Tuberculosis (TB), the leading cause of death from bacterial infections worldwide, results from infection with Mycobacterium tuberculosis (Mtb). The antitubercular agents delamanid (DLM) and pretomanid (PMD) are nitroimidazole prodrugs that require activation by an enzyme intrinsic to Mtb; however, the mechanism(s) of action and the associated metabolic pathways are largely unclear. Profiling of the chemical-genetic interactions of PMD and DLM in Mtb using combined CRISPR screening reveals that the mutation of rv2073c increases susceptibility of Mtb to these nitroimidazole drugs both in vitro and in infected mice, whereas mutation of rv0078 increases drug resistance. Further assays show that Rv2073c might confer intrinsic resistance to DLM/PMD by interfering with inhibition of the drug target, decaprenylphophoryl-2-keto-b-D-erythro-pentose reductase (DprE2), by active nicotinamide adenine dinucleotide (NAD) adducts. Characterization of the metabolic pathways of DLM/PMD in Mtb using a combination of chemical genetics and comparative liquid chromatography-mass spectrometry (LC-MS) analysis of DLM/PMD metabolites reveals that Rv0077c, which is negatively regulated by Rv0078, mediates drug resistance by metabolizing activated DLM/PMD. These results might guide development of new nitroimidazole prodrugs and new regimens for TB treatment.

Rising cases of drug resistance of mycobacterium species are one of the biggest concerns when the goal is to eradicate TB (Tuberculosis) from the world by the year 2030. A limited number of treatment options as MTB (Mycobacterium tuberculosis) is getting resistant to anti-mycobacterial drugs either due to a patient\'s non-compliance towards treatment regimen or if a patient is infected by drug-resistant species of MTB. This review aims to assess the effectiveness of pretomanid, a recently approved drug for the treatment of extensively drug-resistant TB. A thorough search of databases like PubMed, Cochrane library, CDC, Research Gate, and Google scholar was used in order to find case reports and clinical trials providing data on the efficacy of pretomanid in different drug regimens. According to research trials conducted, the drug appears to be efficacious, safe, and well-tolerable. Only headache was the most frequently observed adverse drug event, and a high dose-related increase in serum creatinine level was seen, which came to normal after the drug was discontinued.

BACKGROUND: In 2022, the WHO recommended the 6-month regimens BPaL (bedaquiline + pretomanid + linezolid) and BPaLM (BPaL + moxifloxacin) as treatment options for most forms of drug-resistant TB. SLASH-TB estimates the cost-saving and cost-effectiveness for the healthcare system and patients when a country switches from current standard-of-care treatment regimens to BPaL/BPaLM.
METHODS: Country data from national TB programmes (NTP) are used to calculate the costs for all regimens and treatment outcomes. Where BPaL/BPaLM is not currently used, clinical trial outcomes data are used to estimate cost-effectiveness. DALYs are calculated using the Global Burden of Disease (GBD) database.
RESULTS: We present the results of four countries that have used the tool and shared their data. When shorter and longer regimens are replaced with BPaL/BPaLM, the savings per patient treated in Pakistan, the Philippines, South Africa, and Ukraine are $746, $478, $757, and $2,636, respectively. An increased number of patients would be successfully treated with BPaL/BPaLM regimens, with 411, 1,025, 1,371 and 829 lives saved and 20,179, 27,443, 33,384 and 21,924 DALYs averted annually in the four countries, respectively.
CONCLUSIONS: Through BPaL/BPaLM regimens, drug-resistant TB treatment has become more effective, shorter, less burdensome for patients, cheaper for both health systems and patients, and saves more lives.
BACKGROUND: En 2022, l\'OMS a préconisé l\'utilisation des schémas thérapeutiques (bedaquiline + pretomanid + linezolid) et BPaLM (BPaL + moxifloxacin), d\'une durée de 6 mois, comme alternatives pour traiter la plupart des formes de TB résistante aux médicaments. SLASH-TB a réalisé une estimation des économies et de la rentabilité pour le système de santé et les patients lorsqu\'un pays décide de passer des schémas thérapeutiques standards actuels au BPaL/BPaLM.
UNASSIGNED: Les programmes nationaux de lutte contre la TB (NTP) utilisent les données nationales pour évaluer les coûts des différents schémas thérapeutiques et des résultats des traitements. Si le BPaL/BPaLM n\'est pas utilisé actuellement, les données des essais cliniques sont utilisées pour estimer le rapport coût-efficacité. Les années de vie ajustées sur l\'incapacité (DALYs, pour l’anglais « disability-adjusted life-years ») sont calculées à l\'aide de la base de données Global Burden of Disease (GBD).
UNASSIGNED: Nous présentons les résultats de quatre pays qui ont utilisé l\'outil et partagé leurs données. Lorsque les schémas plus courts et plus longs sont remplacés par BPaL/BPaLM, les économies par patient traité au Pakistan, aux Philippines, en Afrique du Sud et en Ukraine sont respectivement de 746, 478, 757 et 2 636 dollars. L\'utilisation des schémas BPaL/BPaLM permettrait de traiter un plus grand nombre de patients avec succès, ce qui sauverait respectivement 411, 1 025, 1 371 et 829 vies et éviterait 20 179, 27 443, 33 384 et 21 924 DALYs par an dans les quatre pays.
CONCLUSIONS: Les schémas BPaL/BPaLM ont révolutionné le traitement de la tuberculose pharmacorésistante en le rendant plus efficace, plus rapide, moins contraignant pour les patients, plus économique pour les systèmes de santé et les patients, et en sauvant un plus grand nombre de vies.

