pa-824 and Extensively-Drug-Resistant-Tuberculosis

The emergence of drug resistance continues to afflict TB control where drug resistant strains have become a global health concern. Contrary to drug-sensitive TB, the treatment of MDR/XDR-TB is more complicated requiring the administration of second-line drugs that are inefficient than the first line drugs and are associated with greater side effects. The emergence of drug resistant Mtb strains had coincided with an innovation void in the field of drug discovery of anti-mycobacterials. However, the approval of bedaquiline and delamanid recently for use in MDR/XDR-TB has given an impetus to the TB drug discovery. The review discusses the drug discovery efforts in the field of tuberculosis with a focus on the strategies adopted and challenges confronted by TB research community. Here, we discuss the diverse clinical candidates in the current TB drug discovery pipeline. There is an urgent need to combat the current TB menace through multidisciplinary approaches and strategies making use of the recent advances in understanding the molecular biology and pathogenesis of Mtb. The review highlights the recent advances in drug discovery, with the host directed therapeutics and nanoparticles-drug delivery coming up as important tools to fight tuberculosis in the future.

Topics: Antitubercular Agents; Diarylquinolines; Drug Therapy, Combination; Ethambutol; Extensively Drug-Resistant Tuberculosis; Humans; Isoniazid; Mycobacterium tuberculosis; Nitroimidazoles; Oxazoles; Pyrazinamide; Rifampin

Pretomanid is a nitroimidazooxazine drug which inhibits synthesis of mycolic acid. This leads to defective cell wall formation, ultimately causing bacterial cell death. It is active against both replicating and non-replicating M. tuberculosis. Following promising result in a phase III trial, pretomanid was approved by United States Food and Drug Administration in August 2019. This orally active drug has been approved as part of a combination regimen of bedaquiline, pretomanid and linezolid (BPaL regimen) to treat adults with pulmonary extensive drug resistant tuberculosis (TB) or treatment-intolerant or non-responsive multidrug resistant TB. Peripheral neuropathy and increased liver enzymes are some of the reported adverse events associated with pretomanid. However, more studies are required to confirm the role of pretomanid in paediatric, geriatric and HIV co-infection cases.

Topics: Antitubercular Agents; Drug Approval; Drug Therapy, Combination; Extensively Drug-Resistant Tuberculosis; Humans; Nitroimidazoles; United States; United States Food and Drug Administration

Tuberculosis (TB) is the most deadly infectious disease globally. Although most individuals achieve a cure, a substantial portion develop multi-drug resistant TB which is exceedingly difficult to treat, and the number of effective agents is dwindling. Development of new anti-tubercular medications is imperative to combat existing drug resistance and accelerate global eradication of TB. Pretomanid (PA-824) represents one of the newest drug classes (ie, nitroimidazooxazines) approved in 2019 by the United States Food and Drug Administration as part of a multi-drug regimen (with bedaquiline and linezolid, BPaL) and recommended by the World Health Organization (WHO) to treat extensively-resistant (XR-TB) and multi-drug resistant tuberculosis (MDR-TB). Approval was granted through the FDA's Limited Population Pathway for Antibacterial and Antifungal Drugs, which accelerates approval for antimicrobial drugs used to treat life-threatening or serious infections in a limited population with unmet need. This review details the pharmacology, efficacy, and safety of this new agent and describes evidence to date for its role in the treatment of drug resistant TB including published, ongoing, and planned studies.

Topics: Animals; Antitubercular Agents; Drug Therapy, Combination; Extensively Drug-Resistant Tuberculosis; Humans; Nitroimidazoles; Tuberculosis, Multidrug-Resistant

Treatment of drug-sensitive tuberculosis (TB) is effective, whereas that of multidrug-resistant and extensively drug-resistant TB as well as nontuberculous mycobacterial (NTM) disease are less so. Therapy in general requires good adherence to potentially toxic drug regimens over prolonged periods. Poor adherence is associated with resistance development and poor outcome. This review will present promising new treatments, both new drugs and regimens, for difficult mycobacterial pulmonary infections.. A number of new and repurposed drugs including bedaquiline, delamanid, pretomanid, linezolid and clofazimine, and drug regimens, such as the The Evaluation of a Standard Treatment Regimen of Anti-tuberculosis Drugs for Patients With MDR-TB (STREAM) trial regimens, are currently progressing from basic research through clinical trials.

