Publications by authors named "Rodney Dawson"

61 Publications

The effect of Clofazimine Concentration on QT prolongation in patients treated for tuberculosis.

Antimicrob Agents Chemother 2021 Apr 19. Epub 2021 Apr 19.

Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa.

Clofazimine is classified as a WHO group B drug for the treatment of rifampicin-resistant tuberculosis. QT prolongation, which is associated with fatal cardiac arrhythmias, is caused by several anti-tubercular drugs, including clofazimine, but there are no data quantifying the effect of clofazimine concentration on QT prolongation.To describe the effect of clofazimine exposure on QT prolongationFifteen adults drug-susceptible tuberculosis patients received clofazimine mono-therapy as 300 mg daily for three days followed by 100 mg daily in one arm of a 2-week, multi-arm early bactericidal activity trial in South Africa. Pre-treatment Fridericia-corrected QT (QTcF) (105 patients, 524 ECGs) and QTcF's from the clofazimine-monotherapy arm matched with clofazimine concentrations (199 ECGs) were interpreted with a nonlinear mixed-effects model.Clofazimine was associated with significant QT prolongation described by an E function. We predicted clofazimine exposures using 100-mg daily doses and two-weeks loading with 200 and 300 mg daily, respectively. The expected proportions of patients with QTcF change from baseline above 30 ms (ΔQTcF>30) were 2.52%, 11.6%, and 23.0% for 100, 200, and 300-mg daily doses, respectively. At steady state, the expected proportion with ΔQTcF>30 ms was 23.7% and for absolute QTcF>450 ms was 3.42% for all simulated regimens.The use of loading doses of 200 and 300 mg is not predicted to expose patients to increased risk of QT prolongation, compared to the current standard treatment, and is, therefore, an alternative option to achieve therapeutic concentrations faster.
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http://dx.doi.org/10.1128/AAC.02687-20DOI Listing
April 2021

Assessing whether isoniazid is essential during the first 14 days of tuberculosis therapy: a phase 2a, open-label, randomised controlled trial.

Lancet Microbe 2020 Jun 8;1(2):e84-e92. Epub 2020 Jun 8.

Center for TB Research, Department of Medicine, Division of Infectious Diseases, Johns Hopkins School of Medicine, Baltimore, Maryland.

Background: Clinical studies suggest that isoniazid contributes rapid bacterial killing during the initial two days of tuberculosis treatment but that isoniazid's activity declines significantly after day three. We conducted a 14-day phase IIa open label, randomized trial to assess the essentiality of isoniazid in standard tuberculosis therapy.

Methods: A total of 69 adults with newly diagnosed sputum-positive tuberculosis from the South African Western Cape region were enrolled and randomized to a four-arm parallel assignment model. Participants were followed for 14 days as inpatients at either the University of Cape Town Lung Institute or at the TASK Applied Science clinical research organization. All arms received standard daily rifampicin, ethambutol, and pyrazinamide but differed as follows: isoniazid only on days one and two (n=17), isoniazid on days one and two then moxifloxacin on days three through 14 (n=16), no isoniazid (n=18), and a control group that received isoniazid for all 14 days (standard therapy, n=18). The primary endpoint was the rate of colony forming unit (CFU) decline during the first 14 days of treatment.

Results: For 62 participants analyzed, the initial 14-day mean daily fall in log CFU (95% CI) was 0·14 (0·11, 0·18) for participants receiving isoniazid for two days only; 0·13 (0·09, 0·17) for participants receiving isoniazid for two days followed by moxifloxacin; 0·12 (0·08, 0·15) for those not receiving isoniazid; and 0·13 (0·09, 0·16) for the standard therapy group.

Conclusions: The 14 day EBA for the combination rifampicin, ethambutol, and pyrazinamide was not significantly changed by the addition of isoniazid for the first two days or for the first 14 days of treatment. In a post hoc analysis, significantly higher day-two EBAs were observed for all groups among participants with higher baseline sputum CFUs. Our finding that INH does not contribute to EBA suggests that INH could be replaced with another drug during standard treatment to improve efficacy and decrease rates of resistance to first-line drugs. (Funded by the NIH AIDS Clinical Trial Groups and NIH; A5307 ClinicalTrials.gov number, NCT01589497).
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http://dx.doi.org/10.1016/s2666-5247(20)30011-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8023625PMC
June 2020

Increased bactericidal activity but dose-limiting intolerability at 50 mg·kg rifampicin.

Eur Respir J 2021 Feb 4. Epub 2021 Feb 4.

Department of Lung Diseases, Radboud Institute for Health Sciences, Radboud university medical center, Nijmegen, The Netherlands.

Accumulating data have indicated that higher rifampicin doses are more effective and shorten tuberculosis treatment duration. This study evaluated the safety, tolerability, pharmacokinetics, and 7 and 14-day early bactericidal activity (EBA) of increasing doses of rifampicin. Here we report the results of the final cohorts of PanACEA HIGHRIF1, a dose-escalation study in treatment-naive adult smear-positive patients with tuberculosis. Patients received, in consecutive cohorts, 40 or 50 mg·kg rifampicin once daily in monotherapy (day 1-7), supplemented with standard dose isoniazid, pyrazinamide and ethambutol between day 8-14. In the 40 mg·kg cohort (n=15), 13 patients experienced a total of 36 adverse events (AEs) during monotherapy, resulting in one treatment discontinuation. In the 50 mg·kg group (n=17), all patients experienced AEs during monotherapy, 93 in total; 11 patients withdrew or stopped study medication. AEs were mostly mild/moderate and tolerability- rather than safety-related, gastrointestinal disorders, pruritis, hyperbilirubinemia and jaundice. There was a more than proportional increase in the rifampicin geometric mean AUCh for 50 mg·kg compared to 40 mg·kg; 571 mg·L*h (range 320-995) 387 mg·L*h (201-847), while peak exposures saw proportional increases. Protein-unbound exposure after 50 mg·kg (11%, 8-17%) was comparable with lower rifampicin doses. Rifampicin exposures and bilirubin concentrations were correlated (day-3 Spearman's rho 0.670, p<0.001). EBA increased considerably with dose, with the highest seen after 50 mg·kg; 14-day EBA -0.427 logCFU·mL·day (95%CI -0.500, -0.355). In conclusion, although associated with an increased bactericidal effect, the 50 mg·kg dose was not well tolerated. Rifampicin at 40 mg·kg was well tolerated and therefore selected for evaluation in a phase IIC treatment shortening trial.
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http://dx.doi.org/10.1183/13993003.00955-2020DOI Listing
February 2021

Brief psychotherapy administered by non-specialised health workers to address risky substance use in patients with multidrug-resistant tuberculosis: a feasibility and acceptability study.

Pilot Feasibility Stud 2021 Jan 19;7(1):28. Epub 2021 Jan 19.

Centre for TB Research Innovation, University of Cape Town Lung Institute, George Road, Mowbray, Cape Town, 7925, South Africa.

Background: Only 55% of multidrug-resistant tuberculosis (MDR-TB) cases worldwide complete treatment, with problem substance use a risk for default and treatment failure. Nevertheless, there is little research on psychotherapeutic interventions for reducing substance use amongst MDR-TB patients, in general, and on their delivery by non-specialist health workers in particular.

Objectives: To explore the feasibility and acceptability of a non-specialist health worker-delivered 4-session brief motivational interviewing and relapse prevention (MI-RP) intervention for problem substance use and to obtain preliminary data on the effects of this intervention on substance use severity, depressive symptoms, psychological distress and functional impairment at 3 months after hospital discharge.

