upcoming molecules at established and novel targets. The review is designed to provide a clinically applicable understanding of the compounds that are deemed most currently relevant, including those already under clinical study and those that have shown promising pre-clinical results. An extensive review of the efficacy and safety data for key contemporary drugs already incorporated into treatment regimens, such as bedaquiline, pretomanid, and linezolid, is provided. The three levels of the bacterial cell wall (mycolic acid, arabinogalactan, and peptidoglycan layers) are highlighted and important compounds designed to target each layer are delineated. Amongst others, the highly optimistic and potent anti-mycobacterial activity of agents such as BTZ-043, PBTZ 169, and OPC-167832 are emphasized. The evolving spectrum of oxazolidinones, such as sutezolid, delpazolid, and TBI-223, all aiming to exceed the efficacy achieved with linezolid yet offer a safer alternative to the potential toxicity, are reviewed. New and exciting prospective agents with novel mechanisms of impact against TB, including 3-aminomethyl benzoxaboroles and telacebec, are underscored. We describe new diaryloquinolines in development, striving to build on the immense success of bedaquiline. Finally, we discuss some of these compounds that have shown encouraging additive or synergistic benefit when used in combination, providing some promise for the future in treating this ancient scourge.

New Drugs and Regimens for Tuberculosis Disease Treatment in Children and Adolescents

After almost 30 years of relative stagnation, research over the past decade has led to remarkable advances in the treatment of both drug-susceptible (DS) and drug-resistant (DR) tuberculosis (TB) disease in children and adolescents. Compared with the previous standard therapy of at least 6 months, 2 new regimens lasting for only 4 months for the treatment of DS-TB have been studied and are recommended by the World Health Organization (WHO), along with a shortened 6-month regimen for treatment of DS-TB meningitis. In addition, the 18- to 24-month regimens previously used for DR-TB that included painful injectable drugs with high rates of adverse effects have been replaced with shorter, safer all-oral regimens. Advances that have improved treatment include development of new TB drugs (bedaquiline, delamanid, pretomanid), reapplication of older TB drugs (rifampicin and rifapentine), and repurposing of other drugs (clofazimine and linezolid). The development of child-friendly formulations for many of these drugs has further enhanced the ability to safely and effectively treat DS- and DR-TB in children and adolescents. The characteristics and use of these drugs, regimens, and formulations are reviewed.

F, Sterba J, Kaprelyants A. Shotgun proteomic profiling of dormant, ‘non-culturable’ Mycobacterium tuberculosis

Dormant cells of Mycobacterium tuberculosis, in addition to low metabolic activity and a high level of drug resistance, are characterized by ‘non-culturability’–a specific reversible state of the inability of the cells to grow on solid media. The biochemical characterization of this physiological state of the pathogen is only superficial, pending clarification of the metabolic processes that may exist in such cells. In this study, applying LC-MS proteomic profiling, we report the analysis of proteins accumulated in dormant, ‘non-culturable’ M. tuberculosis cells in an in vitro model of self-acidification of mycobacteria in the post-stationary phase, simulating the in vivo persistence conditions—the raw data are available via ProteomeXchange with identifier PXD028849. This approach revealed the preservation of 1379 proteins in cells after 5 months of storage in dormancy; among them, 468 proteins were statistically different from those in the actively growing cells and bore a positive fold change (FC). Differential analysis revealed the proteins of the pH-dependent regulatory system PhoP and allowed the reconstruction of the reactions of central carbon/glycerol metabolism, as well as revealing the salvaged pathways of mycothiol and UMP biosynthesis, establishing the cohort of survival enzymes of dormancy. The annotated pathways mirror the adaptation of the mycobacterial metabolic machinery to life within lipid-rich macrophages: especially the involvement of the methyl citrate and glyoxylate pathways. Thus, the current in vitro model of M. tuberculosis self-acidification reflects the biochemical adaptation of these bacteria to persistence in vivo. Comparative analysis with published proteins displaying antigenic properties makes it possible to distinguish immunoreactive proteins among the proteins bearing a positive FC in dormancy, which may include specific antigens of latent tuberculosis. Additionally, the biotransformatory enzymes (oxidoreductases and hydrolases) capable of prodrug activation and stored up in the dormant state were annotated. These findings may potentially lead to the discovery of immunodiagnostic tests for early latent tuberculosis and trigger the discovery of efficient drugs/prodrugs with potency against non-replicating, dormant populations of mycobacteria.

