High-dose rifapentine with moxifloxacin for pulmonary tuberculosis

Mycobacterial infections in solid organ transplant recipients

Mycobacterium tuberculosis (MTB) infection in solid organ transplant (SOT) recipients remains a major challenge for physicians and surgeons. Active tuberculosis (TB) is associated with increased morbidity and mortality in SOT recipients. MTB usually develops after transplantation in a recipient with latent TB infection (LTBI) before transplantation and may also be transmitted from the donor or acquired from the community. Therefore, screening for LTBI in donors and recipients before transplantation is very important in preventing active disease after transplantation. This review article is based on recently published data, case series, and expert recommendations. We reviewed updated information about the epidemiology, diagnosis, and treatment of latent and active TB before and after transplantation. We also reviewed recent treatments for multidrug-resistant TB.

Improving the Drug Development Pipeline for Mycobacteria: Modelling Antibiotic Exposure in the Hollow Fibre Infection Model

Mycobacterial infections are difficult to treat, requiring a combination of drugs and lengthy treatment times, thereby presenting a substantial burden to both the patient and health services worldwide. The limited treatment options available are under threat due to the emergence of antibiotic resistance in the pathogen, hence necessitating the development of new treatment regimens. Drug development processes are lengthy, resource intensive, and high-risk, which have contributed to market failure as demonstrated by pharmaceutical companies limiting their antimicrobial drug discovery programmes. Pre-clinical protocols evaluating treatment regimens that can mimic in vivo PK/PD attributes can underpin the drug development process. The hollow fibre infection model (HFIM) allows for the pathogen to be exposed to a single or a combination of agents at concentrations achieved in vivo-in plasma or at infection sites. Samples taken from the HFIM, depending on the analyses performed, provide information on the rate of bacterial killing and the emergence of resistance. Thereby, the HFIM is an effective means to investigate the efficacy of a drug combination. Although applicable to a wide variety of infections, the complexity of anti-mycobacterial drug discovery makes the information available from the HFIM invaluable as explored in this review.

Evaluation of implementation and effectiveness of digital adherence technology with differentiated care to support tuberculosis treatment adherence and improve treatment outcomes in Ethiopia: a study protocol for a cluster randomised trial

Background

Digital adherence technologies (DATs) are recommended to support patient-centred, differentiated care to improve tuberculosis (TB) treatment outcomes, but evidence that such technologies improve adherence is limited. We aim to implement and evaluate the effectiveness of smart pillboxes and medication labels linked to an adherence data platform, to create a differentiated care response to patient adherence and improve TB care among adult pulmonary TB participants. Our study is part of the Adherence Support Coalition to End TB (ASCENT) project in Ethiopia.

Methods/Design

We will conduct a pragmatic three-arm cluster-randomised trial with 78 health facilities in two regions in Ethiopia. Facilities are randomised (1:1:1) to either of the two intervention arms or standard of care. Adults aged ≥ 18 years with drug-sensitive (DS) pulmonary TB are enrolled over 12 months and followed-up for 12 months after treatment initiation. Participants in facilities randomised to either of the two intervention arms are offered a DAT linked to the web-based ASCENT adherence platform for daily adherence monitoring and differentiated response to patient adherence for those who have missed doses. Participants at standard of care facilities receive routine care. For those that had bacteriologically confirmed TB at treatment initiation and can produce sputum without induction, sputum culture will be performed approximately 6 months after the end of treatment to measure disease recurrence. The primary endpoint is a composite unfavourable outcome measured over 12 months from TB treatment initiation defined as either poor end of treatment outcome (lost to follow-up, death, or treatment failure) or treatment recurrence measured 6 months after the scheduled end of treatment. This study will also evaluate the effectiveness, feasibility, and cost-effectiveness of DAT systems for DS-TB patients.

Discussion

This trial will evaluate the impact and contextual factors of medication label and smart pillbox with a differentiated response to patient care, among adult pulmonary DS-TB participants in Ethiopia. If successful, this evaluation will generate valuable evidence via a shared evaluation framework for optimal use and scale-up.

Trial registration: Pan African Clinical Trials Registry PACTR202008776694999, https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=12241, registered on August 11, 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06833-x.

Precision-Enhancing Risk Stratification Tools for Selecting Optimal Treatment Durations in Tuberculosis Clinical Trials

Rationale: No evidence-based tools exist to enhance precision in the selection of patient-specific optimal treatment durations to study in tuberculosis clinical trials. Objectives: To develop risk stratification tools that assign patients with tuberculosis into risk groups of unfavorable outcome and inform selection of optimal treatment duration for each patient strata to study in clinical trials. Methods: Publicly available data from four phase 3 trials, each evaluating treatment duration shortening from 6 to 4 months, were used to develop parametric time-to-event models that describe unfavorable outcomes. Regimen, baseline, and on-treatment characteristics were evaluated as predictors of outcomes. Exact regression coefficients of predictors were used to assign risk groups and predict optimal treatment durations. Measurements and Main Results: The parametric model had an area under the receiver operating characteristic curve of 0.72. A six-item risk score (HIV status, smear grade, sex, cavitary disease status, body mass index, and Month 2 culture status) successfully grouped participants into low (1,060/3,791; 28%), moderate (1,740/3,791; 46%), and high (991/3,791; 26%) risk, requiring treatment durations of 4, 6, and greater than 6 months, respectively, to reach a target cure rate of 93% when receiving standard-dose rifamycin-containing regimens. With current one-duration-fits-all approaches, high-risk groups have a 3.7-fold (95% confidence interval, 2.7-5.1) and 2.4-fold (1.9-2.9) higher hazard risk of unfavorable outcomes compared with low- and moderate-risk groups, respectively. Four-month regimens were noninferior to the standard 6-month regimen in the low-risk group. Conclusions: Our model discrimination was modest but consistent with current models of unfavorable outcomes. Our results showed that stratified medicine approaches are feasible and may achieve high cure rates in all patients with tuberculosis. An interactive risk stratification tool is provided to facilitate decision-making in the regimen development pathway.

Recurrent pulmonary tuberculosis after treatment success: a population-based retrospective study in China

OBJECTIVES

Post-treatment recurrence remains a challenge for the global control of tuberculosis (TB). This study investigated longitudinal data on pulmonary TB recurrence rates and its risk factors among successfully treated smear-positive tuberculosis cases in China.

METHODS

From 1 January 2009 to 31 December 2016, we evaluated 33,441 treatment-naïve patients diagnosed with sputum smear-positive, non-multidrug-resistant TB in Hangzhou, China. We included the data of 9,828 patients with TB who were successfully treated.