Methods: Between December 2015 and October 2016, consenting MDR-TB patients admitted to Brewelskloof Hospital who screened at moderate to severe risk for substance-related problems on the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) were enrolled, and a baseline questionnaire administered. In the 4 weeks prior to planned discharge, trained counsellors delivered the MI-RP intervention. The baseline questionnaire was re-administered 3 months post-discharge and qualitative interviews were conducted with a randomly selected sample of participants (n = 10).

Results: Sixty patients were screened: 40 (66%) met inclusion criteria of which 39 (98%) were enrolled. Of the enrolled patients, 26 (67%) completed the counselling sessions and the final assessment. Qualitative interviews revealed participants' perceptions of the value of the intervention. From baseline to follow-up, patients reported reductions in substance use severity, symptoms of depression, distress and functional impairment.

Conclusion: In this feasibility study, participant retention in the study was moderate. We found preliminary evidence supporting the benefits of the intervention for reducing substance use and symptoms of psychological distress, supported by qualitative reports of patient experiences. Randomised studies are needed to demonstrate efficacy of this intervention before considering potential for wider implementation.

Trial Registration: South African National Clinical Trials Register ( DOH-27-0315-5007 ) on 01/04/2015 ( http://www.sanctr.gov.za ).
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http://dx.doi.org/10.1186/s40814-020-00764-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7814702PMC
January 2021

A validated liquid chromatography tandem mass spectrometry assay for the analysis of pretomanid in plasma samples from pulmonary tuberculosis patients.

J Pharm Biomed Anal 2021 Feb 30;195:113885. Epub 2020 Dec 30.

Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa.

A method for the extraction and quantification of pretomanid in 40 μL of human plasma, by high performance liquid chromatography with tandem mass spectrometry (LC-MS/MS) detection was developed and validated. Samples were prepared using liquid-liquid extraction and chromatographic separation was achieved on an Agilent Poroshell C18 column using an isocratic elution at a flow rate of 400 μL/min. Electrospray ionization with mass detection at unit resolution in the multiple reaction monitoring (MRM) mode on an AB Sciex API 3200 mass spectrometer was used. Over the validation period, accuracy, precision, selectivity, sensitivity, recovery and stability were assessed. The calibration range was 10 - 10 000 ng/mL. Inter- and intra-day precision, expressed as the coefficient of variation (%CV), was shown to be lower than 9% at all concentrations tested with accuracies between 95.2 and 110 %. The recovery was 72.4 % overall and reproducible at the low, medium and high end of the calibration range. The method was shown to be specific for pretomanid with no significant matrix effects observed. The validated method facilitated the analysis of pretomanid in plasma collected from adults with pulmonary TB as part of a clinical pharmacokinetic study.
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http://dx.doi.org/10.1016/j.jpba.2020.113885DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7868581PMC
February 2021

Pretomanid Pharmacokinetics in the Presence of Rifamycins: Interim Results from a Randomized Trial among Patients with Tuberculosis.

Antimicrob Agents Chemother 2021 01 20;65(2). Epub 2021 Jan 20.

University of Cape Town, Division of Clinical Pharmacology, Cape Town, South Africa.

Shorter, more potent regimens are needed for tuberculosis. The nitroimidazole pretomanid was recently approved for extensively drug-resistant tuberculosis in combination with bedaquiline and linezolid. Pretomanid may also have benefit as a treatment-shortening agent for drug-sensitive tuberculosis. It is unclear how and whether it can be used together with rifamycins, which are key sterilizing first-line drugs. In this analysis, data were pooled from two studies: the Assessing Pretomanid for Tuberculosis (APT) trial, in which patients with drug-sensitive pulmonary TB received pretomanid, isoniazid, and pyrazinamide plus either rifampin or rifabutin versus standard of care under fed conditions, and the AIDS Clinical Trials Group 5306 (A5306) trial, a phase I study in healthy volunteers receiving pretomanid alone or in combination with rifampin under fasting conditions. In our population pharmacokinetic (PK) model, participants taking rifampin had 44.4 and 59.3% reductions in pretomanid AUC (area under the concentration-time curve) compared to those taking rifabutin or pretomanid alone (due to 80 or 146% faster clearance) in the APT and A5306 trials, respectively. Median maximum concentrations () in the rifampin and rifabutin arms were 2.14 and 3.35 mg/liter, while median AUC values were 30.1 and 59.5 mg·h/liter, respectively. Though pretomanid exposure in APT was significantly reduced with rifampin, AUC values were similar to those associated with effective treatment in registrational trials, likely because APT participants were fed with dosing, enhancing pretomanid relative bioavailability and exposures. Pretomanid concentrations with rifabutin were high but in range with prior observations. While pretomanid exposures with rifampin are unlikely to impair efficacy, our data suggest that pretomanid should be taken with food if prescribed with rifampin. (This study has been registered at ClinicalTrials.gov under identifier NCT02256696.).
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http://dx.doi.org/10.1128/AAC.01196-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7849006PMC
January 2021

Clofazimine pharmacokinetics in patients with TB: dosing implications.

J Antimicrob Chemother 2020 11;75(11):3269-3277

Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa.

Background: Clofazimine is in widespread use as a key component of drug-resistant TB regimens, but the recommended dose is not evidence based. Pharmacokinetic data from relevant patient populations are needed to inform dose optimization.

Objectives: To determine clofazimine exposure, evaluate covariate effects on variability, and simulate exposures for different dosing strategies in South African TB patients.

Patients And Methods: Clinical and pharmacokinetic data were obtained from participants with pulmonary TB enrolled in two studies with intensive and sparse sampling for up to 6 months. Plasma concentrations were measured by LC-MS/MS and interpreted with non-linear mixed-effects modelling. Body size descriptors and other potential covariates were tested on pharmacokinetic parameters. We simulated different dosing regimens to safely shorten time to average daily concentration above a putative target concentration of 0.25 mg/L.

Results: We analysed 1570 clofazimine concentrations from 139 participants; 79 (57%) had drug-resistant TB and 54 (39%) were HIV infected. Clofazimine pharmacokinetics were well characterized by a three-compartment model. Clearance was 11.5 L/h and peripheral volume 10 500 L for a typical participant. Lower plasma exposures were observed in women during the first few months of treatment, explained by higher body fat fraction. Model-based simulations estimated that a loading dose of 200 mg daily for 2 weeks would achieve average daily concentrations above a target efficacy concentration 37 days earlier in a typical TB participant.

Conclusions: Clofazimine was widely distributed with a long elimination half-life. Disposition was strongly influenced by body fat content, with potential dosing implications for women with TB.
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http://dx.doi.org/10.1093/jac/dkaa310DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7566350PMC
November 2020

Myocardial Steatosis Among Antiretroviral Therapy-Treated People With Human Immunodeficiency Virus Participating in the REPRIEVE Trial.

J Infect Dis 2020 07;222(Suppl 1):S63-S69

Infectious Diseases Section, Department of Medicine, Veterans Affairs Greater Los Angeles Healthcare System and David Geffen School of Medicine at the University of California, Los Angeles, Los Angeles, California, USA.

Background: People with human immunodeficiency virus (PWH) face increased risks for heart failure and adverse heart failure outcomes. Myocardial steatosis predisposes to diastolic dysfunction, a heart failure precursor. We aimed to characterize myocardial steatosis and associated potential risk factors among a subset of the Randomized Trial to Prevent Vascular Events in HIV (REPRIEVE) participants.

