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Preclinical Evaluations To Identify Optimal Linezolid Regimens for Tuberculosis Therapy.

ABSTRACT: Linezolid is an oxazolidinone with potent activity against Mycobacterium tuberculosis. Linezolid toxicity in patients correlates with the dose and duration of therapy. These toxicities are attributable to the inhibition of mitochondrial protein synthesis. Clinically relevant linezolid regimens were simulated in the in vitro hollow-fiber infection model (HFIM) system to identify the linezolid therapies that minimize toxicity, maximize antibacterial activity, and prevent drug resistance. Linezolid inhibited mitochondrial proteins in an exposure-dependent manner, with toxicity being driven by trough concentrations. Once-daily linezolid killed M. tuberculosis in an exposure-dependent manner. Further, 300 mg linezolid given every 12 hours generated more bacterial kill but more toxicity than 600 mg linezolid given once daily. None of the regimens prevented linezolid resistance. These findings show that with linezolid monotherapy, a clear tradeoff exists between antibacterial activity and toxicity. By identifying the pharmacokinetic parameters linked with toxicity and antibacterial activity, these data can provide guidance for clinical trials evaluating linezolid in multidrug antituberculosis regimens.The emergence and spread of multidrug-resistant M. tuberculosis are a major threat to global public health. Linezolid is an oxazolidinone that is licensed for human use and has demonstrated potent activity against multidrug-resistant M. tuberculosis. However, long-term use of linezolid has shown to be toxic in patients, often resulting in thrombocytopenia. We examined therapeutic linezolid regimens in an in vitro model to characterize the exposure-toxicity relationship. The antibacterial activity against M. tuberculosis was also assessed for these regimens, including the amplification or suppression of resistant mutant subpopulations by the chosen regimen. Higher exposures of linezolid resulted in greater antibacterial activity, but with more toxicity and, for some regimens, increased resistant mutant subpopulation amplification, illustrating the trade-off between activity and toxicity. These findings can provide valuable insight for designing optimal dosage regimens for linezolid that are part of the long combination courses used to treat multidrug-resistant M. tuberculosis.

SUBMITTER: Brown AN

PROVIDER: S-EPMC4631805 | biostudies-other | 2015 Nov

REPOSITORIES: biostudies-other

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Preclinical Evaluations To Identify Optimal Linezolid Regimens for Tuberculosis Therapy.

Brown Ashley N AN Drusano George L GL Adams Jonathan R JR Rodriquez Jaime L JL Jambunathan Kalyani K Baluya Dodge L DL Brown David L DL Kwara Awewura A Mirsalis Jon C JC Hafner Richard R Louie Arnold A

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<h4>Unlabelled</h4>Linezolid is an oxazolidinone with potent activity against Mycobacterium tuberculosis. Linezolid toxicity in patients correlates with the dose and duration of therapy. These toxicities are attributable to the inhibition of mitochondrial protein synthesis. Clinically relevant linezolid regimens were simulated in the in vitro hollow-fiber infection model (HFIM) system to identify the linezolid therapies that minimize toxicity, maximize antibacterial activity, and prevent drug re ...[more]