Topics: Amikacin; Anti-Bacterial Agents; Clofazimine; Diarylquinolines; Extensively Drug-Resistant Tuberculosis; Humans; Linezolid; Liposomes; Lung Diseases; Microbial Sensitivity Tests; Mycobacterium Infections, Nontuberculous; Nitroimidazoles; Oxazoles

Multidrug-resistant and extensively drug-resistant tuberculosis (MDR-TB and XDR-TB, respectively) continue to represent a challenge for clinicians and public health authorities. Unfortunately, although there have been encouraging reports of higher success rates, the overall rate of favorable outcomes of M/XDR-TB treatment is only 54%, or much lower when the spectrum of drug resistance is beyond that of XDR-TB. Treating M/XDR-TB continues to be a difficult task, because of the high incidence of adverse events, the long duration of treatment, the high cost of the regimens used, and the drain on health care resources. Various trials and studies have recently been undertaken (some already published and others ongoing), all aimed at improving outcomes of M/XDR-TB treatment by changing the overall approach, shortening treatment duration, and developing a universal regimen. The objective of this review was to summarize what has been achieved to date, as far as new and repurposed drugs are concerned, with a special focus on delamanid, bedaquiline, pretomanid, clofazimine, carbapenems, and linezolid. After more than 40 years of neglect, greater attention has recently been paid to the need for new drugs to fight the "white plague", and promising results are being reported.

Topics: Antitubercular Agents; Clinical Trials as Topic; Diarylquinolines; Drug Repositioning; Extensively Drug-Resistant Tuberculosis; Humans; Nitroimidazoles; Oxazoles

The United Nations Millennium Development Goal of reversing the global spread of tuberculosis by 2015 has been offset by the rampant re-emergence of drug-resistant tuberculosis, in particular fluoroquinolone-resistant multidrug-resistant and extensively drug-resistant tuberculosis. After decades of quiescence in the development of antituberculosis medications, bedaquiline and delamanid have been conditionally approved for the treatment of drug-resistant tuberculosis, while several other novel compounds (AZD5847, PA-824, SQ109 and sutezolid) have been evaluated in phase II clinical trials. Before novel drugs can find their place in the battle against drug-resistant tuberculosis, linezolid has been compassionately used with success in the treatment of fluoroquinolone-resistant multidrug-resistant tuberculosis. This review largely discusses six novel drugs that have been evaluated in phase II and III clinical trials, with focus on the clinical evidence for efficacy and safety, potential drug interactions, and prospect for using multiple novel drugs in new regimens.

Topics: Adamantane; Antitubercular Agents; Clinical Trials, Phase II as Topic; Clinical Trials, Phase III as Topic; Diarylquinolines; Drug Therapy, Combination; Ethylenediamines; Extensively Drug-Resistant Tuberculosis; Female; Follow-Up Studies; Humans; Male; Nitroimidazoles; Oxazoles; Oxazolidinones; Treatment Outcome; Tuberculosis, Multidrug-Resistant

The current 6-month tuberculosis (TB) therapy is suboptimal with significant side effects and a poor patient compliance problem that frequently selects drug-resistant organisms. The increasing drug-resistant TB problem highlights the need to develop new and more effective drugs. Significant progress has been made recently with several new drug candidates currently in clinical trials. Improved understanding of persister biology and development of persister drugs are likely to be important for developing a more effective therapy.