RESULTS

A total of 4.9% were recurrent cases (479/9,828), identified within a median observation period lasting 1,565 days. Altogether, 51.1% (245/479) of the recurrences occurred within one year. The cumulative 2- and 5-year recurrence rates were 3.90% (95% confidence interval [CI], 3.3%-4.5%) and 5.4% (95% CI, 4.8%-6.0%), respectively. Prolonged treatment (over 7 months) was occurred in 64.7% (6,363/9,828), with median treatment duration of 242 (interquartile range, 195-348) days. Male sex (adjusted hazard ratio [aHR] [95% CI] = 1.61 [1.30-2.00], P<0.001), ≥ 60-years age (aHR [95% CI] = 2.03 [1.70-2.44], P<0.001), pulmonary cavity (aHR [95% CI] = 1.51 [1.25-1.82], P<0.001) and sputum positive at 2 months (aHR [95% CI] =1.39 [1.05-1.81], P=0.02) increased the risk of TB recurrence. Prolonged treatment was associated with reduced TB recurrence (aHR [95% CI] =0.73 [0.61-0.88], P=0.001).

CONCLUSIONS

Recurrence remains a problem for successfully treated patients with sputum smear-positive pulmonary TB, especially those with independent risk factors. Further analysis of prolonged treatment is required.

Predictors of unfavorable responses to therapy in rifampicin-sensitive pulmonary tuberculosis using an integrated approach of radiological presentation and sputum mycobacterial burden

INTRODUCTION

Despite the exalted status of sputum mycobacterial load for gauging pulmonary tuberculosis treatment and progress, Chest X-rays supplement valuable information for taking instantaneous therapeutic decisions, especially during the COVID-19 pandemic. Even though literature on individual parameters is overwhelming, few studies have explored the interaction between radiographic parameters denoting severity with mycobacterial burden signifying infectivity. By using a sophisticated approach of integrating Chest X-ray parameters with sputum mycobacterial characteristics, evaluated at all the three crucial time points of TB treatment namely pre-treatment, end of intensive phase and completion of treatment, utilizing the interactive Cox Proportional Hazards model, we aimed to precisely deduce predictors of unfavorable response to TB treatment.

MATERIALS AND METHOD

We extracted de-identified data from well characterized clinical trial cohorts that recruited rifampicin-sensitive Pulmonary TB patients without any comorbidities, taking their first spell of anti-tuberculosis therapy under supervision and meticulous follow up for 24 months post treatment completion, to accurately predict TB outcomes. Radiographic data independently obtained, interpreted by two experienced pulmonologists was collated with demographic details and, sputum smear and culture grades of participants by an independent statistician and analyzed using the Cox Proportional Hazards model, to not only adjust for confounding factors including treatment effect, but also explore the interaction between radiological and bacteriological parameters for better therapeutic application.

RESULTS

Of 667 TB patients with data available, cavitation, extent of involvement, lower zone involvement, smear and culture grade at baseline were significant parameters predisposing to an unfavorable TB treatment outcome in the univariate analysis. Reduction in radiological lesions in Chest X-ray by at least 50% at 2 months and 75% at the end of treatment helped in averting unfavorable responses. Smear and Culture conversion at the end of 2 months was highly significant as a predictor (p<0.001). In the multivariate analysis, the adjusted hazards ratios (HR) for an unfavorable response to TB therapy for extent of involvement, baseline cavitation and persistence (post treatment) were 1.21 (95% CI: 1.01-1.44), 1.73 (95% CI: 1.05-2.84) and 2.68 (95% CI: 1.4-5.12) respectively. A 3+ smear had an HR of 1.94 (95% CI: 0.81-4.64). Further probing into the interaction, among patients with 3+ and 2+ smears, HRs for cavitation were 3.26 (95% CI: 1.33-8.00) and 1.92 (95% CI: 0.80-4.60) while for >2 zones, were 3.05 (95% CI: 1.12-8.23) and 1.92 (95% CI: 0.72-5.08) respectively. Patients without cavitation, zonal involvement <2, and a smear grade less than 2+ had a better prognosis and constituted minimal disease.

CONCLUSION

Baseline Cavitation, Opacities occupying >2 zones and 3+ smear grade individually and independently forecasted a poorer TB outcome. The interaction model revealed that Zonal involvement confined to 2 zones, without a cavity and smear grade up to 2+, constituting "minimal disease", had a better prognosis. Radiological clearance >50% along with smear conversion at the end of intensive phase of treatment, observed to be a reasonable alternative to culture conversion in predicting a successful outcome. These parameters may potentially take up key positions as stratification factors for future trials contemplating on shorter TB regimens.

The pharmacotherapeutic management of pulmonary tuberculosis: an update of the state-of-the-art

INTRODUCTION

Pulmonary tuberculosis (TB) remains an important global health challenge of the 21st century, and the emerging resistance against anti-TB drugs is still a growing concern. And while there was a significant cumulative reduction in the incidence of TB between 2015 and 2019, 2.8% of all TB cases in 2019 were reported to be drug resistant.

AREA COVERED

This review provides the reader with an update on pharmacotherapy for patients with TB susceptible or resistant to drug therapy. The authors also include promising investigational drugs herein. Finally, the authors share with the reader their expert opinions on the current state of the art and their future perspectives.

EXPERT OPINION

The current pharmacotherapeutic management aims to enhance favorable treatment outcomes and reduce treatment-related adverse events. One approach is to use shorter and all-oral regimens for eligible patients. Traditional longer regimens for most patients are also optimized to lower incidence of treatment failure and serious adverse events.

A Rapid Pharmacogenomic Assay to Detect NAT2 Polymorphisms and Guide Isoniazid Dosing for Tuberculosis Treatment

RATIONALE

Standardized dosing of anti-tubercular drugs contributes to a substantial incidence of toxicities, inadequate treatment response, and relapse, in part due to variable drug levels achieved. Single nucleotide polymorphisms (SNPs) in the N-acetyltransferase-2 (NAT2) gene explain the majority of interindividual pharmacokinetic variability of isoniazid (INH). However, an obstacle to implementing pharmacogenomic-guided dosing is the lack of a point-of-care assay.

OBJECTIVES

To develop and test a NAT2 classification algorithm, validate its performance in predicting isoniazid clearance, and develop a prototype pharmacogenomic assay.

METHODS

We trained random forest models to predict NAT2 acetylation genotype from unphased SNP data using a global collection of 8,561 phased genomes. We enrolled 48 pulmonary TB patients, performed sparse pharmacokinetic sampling, and tested the acetylator prediction algorithm accuracy against estimated INH clearance. We then developed a cartridge-based multiplex qPCR assay on the GeneXpert platform and assessed its analytical sensitivity on whole blood samples from healthy individuals.