Methods: Eighty-two PWH without known heart failure successfully underwent cardiovascular magnetic resonance spectroscopy, yielding data on intramyocardial triglyceride (IMTG) content (a continuous marker for myocardial steatosis extent). Logistic regression models were applied to investigate associations between select clinical characteristics and odds of increased or markedly increased IMTG content.

Results: Median (Q1, Q3) IMTG content was 0.59% (0.28%, 1.15%). IMTG content was increased (> 0.5%) among 52% and markedly increased (> 1.5%) among 22% of participants. Parameters associated with increased IMTG content included age (P = .013), body mass index (BMI) ≥ 25 kg/m2 (P = .055), history of intravenous drug use (IVDU) (P = .033), and nadir CD4 count < 350 cells/mm³ (P = .055). Age and BMI ≥ 25 kg/m2 were additionally associated with increased odds of markedly increased IMTG content (P = .049 and P = .046, respectively).

Conclusions: A substantial proportion of antiretroviral therapy-treated PWH exhibited myocardial steatosis. Age, BMI ≥ 25 kg/m2, low nadir CD4 count, and history of IVDU emerged as possible risk factors for myocardial steatosis in this group.

Clinical Trials Registration: NCT02344290; NCT03238755.
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http://dx.doi.org/10.1093/infdis/jiaa245DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7347082PMC
July 2020

Transition from Restrictive to Obstructive Lung Function Impairment During Treatment and Follow-Up of Active Tuberculosis.

Int J Chron Obstruct Pulmon Dis 2020 11;15:1039-1047. Epub 2020 May 11.

University of Cape Town Lung Institute, and Division of Pulmonology, Department of Medicine, University of Cape Town, Cape Town, South Africa.

Background: Pulmonary tuberculosis (PTB) is associated with many forms of chronic lung disease including the development of chronic airflow obstruction (AFO). However, the nature, evolution and mechanisms responsible for the AFO after PTB are poorly understood. The aim of this study was to examine the progression of changes in lung physiology in patients treated for PTB.

Methods: Immunocompetent, previously healthy, adult patients receiving ambulatory treatment for a first episode of tuberculosis were prospectively followed up with serial lung physiology and quantitative computed tomography (CT) lung scans performed at diagnosis of tuberculosis, 2, 6, 12 and 18 months during and after the completion of treatment.

Results: Forty-nine patients (median age 26 years; 37.2% males) were included, and 43 were studied. During treatment, lung volumes improved and CT fibrosis scores decreased, but features of AFO and gas trapping emerged, while reduced diffusing capacity (DLco) seen in a majority of patients persisted. Significant increases in total lung capacity (TLC) by plethysmography were seen in the year following treatment completion (median change 5.9% pred., P<0.01) and were driven by large increases in residual volume (RV) (median change +19%pred., P<0.01) but not inspiratory capacity (IC; P=0.41). The change in RV/TLC correlated with significant progression of radiological gas trapping after treatment (P=0.04) but not with emphysema scores. One year after completing treatment, 18.6% of patients had residual restriction (total lung capacity, TLC <80%pred), 16.3% had AFO, 32.6% had gas trapping (RV/TLC>45%), and 78.6% had reduced DLco.

Conclusion: Simple spirometry alone does not fully reveal the residual respiratory impairments resulting after a first episode of PTB. Changes in physiology evolve after treatment completion, and these findings when taken together, suggest emergence of gas trapping after treatment likely caused by progression of small airway pathology during the healing process.
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http://dx.doi.org/10.2147/COPD.S219731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7227812PMC
May 2020

Fourteen-Day Bactericidal Activity, Safety, and Pharmacokinetics of Linezolid in Adults with Drug-Sensitive Pulmonary Tuberculosis.

Antimicrob Agents Chemother 2020 03 24;64(4). Epub 2020 Mar 24.

TB Alliance, New York, New York, USA.

Linezolid is increasingly used for the treatment of tuberculosis resistant to first-line agents, but the most effective dosing strategy is yet unknown. From November 2014 to November 2016, we randomized 114 drug-sensitive treatment-naive pulmonary tuberculosis patients from Cape Town, South Africa, to one of six 14-day treatment arms containing linezolid at 300 mg once daily (QD), 300 mg twice daily (BD), 600 mg QD, 600 mg BD, 1,200 mg QD, 1,200 mg three times per week (TIW), or a combination of isoniazid, rifampin, pyrazinamide, and ethambutol. Sixteen-hour sputum samples were collected overnight, and bactericidal activity was characterized by the daily percentage change in time to positivity (TTP) and the daily rate of change in log(CFU). We also assessed the safety and pharmacokinetics of the study treatments. We found that bactericidal activity increased with increasing doses of linezolid. Based on the daily percentage change in TTP, activity was highest for 1,200 mg QD (4.5%; 95% Bayesian confidence interval [BCI], 3.3 to 5.6), followed by 600 mg BD (4.1%; BCI, 2.5 to 5.7), 600 mg QD (4.1%; BCI, 2.9 to 5.3), 300 mg BD (3.3%; BCI, 1.9 to 4.7), 300 mg QD (2.3%; BCI, 1.1 to 3.5), and 1,200 mg TIW (2.2%; BCI, 1.1 to 3.3). Similar results were seen with bactericidal activity characterized by the daily rate of change in CFU count. Antimycobacterial activity correlated positively with plasma drug exposure and percentage time over MIC. There were no unexpected adverse events. All linezolid doses showed bactericidal activity. For the same total daily dose, once-daily dosing proved to be at least as effective as a divided twice-daily dose. An intermittent dosing regimen, with 1,200 mg given three times weekly, showed the least activity. (This study has been registered at ClinicalTrials.gov under identifier NCT02279875.).
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http://dx.doi.org/10.1128/AAC.02012-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7179319PMC
March 2020

Bedaquiline, moxifloxacin, pretomanid, and pyrazinamide during the first 8 weeks of treatment of patients with drug-susceptible or drug-resistant pulmonary tuberculosis: a multicentre, open-label, partially randomised, phase 2b trial.

Lancet Respir Med 2019 12 12;7(12):1048-1058. Epub 2019 Nov 12.

Global Alliance for TB Drug Development, New York, NY, USA.

Background: New anti-tuberculosis regimens that are shorter, simpler, and less toxic than those that are currently available are needed as part of the global effort to address the tuberculosis epidemic. We aimed to investigate the bactericidal activity and safety profile of combinations of bedaquiline, pretomanid, moxifloxacin, and pyrazinamide in the first 8 weeks of treatment of pulmonary tuberculosis.