BACKGROUND: In 2022, the WHO announced that the 6-month BPaL/M regimen should be used for drug-resistant TB (DR-TB). We estimate the patient and provider costs of BPaL compared to current standard-of-care treatment in the Philippines.
METHODS: Patients on BPaL under operational research, or 9-11-month standard short oral regimen (SSOR) and 18-21-month standard long oral regimen (SLOR) under programmatic conditions were interviewed using the WHO cross-sectional TB patient cost tool. Provider costs were assessed through a bottom-up and top-down costing analysis.
RESULTS: Total patient costs per treatment episode were lowest with BPaL (USD518.0) and increased with use of SSOR (USD825.8) and SLOR (USD1,023.0). Total provider costs per successful treatment were lowest with BPaL (USD1,994.5) and increased with SSOR (USD3,121.5) and SLOR (USD10,032.4). Compared to SSOR, BPaL treatment was cost-effective at even the lowest willingness to pay threshold. As expected, SLOR was the costliest and least effective regimen.
CONCLUSIONS: Costs incurred by patients on BPaL were 37% (95% CI 22-56) less than SSOR and 50% (95% CI 32-68) less than SLOR, while providers could save 36% (95% CI 21-56) to 80% (95% CI 64-93) per successful treatment, respectively. The study shows that treatment of DR-TB with BPaL was cost-saving for patients and cost-effective for the health system.
BACKGROUND: En 2022, l\'OMS a annoncé que le traitement BPaL/M de 6 mois devrait être utilisé pour la TB pharmacorésistante (DR-TB). Nous estimons les coûts du BPaL pour les patients et les prestataires par rapport au traitement standard actuel aux Philippines.
UNASSIGNED: Des patients sous BPaL dans le cadre d\'une recherche opérationnelle, ou un régime oral court standard de 9 à 11 mois (SSOR, pour l’anglais « standard short oral regimen ») et un régime oral long standard de 18 à 21 mois (SLOR, pour l’anglais « standard long oral regimen ») dans des conditions programmatiques ont été interrogés à l\'aide de l\'outil transversal de l\'OMS sur le coût pour les patients atteints de TB. Les coûts des fournisseurs ont été évalués par une analyse ascendante et descendante des coûts.
UNASSIGNED: Les coûts totaux pour les patients par épisode de traitement étaient les plus bas avec BPaL (518,0 USD) et augmentaient avec l\'utilisation de SSOR (825,8 USD) et SLOR (1 023,0 USD). Les coûts totaux des prestataires par traitement réussi étaient les plus bas avec BPaL (1 994,5 USD) et ont augmenté avec SSOR (3 121,5 USD) et SLOR (10 032,4 USD). Comparé à SSOR, le traitement BPaL était rentable même au seuil de volonté de payer le plus bas. Comme prévu, le SLOR était le régime le plus coûteux et le moins efficace.
CONCLUSIONS: Les coûts encourus par les patients sous BPaL étaient inférieurs de 37% (IC à 95% 22–56) à ceux du SSOR et de 50% (IC à 95% 32–68) à ceux du SLOR, tandis que les prestataires pouvaient économiser respectivement 36 % (IC à 95% 21–56) à 80% (IC à 95% 64–93) par traitement réussi. L\'étude montre que le traitement de la DR-TB par BPaL a permis de réaliser des économies pour les patients et pour le système de santé.

Pretomanid (PTM), an oral antibiotic used in the treatment of adults with pulmonary extensively drug-resistant, nonresponsive multidrug-resistant tuberculosis (MDR-TB). It is a poor glass former, that shows high recrystallization tendency from the amorphous and supersaturated state, resulting in low aqueous solubility and suboptimal absorption through the gastrointestinal tract. The present investigation aimed to develop high drug loaded ternary amorphous solid dispersions (ASDs) of PTM with improved stability and enhanced biopharmaceutical performance by utilizing a combination of polymers. The polymers were comprehensively screened based on drug-polymer miscibility and saturation solubility analysis. A combination of Hydroxypropyl Methylcellulose Acetate Succinate (HPMCAS-HF) and Polyvinylpyrrolidone K-30 (PVP K-30) showed synergism in drug-polymer miscibility as evidenced through pronounced depression in the melting endotherm of PTM. The Powder X-ray Diffraction (P-XRD) diffractograms of 30% w/w PTM loaded ternary ASDs displayed the halo pattern, contrary to the binary ASDs. Drug-polymer interactions (hydrophobic forces) involved between PTM and polymers were detected through Fourier Transform Infrared Spectroscopy (FT-IR) and Nuclear Magnetic Resonance Spectroscopy (13C-NMR) which contributed to the synergistic enhancement in solubility and dissolution of ternary ASDs with sustained release over 12 h. Ternary ASDs demonstrated better in-vivo performance compared to the binary ASDs, showing a 4.63-fold increase in maximum plasma concentration. All ASDs remained stable and resisted phase separation during short-term stability studies for 3 months at ambient conditions. It was concluded that the hydrophobic and hydrophilic polymeric combination (HPMCAS-HF and PVP K-30, respectively) effectively prevented the crystallization and ensured sustained drug release with improved in-vivo absorption of PTM.