Topics: Adamantane; AIDS-Related Opportunistic Infections; Animals; Anti-Bacterial Agents; Antitubercular Agents; Drug Administration Schedule; Drug Resistance, Bacterial; Drug Therapy, Combination; Drugs, Investigational; Ethylenediamines; Extensively Drug-Resistant Tuberculosis; Fluoroquinolones; Humans; Isoniazid; Mycobacterium tuberculosis; Nitroimidazoles; Oxazoles; Pyrazinamide; Rifampin; Treatment Refusal; Tuberculosis, Multidrug-Resistant; Tuberculosis, Pulmonary

Patients with highly drug-resistant forms of tuberculosis have limited treatment options and historically have had poor outcomes.. In an open-label, single-group study in which follow-up is ongoing at three South African sites, we investigated treatment with three oral drugs - bedaquiline, pretomanid, and linezolid - that have bactericidal activity against tuberculosis and to which there is little preexisting resistance. We evaluated the safety and efficacy of the drug combination for 26 weeks in patients with extensively drug-resistant tuberculosis and patients with multidrug-resistant tuberculosis that was not responsive to treatment or for which a second-line regimen had been discontinued because of side effects. The primary end point was the incidence of an unfavorable outcome, defined as treatment failure (bacteriologic or clinical) or relapse during follow-up, which continued until 6 months after the end of treatment. Patients were classified as having a favorable outcome at 6 months if they had resolution of clinical disease, a negative culture status, and had not already been classified as having had an unfavorable outcome. Other efficacy end points and safety were also evaluated.. A total of 109 patients were enrolled in the study and were included in the evaluation of efficacy and safety end points. At 6 months after the end of treatment in the intention-to-treat analysis, 11 patients (10%) had an unfavorable outcome and 98 patients (90%; 95% confidence interval, 83 to 95) had a favorable outcome. The 11 unfavorable outcomes were 7 deaths (6 during treatment and 1 from an unknown cause during follow-up), 1 withdrawal of consent during treatment, 2 relapses during follow-up, and 1 loss to follow-up. The expected linezolid toxic effects of peripheral neuropathy (occurring in 81% of patients) and myelosuppression (48%), although common, were manageable, often leading to dose reductions or interruptions in treatment with linezolid.. The combination of bedaquiline, pretomanid, and linezolid led to a favorable outcome at 6 months after the end of therapy in a high percentage of patients with highly drug-resistant forms of tuberculosis; some associated toxic effects were observed. (Funded by the TB Alliance and others; ClinicalTrials.gov number, NCT02333799.).

Topics: Administration, Oral; Adolescent; Adult; Antitubercular Agents; Bacterial Load; Diarylquinolines; Drug Therapy, Combination; Extensively Drug-Resistant Tuberculosis; Female; Humans; Intention to Treat Analysis; Linezolid; Male; Middle Aged; Mycobacterium tuberculosis; Nitroimidazoles; Treatment Outcome; Tuberculosis, Multidrug-Resistant; Tuberculosis, Pulmonary; Young Adult

Bedaquiline, pretomanid and linezolid (BPaL) is a new all oral, 6-month regimen comprised of bedaquiline, the new drug pretomanid and linezolid, endorsed by the WHO for use under operational research conditions in patients with extensively drug-resistant tuberculosis (XDR-TB). We quantified per-patient treatment costs and the 5-year budgetary impact of introducing BPaL in Indonesia, Kyrgyzstan and Nigeria.. Per-patient treatment cost of BPaL regimen was compared head-to-head with the conventional XDR-TB treatment regimen for respective countries based on cost estimates primarily assessed using microcosting method and expected frequency of each TB service. The 5-year budget impact of gradual introduction of BPaL against the status quo was assessed using a Markov model that represented patient's treatment management and outcome pathways.. The cost per patient completing treatment with BPaL was US$7142 in Indonesia, US$4782 in Kyrgyzstan and US$7152 in Nigeria - 57%, 78% and 68% lower than the conventional regimens in the respective countries. A gradual adoption of the BPaL regimen over 5 years would result in an 5-year average national TB service budget reduction of 17% (US$128 780) in XDR-TB treatment-related expenditure in Indonesia, 15% (US$700 247) in Kyrgyzstan and 32% (US$1 543 047) in Nigeria.. Our study demonstrates that the BPaL regimen can be highly cost-saving compared with the conventional regimens to treat patients with XDR-TB in high drug-resistant TB burden settings. This supports the rapid adoption of the BPaL regimen to address the significant programmatic and clinical challenges in managing patients with XDR-TB in high DR-TB burden countries.