Methods: In this multicentre, open-label, partially randomised, phase 2b trial, we prospectively recruited patients with drug-susceptible or rifampicin-resistant pulmonary tuberculosis from seven sites in South Africa, two in Tanzania, and one in Uganda. Patients aged 18 years or older with sputum smear grade 1+ or higher were eligible for enrolment, and a molecular assay (GeneXpert or MTBDRplus) was used to confirm the diagnosis of tuberculosis and to distinguish between drug-susceptible and rifampicin-resistant tuberculosis. Patients who were HIV positive with a baseline CD4 cell count of less than 100 cells per uL were excluded. Patients with drug-susceptible tuberculosis were randomly assigned (1:1:1) using numbered treatment packs with sequential allocation by the pharmacist to receive 56 days of treatment with standard tuberculosis therapy (oral isoniazid, rifampicin, pyrazinamide, and ethambutol; HRZE), or pretomanid (oral 200 mg daily) and pyrazinamide (oral 1500 mg daily) with either oral bedaquiline 400 mg daily on days 1-14 then 200 mg three times per week (BPaZ) or oral bedaquiline 200 mg daily (BPaZ). Patients with rifampicin-resistant tuberculosis received 56 days of the BPaZ regimen plus moxifloxacin 400 mg daily (BPaMZ). All treatment groups were open label, and randomisation was not stratified. Patients, trial investigators and staff, pharmacists or dispensers, laboratory staff (with the exception of the mycobacteriology laboratory staff), sponsor staff, and applicable contract research organisations were not masked. The primary efficacy outcome was daily percentage change in time to sputum culture positivity (TTP) in liquid medium over days 0-56 in the drug-susceptible tuberculosis population, based on non-linear mixed-effects regression modelling of log (TTP) over time. The efficacy analysis population contained patients who received at least one dose of medication and who had efficacy data available and had no major protocol violations. The safety population contained patients who received at least one dose of medication. This study is registered with ClinicalTrials.gov, NCT02193776, and all patients have completed follow-up.

Findings: Between Oct 24, 2014, and Dec 15, 2015, we enrolled 180 patients with drug-susceptible tuberculosis (59 were randomly assigned to BPaZ, 60 to BPaZ, and 61 to HRZE) and 60 patients with rifampicin-resistant tuberculosis. 57 patients in the BPaZ group, 56 in the BPaZ group, and 59 in the HRZE group were included in the primary analysis. BPaZ produced the highest daily percentage change in TTP (5·17% [95% Bayesian credibility interval 4·61-5·77]), followed by BPaZ (4·87% [4·31-5·47]) and HRZE group (4·04% [3·67-4·42]). The bactericidal activity in BPaZ and BPaZ groups versus that in the HRZE group was significantly different. Higher proportions of patients in the BPaZ (six [10%] of 59) and BPaZ (five [8%] of 60) groups discontinued the study drug than in the HRZE group (two [3%] of 61) because of adverse events. Liver enzyme elevations were the most common grade 3 or 4 adverse events and resulted in the withdrawal of ten patients (five [8%] in the BPaZ group, three [5%] in the BPaZ group, and two [3%] in the HRZE group). Serious treatment-related adverse events affected two (3%) patients in the BPaZ group and one (2%) patient in the HRZE group. Seven (4%) patients with drug-susceptible tuberculosis died and four (7%) patients with rifampicin-resistant tuberculosis died. None of the deaths were considered to be related to treatment.

Interpretation: BPaZ is a promising regimen to treat patients with drug-susceptible tuberculosis. The bactericidal activity of both these regimens suggests that they have the potential to shorten treatment, and the simplified dosing schedule of BPaZ could improve treatment adherence in the field. However, these findings must be investigated further in a phase 3 trial assessing treatment outcomes.

Funding: TB Alliance, UK Department for International Development, Bill & Melinda Gates Foundation, US Agency for International Development, Directorate General for International Cooperation of the Netherlands, Irish Aid, Australia Department of Foreign Affairs and Trade, and the Federal Ministry for Education and Research of Germany.
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http://dx.doi.org/10.1016/S2213-2600(19)30366-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7641992PMC
December 2019

Toxicity related to standard TB therapy for pulmonary tuberculosis and treatment outcomes in the REMoxTB study according to HIV status.

BMC Pulm Med 2019 Aug 14;19(1):152. Epub 2019 Aug 14.

University of St Andrews Medical School, St Andrews, UK.

Background: The phase III REMoxTB study prospectively enrolled HIV-positive (with CD4+ count > 250 cells, not on anti-retroviral therapy) and HIV-negative patients. We investigated the incidence of adverse events and cure rates according to HIV status for patients receiving standard TB therapy in the trial.

Methods: Forty-two HIV-positive cases were matched to 220 HIV-negative controls by age, gender, ethnicity, and trial site using coarsened exact matching. Grade 3 and 4 adverse events (AEs) were summarised by MedDRA System Organ Class. Kaplan-Meier curves for time to first grade 3 or 4 AE were constructed according to HIV status with hazard ratios calculated. Patients were considered cured if they were culture negative 18 months after commencing therapy with ≥2 consecutive negative culture results.

Results: Twenty of 42 (47.6%) HIV-positive and 34 of 220 (15.5%) HIV-negative patients experienced ≥1 grade 3 or 4 AE, respectively. The majority of these were hepatobiliary disorders that accounted for 12 of 40 (30.0%) events occurring in 6 of 42 (14.3%) HIV-positive patients and for 15 of 60 (25.0%) events occurring in 9 of 220 (4.1%) HIV-negative patients. The median time to first grade 3 or 4 AE was 54 days (IQR 15.5-59.0) for HIV-positive and 29.5 days (IQR 9.0-119.0) for HIV-negative patients, respectively. The hazard ratio for experiencing a grade 3 or 4 AE among HIV-positive patients was 3.25 (95% CI 1.87-5.66, p < 0.01). Cure rates were similar, with 38 of 42 (90.5%) HIV-positive and 195 of 220 (88.6%) HIV-negative patients (p = 0.73) cured at 18 months.

Conclusions: HIV-positive patients receiving standard TB therapy in the REMoxTB study were at greater risk of adverse events during treatment but cure rates were similar when compared to a matched sample of HIV-negative patients.
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http://dx.doi.org/10.1186/s12890-019-0907-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6694514PMC
August 2019

Feasibility of Identifying Household Contacts of Rifampin-and Multidrug-resistant Tuberculosis Cases at High Risk of Progression to Tuberculosis Disease.

Clin Infect Dis 2020 01;70(3):425-435

Aurum Institute, Parktown, South Africa.

Background: We assessed multidrug-resistant tuberculosis (MDR-TB) cases and their household contacts (HHCs) to inform the development of an interventional clinical trial.

Methods: We conducted a cross-sectional study of adult MDR-TB cases and their HHCs in 8 countries with high TB burdens. HHCs underwent symptom screenings, chest radiographies, sputum TB bacteriologies, TB infection (TBI) testing (tuberculin skin test [TST] and interferon gamma release assay [IGRA]), and human immunodeficiency virus (HIV) testing.

Results: From October 2015 to April 2016, 1016 HHCs from 284 MDR-TB cases were enrolled. At diagnosis, 69% of MDR-TB cases were positive for acid-fast bacilli sputum smears and 43% had cavitary disease; at study entry, 35% remained smear positive after a median MDR-TB treatment duration of 8.8 weeks. There were 9 HHCs that were diagnosed with TB prior to entry and excluded. Of the remaining 1007 HHCs, 41% were male and the median age was 25 years. There were 121 (12%) HHCs that had new cases of TB identified: 17 (2%) were confirmed, 33 (3%) probable, and 71 (7%) possible TB cases. The TBI prevalence (defined as either TST or IGRA positivity) was 72% and varied by age, test used, and country. Of 1007 HHCs, 775 (77%) were considered high-risk per these mutually exclusive groups: 102 (10%) were aged <5 years; 63 (6%) were aged ≥5 and were infected with HIV; and 610 (61%) were aged ≥5 years, were negative for HIV or had an unknown HIV status, and were TBI positive. Only 21 (2%) HHCs were on preventive therapy.