MEASUREMENTS AND MAIN RESULTS

With a 5-SNP model trained on two-thirds of the data (n=5,738), out-of-sample acetylation genotype prediction accuracy on the remaining third (n=2,823) was 100%. Among the 48 TB patients, predicted acetylator types were: 27 (56.2%) slow, 16 (33.3%) intermediate and 5 (10.4%) rapid. INH clearance rates were lowest in predicted slow acetylators (median 14.5 L/hr), moderate in intermediate acetylators (median 40.3 L/hr) and highest in fast acetylators (median 53.0 L/hr). The cartridge-based assay accurately detected all allele patterns directly from 25 ul of whole blood.

CONCLUSIONS

An automated pharmacogenomic assay on a platform widely used globally for tuberculosis diagnosis could enable personalized dosing of isoniazid.

A systematic review of endpoint definitions in late phase pulmonary tuberculosis therapeutic trials

BACKGROUND

Safe, more efficacious treatments are needed to address the considerable morbidity and mortality associated with pulmonary tuberculosis (TB). However, the current practice in TB therapeutics trials is to use composite binary outcomes, which in the absence of standardization may inflate false positive and negative errors in evaluating regimens. The lack of standardization of outcomes is a barrier to the identification of highly efficacious regimens and the introduction of innovative methodologies METHODS: We conducted a systematic review of trials designed to advance new pulmonary TB drugs or regimens for regulatory approval and inform practice guidelines. Trials were primarily identified from the WHO International Clinical Trial Registry Platform (ICTRP). Only trials that collected post-treatment follow-up data and enrolled at least 100 patients were included. Protocols and Statistical Analysis Plans (SAP) for eligible trials from 1995 to the present were obtained from trial investigators. Details of outcome data, both explicit and implied, were abstracted and organized into three broad categories: favorable, unfavorable, and not assessable. Within these categories, individual trial definitions were recorded and collated, and areas of broad consensus and disagreement were identified and described.

RESULTS

From 2205 trials in any way related to TB, 51 were selected for protocol and SAP review, from which 31 were both eligible and had accessible documentation. Within the three designated categories, we found broad consensus in the definitions of favorable and unfavorable outcomes, although specific details were not always provided, and when explicitly addressed, were heterogeneous. Favorable outcomes were handled the most consistently but were widely variable with respect to specification. In some cases, the same events were defined differently by different protocols, particularly in distinguishing unfavorable from not assessable events. Death was often interpreted as conditional on cause. Patients who did not complete the study because of withdrawal or loss to follow-up presented a particular challenge to consistent interpretation and analytic treatment of outcomes.

CONCLUSIONS

In a review of 31 clinical trials, we found that outcome definitions were heterogeneous, highlighting the need to establish clearer specification and a move towards universal standardization of outcomes across pulmonary TB trials. The ICH E9 (R1) addendum provides guidelines for undertaking and achieving this goal.

PROSPERO REGISTRATION

PROSPERO CRD42020197993 . Registration 11 August 2020.

[MDR tuberculosis, Alpha-1-anti-trypsin Deficiency, Cough in a Geriatric Nurse]

Multidrug-resistant tuberculosis (MDR-TB) is of low proportion in comparison to the total number of TB patients, however, due to the necessity of a complex medication with potentially severe and life threatening adverse reactions, long term sequelae, and unfavorable outcome special attention is essential. We report the case of a 30-year-old geriatric nurse with a history of chronic cough and hereditary alpha-1-anti-trypsin deficiency (AATD), who suffered from MDR-TB and experienced a number of severe adverse reactions.

Bacterial load slopes represent biomarkers of tuberculosis therapy success, failure, and relapse

There is an urgent need to discover biomarkers that are predictive of long-term TB treatment outcomes, since treatment is expense and prolonged to document relapse. We used mathematical modeling and machine learning to characterize a predictive biomarker for TB treatment outcomes. We computed bacterial kill rates, γ_f for fast- and γ_s for slow/non-replicating bacteria, using patient sputum data to determine treatment duration by computing time-to-extinction of all bacterial subpopulations. We then derived a γ_s-slope-based rule using first 8 weeks sputum data, that demonstrated a sensitivity of 92% and a specificity of 89% at predicting relapse-free cure for 2, 3, 4, and 6 months TB regimens. In comparison, current methods (two-month sputum culture conversion and the Extended-EBA) methods performed poorly, with sensitivities less than 34%. These biomarkers will accelerate evaluation of novel TB regimens, aid better clinical trial designs and will allow personalization of therapy duration in routine treatment programs.

Defining Outcomes of Tuberculosis (Treatment): From the Past to the Future

Untreated active tuberculosis (TB) has a very high long-term mortality. Treatment of TB reduces mortality dramatically and should maximize cure, preventing ongoing transmission and TB sequelae. However, predicting the risk of failure and relapse is crucial for the management of individual patients and for the evaluation of effectiveness of programs. Various outcome definitions for drug-sensitive and drug-resistant TB were developed, implemented, and endorsed since introduction of TB chemotherapy by the World Health Organization (WHO), mostly based on culture and smear results. They should be applicable for individual patient care, surveillance, and research. Definitions with focus on program evaluation differ from definitions to evaluate the efficacy and effectiveness of regimens. Lack of sputum production at the later stage of treatment reduces the easy applicability of current definitions. Definitions of failure and cure are sometimes difficult to apply. Alternative approaches suggest culture positivity at 6 months or more of treatment as an indicator for failure. New definitions for cure including a relapse-free period posttreatment and reduced number of culture and smear results are considered. Increasing variation and individualization of treatment and its duration urgently require new approaches using pathogen- or host-specific biomarkers, which indicate risk of failure and define cure. Such biomarkers are under evaluation but still far from translation in clinical routine practice.

Chemical Classes Presenting Novel Antituberculosis Agents Currently in Different Phases of Drug Development: A 2010-2020 Review

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is a curable airborne disease currently treated using a drug regimen consisting of four drugs. Global TB control has been a persistent challenge for many decades due to the emergence of drug-resistant Mtb strains. The duration and complexity of TB treatment are the main issues leading to treatment failures. Other challenges faced by currently deployed TB regimens include drug-drug interactions, miss-matched pharmacokinetics parameters of drugs in a regimen, and lack of activity against slow replicating sub-population. These challenges underpin the continuous search for novel TB drugs and treatment regimens. This review summarizes new TB drugs/drug candidates under development with emphasis on their chemical classes, biological targets, mode of resistance generation, and pharmacokinetic properties. As effective TB treatment requires a combination of drugs, the issue of drug-drug interaction is, therefore, of great concern; herein, we have compiled drug-drug interaction reports, as well as efficacy reports for drug combinations studies involving antitubercular agents in clinical development.