Topics: Antitubercular Agents; Diarylquinolines; Extensively Drug-Resistant Tuberculosis; Humans; Linezolid; Nitroimidazoles

Patients with highly resistant tuberculosis have few treatment options. Bedaquiline, pretomanid and linezolid regimen (BPaL) is a new regimen shown to have favourable outcomes after six months. We present an economic evaluation of introducing BPaL against the extensively drug-resistant tuberculosis (XDR-TB) standard of care in three epidemiological settings.. Cost-effectiveness analysis using Markov cohort model.. South Africa, Georgia and the Philippines.. XDR-TB and multidrug-resistant tuberculosis (MDR-TB) failure and treatment intolerant patients.. BPaL regimen. PRIMARY AND SECONDARY OUTCOME MEASURES: (1) Incremental cost per disability-adjusted life years averted by using BPaL against standard of care at the Global Drug Facility list price. (2) The potential maximum price at which the BPaL regimen could become cost neutral.. BPaL for XDR-TB is likely to be cost saving in all study settings when pretomanid is priced at the Global Drug Facility list price. The magnitude of these savings depends on the prevalence of XDR-TB in the country and can amount, over 5 years, to approximately US$ 3 million in South Africa, US$ 200 000 and US$ 60 000 in Georgia and the Philippines, respectively. In South Africa, related future costs of antiretroviral treatment (ART) due to survival of more patients following treatment with BPaL reduced the magnitude of expected savings to approximately US$ 1 million. Overall, when BPaL is introduced to a wider population, including MDR-TB treatment failure and treatment intolerant, we observe increased savings and clinical benefits. The potential threshold price at which the probability of the introduction of BPaL becoming cost neutral begins to increase is higher in Georgia and the Philippines (US$ 3650 and US$ 3800, respectively) compared with South Africa (US$ 500) including ART costs.. Our results estimate that BPaL can be a cost-saving addition to the local TB programmes in varied programmatic settings.

Topics: Antitubercular Agents; Cost-Benefit Analysis; Diarylquinolines; Extensively Drug-Resistant Tuberculosis; Georgia; Humans; Linezolid; Nitroimidazoles; Philippines; South Africa; Tuberculosis, Multidrug-Resistant

Drug-resistant tuberculosis (DR-TB) continues to pose a threat to the global eradication of TB. Regimens for extensively drug-resistant (XDR) TB are lengthy and poorly tolerated, often with unsuccessful outcomes. The TB Alliance Nix-TB trial investigated the safety and efficacy of a 26-week regimen of bedaquiline, pretomanid and linezolid (BPaL) in participants with XDR-TB, multidrug-resistant (MDR) TB treatment failure or intolerance. In this trial 9 out of 10 participants were cured. We describe a trial participant with XDR-TB who presented with new-onset seizures soon after BPaL treatment completion. Imaging showed a right temporal ring-enhancing lesion, and a sterile tuberculous granuloma was confirmed after a diagnostic, excisional biopsy. Learning points include management of a participant with a tuberculoma after BPaL completion, efficacy of new medications for central nervous system (CNS) TB and a review of their CNS penetration. This is the first case of pretomanid use in CNS TB.