Conclusions: The majority of HHCs in these high-burden countries were at high risk of TB disease and infection, yet few were receiving routine preventive therapy. Trials of novel, preventive therapies are urgently needed to inform treatment policy and practice.
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http://dx.doi.org/10.1093/cid/ciz235DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7188224PMC
January 2020

Willingness to Take Multidrug-resistant Tuberculosis (MDR-TB) Preventive Therapy Among Adult and Adolescent Household Contacts of MDR-TB Index Cases: An International Multisite Cross-sectional Study.

Clin Infect Dis 2020 01;70(3):436-445

Centers for Disease Control and Prevention, Atlanta, Georgia.

Background: Household contacts (HHCs) of individuals with multidrug-resistant tuberculosis (MDR-TB) are at high risk of infection and subsequent disease. There is limited evidence on the willingness of MDR-TB HHCs to take MDR-TB preventive therapy (MDR TPT) to decrease their risk of TB disease.

Methods: In this cross-sectional study of HHCs of MDR-TB and rifampicin-resistant tuberculosis (RR-TB) index cases from 16 clinical research sites in 8 countries, enrollees were interviewed to assess willingness to take a hypothetical, newly developed MDR TPT if offered. To identify factors associated with willingness to take MDR TPT, a marginal logistic model was fitted using generalized estimating equations to account for household-level clustering.

Results: From 278 MDR-TB/RR-TB index case households, 743 HHCs were enrolled; the median age of HHCs was 33 (interquartile range, 22-49) years, and 62% were women. HHC willingness to take hypothetical MDR TPT was high (79%) and remained high even with the potential for mild side effects (70%). Increased willingness was significantly associated with current employment or schooling (adjusted odds ratio [aOR], 1.83 [95% confidence interval {CI}, 1.07-3.13]), appropriate TB-related knowledge (aOR, 2.22 [95% CI, 1.23-3.99]), confidence in taking MDR TPT (aOR, 7.16 [95% CI, 3.33-15.42]), and being comfortable telling others about taking MDR TPT (aOR, 2.29 [95% CI, 1.29-4.06]).

Conclusions: The high percentage of HHCs of MDR-TB/RR-TB index cases willing to take hypothetical MDR TPT provides important evidence for the potential uptake of effective MDR TPT when implemented. Identified HHC-level variables associated with willingness may inform education and counseling efforts to increase HHC confidence in and uptake of MDR TPT.
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http://dx.doi.org/10.1093/cid/ciz254DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7188234PMC
January 2020

A Population Pharmacokinetic Analysis Shows that Arylacetamide Deacetylase (AADAC) Gene Polymorphism and HIV Infection Affect the Exposure of Rifapentine.

Antimicrob Agents Chemother 2019 04 27;63(4). Epub 2019 Mar 27.

Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa.

Rifapentine is a rifamycin used to treat tuberculosis. As is the case for rifampin, plasma exposures of rifapentine are associated with the treatment response. While concomitant food intake and HIV infection explain part of the pharmacokinetic variability associated with rifapentine, few studies have evaluated the contribution of genetic polymorphisms. We evaluated the effects of functionally significant polymorphisms of the genes encoding OATP1B1, the pregnane X receptor (PXR), constitutive androstane (CAR), and arylacetamide deacetylase (AADAC) on rifapentine exposure. Two studies evaluating novel regimens among southern African patients with drug-susceptible pulmonary tuberculosis were included in this analysis. In the RIFAQUIN study, rifapentine was administered in the continuation phase of antituberculosis treatment in 1,200-mg-once-weekly or 900-mg-twice-weekly doses. In the Daily RPE study, 450 or 600 mg was given daily during the intensive phase of treatment. Nonlinear mixed-effects modeling was used to describe the pharmacokinetics of rifapentine and to identify significant covariates. A total of 1,144 drug concentration measurements from 326 patients were included in the analysis. Pharmacogenetic information was available for 162 patients. A one-compartment model with first-order elimination and transit compartment absorption described the data well. In a typical patient (body weight, 56 kg; fat-free mass, 45 kg), the values of clearance and volume of distribution were 1.33 liters/h and 25 liters, respectively. Patients carrying the AA variant (65.4%) of rs1803155 were found to have a 10.4% lower clearance. HIV-infected patients had a 21.9% lower bioavailability. Once-weekly doses of 1,200 mg were associated with a reduced clearance (13.2%) compared to that achieved with more frequently administered doses. Bioavailability was 23.3% lower among patients participating in the Daily RPE study than in those participating in the RIFAQUIN study. This is the first study to report the effect of rs1803155AA on rifapentine clearance. The observed increase in exposure is modest and unlikely to be of clinical relevance. The difference in bioavailability between the two studies is probably related to the differences in food intake concomitant with the dose. HIV-coinfected patients had lower rifapentine exposures.
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http://dx.doi.org/10.1128/AAC.01964-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6437540PMC
April 2019

Toxicity associated with tuberculosis chemotherapy in the REMoxTB study.

BMC Infect Dis 2018 07 11;18(1):317. Epub 2018 Jul 11.

University of St Andrews Medical School, St Andrews, UK.

Background: The incidence and severity of tuberculosis chemotherapy toxicity is poorly characterised. We used data available from patients in the REMoxTB trial to provide an assessment of the risks associated with the standard regimen and two experimental regimens containing moxifloxacin.

Methods: All grade 3 & 4 adverse events (AEs) and their relationship to treatment for patients who had taken at least one dose of therapy in the REMoxTB clinical trial were recorded. Univariable logistic regression was used to test the relationship of baseline characteristics to the incidence of grade 3 & 4 AEs and significant characteristics (p < 0.10) were incorporated into a multivariable model. The timing of AEs during therapy was analysed in standard therapy and the experimental arms. Logistic regression was used to investigate the relationship between AEs (total and related-only) and microbiological cure on treatment.

Results: In the standard therapy arm 57 (8.9%) of 639 patients experienced ≥1 related AEs with 80 of the total 113 related events (70.8%) occurring in the intensive phase of treatment. Both four-month experimental arms ("isoniazid arm" with moxifloxacin substituted for ethambutol & "ethambutol arm" with moxifloxacin substituted for isoniazid) had a lower total of related grade 3 & 4 AEs than standard therapy (63 & 65 vs 113 AEs). Female gender (adjOR 1.97, 95% CI 0.91-1.83) and HIV-positive status (adjOR 3.33, 95% CI 1.55-7.14) were significantly associated with experiencing ≥1 related AE (p < 0.05) on standard therapy. The most common adverse events on standard therapy related to hepatobiliary, musculoskeletal and metabolic disorders. Patients who experienced ≥1 related AE were more likely to fail treatment or relapse (adjOR 3.11, 95% CI 1.59-6.10, p < 0.001).

Conclusions: Most AEs considered related to standard therapy occurred in the intensive phase of treatment with female patients and HIV-positive patients demonstrating a significantly higher risk of AEs during treatment. Almost a tenth of standard therapy patients had a significant side effect, whereas both experimental arms recorded a lower incidence of toxicity. That patients with one or more AE are more likely to fail treatment suggests that treatment outcomes could be improved by identifying such patients through targeted monitoring.
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http://dx.doi.org/10.1186/s12879-018-3230-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6042413PMC
July 2018

The Potential for Treatment Shortening With Higher Rifampicin Doses: Relating Drug Exposure to Treatment Response in Patients With Pulmonary Tuberculosis.

Clin Infect Dis 2018 06;67(1):34-41

Department of Pharmacy, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.