Population Pharmacokinetics of Delamanid and its Main Metabolite DM-6705 in Drug-Resistant Tuberculosis Patients Receiving Delamanid Alone or Coadministered with Bedaquiline

BACKGROUND AND OBJECTIVE

Delamanid is a nitroimidazole, a novel class of drug for treating tuberculosis, and is primarily metabolized by albumin into the metabolite DM-6705. The aims of this analysis were to develop a population pharmacokinetic (PK) model to characterize the concentration-time course of delamanid and DM-6705 in adults with drug-resistant tuberculosis and to explore a potential drug-drug interaction with bedaquiline when coadministered.

METHODS

Delamanid and DM-6705 concentrations after oral administration, from 52 participants (of whom 26 took bedaquiline concurrently and 20 were HIV-1 positive) enrolled in the DELIBERATE trial were analyzed using nonlinear mixed-effects modeling.

RESULTS

Delamanid PK were described by a one-compartment disposition model with transit compartment absorption (mean absorption time of 1.45 h [95% confidence interval 0.501-2.20]) and linear elimination, while the PK of DM-6705 metabolite were described by a one-compartment disposition model with delamanid clearance as input and linear elimination. Predicted terminal half-life values for delamanid and DM-6705 were 15.1 h and 7.8 days, respectively. The impact of plasma albumin concentrations on delamanid metabolism was not significant. Bedaquiline coadministration did not affect delamanid PK. Other than allometric scaling with body weight, no patients' demographics were significant (including HIV).

CONCLUSIONS

This is the first joint PK model of delamanid and its DM-6705 metabolite. As such, it can be utilized in future exposure-response or exposure-safety analyses. Importantly, albumin concentrations, bedaquiline coadministration, and HIV co-infection (dolutegravir coadministration) did not have an effect on delamanid and DM-6705 PK.

Recent updates in natural terpenoids as potential anti-mycobacterial agents

Tuberculosis is considered as a leading health issue globally. Even though, the todays first line anti-mycobacterial treatments used in the hospital have low deaths, multidrug-resistance forms of the ailment have now spread globally and become a major issue. The wide-ranging biodiversity of medicinal plants, ocean animals have gained considerable attention for drug discovery in previous spans, and the emergence of TB drug resistance has inspired interest in judging natural products (NPs) to cure this disease. Till now, several compounds have been isolated from natural sources with anti-mycobacterial activity, few of which demonstrate significant activity and have the potential for further development. Worldwide huge natural flora and fauna are existing, this flora and fauna must be investigated for new potent lead against infectious TB. This review systematically surveys various classes of terpenoid molecules obtained from different medicinal plants, fungi, sponges, and sea plumes with anti-TB activity, which could be useful for further optimization and development in this field.

Treatment strategies with alternative treatment options for patients with Mycobacterium avium complex pulmonary disease