Topics: Antitubercular Agents; Diarylquinolines; Extensively Drug-Resistant Tuberculosis; Granuloma; Humans; Linezolid; Nitroimidazoles; Treatment Outcome; Tuberculosis, Multidrug-Resistant

Topics: Administration, Inhalation; Amikacin; Anti-Bacterial Agents; Antifungal Agents; Cross Infection; Drug Approval; Drug Resistance, Microbial; Drug Therapy, Combination; Extensively Drug-Resistant Tuberculosis; Humans; Liposomes; Mycobacterium avium Complex; Mycobacterium avium-intracellulare Infection; Nitroimidazoles; Pneumonia, Bacterial; Pneumonia, Ventilator-Associated; Sisomicin; United States; United States Food and Drug Administration

A population pharmacokinetic (PopPK) model for pretomanid was developed using data from 14 studies in the pretomanid development program: six phase 1 studies, six phase 2 studies, and two phase 3 studies. The final analysis data set contained 17,725 observations from 1,054 subjects, including healthy subjects and subjects with drug-sensitive, multidrug-resistant, or extensively drug-resistant pulmonary tuberculosis dosed pretomanid in monotherapy or combination therapy for up to 6 months. Pretomanid pharmacokinetic behavior was described by a one-compartment model that at a given dose was linear in its absorption and clearance processes but where the rate of absorption and extent of bioavailability changed with dose. Clearance and volume of distribution scaled allometrically with weight. Apparent clearance in females was 18% less than in males. Among HIV-positive subjects, absent the effect of CYP3A4-inducing antiretrovirals, apparent clearance was 6% higher. Some effects of total bilirubin and albumin were found, but the impacts on exposure were small. Bioavailability in the fasted condition was about half that in the fed condition. Relative bioavailability decreased with increasing dose in the fasted condition, but not for doses of ≤200 mg in the fed condition. HIV-positive subjects taking efavirenz and lopinavir/ritonavir had exposures that were reduced by 46 and 17%, respectively. There was little evidence for noteworthy effects of regimen partners on pretomanid. Standard diagnostics indicated that the model described the voluminous, diverse data well, so that the model could be used to generate exposure metrics for exposure/response analyses to be reported elsewhere.

Topics: Antitubercular Agents; Biological Availability; Clinical Trials as Topic; Extensively Drug-Resistant Tuberculosis; Female; HIV Infections; Humans; Lopinavir; Male; Nitroimidazoles; Rifampin; Ritonavir; Tuberculosis, Multidrug-Resistant; Tuberculosis, Pulmonary

Delamanid exhibited greater in vitro potency than pretomanid against multidrug-resistant (MDR-) and extensively drug-resistant tuberculosis (XDR-TB) isolates. The pretomanid minimum inhibitory concentration (MIC) values of four MDR-TB isolates were found to be resistant to delamanid ranging from 0.031 to 0.063 mg/L. A novel nonsynonymous mutation within the fbiA gene (Glu249Lys) may be contributing to high-level resistance to delamanid and pretomanid in Mycobacterium tuberculosis.

Topics: Antitubercular Agents; Bacterial Proteins; Drug Resistance, Multiple, Bacterial; Extensively Drug-Resistant Tuberculosis; Microbial Sensitivity Tests; Mutation; Mycobacterium tuberculosis; Nitroimidazoles; Tuberculosis, Multidrug-Resistant

Topics: AIDS-Related Opportunistic Infections; Antitubercular Agents; Baltimore; Clinical Trials as Topic; Diarylquinolines; Drug Therapy, Combination; Extensively Drug-Resistant Tuberculosis; Humans; Linezolid; Mycobacterium tuberculosis; Nitroimidazoles; South Africa; Sputum; Treatment Outcome

The recent approval of new tuberculosis (TB) drugs raises hope for new and more effective anti-tuberculosis treatment regimens. The Global Alliance for TB Drug Development (TB Alliance) is committed to ensuring that new anti-tuberculosis drugs fulfill the needs of patients, their families and the local health services that serve the communities. Here we present highlights of the TB Alliance's pipeline of regimen development, with novel regimens for patients with drug-susceptible, multidrug-resistant and extensively drug-resistant TB. The ongoing clinical trials (STAND, NC-005, Nix-TB and LIN-CL001) are outlined and their rationale and goals presented.