Background: Tuberculosis remains a huge public health problem and the prolonged treatment duration obstructs effective tuberculosis control. Higher rifampicin doses have been associated with better bactericidal activity, but optimal dosing is uncertain. This analysis aimed to characterize the relationship between rifampicin plasma exposure and treatment response over 6 months in a recent study investigating the potential for treatment shortening with high-dose rifampicin.

Methods: Data were analyzed from 336 patients with pulmonary tuberculosis (97 with pharmacokinetic data) treated with rifampicin doses of 10, 20, or 35 mg/kg. The response measure was time to stable sputum culture conversion (TSCC). We derived individual exposure metrics with a previously developed population pharmacokinetic model of rifampicin. TSCC was modeled using a parametric time-to-event approach, and a sequential exposure-response analysis was performed.

Results: Higher rifampicin exposures increased the probability of early culture conversion. No maximal limit of the effect was detected within the observed range. The expected proportion of patients with stable culture conversion on liquid medium at week 8 was predicted to increase from 39% (95% confidence interval, 37%-41%) to 55% (49%-61%), with the rifampicin area under the curve increasing from 20 to 175 mg/L·h (representative for 10 and 35 mg/kg, respectively). Other predictors of TSCC were baseline bacterial load, proportion of culture results unavailable, and substitution of ethambutol for either moxifloxacin or SQ109.

Conclusions: Increasing rifampicin exposure shortened TSCC, and the effect did not plateau, indicating that doses >35 mg/kg could be yet more effective. Optimizing rifampicin dosage while preventing toxicity is a clinical priority.
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http://dx.doi.org/10.1093/cid/ciy026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6005123PMC
June 2018

Greater Early Bactericidal Activity at Higher Rifampicin Doses Revealed by Modeling and Clinical Trial Simulations.

J Infect Dis 2018 08;218(6):991-999

Department of Pharmaceutical Biosciences, Uppsala University, Sweden.

Background: The currently recommended rifampicin dose (10 mg/kg) for treating tuberculosis is suboptimal. The PanACEA HIGHRIF1 trial evaluated the pharmacokinetics and early bactericidal activity of rifampicin doses of up to 40 mg/kg. Conventional statistical analyses revealed no significant exposure-response relationship. Our objectives were to explore the exposure-response relationship for high-dose rifampicin by using pharmacokinetic-pharmacodynamic modeling and to predict the early bactericidal activity of 50 mg/kg rifampicin.

Methods: Data included time to Mycobacterium tuberculosis positivity of liquid cultures of sputum specimens from 83 patients with tuberculosis who were treated with 10 mg/kg rifampicin (n = 8; reference arm) or 20, 25, 30, 35, or 40 mg/kg rifampicin (n = 15/arm) for 7 days. We used a semimechanistic time-to-event approach to model the time-to-positivity data. Rifampicin exposure and baseline time to culture positivity were explored as covariates.

Results: The baseline time to culture positivity was a significant covariate on the predicted initial bacterial load, and rifampicin exposure was a significant covariate on the bacterial kill rate in sputum resulting in increased early bactericidal activity. The 90% prediction interval for the predicted median day 7 increase in time to positivity for 50 mg/kg rifampicin was 7.25-10.3 days.

Conclusions: A significant exposure-response relationship was found between rifampicin exposure and early bactericidal activity. Clinical trial simulations showed greater early bactericidal activity for 50 mg/kg rifampicin.

Clinical Trials Registration: NCT01392911.
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http://dx.doi.org/10.1093/infdis/jiy242DOI Listing
August 2018

Liver toxicity associated with tuberculosis chemotherapy in the REMoxTB study.

BMC Med 2018 03 28;16(1):46. Epub 2018 Mar 28.

University of St Andrews Medical School, St Andrews, UK.

Background: Drug-induced liver injury (DILI) is a common complication of tuberculosis treatment. We utilised data from the REMoxTB clinical trial to describe the incidence of predisposing factors and the natural history in patients with liver enzyme levels elevated in response to tuberculosis treatment.

Methods: Patients received either standard tuberculosis treatment (2EHRZ/4HR), or a 4-month regimen in which moxifloxacin replaced either ethambutol (isoniazid arm, 2MHRZ/2MHR) or isoniazid (ethambutol arm, 2EMRZ/2MR). Hepatic enzymes were measured at 0, 2, 4, 8, 12 and 17 weeks and as clinically indicated during reported adverse events. Patients included were those receiving at least one dose of drug and with two or more hepatic enzyme measurements.

Results: A total of 1928 patients were included (639 2EHRZ/4HR, 654 2MHRZ/2MHR and 635 2EMRZ/2MR). DILI was defined as peak alanine aminotransferase (ALT) ≥ 5 times the upper limit of normal (5 × ULN) or ALT ≥ 3 × ULN with total bilirubin > 2 × ULN. DILI was identified in 58 of the 1928 (3.0%) patients at a median time of 28 days (interquartile range IQR 14-56). Of 639 (6.4%) patients taking standard tuberculosis therapy, 41 experienced clinically significant enzyme elevations (peak ALT ≥ 3 × ULN). On standard therapy, 21.1% of patients aged >55 years developed a peak ALT/aspartate aminotransferase (AST) ≥ 3 × ULN (p = 0.01) and 15% of HIV-positive patients experienced a peak ALT/AST ≥ 3 × ULN compared to 9% of HIV-negative patients (p = 0.160). The median peak ALT/AST was higher in isoniazid-containing regimens vs no-isoniazid regimens (p < 0.05), and lower in moxifloxacin-containing arms vs no-moxifloxacin arms (p < 0.05). Patients receiving isoniazid reached a peak ALT ≥ 3 × ULN 9.5 days earlier than those on the ethambutol arm (median time of 28 days vs 18.5 days). Of the 67 Asian patients with a peak ALT/AST ≥ 3 × ULN, 57 (85.1%) were on an isoniazid-containing regimen (p = 0.008).

Conclusions: Our results provide evidence of the risk of DILI in tuberculosis patients on standard treatment. Older patients on standard therapy, HIV-positive patients, Asian patients and those receiving isoniazid were at higher risk of elevated enzyme levels. Monitoring hepatic enzymes during the first 2 months of standard therapy detected approximately 75% of patients with a peak enzyme elevation ≥3 × ULN, suggesting this should be a standard of care. These results provide evidence for the potential of moxifloxacin in hepatic sparing.
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http://dx.doi.org/10.1186/s12916-018-1033-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5875008PMC
March 2018

Using biomarkers to predict TB treatment duration (Predict TB): a prospective, randomized, noninferiority, treatment shortening clinical trial.

Gates Open Res 2017 Nov 6;1. Epub 2017 Nov 6.

Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA.