Diseases caused by Mycobacterium avium complex (MAC) infection in the lungs are increasing worldwide. The recurrence rate of MAC-pulmonary disease (PD) has been reported to be as high as 25-45%. A significant percentage of recurrences occurs because of reinfection with a new genotype from the environment. A focus on reducing exposure to MAC organisms from the environment is therefore an essential component of the management of this disease as well as standard MAC-PD treatment. A macrolide-containing three-drug regimen is recommended over a two-drug regimen as a standard treatment, and azithromycin is recommended rather than clarithromycin. Both the 2007 and 2020 guidelines recommend a treatment duration of MAC-PD of at least one year after the culture conversion. Previous clinical studies have reported that ethambutol could prevent macrolide resistance. Furthermore, the concomitant use of aminoglycoside, amikacin liposomal inhalation, clofazimine, linezolid, bedaquiline, and fluoroquinolone with modification of guideline-based therapy has been studied. Long-term management of MAC-PD remains challenging because of the discontinuation of multi-drug regimens and the acquisition of macrolide resistance. Moreover, the poor compliance of guideline-based therapy for MAC-PD treatment worldwide is concerning since it causes macrolide resistance. Therefore, in this review, we focus on MAC-PD treatment and summarize various treatment options when standard treatment cannot be maintained, with reference to the latest ATS/ERS/ESCMID/IDSA clinical practice guidelines revised in 2020.

Resistance and tolerance of Mycobacterium tuberculosis to antimicrobial agents-How M. tuberculosis can escape antibiotics

Tuberculosis (TB) poses a serious threat to public health worldwide since it was discovered. Until now, TB has been one of the top 10 causes of death from a single infectious disease globally. The treatment of active TB cases majorly relies on various anti-tuberculosis drugs. However, under the selection pressure by drugs, the continuous evolution of Mycobacterium tuberculosis (Mtb) facilitates the emergence of drug-resistant strains, further resulting in the accumulation of tubercle bacilli with multiple drug resistance, especially deadly multidrug-resistant TB and extensively drug-resistant TB. Researches on the mechanism of drug action and drug resistance of Mtb provide a new scheme for clinical management of TB patients, and prevention of drug resistance. In this review, we summarized the molecular mechanisms of drug resistance of existing anti-TB drugs to better understand the evolution of drug resistance of Mtb, which will provide more effective strategies against drug-resistant TB, and accelerate the achievement of the EndTB Strategy by 2035. This article is categorized under: Infectious Diseases > Molecular and Cellular Physiology.

Mycobacterium tuberculosis and Pulmonary Rehabilitation: From Novel Pharmacotherapeutic Approaches to Management of Post-Tuberculosis Sequelae

Tuberculosis (TB) is still a worldwide public health burden, as more than 1.3 million deaths are expected to be reported in 2021. Even though almost 20 million patients have completed specific anti-TB treatment and survived in 2020, little information is known regarding their pulmonary sequelae, quality of life, and their need to follow rehabilitation services as researchers shifted towards proper diagnosis and treatment rather than analyzing post-disease development. Understanding the underlying immunologic and pathogenic mechanisms during mycobacterial infection, which have been incompletely elucidated until now, and the development of novel anti-TB agents could lead to the proper application of rehabilitation care, as TB sequelae result from interaction between the host and Mycobacterium tuberculosis. This review addresses the importance of host immune responses in TB and novel potential anti-TB drugs’ mechanisms, as well as the assessment of risk factors for post-TB disease and usefulness of guidance and optimization of pulmonary rehabilitation. The use of rehabilitation programs for patients who successfully completed anti-tuberculotic treatment represents a potent multifaceted measure in preventing the increase of mortality rates, as researchers conclude that a patient with a TB diagnosis, even when properly completing pharmacotherapy, is threatened by a potential life loss of 4 years, in comparison to healthy individuals. Dissemination of pulmonary rehabilitation services and constant actualization of protocols could strengthen management of post-TB disease among under-resourced individuals.

Implications of Mycobacterium tuberculosis Metabolic Adaptability on Drug Discovery and Development

Tuberculosis remains a global health threat that is being exacerbated by the increase in infections attributed to drug resistant Mycobacterium tuberculosis. To combat this, there has been a surge in drug discovery programs to develop new, potent compounds and identify promising drug targets in the pathogen. Two areas of M. tuberculosis biology that have emerged as rich sources of potential novel drug targets are cell wall biosynthesis and energy metabolism. Both processes are important for survival of M. tuberculosis under replicating and nonreplicating conditions. However, both processes are also inherently adaptable under different conditions. Furthermore, cell wall biosynthesis is energy intensive and, thus, reliant on an efficiently functioning energy production system. This Perspective focuses on the interplay between cell wall biosynthesis and energy metabolism in M. tuberculosis, how adaptations in one pathway may affect the other, and what consequences this could have for drug discovery and development and the identification of novel drug targets.