Detection of active mycobacterium tuberculosis at 6th month exit among declared successfully treated cases in Pakistan

OBJECTIVES

Tuberculosis (TB) is a significant public health concern, and the basis of successful anti-tuberculosis treatment (ATT) rests on the complete eradication of live bacilli from a patient. This study was conducted to detect the live TB bacilli in Lowenstein Jensen culture media among exit cases of TB who were declared successfully treated, either cured or treatment completed.

METHODS

This cross-sectional study was conducted across Pakistan. Fifty-eight active TB DOTS centers were selected. The sample size of 3355 TB cases were equally distributed in all DOTS facilities. A detailed questionnaire was developed to record the information from TB DOTS and patients. After successful treatment, the sputum was taken from TB cases and examined to detect live bacilli on L-J culture.

RESULTS

A total of 3355 TB cases were enrolled in the study. The male to female proportion was 1704(50.9%) and 1651(49.2%). Initially, 1993(59.4%) cases were cured, and 1362(40.6%) were declared as treatment completed cases. At exit, 324(9.65%) cases were again ZN smear-positive, and 328(9.77%) were positive on L-J culture, after being declared successfully treated for TB.

CONCLUSIONS

To eradicate live TB bacilli, all TB cases should be subjected to L-J culture at the end of ATT.

Four-Month Rifapentine Regimens with or without Moxifloxacin for Tuberculosis

BACKGROUND

Rifapentine-based regimens have potent antimycobacterial activity that may allow for a shorter course in patients with drug-susceptible pulmonary tuberculosis.

METHODS

In an open-label, phase 3, randomized, controlled trial involving persons with newly diagnosed pulmonary tuberculosis from 13 countries, we compared two 4-month rifapentine-based regimens with a standard 6-month regimen consisting of rifampin, isoniazid, pyrazinamide, and ethambutol (control) using a noninferiority margin of 6.6 percentage points. In one 4-month regimen, rifampin was replaced with rifapentine; in the other, rifampin was replaced with rifapentine and ethambutol with moxifloxacin. The primary efficacy outcome was survival free of tuberculosis at 12 months.

RESULTS

Among 2516 participants who had undergone randomization, 2343 had a culture positive for Mycobacterium tuberculosis that was not resistant to isoniazid, rifampin, or fluoroquinolones (microbiologically eligible population; 768 in the control group, 791 in the rifapentine-moxifloxacin group, and 784 in the rifapentine group), of whom 194 were coinfected with human immunodeficiency virus and 1703 had cavitation on chest radiography. A total of 2234 participants could be assessed for the primary outcome (assessable population; 726 in the control group, 756 in the rifapentine-moxifloxacin group, and 752 in the rifapentine group). Rifapentine with moxifloxacin was noninferior to the control in the microbiologically eligible population (15.5% vs. 14.6% had an unfavorable outcome; difference, 1.0 percentage point; 95% confidence interval [CI], -2.6 to 4.5) and in the assessable population (11.6% vs. 9.6%; difference, 2.0 percentage points; 95% CI, -1.1 to 5.1). Noninferiority was shown in the secondary and sensitivity analyses. Rifapentine without moxifloxacin was not shown to be noninferior to the control in either population (17.7% vs. 14.6% with an unfavorable outcome in the microbiologically eligible population; difference, 3.0 percentage points [95% CI, -0.6 to 6.6]; and 14.2% vs. 9.6% in the assessable population; difference, 4.4 percentage points [95% CI, 1.2 to 7.7]). Adverse events of grade 3 or higher occurred during the on-treatment period in 19.3% of participants in the control group, 18.8% in the rifapentine-moxifloxacin group, and 14.3% in the rifapentine group.

CONCLUSIONS

The efficacy of a 4-month rifapentine-based regimen containing moxifloxacin was noninferior to the standard 6-month regimen in the treatment of tuberculosis. (Funded by the Centers for Disease Control and Prevention and others; Study 31/A5349 ClinicalTrials.gov number, NCT02410772.).

The Treatment of Tuberculosis

Tuberculosis (TB) remains a leading cause of infectious death worldwide, and poverty is a major driver. Clinically, TB presents as "latent" TB and active TB disease, and the treatment for each is different. TB drugs can display "early bactericidal activity (EBA)" and / or "sterilizing activity" (clearing persisters). Isoniazid is excellent at the former, and rifampin is excellent at the latter. Pyrazinamide and ethambutol complete the first-line regimen for drug-susceptible TB, each playing a specific role. Drug-resistant TB is an increasing concern, being met, in part, with repurposed drugs (including moxifloxacin, levofloxacin, linezolid, clofazimine, and beta-lactams) and new drugs (including bedaquiline, pretomanid, and delamanid). One challenge is to select drugs without overlapping adverse drug reaction profiles. QTc interval prolongation is one such concern, but to date, it has been manageable. Drug penetration into organism sanctuaries, such as the central nervous system, bone, and pulmonary TB cavities remain important challenges. The pharmacodynamics of most TB drugs can be described by the area under the curve (AUC) divided by the minimal inhibitory concentration (MIC). The hollow fiber infection model (HFIM) and various animal models (especially mouse and macaque) allow for sophisticated pharmacokinetic/pharmacodynamic experiments. These experiments may hasten the selection of the most potent, shortest possible regimens to treat even extremely drug resistant TB. These findings can be translated to humans by optimizing drug exposure in each patient, using therapeutic drug monitoring and dose individualization.

Dynamics of sputum conversion during effective tuberculosis treatment: A systematic review and meta-analysis

BACKGROUND

Two weeks' isolation is widely recommended for people commencing treatment for pulmonary tuberculosis (TB). The evidence that this corresponds to clearance of potentially infectious tuberculous mycobacteria in sputum is not well established. This World Health Organization-commissioned review investigated sputum sterilisation dynamics during TB treatment.