: By the early 1980s, tuberculosis treatment was shortened from 24 to 6 months, maintaining relapse rates of 1-2%. Subsequent trials attempting shorter durations have failed, with 4-month arms consistently having relapse rates of 15-20%. One trial shortened treatment only among those without baseline cavity on chest x-ray and whose month 2 sputum culture converted to negative. The 4-month arm relapse rate decreased to 7% but was still significantly worse than the 6-month arm (1.6%, P<0.01).  We hypothesize that PET/CT characteristics at baseline, PET/CT changes at one month, and markers of residual bacterial load will identify patients with tuberculosis who can be cured with 4 months (16 weeks) of standard treatment. : This is a prospective, multicenter, randomized, phase 2b, noninferiority clinical trial of pulmonary tuberculosis participants. Those eligible start standard of care treatment. PET/CT scans are done at weeks 0, 4, and 16 or 24. Participants who do not meet early treatment completion criteria (baseline radiologic severity, radiologic response at one month, and GeneXpert-detectable bacilli at four months) are placed in Arm A (24 weeks of standard therapy). Those who meet the early treatment completion criteria are randomized at week 16 to continue treatment to week 24 (Arm B) or complete treatment at week 16 (Arm C). The primary endpoint compares the treatment success rate at 18 months between Arms B and C. : Multiple biomarkers have been assessed to predict TB treatment outcomes. This study uses PET/CT scans and GeneXpert (Xpert) cycle threshold to risk stratify participants. PET/CT scans are not applicable to global public health but could be used in clinical trials to stratify participants and possibly become a surrogate endpoint. If the Predict TB trial is successful, other immunological biomarkers or transcriptional signatures that correlate with treatment outcome may be identified.

Trial Registration: NCT02821832.
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http://dx.doi.org/10.12688/gatesopenres.12750.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5841574PMC
November 2017

Diagnostic Outcomes After Chest Radiograph Interpretation in Patients With Suspected Tuberculosis and Negative Sputum Smears in a High-Burden Human Immunodeficiency Virus and Tuberculosis Setting.

Open Forum Infect Dis 2017 17;4(3):ofx123. Epub 2017 Jun 17.

Department of Internal Medicine, Edendale Hospital, University of KwaZulu-Natal, Pietermaritzburg, South Africa.

Background: Evaluation of patients with suspected tuberculosis and negative sputum smears for acid-fast bacilli (AFB) is challenging, especially in high human immunodeficiency virus coinfection settings where sputum smears have lower sensitivity for detecting AFB.

Methods: We examined the utility of chest radiographs for detecting smear-negative pulmonary tuberculosis. Three hundred sixty sputum smear-negative patients who were referred from primary care clinics in the KwaZulu-Natal province of South Africa were evaluated. Chest radiographs were read by experienced pulmonologists using a previously validated Chest X-Ray Reading and Recording System (CRRS).

Results: Agreement between observers using CRRS was high at 91% with a Cohen's kappa of 0.64 (95% confidence interval [CI] = 0.52-0.76). Against a reference standard of sputum culture, sensitivity was 93% (95% CI = 86%-97%), whereas specificity was 14% (95% CI = 10%-19%). Performance against clinical diagnosis (following World Health Organization guidelines) was similar with sensitivity of 92% (95% CI = 88%-95%) and specificity of 20% (95% CI = 13%-28%).

Conclusion: The low specificity of CRRS in this setting indicates poor diagnostic utility for detecting pulmonary tuberculosis.
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http://dx.doi.org/10.1093/ofid/ofx123DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5508775PMC
June 2017

A Population Pharmacokinetic Model Incorporating Saturable Pharmacokinetics and Autoinduction for High Rifampicin Doses.

Clin Pharmacol Ther 2018 04 7;103(4):674-683. Epub 2017 Aug 7.

Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.

Accumulating evidence suggests that increasing doses of rifampicin may shorten tuberculosis treatment. The PanACEA HIGHRIF1 trial assessed safety, pharmacokinetics, and antimycobacterial activity of rifampicin at doses up to 40 mg/kg. Eighty-three pulmonary tuberculosis patients received 10, 20, 25, 30, 35, or 40 mg/kg rifampicin daily over 2 weeks, supplemented with standard doses of isoniazid, pyrazinamide, and ethambutol in the second week. This study aimed at characterizing rifampicin pharmacokinetics observed in HIGHRIF1 using nonlinear mixed effects modeling. The final population pharmacokinetic model included an enzyme turnover model accounting for time-dependent elimination due to autoinduction, concentration-dependent clearance, and dose-dependent bioavailability. The relationship between clearance and concentration was characterized by a Michaelis-Menten relationship. The relationship between bioavailability and dose was described using an E relationship. The model will be key in determining exposure-response relationships for rifampicin and should be considered when designing future trials and when treating future patients with high-dose rifampicin.
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http://dx.doi.org/10.1002/cpt.778DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5888114PMC
April 2018

Anaerobic Bacterial Fermentation Products Increase Tuberculosis Risk in Antiretroviral-Drug-Treated HIV Patients.

Cell Host Microbe 2017 Apr 30;21(4):530-537.e4. Epub 2017 Mar 30.

Division of Pulmonary, Critical Care and Sleep Medicine, School of Medicine, New York University, New York, NY 10016, USA. Electronic address:

Despite the immune-reconstitution with antiretroviral therapy (ART), HIV-infected individuals remain highly susceptible to tuberculosis (TB) and have an enrichment of oral anaerobes in the lung. Products of bacterial anaerobic metabolism, like butyrate and other short-chain fatty acids (SCFAs), induce regulatory T cells (Tregs). We tested whether SCFAs contribute to poor TB control in a longitudinal cohort of ART-treated HIV-infected South Africans. Increase in serum SCFAs was associated with increased TB susceptibility. SCFAs inhibited IFN-γ and IL-17A production in peripheral blood mononuclear cells from HIV-infected ART-treated individuals in response to M. tuberculosis antigen stimulation. Pulmonary SCFAs correlated with increased oral anaerobes, such as Prevotella in the lung, and with M. tuberculosis antigen-induced Tregs. Metabolites from anaerobic bacterial fermentation may, therefore, increase TB susceptibility by suppressing IFN-γ and IL-17A production during the cellular immune response to M. tuberculosis.
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http://dx.doi.org/10.1016/j.chom.2017.03.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5465639PMC
April 2017

High-dose rifampicin, moxifloxacin, and SQ109 for treating tuberculosis: a multi-arm, multi-stage randomised controlled trial.

Lancet Infect Dis 2017 01 26;17(1):39-49. Epub 2016 Oct 26.

Division of Infectious Diseases and Tropical Medicine, Medical Centre of the University of Munich, Munich, Germany; German Center for Infection Research, Partner Site Munich, Germany.

Background: Tuberculosis is the world's leading infectious disease killer. We aimed to identify shorter, safer drug regimens for the treatment of tuberculosis.

Methods: We did a randomised controlled, open-label trial with a multi-arm, multi-stage design. The trial was done in seven sites in South Africa and Tanzania, including hospitals, health centres, and clinical trial centres. Patients with newly diagnosed, rifampicin-sensitive, previously untreated pulmonary tuberculosis were randomly assigned in a 1:1:1:1:2 ratio to receive (all orally) either 35 mg/kg rifampicin per day with 15-20 mg/kg ethambutol, 20 mg/kg rifampicin per day with 400 mg moxifloxacin, 20 mg/kg rifampicin per day with 300 mg SQ109, 10 mg/kg rifampicin per day with 300 mg SQ109, or a daily standard control regimen (10 mg/kg rifampicin, 5 mg/kg isoniazid, 25 mg/kg pyrazinamide, and 15-20 mg/kg ethambutol). Experimental treatments were given with oral 5 mg/kg isoniazid and 25 mg/kg pyrazinamide per day for 12 weeks, followed by 14 weeks of 5 mg/kg isoniazid and 10 mg/kg rifampicin per day. Because of the orange discoloration of body fluids with higher doses of rifampicin it was not possible to mask patients and clinicians to treatment allocation. The primary endpoint was time to culture conversion in liquid media within 12 weeks. Patients without evidence of rifampicin resistance on phenotypic test who took at least one dose of study treatment and had one positive culture on liquid or solid media before or within the first 2 weeks of treatment were included in the primary analysis (modified intention to treat). Time-to-event data were analysed using a Cox proportional-hazards regression model and adjusted for minimisation variables. The proportional hazard assumption was tested using Schoelfeld residuals, with threshold p<0·05 for non-proportionality. The trial is registered with ClinicalTrials.gov (NCT01785186).