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.

The BPaLM regimen (bedaquiline, pretomanid, linezolid and moxifloxacin) recently recommended by the World Health Organization offers short, safe, and effective treatment for multidrug-resistant/rifampicin-resistant tuberculosis (TB). In a survey with national TB focal points in 18 central and western European countries to explore barriers for the implementation of BPaLM, only three reported full availability of pretomanid, a necessary component of this regimen. Implementation barriers included financing and procurement. Solutions on national and supranational level are needed to guarantee universal access.

Drug-resistant tuberculosis (TB) is a major global health challenge in part because there are fewer effective treatments and these treatments have been prolonged and more toxic. The evidence base for more effective, shorter, standardized treatments is evolving rapidly. Herein, we report the first case of pre-extensively drug-resistant pulmonary TB treated with a novel six-month all oral bedaquiline, pretomanid and linezolid (BPaL) regimen in Canada. Recent clinical trial data supporting BPaL therapy is presented in the context of current and evolving clinical guidelines. In this article, we highlight significant implementation challenges and make recommendations for what needs to be addressed to ensure safe programmatic use of BPaL in Canada. Key recommendations include the development of infrastructure for timely access to novel TB drug susceptibility testing, streamlining access to novel TB drugs, and cautious use of such drugs in collaboration with care teams with expertise in drug-resistant TB management.

A major challenge for tuberculosis (TB) drug development is to prioritize promising combination regimens from a large and growing number of possibilities. This includes demonstrating individual drug contributions to the activity of higher-order combinations. A BALB/c mouse TB infection model was used to evaluate the contributions of each drug and pairwise combination in the clinically relevant Nix-TB regimen [bedaquiline-pretomanid-linezolid (BPaL)] during the first 3 weeks of treatment at human equivalent doses. The rRNA synthesis (RS) ratio, an exploratory pharmacodynamic (PD) marker of ongoing Mycobacterium tuberculosis rRNA synthesis, together with solid culture CFU counts and liquid culture time to positivity (TTP) were used as PD markers of treatment response in lung tissue; and their time-course profiles were mathematically modeled using rate equations with pharmacologically interpretable parameters. Antimicrobial interactions were quantified using Bliss independence and Isserlis formulas. Subadditive (or antagonistic) and additive effects on bacillary load, assessed by CFU and TTP, were found for bedaquiline-pretomanid and linezolid-containing pairs, respectively. In contrast, subadditive and additive effects on rRNA synthesis were found for pretomanid-linezolid and bedaquiline-containing pairs, respectively. Additionally, accurate predictions of the response to BPaL for all three PD markers were made using only the single-drug and pairwise effects together with an assumption of negligible three-way drug interactions. The results represent an experimental and PD modeling approach aimed at reducing combinatorial complexity and improving the cost-effectiveness of in vivo systems for preclinical TB regimen development.

Both latent and multidrug-resistant tuberculosis (TB) have been causing significant concern worldwide. A novel drug, pretomanid (PA-824), has shown a potent bactericidal effect against both active and latent forms of Mycobacterium tuberculosis (MTb) and a synergistic effect when combined with pyrazinamide and moxifloxacin. This study aimed to develop triple combination spray dried inhalable formulations composed of antitubercular drugs, pretomanid, moxifloxacin, and pyrazinamide (1:2:8 w/w/w), alone (PaMP) and in combination with an aerosolization enhancer, L-leucine (20 % w/w, PaMPL). The formulation PaMPL consisted of hollow, spherical, dimpled particles (<5 μm) and showed good aerosolization behaviour with a fine particle fraction of 70 %. Solid-state characterization of formulations with and without L-leucine confirmed the amorphous nature of moxifloxacin and pretomanid and the crystalline nature of pyrazinamide with polymorphic transformation after the spray drying process. Further, the X-ray photoelectron spectroscopic analysis revealed the predominant surface composition of L-leucine on PaMPL dry powder particles. The dose-response cytotoxicity results showed pyrazinamide and moxifloxacin were non-toxic in both A549 and Calu-3 cell lines up to 150 µg/mL. However, the cell viability gradually decreased to 50 % when the pretomanid concentration increased to 150 µg/mL. The in vitro efficacy studies demonstrated that the triple combination formulation had more prominent antibacterial activity with a minimum inhibitory concentration (MIC) of 1 µg/mL against the MTb H37Rv strain as compared to individual drugs. In conclusion, the triple combination of pretomanid, moxifloxacin, and pyrazinamide as an inhalable dry powder formulation will potentially improve treatment efficacy with fewer systemic side effects in patients suffering from latent and multidrug-resistant TB.