METHODS AND FINDINGS

For the main analysis, 2 systematic literature searches of OvidSP MEDLINE, Embase, and Global Health, and EBSCO CINAHL Plus were conducted to identify studies with data on TB infectiousness (all studies to search date, 1 December 2017) and all randomised controlled trials (RCTs) for drug-susceptible TB (from 1 January 1990 to search date, 20 February 2018). Included articles reported on patients receiving effective treatment for culture-confirmed drug-susceptible pulmonary TB. The outcome of interest was sputum bacteriological conversion: the proportion of patients having converted by a defined time point or a summary measure of time to conversion, assessed by smear or culture. Any study design with 10 or more particpants was considered. Record sifting and data extraction were performed in duplicate. Random effects meta-analyses were performed. A narrative summary additionally describes the results of a systematic search for data evaluating infectiousness from humans to experimental animals (PubMed, all studies to 27 March 2018). Other evidence on duration of infectiousness-including studies reporting on cough dynamics, human tuberculin skin test conversion, or early bactericidal activity of TB treatments-was outside the scope of this review. The literature search was repeated on 22 November 2020, at the request of the editors, to identify studies published after the previous censor date. Four small studies reporting 3 different outcome measures were identified, which included no data that would alter the findings of the review; they are not included in the meta-analyses. Of 5,290 identified records, 44 were included. Twenty-seven (61%) were RCTs and 17 (39%) were cohort studies. Thirteen studies (30%) reported data from Africa, 12 (27%) from Asia, 6 (14%) from South America, 5 (11%) from North America, and 4 (9%) from Europe. Four studies reported data from multiple continents. Summary estimates suggested smear conversion in 9% of patients at 2 weeks (95% CI 3%-24%, 1 single study [N = 1]), and 82% of patients at 2 months of treatment (95% CI 78%-86%, N = 10). Among baseline smear-positive patients, solid culture conversion occurred by 2 weeks in 5% (95% CI 0%-14%, N = 2), increasing to 88% at 2 months (95% CI 84%-92%, N = 20). At equivalent time points, liquid culture conversion was achieved in 3% (95% CI 1%-16%, N = 1) and 59% (95% CI 47%-70%, N = 8). Significant heterogeneity was observed. Further interrogation of the data to explain this heterogeneity was limited by the lack of disaggregation of results, including by factors such as HIV status, baseline smear status, and the presence or absence of lung cavitation.

CONCLUSIONS

This systematic review found that most patients remained culture positive at 2 weeks of TB treatment, challenging the view that individuals are not infectious after this interval. Culture positivity is, however, only 1 component of infectiousness, with reduced cough frequency and aerosol generation after TB treatment initiation likely to also be important. Studies that integrate our findings with data on cough dynamics could provide a more complete perspective on potential transmission of Mycobacterium tuberculosis by individuals on treatment.

TRIAL REGISTRATION

Systematic review registration: PROSPERO 85226.

Standard versus high dose of rifampicin in the treatment of pulmonary tuberculosis: a systematic review and meta-analysis

OBJECTIVES

A growing amount of evidence suggests that the rifampicin dosing currently recommended for tuberculosis treatment could be associated with inadequate exposure and unfavourable outcomes. We aimed to compare clinical and microbiological efficacy and safety outcomes of standard and higher rifampicin dosing.

METHODS

Data sources were MEDLINE, Google Scholar and the Cochrane Library. This was a systematic review and meta-analysis that included experimental or observational studies comparing 8-week sputum culture conversion, treatment failure, or safety outcomes in naïve patients with pulmonary tuberculosis treated with standard (10 mg/kg) or higher doses of rifampicin.

RESULTS

Of a total of 9683 citations screened, eight randomized controlled trials were included, accounting for 1897 subjects; the risk of bias was low in three studies, high in two and intermediate in three. At week 8 a higher proportion of patients in the high-dose group obtained a sputum culture conversion than those in the standard dose group (83.7% versus 80.6%, RR 1.06; 95%CI 1.01-1.12, p 0.028); this result was confirmed in the sub-analysis including patients treated with a rifampicin dose of ≥20 mg/kg, but not in those treated with 11-19 mg/kg. Events of treatment failure at end of treatment showed no significant difference between the two groups (RR 0.84; 95%CI 0.59-1.21, p 0.362). In the analysis evaluating safety outcome, the difference in the occurrence of a grade 3 or 4 liver toxicity or adverse drug reactions leading to discontinuation was not significant at the statistical analysis among the groups (7.2% versus 5.4%, RR 1.19; 95%CI 0.81-1.73, p 0.370, and 1.5% versus 0.6%, RR 2.31; 95%CI 0.65-8.21, p 0.195, respectively). No statistical heterogeneity among studies was observed for each outcome.

CONCLUSIONS

High doses of rifampicin were associated with an increased rate of sputum culture conversion at 8 weeks of treatment, particularly in patients receiving ≥20 mg/kg.

Temporal Factors and Missed Doses of Tuberculosis Treatment. A Causal Associations Approach to Analyses of Digital Adherence Data

Rationale: Tuberculosis treatment lasts for 6 months or more. Treatment adherence is critical; regimen length, among other factors, makes this challenging. Globally, analyses mapping common types of nonadherence are lacking. For example, is there a greater challenge resulting from early treatment cessation (discontinuation) or intermittent missed doses (suboptimal dosing implementation)? This is essential knowledge for the development of effective interventions and more “forgiving” regimens, as well as to direct national tuberculosis programs.

Objectives: To granularly describe how patients take their tuberculosis medication and the temporal factors associated with missed doses.

Methods: The present study included patients with pulmonary tuberculosis enrolled in the control arm of a pragmatic, cluster-randomized trial in China of electronic reminders to improve treatment adherence. Treatment was the standard 6-month course (180 d), dosed every other day (90 doses). Medication monitor boxes recorded adherence (box opening) without prompting reminders. Patterns of adherence were visualized and described. Mixed-effects logistic regression models examined the temporal factors associated with per-dose suboptimal dosing implementation, adjusting for clustering within a participant. Cox regression models were used to examine the association between early suboptimal dosing implementation and permanent discontinuation.

Results: Across 780 patients, 16,794 (23.9%) of 70,200 doses were missed, 9,487 of which were from suboptimal dosing implementation (56.5%). By 60 days, 5.1% of participants had discontinued, and 14.4% had discontinued by 120 days. Most participants (95.9%) missed at least one dose. The majority of gaps were of a single dose (71.4%), although 22.6% of participants had at least one gap of 2 weeks or more. In adjusted models, the initiation–continuation phase transition (odds ratio, 3.07 [95% confidence interval, 2.68–3.51]) and national holidays (1.52 [1.39–1.65]) were associated with increased odds of suboptimal dosing implementation. Early-stage suboptimal dosing implementation was associated with increased discontinuation rates.

Conclusions: Digital tools provide an unprecedented step change in describing and addressing nonadherence. In our setting, nonadherence was common; patients displayed a complex range of patterns. Dividing nonadherence into suboptimal dosing implementation and discontinuation, we found that both increased over time. Discontinuation was associated with early suboptimal dosing implementation. These apparent causal associations between temporal factors and nonadherence present opportunities for targeted interventions.

Clinical trial registered with the ISRCTN Registry (ISRCTN46846388).