Topics: Antitubercular Agents; Clinical Protocols; Diarylquinolines; Dose-Response Relationship, Drug; Ethambutol; Extensively Drug-Resistant Tuberculosis; Fluoroquinolones; Humans; Isoniazid; Linezolid; Moxifloxacin; Nitroimidazoles; Pyrazinamide; Randomized Controlled Trials as Topic; Research Design; Rifampin; Tuberculosis, Multidrug-Resistant

There presently is no rapid method to assess the bactericidal activity of new regimens for tuberculosis. This study examined PNU-100480, TMC207, PA-824, SQ109, and pyrazinamide, singly and in various combinations, against intracellular M. tuberculosis, using whole blood culture (WBA). The addition of 1,25-dihydroxy vitamin D facilitated detection of the activity of TMC207 in the 3-day cultures. Pyrazinamide failed to show significant activity against a PZA-resistant strain (M. bovis BCG), and was not further considered. Low, mid, and high therapeutic concentrations of each remaining drug were tested individually and in a paired checkerboard fashion. Observed bactericidal activity was compared to that predicted by the sum of the effects of individual drugs. Combinations of PNU-100480, TMC207, and SQ109 were fully additive, whereas those including PA-824 were less than additive or antagonistic. The cumulative activities of 2, 3, and 4 drug combinations were predicted based on the observed concentration-activity relationship, published pharmacokinetic data, and, for PNU-100480, published WBA data after oral dosing. The most active regimens, including PNU-100480, TMC207, and SQ109, were predicted to have cumulative activity comparable to standard TB therapy. Further testing of regimens including these compounds is warranted. Measurement of whole blood bactericidal activity can accelerate the development of novel TB regimens.

Topics: Adamantane; Antitubercular Agents; Diarylquinolines; Drug Monitoring; Drug Therapy, Combination; Ethylenediamines; Extensively Drug-Resistant Tuberculosis; Humans; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Nitroimidazoles; Oxazolidinones; Pyrazinamide; Quinolines; Reproducibility of Results; Time Factors

Novel treatments for multidrug-resistant tuberculosis (MDR-TB), extensively drug-resistant tuberculosis (XDR-TB), or latent TB are needed urgently. Recently, we reported the formulation and characterization of the nitroimidazo-oxazine PA-824 for efficient aerosol delivery as dry powder porous particles and the subsequent disposition in guinea pigs after pulmonary administration. The objective of the present study was to evaluate the effects of these PA-824 therapeutic aerosols on the extent of TB infection in the low-inoculum aerosol infection guinea pig model. Four weeks after infection by the pulmonary route, animals received daily treatment for 4 weeks of either a high or a low dose of PA-824 dry powder aerosol. Animals received PA-824 cyclodextrin/lecithin suspensions orally as positive controls, and those receiving placebo particles or no treatment were negative controls. The lungs and spleens of animals receiving the high dose of inhaled PA-824 particles exhibited a lower degree of inflammation (indicated by wet tissue weights), bacterial burden, and tissue damage (indicated by histopathology) than those of untreated or placebo animals. Treatment with oral PA-824 cyclodextrin/lecithin suspension resulted in a more significant reduction in the bacterial burden of lungs and spleen, consistent with a dose that was larger than inhaled doses (eight times the inhaled low dose and four times the inhaled high dose). However, histopathological analysis revealed that the extent of tissue damage was comparable in groups receiving the oral or either inhaled dose. The present studies indicate the potential use of PA-824 dry powder aerosols in the treatment of TB.

Topics: Administration, Inhalation; Administration, Oral; Aerosols; Animals; Antitubercular Agents; Chemistry, Pharmaceutical; Colony Count, Microbial; Disease Models, Animal; Extensively Drug-Resistant Tuberculosis; Guinea Pigs; Humans; Latent Tuberculosis; Lung; Male; Nitroimidazoles; Particle Size; Powders; Spleen; Tuberculosis, Multidrug-Resistant; Tuberculosis, Pulmonary