Findings: Between May 7, 2013, and March 25, 2014, we enrolled and randomly assigned 365 patients to different treatment arms (63 to rifampicin 35 mg/kg, isoniazid, pyrazinamide, and ethambutol; 59 to rifampicin 10 mg/kg, isoniazid, pyrazinamide, SQ109; 57 to rifampicin 20 mg/kg, isoniazid, pyrazinamide, and SQ109; 63 to rifampicin 10 mg/kg, isoniazid, pyrazinamide, and moxifloxacin; and 123 to the control arm). Recruitment was stopped early in the arms containing SQ109 since prespecified efficacy thresholds were not met at the planned interim analysis. Time to stable culture conversion in liquid media was faster in the 35 mg/kg rifampicin group than in the control group (median 48 days vs 62 days, adjusted hazard ratio 1·78; 95% CI 1·22-2·58, p=0·003), but not in other experimental arms. There was no difference in any of the groups in time to culture conversion on solid media. 11 patients had treatment failure or recurrent disease during post-treatment follow-up: one in the 35 mg/kg rifampicin arm and none in the moxifloxacin arm. 45 (12%) of 365 patients reported grade 3-5 adverse events, with similar proportions in each arm.

Interpretation: A dose of 35 mg/kg rifampicin was safe, reduced the time to culture conversion in liquid media, and could be a promising component of future, shorter regimens. Our adaptive trial design was successfully implemented in a multi-centre, high tuberculosis burden setting, and could speed regimen development at reduced cost.

Funding: The study was funded by the European and Developing Countries Clinical Trials partnership (EDCTP), the German Ministry for Education and Research (BmBF), and the Medical Research Council UK (MRC).
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http://dx.doi.org/10.1016/S1473-3099(16)30274-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5159618PMC
January 2017

Safety and Immunogenicity of Adenovirus 35 Tuberculosis Vaccine Candidate in Adults with Active or Previous Tuberculosis. A Randomized Trial.

Am J Respir Crit Care Med 2017 05;195(9):1171-1180

1 University of Cape Town Lung Institute, Division of Pulmonology, Department of Medicine.

Rationale: Administration of tuberculosis (TB) vaccines in participants with previous or current pulmonary TB may have the potential for causing harmful postvaccination immunologic (Koch-type) reactions.

Objectives: To assess the safety and immunogenicity of three dose levels of the AERAS-402 live, replication-deficient adenovirus 35-vectored TB candidate vaccine, containing three mycobacterial antigens, in individuals with current or previous pulmonary TB.

Methods: We performed a phase II randomized, placebo-controlled, double-blinded dose-escalation study in an HIV-negative adult South African cohort (n = 72) with active pulmonary TB (on treatment for 1-4 mo) or pulmonary TB treated at least 12 months before study entry and considered cured. Safety endpoints included clinical assessment, flow volume curves, diffusing capacity of the lung for carbon monoxide, pulse oximetry, chest radiograph, and high-resolution thoracic computerized tomography scans. Cytokine expression by CD4 and CD8 T cells, after stimulation with Ag85A, Ag85B, and TB10.4 peptide pools, was examined by intracellular cytokine staining.

Measurements And Main Results: No apparent temporal or dose-related changes in clinical status (specifically acute, Koch phenomenon-like reactions), lung function, or radiology attributable to vaccine were observed. Injection site reactions were mild or moderate. Hematuria (by dipstick only) occurred in 25 (41%) of 61 AERAS-402 recipients and 3 (27%) of 11 placebo recipients, although no gross hematuria was reported. AERAS-402 induced robust CD8 and moderate CD4 T-cell responses, mainly to Ag85B in both vaccine groups.

Conclusions: Administration of the AERAS-402 candidate TB vaccine to participants with current or previous pulmonary TB induced a robust immune response and is not associated with clinically significant pulmonary complications. Clinical trial registered with www.clinicaltrials.gov (NCT 02414828) and in the South African National Clinical Trials Register ( www.sanctr.gov.za DOH 27-0808-2060).
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http://dx.doi.org/10.1164/rccm.201603-0654OCDOI Listing
May 2017

An automated tuberculosis screening strategy combining X-ray-based computer-aided detection and clinical information.

Sci Rep 2016 04 29;6:25265. Epub 2016 Apr 29.

Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, Gelderland, the Netherlands.

Lack of human resources and radiological interpretation expertise impair tuberculosis (TB) screening programmes in TB-endemic countries. Computer-aided detection (CAD) constitutes a viable alternative for chest radiograph (CXR) reading. However, no automated techniques that exploit the additional clinical information typically available during screening exist. To address this issue and optimally exploit this information, a machine learning-based combination framework is introduced. We have evaluated this framework on a database containing 392 patient records from suspected TB subjects prospectively recruited in Cape Town, South Africa. Each record comprised a CAD score, automatically computed from a CXR, and 12 clinical features. Comparisons with strategies relying on either CAD scores or clinical information alone were performed. Our results indicate that the combination framework outperforms the individual strategies in terms of the area under the receiving operating characteristic curve (0.84 versus 0.78 and 0.72), specificity at 95% sensitivity (49% versus 24% and 31%) and negative predictive value (98% versus 95% and 96%). Thus, it is believed that combining CAD and clinical information to estimate the risk of active disease is a promising tool for TB screening.
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http://dx.doi.org/10.1038/srep25265DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4850474PMC
April 2016

Limited role of culture conversion for decision-making in individual patient care and for advancing novel regimens to confirmatory clinical trials.

BMC Med 2016 Feb 4;14:19. Epub 2016 Feb 4.

School of Medicine, University of St Andrews, St Andrews, UK.

Background: Despite recent increased clinical trials activity, no regimen has proved able to replace the standard 6-month regimen for drug-sensitive tuberculosis. Understanding the relationship between microbiological markers measured during treatment and long-term clinical outcomes is critical to evaluate their usefulness for decision-making for both individual patient care and for advancing novel regimens into time-consuming and expensive pivotal phase III trials.

Methods: Using data from the randomized controlled phase III trial REMoxTB, we evaluated sputum-based markers of speed of clearance of bacilli: time to smear negative status; time to culture negative status on LJ or in MGIT; daily rate of change of log10(TTP) to day 56; and smear or culture results at weeks 6, 8 or 12; as individual- and trial-level surrogate endpoints for long-term clinical outcome.

Results: Time to culture negative status on LJ or in MGIT, time to smear negative status and daily rate of change in log10(TTP) were each independent predictors of clinical outcome, adjusted for treatment (p <0.001). However, discrimination between low and high risk patients, as measured by the c-statistic, was modest and not much higher than the reference model adjusted for BMI, history of smoking, HIV status, cavitation, gender and MGIT TTP.

Conclusions: Culture conversion during treatment for tuberculosis, however measured, has only a limited role in decision-making for advancing regimens into phase III trials or in predicting the outcome of treatment for individual patients. REMoxTB ClinicalTrials.gov number: NCT00864383.
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http://dx.doi.org/10.1186/s12916-016-0565-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4743210PMC
February 2016