A multi-scale pipeline linking drug transcriptomics with pharmacokinetics predicts in vivo interactions of tuberculosis drugs

Tuberculosis (TB) is the deadliest infectious disease worldwide. The design of new treatments for TB is hindered by the large number of candidate drugs, drug combinations, dosing choices, and complex pharmaco-kinetics/dynamics (PK/PD). Here we study the interplay of these factors in designing combination therapies by linking a machine-learning model, INDIGO-MTB, which predicts in vitro drug interactions using drug transcriptomics, with a multi-scale model of drug PK/PD and pathogen-immune interactions called GranSim. We calculate an in vivo drug interaction score (iDIS) from dynamics of drug diffusion, spatial distribution, and activity within lesions against various pathogen sub-populations. The iDIS of drug regimens evaluated against non-replicating bacteria significantly correlates with efficacy metrics from clinical trials. Our approach identifies mechanisms that can amplify synergistic or mitigate antagonistic drug interactions in vivo by modulating the relative distribution of drugs. Our mechanistic framework enables efficient evaluation of in vivo drug interactions and optimization of combination therapies.

Are We There Yet? Short-Course Regimens in TB and HIV: From Prevention to Treatment of Latent to XDR TB

PURPOSE OF REVIEW

Despite broad uptake of antiretroviral therapy (ART), tuberculosis (TB) incidence and mortality among people with HIV remain unacceptably high. Short-course regimens for TB, incorporating both novel and established drugs, offer the potential to enhance adherence and completion rates, thereby reducing the global TB burden. This review will outline short-course regimens for TB among patients with HIV.

RECENT FINDINGS

After many years without new agents, there is now active testing of many novel drugs to treat TB, both for latent infection and active disease. Though not all studies have included patients with HIV, many have, and there are ongoing trials to address key implementation challenges such as potent drug-drug interactions with ART. The goal of short-course regimens for TB is to enhance treatment completion without compromising efficacy. Particularly among patients with HIV, studying these shortened regimens and integrating them into clinical care are of urgent importance. There are now multiple short-course regimens for latent infection and active disease that are safe and effective among patients with HIV.

Fourteen-day PET/CT imaging to monitor drug combination activity in treated individuals with tuberculosis

Early bactericidal activity studies monitor daily sputum bacterial counts in individuals with tuberculosis (TB) for 14 days during experimental drug treatment. The rate of change in sputum bacterial load over time provides an informative, but imperfect, estimate of drug activity and is considered a critical step in development of new TB drugs. In this clinical study, 160 participants with TB received isoniazid, pyrazinamide, or rifampicin, components of first-line chemotherapy, and moxifloxacin individually and in combination. In addition to standard bacterial enumeration in sputum, participants underwent 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography and computerized tomography ([18F]FDG-PET/CT) at the beginning and end of the 14-day drug treatment. Quantitating radiological responses to drug treatment provided comparative single and combination drug activity measures across lung lesion types that correlated more closely with established clinical outcomes when combined with sputum enumeration compared to sputum enumeration alone. Rifampicin and rifampicin-containing drug combinations were most effective in reducing both lung lesion volume measured by CT imaging and lesion-associated inflammation measured by PET imaging. Moxifloxacin was not superior to rifampicin in any measure by PET/CT imaging, consistent with its performance in recent phase 3 clinical trials. PET/CT imaging revealed synergy between isoniazid and pyrazinamide and demonstrated that the activity of pyrazinamide was limited to lung lesion, showing the highest FDG uptake during the first 2 weeks of drug treatment. [18F]FDG-PET/CT imaging may be useful for measuring the activity of single drugs and drug combinations during evaluation of potential new TB drug regimens before phase 3 trials.

Multi-drug resistant tuberculosis, ten years later

Drug-resistant tuberculosis, especially those with resistance to rifampicin (RR-TB), has become one of the main obstacles to achieving the dream of eradicating tuberculosis. Furthermore, it is necessary to combine three or four different drugs in the attempt to cure TB, however, unfortunately, there are few available that can be considered genuinely effective. Fortunately, the notable worldwide increase in RR-TB in recent years has led to the investment of resources in the development of new drugs for TB, and other drugs investigated for other diseases have been successfully tested on TB. This has resulted in a clear change in the clinical management of these patients over the last 3-4 years, and it is now easier to design therapeutic regimens and achieve higher success rates. All these changes are updated in this review.

Shortened Tuberculosis Treatment for People with HIV in South Africa. A Model-based Evaluation and Cost-effectiveness Analysis

Rationale: Recent tuberculosis treatment trials failed to show that some 4-month (4m) regimens were noninferior to conventional 6-month (6m) regimens for a composite clinical outcome. Novel shortened regimens may still have important clinical and economic benefits in populations with high loss to follow-up (LTFU) and in subgroups such as people with human immunodeficiency virus.Objectives: To identify scenarios in which a novel 4m regimen would be preferred to a conventional 6m regimen for treatment of drug-susceptible tuberculosis in people with human immunodeficiency virus in South Africa, in terms of short-term and long-term clinical and economic outcomes.Methods: We used the Cost-Effectiveness of Preventing AIDS Complications-International microsimulation model to project outcomes modeled on participants in the OFLOTUB trial. For calibration purposes, we did a base case analysis by applying trial-informed parameters for the 4m/6m regimens, including monthly LTFU during treatment (0.68%/0.83%), average monthly tuberculosis recurrence (0.65%/0.31%), and monthly drug costs (U.S. dollars [USD]25.90/3.70). We then evaluated different scenarios and 4m regimen characteristics, varying key parameters, including LTFU (informed by observational cohort data), recurrence, and cost. We projected outcomes, including 2-year mortality and life expectancy. We conducted a cost-effectiveness analysis, evaluating the incremental cost-effectiveness ratio of a 4m versus 6m regimen.Results: In the base case model analysis, risk of the composite unfavorable outcome in the 4m/6m groups was 19.8%/15.9%, similar to the trial; projected life expectancies were 22.1/22.3 years. In analyses of alternative scenarios and 4m regimen characteristics, a 4m regimen yielded lower risk of the composite unfavorable outcome than the conventional 6m regimen if LTFU increased to greater than 3.5%/mo or if average recurrence after a 4m regimen decreased to less than 0.45%/mo, and it yielded higher life expectancy if LTFU was greater than 3.5%/mo or if recurrence was less than 0.5%/mo. A 4m regimen was not cost-effective in the base case but became cost-effective (incremental cost-effectiveness ratio <USD940/yr of life saved) in two-way sensitivity analysis; for example, if LTFU was greater than or equal to 5.3%/mo and either average recurrence was less than or equal to 0.5%/mo or drug cost was less than or equal to USD15/mo.Conclusions: A novel shortened tuberculosis treatment regimen could improve outcomes such as survival despite conferring a higher recurrence risk, particularly in settings where LTFU is higher than that seen in recent trials.

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

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 (C_max) in the rifampin and rifabutin arms were 2.14 and 3.35 mg/liter, while median AUC_0-24 values were 30.1 and 59.5 mg·h/liter, respectively. Though pretomanid exposure in APT was significantly reduced with rifampin, AUC_0-24 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.).