PMID: 26530386

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Project description:BackgroundThe bedaquiline-pretomanid-linezolid regimen has been reported to have 90% efficacy against highly drug-resistant tuberculosis, but the incidence of adverse events with 1200 mg of linezolid daily has been high. The appropriate dose of linezolid and duration of treatment with this agent to minimize toxic effects while maintaining efficacy against highly drug-resistant tuberculosis are unclear.MethodsWe enrolled participants with extensively drug-resistant (XDR) tuberculosis (i.e., resistant to rifampin, a fluoroquinolone, and an aminoglycoside), pre-XDR tuberculosis (i.e., resistant to rifampin and to either a fluoroquinolone or an aminoglycoside), or rifampin-resistant tuberculosis that was not responsive to treatment or for which a second-line regimen had been discontinued because of side effects. We randomly assigned the participants to receive bedaquiline for 26 weeks (200 mg daily for 8 weeks, then 100 mg daily for 18 weeks), pretomanid (200 mg daily for 26 weeks), and daily linezolid at a dose of 1200 mg for 26 weeks or 9 weeks or 600 mg for 26 weeks or 9 weeks. The primary end point in the modified intention-to-treat population was the incidence of an unfavorable outcome, defined as treatment failure or disease relapse (clinical or bacteriologic) at 26 weeks after completion of treatment. Safety was also evaluated.ResultsA total of 181 participants were enrolled, 88% of whom had XDR or pre-XDR tuberculosis. Among participants who received bedaquiline-pretomanid-linezolid with linezolid at a dose of 1200 mg for 26 weeks or 9 weeks or 600 mg for 26 weeks or 9 weeks, 93%, 89%, 91%, and 84%, respectively, had a favorable outcome; peripheral neuropathy occurred in 38%, 24%, 24%, and 13%, respectively; myelosuppression occurred in 22%, 15%, 2%, and 7%, respectively; and the linezolid dose was modified (i.e., interrupted, reduced, or discontinued) in 51%, 30%, 13%, and 13%, respectively. Optic neuropathy developed in 4 participants (9%) who had received linezolid at a dose of 1200 mg for 26 weeks; all the cases resolved. Six of the seven unfavorable microbiologic outcomes through 78 weeks of follow-up occurred in participants assigned to the 9-week linezolid groups.ConclusionsA total of 84 to 93% of the participants across all four bedaquiline-pretomanid-linezolid treatment groups had a favorable outcome. The overall risk-benefit ratio favored the group that received the three-drug regimen with linezolid at a dose of 600 mg for 26 weeks, with a lower incidence of adverse events reported and fewer linezolid dose modifications. (Funded by the TB Alliance and others; ZeNix ClinicalTrials.gov number, NCT03086486.).

Project description:BackgroundLimited evidence for the implementation of new health technologies in low- and middle-income countries (LMICs) may lead to uncertainties in economic evaluations and cause the evaluations to produce inaccurate information for decision making. We performed a systematic review of economic evaluations on implementing new short-course regimens (SCR) for drug-sensitive and drug-resistant tuberculosis (TB), to explore how uncertainties due to the limited evidence in the studies were dealt with and to identify useful information for decision making from these studies.MethodsWe searched in electronic databases PubMed, EMBASE, NHSEED, and CEA registry for economic evaluations addressing the implementation of new anti-TB SCRs in LMICs published until September 2018. We included studies addressing both the cost and outcomes of implementing a new regimen for drug-sensitive and drug-resistant TB with a shorter treatment duration than the currently used regimens. The quality of the included studies was assessed using The Consensus Health Economic Criteria checklist. We extracted information from the included studies on uncertainties and how they were managed. The management of uncertainties was compared with approaches used in early health technology assessments (HTAs), including sensitivity analyses and pragmatic scenario analyses. We extracted information that could be useful for decision making such as cost-effectiveness conclusions, and barriers to implementing the intervention.ResultsFour of the 322 studies found in the search met the eligibility criteria. Three studies were model-based studies that investigated the cost effectiveness of a new first-line SCR. One study was an empirical study investigating the cost effectiveness of new regimens for drug-resistant TB. The model-based studies addressed uncertainties due to limited evidence through various sensitivity analyses as in early HTAs. They performed a deterministic sensitivity analysis and found the main drivers of the cost-effectiveness outcomes, that is, the rate of treatment default and treatment delivery costs. Additionally, two of the model-based studies performed a pragmatic scenario analysis and found a potential barrier to implementing the new first-line SCR, that is, a weak health system with a low TB care utilization rate. The empirical study only performed a few scenario analyses with different regimen prices and volumes of TB care utilization. Therefore, the study could only provide information on the main cost drivers.ConclusionUsing an approach similar to that used in early HTAs, where uncertainties due to the limited evidence are rigorously explored upfront, the economic evaluations could inform not only the decision to implement the intervention but also how to manage risks and implementation barriers.

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Preclinical Evaluations To Identify Optimal Linezolid Regimens for Tuberculosis Therapy.

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Preclinical Evaluations To Identify Optimal Linezolid Regimens for Tuberculosis Therapy.

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