A Comprehensive Understanding of Interlayer Engineering in Layered Manganese and Vanadium Cathodes for Aqueous Zn-ion Batteries

Rechargeable aqueous zinc-ion batteries (AZIBs) hold a budding technology for large-scale stationary energy storage devices due to their inherent safety, cost-effectiveness, eco-friendly, and acceptable electrochemical performance. However, developing a cathode material with fast kinetics and durable structural stability for Zn 2+ intercalation is still an arduous challenge. Compared with other cathode materials, layered manganese/vanadium (Mn/V) oxides that feature merits of adjustable interlayer spacing and considerable specific capacity have attracted much interest in AZIBs. However, the intrinsic sluggish reaction kinetics, inferior electrical conductivity, and notorious dissolution of active materials still obstruct the realization of their full potentials. Interlayer engineering of pre-intercalation is regarded as an effective solution to overcome these problems. In this review, we start from the crystal structure and reaction mechanism of layered Mn/V oxide cathodes to critical issues and recent progress in interlayer engineering. Finally, some future perspectives are outlined for the development of high-performance AZIBs.

MDR Tuberculosis Treatment

Multidrug-resistant (MDR) tuberculosis (TB), resistant to isoniazid and rifampicin, continues to be one of the most important threats to controlling the TB epidemic. Over the last few years, there have been promising pharmacological advances in the paradigm of MDR TB treatment: new and repurposed drugs have shown excellent bactericidal and sterilizing activity against Mycobacterium tuberculosis and several all-oral short regimens to treat MDR TB have shown promising results. The purpose of this comprehensive review is to summarize the most important drugs currently used to treat MDR TB, the recommended regimens to treat MDR TB, and we also summarize new insights into the treatment of patients with MDR TB.

In Vitro and In Vivo Inhibition of the Mycobacterium tuberculosis Phosphopantetheinyl Transferase PptT by Amidinoureas

A newly validated target for tuberculosis treatment is phosphopantetheinyl transferase, an essential enzyme that plays a critical role in the biosynthesis of cellular lipids and virulence factors in Mycobacterium tuberculosis. The structure-activity relationships of a recently disclosed inhibitor, amidinourea (AU) 8918 (1), were explored, focusing on the biochemical potency, determination of whole-cell on-target activity for active compounds, and profiling of selective active congeners. These studies show that the AU moiety in AU 8918 is largely optimized and that potency enhancements are obtained in analogues containing a para-substituted aromatic ring. Preliminary data reveal that while some analogues, including 1, have demonstrated cardiotoxicity (e.g., changes in cardiomyocyte beat rate, amplitude, and peak width) and inhibit Ca_v1.2 and Na_v1.5 ion channels (although not hERG channels), inhibition of the ion channels is largely diminished for some of the para-substituted analogues, such as 5k (p-benzamide) and 5n (p-phenylsulfonamide).

Phenotypic heterogeneity in persisters: a novel 'hunker' theory of persistence

Persistence has been linked to treatment failure since its discovery over 70 years ago and understanding formation, nature and survival of this key antibiotic refractory subpopulation is crucial to enhancing treatment success and combatting the threat of antimicrobial resistance (AMR). The term 'persistence' is often used interchangeably with other terms such as tolerance or dormancy. In this review we focus on 'antibiotic persistence' which we broadly define as a feature of a subpopulation of bacterial cells that possesses the non-heritable character of surviving exposure to one or more antibiotics; and persisters as cells that possess this characteristic. We discuss novel molecular mechanisms involved in persister cell formation, as well as environmental factors which can contribute to increased antibiotic persistence in vivo, highlighting recent developments advanced by single-cell studies. We also aim to provide a comprehensive model of persistence, the 'hunker' theory which is grounded in intrinsic heterogeneity of bacterial populations and a myriad of 'hunkering down' mechanisms which can contribute to antibiotic survival of the persister subpopulation. Finally, we discuss antibiotic persistence as a 'stepping-stone' to AMR and stress the urgent need to develop effective anti-persister treatment regimes to treat this highly clinically relevant bacterial sub-population.