Novel therapeutic evaluation biomarkers of lipid metabolism targets in uncomplicated pulmonary tuberculosis patients

Currently, the management of pulmonary tuberculosis (TB) lacks potent medications and accurate efficacy evaluation biomarkers. In view of the fact that the host lipids are the important energy source of Mycobacterium tuberculosis (Mtb), UPLC-MS/MS based on lipid metabolism was used to monitor the plasma lipid spectrum of TB patients from the initial diagnosis to cured. The analysis showed that TB patients presented aberrant metabolism of phospholipids, glycerides, and sphingolipids. Upon the treatment, the abnormal expression of Cer (d18:1/24:0), CerP (d18:1/20:3), LPE (0:0/22:0), LPA (0:0/16:0), and LPA (0:0/18:0) in TB patients were gradually normalized, indicating that the intervention of lipid metabolism could block energy metabolism and inhibit the cell wall synthesis of Mtb. Furthermore, the increase in ceramide (Cer) levels could promote autophagosome-lysosome fusion. LPA (0:0/16:0) and LPA (0:0/18:0) had a great potential in the early diagnosis (both sensitivity and specificity were 100%) and efficacy evaluation (both sensitivity and specificity were 100%) of TB, indicating that the above lipid metabolites could be used as potential biomarkers for TB.

Safety and immunogenicity of the adjunct therapeutic vaccine ID93 + GLA-SE in adults who have completed treatment for tuberculosis: a randomised, double-blind, placebo-controlled, phase 2a trial

BACKGROUND

A therapeutic vaccine that prevents recurrent tuberculosis would be a major advance in the development of shorter treatment regimens. We aimed to assess the safety and immunogenicity of the ID93 + GLA-SE vaccine at various doses and injection schedules in patients with previously treated tuberculosis.

METHODS

This randomised, double-blind, placebo-controlled, phase 2a trial was conducted at three clinical sites near Cape Town, South Africa. Patients were recruited at local clinics after receiving 4 months of tuberculosis treatment, and screened for eligibility after providing written informed consent. Participants were aged 18-60 years, BCG-vaccinated, HIV-uninfected, and diagnosed with drug-sensitive pulmonary tuberculosis. Eligible patients had completed standard treatment for pulmonary tuberculosis in the past 28 days. Participants were enrolled after completing standard treatment and randomly assigned sequentially to receive vaccine or placebo in three cohorts: 2 μg intramuscular ID93 + 2 μg GLA-SE on days 0 and 56 (cohort 1); 10 μg ID93 + 2 μg GLA-SE on days 0 and 56 (cohort 2); 2 μg ID93 + 5 μg GLA-SE on days 0 and 56 and placebo on day 28 (cohort 3); 2 μg ID93 + 5 μg GLA-SE on days 0, 28, and 56 (cohort 3); or placebo on days 0 and 56 (cohorts 1 and 2), with the placebo group for cohort 3 receiving an additional injection on day 28. Randomisation was in a ratio of 3:1 for ID93 + GLA-SE and saline placebo in cohorts 1 and 2, and in a ratio of 3:3:1 for (2 ×) ID93 + GLA-SE, (3 ×) ID93 + GLA-SE, and placebo in cohort 3. The primary outcomes were safety and immunogenicity (vaccine-specific antibody response and T-cell response). For the safety outcome, participants were observed for 30 min after each injection, injection site reactions and systemic adverse events were monitored until day 84, and serious adverse events and adverse events of special interest were monitored for 6 months after the last injection. Vaccine-specific antibody responses were measured by serum ELISA, and T-cell responses after stimulation with vaccine antigens were measured in cryopreserved peripheral blood mononuclear cells specimens using intracellular cytokine staining followed by flow cytometry. This study is registered with ClinicalTrials.gov, number NCT02465216.

FINDINGS

Between June 17, 2015, and May 30, 2016, we assessed 177 patients for inclusion. 61 eligible patients were randomly assigned to receive: saline placebo (n=5) or (2 ×) 2 μg ID93 + 2 μg GLA-SE (n=15) on days 0 and 56 (cohort 1); saline placebo (n=2) or (2 ×) 10 μg ID93 + 2 μg GLA-SE (n=5) on days 0 and 56 (cohort 2); saline placebo (n=5) on days 0, 28 and 56, or 2 μg ID93 + 5 μg GLA-SE (n=15) on days 0 and 56 and placebo injection on day 28, or (3 ×) 2 μg ID93 + 5 μg GLA-SE (n=14) on days 0, 28, and 56 (cohort 3). ID93 + GLA-SE induced robust and durable antibody responses and specific, polyfunctional CD4 T-cell responses to vaccine antigens. Two injections of the 2 μg ID93 + 5 μg GLA-SE dose induced antigen-specific IgG and CD4 T-cell responses that were significantly higher than those with placebo and persisted for the 6-month study duration. Mild to moderate injection site pain was reported after vaccination across all dose combinations, and induration and erythema in patients given 2 μg ID93 + 5 μg GLA-SE in two or three doses. One participant had grade 3 erythema and induration at the injection site. No vaccine-related serious adverse events were observed.

INTERPRETATION

Vaccination with ID93 + GLA-SE was safe and immunogenic for all tested regimens. These data support further evaluation of ID93 + GLA-SE in therapeutic vaccination strategies to improve tuberculosis treatment outcomes.

FUNDING

Wellcome Trust (102028/Z/13/Z).

All nonadherence is equal but is some more equal than others? Tuberculosis in the digital era

Adherence to treatment for tuberculosis (TB) has been a concern for many decades, resulting in the World Health Organization's recommendation of the direct observation of treatment in the 1990s. Recent advances in digital adherence technologies (DATs) have renewed discussion on how to best address nonadherence, as well as offering important information on dose-by-dose adherence patterns and their variability between countries and settings. Previous studies have largely focussed on percentage thresholds to delineate sufficient adherence, but this is misleading and limited, given the complex and dynamic nature of adherence over the treatment course. Instead, we apply a standardised taxonomy - as adopted by the international adherence community - to dose-by-dose medication-taking data, which divides missed doses into 1) late/noninitiation (starting treatment later than expected/not starting), 2) discontinuation (ending treatment early), and 3) suboptimal implementation (intermittent missed doses). Using this taxonomy, we can consider the implications of different forms of nonadherence for intervention and regimen design. For example, can treatment regimens be adapted to increase the "forgiveness" of common patterns of suboptimal implementation to protect against treatment failure and the development of drug resistance? Is it reasonable to treat all missed doses of treatment as equally problematic and equally common when deploying DATs? Can DAT data be used to indicate the patients that need enhanced levels of support during their treatment course? Critically, we pinpoint key areas where knowledge regarding treatment adherence is sparse and impeding scientific progress.