Screening approaches and therapeutic targets: The two driving wheels of tuberculosis drug discovery

Tuberculosis (TB) is an infectious disease, infecting a quarter of world's population. Drug resistant TB further exacerbates the grim scenario of the drying TB drug discovery pipeline. The limited arsenal to fight TB presses the need for thorough efforts for identifying promising hits to combat the disease. The review highlights the efforts in the field of tuberculosis drug discovery, with an emphasis on massive drug screening campaigns for identifying novel hits against Mtb in both industry and academia. As an intracellular pathogen, mycobacteria reside in a complicated intracellular environment with multiple factors at play. Here, we outline various strategies employed in an effort to mimic the intracellular milieu for bringing the screening models closer to the actual settings. The review also focuses on the novel targets and pathways that could aid in target-based drug discovery in TB. The recent high throughput screening efforts resulting in the identification of potent hits against Mtb has been summarized in this article. There is a pressing need for effective screening strategies and approaches employing innovative tools and recent technologies; including nanotechnology, gene-editing tools such as CRISPR-cas system, host-directed bacterial killing and high content screening to augment the TB drug discovery pipeline with safer and shorter drug regimens.

Relationship between the Crystal Structure and Tuberculostatic Activity of Some 2-Amidinothiosemicarbazone Derivatives of Pyridine

Tuberculosis remains one of the most common diseases affecting developing countries due to difficult living conditions, the rapidly increasing resistance of M. tuberculosis strains and the small number of effective anti-tuberculosis drugs. This study concerns the relationship between molecular structure observed in a solid-state by X-ray diffraction and the ¹⁵N NMR of a group of pyridine derivatives, from which promising activity against M. tuberculosis was reported earlier. It was found that the compounds exist in two tautomeric forms: neutral and zwitterionic. The latter form forced the molecules to adopt a stable, unique, flat frame due to conjugation and the intramolecular hydrogen bond system. As the compounds exist in a zwitterionic form in the crystal state generally showing higher activity against tuberculosis, it may indicate that this geometry of molecules is the “active” form.

OUP accepted manuscript

Given the low treatment success rates of drug-resistant tuberculosis (TB), novel TB drugs are urgently needed. The landscape of TB treatment has changed considerably over the last decade with the approval of three new compounds: bedaquiline, delamanid and pretomanid. Of these, delamanid and pretomanid belong to the same class of drugs, the nitroimidazoles. In order to close the knowledge gap on how delamanid and pretomanid compare with each other, we summarize the main findings from preclinical research on these two compounds. We discuss the compound identification, mechanism of action, drug resistance, in vitro activity, in vivo pharmacokinetic profiles, and preclinical in vivo activity and efficacy. Although delamanid and pretomanid share many similarities, several differences could be identified. One finding of particular interest is that certain Mycobacterium tuberculosis isolates have been described that are resistant to either delamanid or pretomanid, but with preserved susceptibility to the other compound. This might imply that delamanid and pretomanid could replace one another in certain regimens. Regarding bactericidal activity, based on in vitro and preclinical in vivo activity, delamanid has lower MICs and higher mycobacterial load reductions at lower drug concentrations and doses compared with pretomanid. However, when comparing in vivo preclinical bactericidal activity at dose levels equivalent to currently approved clinical doses based on drug exposure, this difference in activity between the two compounds fades. However, it is important to interpret these comparative results with caution knowing the variability inherent in preclinical in vitro and in vivo models.

Nano-Drug Delivery Systems: Possible End to the Rising Threats of Tuberculosis

Tuberculosis (TB) is still one of the deadliest disease across the globe caused by Mycobacterium tuberculosis (Mtb). Mtb invades host macrophages and other immune cells, modifies their lysosome trafficking proteins, prevents phagolysosomes formation, and inhibits the TNF receptor-dependent apoptosis in macrophages and monocytes. Tuberculosis (TB) killed 1.4 million people worldwide in the year 2019. Despite the advancements in tuberculosis (TB) treatments, multidrugresistant tuberculosis (MDR-TB) remains a severe threat to human health. The complications are further compounded by the emergence of MDR/XDR strains and the failure of conventional drug regimens to eradicate the resistant bacterial strains. Thus, new therapeutic approaches aim to ensure cure without relapse, to prevent the occurrence of deaths and emergence of drug-resistant strains. In this context, this review article summarises the essential nanotechnology-related research outcomes in the treatment of tuberculosis (TB), including drug-susceptible and drug-resistant strains of Mtb. The novel anti-tuberculosis drug delivery systems are also being detailed. This article highlights recent advances in tuberculosis (TB) treatments, including the use of novel drug delivery technologies such as solid lipid nanoparticles, liposomes, polymeric micelles, nano-suspensions, nano-emulsion, niosomes, liposomes, polymeric nanoparticles and microparticles for the delivery of anti-TB drugs and hence eradication and control of both drug-susceptible as well as drug-resistant strains of Mtb.

Population Pharmacokinetic and Concentration-QTc Analysis of Delamanid in Pediatric Participants with Multidrug-Resistant Tuberculosis

A population pharmacokinetic analysis of delamanid and its major metabolite DM-6705 was conducted to characterize the pharmacokinetics of delamanid and DM-6705 in pediatric participants with multidrug-resistant tuberculosis (MDR-TB). Data from participants between the ages of 0.67 and 17 years, enrolled in 2 clinical trials, were utilized for the analysis. The final data set contained 634 delamanid and 706 DM-6705 valid plasma concentrations from 37 children. A transit model with three compartments best described the absorption of delamanid. Two-compartment models for each component with linear elimination were selected to characterize the dispositions of delamanid and DM-6705, respectively. The covariates included in the model were body weight on the apparent volume of distribution and apparent clearance (for both delamanid and DM-6705); formulation (dispersible versus film-coated tablet) on the mean absorption time; age, formulation, and dose on the bioavailability of delamanid; and age on the fraction of delamanid metabolized to DM-6705. Based on the simulations, doses for participants within different age/weight groups that result in delamanid exposure comparable to that in adults following the approved adult dose were calculated. By concentration-QTc (QTcB [QT corrected by Bazett’s formula]) analysis, a significant positive correlation was detected with concentrations of DM-6705. However, the model-predicted upper bounds of the 90% confidence intervals of ΔQTc values were <10 ms at the simulated maximum concentration (C_max) of DM-6705 following the administration of the maximum doses simulated. This suggests that the effect on the QT interval following the proposed dosing is unlikely to be clinically meaningful in children with MDR-TB who receive delamanid.

Systematic measurement of combination-drug landscapes to predict in vivo treatment outcomes for tuberculosis

Lengthy multidrug chemotherapy is required to achieve a durable cure in tuberculosis. However, we lack well-validated, high-throughput in vitro models that predict animal outcomes. Here, we provide an extensible approach to rationally prioritize combination therapies for testing in in vivo mouse models of tuberculosis. We systematically measured Mycobacterium tuberculosis response to all two- and three-drug combinations among ten antibiotics in eight conditions that reproduce lesion microenvironments, resulting in >500,000 measurements. Using these in vitro data, we developed classifiers predictive of multidrug treatment outcome in a mouse model of disease relapse and identified ensembles of in vitro models that best describe in vivo treatment outcomes. We identified signatures of potencies and drug interactions in specific in vitro models that distinguish whether drug combinations are better than the standard of care in two important preclinical mouse models. Our framework is generalizable to other difficult-to-treat diseases requiring combination therapies. A record of this paper's transparent peer review process is included in the supplemental information.