A framework for considering the risk-benefit trade-off in designing noninferiority trials using composite outcome approaches

When a new treatment regimen is expected to have comparable or slightly worse efficacy to that of the control regimen but has benefits in other domains such as safety and tolerability, a noninferiority (NI) trial may be appropriate but is fraught with difficulty in justifying an acceptable NI margin that is based on both clinical and statistical input. To overcome this, we propose to utilize composite risk-benefit outcomes that combine elements from domains of importance (eg, efficacy, safety, and tolerability). The composite outcome itself may be analyzed using a superiority framework, or it can be used as a tool at the design stage of a NI trial for selecting an NI margin for efficacy that balances changes in risks and benefits. In the latter case, the choice of NI margin may be based on a novel quantity called the maximum allowable decrease in efficacy (MADE), defined as the marginal difference in efficacy between arms that would yield a null treatment effect for the composite outcome given an assumed distribution for the composite outcome. We observe that MADE: (1) is larger when the safety improvement for the experimental arm is larger, (2) depends on the association between the efficacy and safety outcomes, and (3) depends on the control arm efficacy rate. We use a numerical example for power comparisons between a superiority test for the composite outcome vs a noninferiority test for efficacy using the MADE as the NI margin, and apply the methods to a TB treatment trial.

Predicting TB treatment outcomes using baseline risk and treatment response markers: developing the PredictTB early treatment completion criteria

Standard treatment of drug-sensitive pulmonary tuberculosis requires six months of treatment. Several randomized clinical trials have attempted to shorten treatment to four months using various strategies but thus far all have failed. The PredictTB trial is an ongoing international randomized clinical trial testing a treatment shortening strategy whereby only drug-sensitive pulmonary TB patients who meet the study early treatment completion criteria are randomized to four vs. six months of treatment. The PredictTB early treatment completion criteria were developed based on a cohort of 92 pulmonary tuberculosis patients treated programmatically through the local tuberculosis treatment program in Cape Town, South Africa, with FDG-PET/CT scans also performed at baseline and week 4 of treatment. Patients were followed for one year after the end of therapy for programmatic treatment outcomes. This methodology paper describes how the PET/CT scans and GeneXpert cycle threshold data of this cohort were analyzed to develop the early treatment completion algorithm currently being used in the PredictTB trial.

Rifapentine Population Pharmacokinetics and Dosing Recommendations for Latent Tuberculosis Infection

Rationale: Rifapentine has been investigated at various doses, frequencies, and dosing algorithms, but clarity on the optimal dosing approach is lacking.Objectives: To characterize rifapentine population pharmacokinetics, including autoinduction, and determine optimal dosing strategies for short-course rifapentine-based regimens for latent tuberculosis infection.Methods: Rifapentine pharmacokinetic studies were identified though a systematic review of literature. Individual plasma concentrations were pooled, and nonlinear mixed-effects modeling was performed. A subset of data was reserved for external validation. Simulations were performed under various dosing conditions, including current weight-based methods; and alternative methods driven by identified covariates.Measurements and Main Results: We identified nine clinical studies with a total of 863 participants with pharmacokinetic data (n = 4,301 plasma samples). Rifapentine population pharmacokinetics were described successfully with a one-compartment distribution model. Autoinduction of clearance was driven by rifapentine plasma concentrations. The maximum effect was a 72% increase in clearance and was reached after 21 days. Drug bioavailability decreased by 27% with HIV infection, decreased by 28% with fasting, and increased by 49% with a high-fat meal. Body weight was not a clinically relevant predictor of clearance. Pharmacokinetic simulations showed that current weight-based dosing leads to lower exposures in individuals with low weight, which can be overcome with flat dosing. In HIV-positive patients, 30% higher doses are required to match drug exposure in HIV-negative patients.Conclusions: Weight-based dosing of rifapentine should be removed from clinical guidelines, and higher doses for HIV-positive patients should be considered to provide equivalent efficacy.

Fully weekly antituberculosis regimen: a proof-of-concept study

BACKGROUND

The World Health Organization recommends supervising the treatment of tuberculosis. Intermittent regimens have the potential to simplify the supervision and improve compliance. Our objective was to analyse the sterilising activity of once-weekly regimens based on drugs with a long half-life, bedaquiline and rifapentine, in a murine model of tuberculosis.

METHODS

300 Swiss mice were infected intravenously infected with ×10^-6 CFU Mycobacterium tuberculosis H37Rv. Mice were treated once weekly with regimens containing: 1) bedaquiline, rifapentine and pyrazinamide (BPZ); 2) BPZ plus moxifloxacin (BPZM); 3) BPZM plus clofazimine (BPZMC); 4) the standard daily regimen of tuberculosis. All regimens were given for 4 or 6 months. Bactericidal and sterilising activity were assessed.

RESULTS

After 2 months of treatment, the mean count in lungs was 0.76±0.60 log₁₀ CFU in mice treated with the daily control regimen and negative in all mice treated with once-weekly regimens (p<0.05 compared to the daily control). All mice had negative lung cultures on completion of either 4 or 6 months of treatment, whereas 3 months after 4 and 6 months of treatment, respectively, the relapse rate was 64% and 13% in the standard daily regimen, 5% and 0% in BPZ, 0% and 0% in BPMZ and 0% and 5% in BPMZC (p<0.05 for all once-weekly regimens versus 4-month daily control; p>0.05 for all once-weekly regimens versus 6-month daily control).

CONCLUSIONS

BPZ-based once-weekly regimens have higher sterilising activity than the standard daily regimen and could greatly simplify treatment administration and possibly shorten the duration of tuberculosis treatment.

Mathematical model and tool to explore shorter multi-drug therapy options for active pulmonary tuberculosis

Standard treatment for active tuberculosis (TB) requires drug treatment with at least four drugs over six months. Shorter-duration therapy would mean less need for strict adherence, and reduced risk of bacterial resistance. A system pharmacology model of TB infection, and drug therapy was developed and used to simulate the outcome of different drug therapy scenarios. The model incorporated human immune response, granuloma lesions, multi-drug antimicrobial chemotherapy, and bacterial resistance. A dynamic population pharmacokinetic/pharmacodynamic (PK/PD) simulation model including rifampin, isoniazid, pyrazinamide, and ethambutol was developed and parameters aligned with previous experimental data. Population therapy outcomes for simulations were found to be generally consistent with summary results from previous clinical trials, for a range of drug dose and duration scenarios. An online tool developed from this model is released as open source software. The TB simulation tool could support analysis of new therapy options, novel drug types, and combinations, incorporating factors such as patient adherence behavior.

A comprehensive in-silico model of pulmonary tuberculosis successfully predicted previous clinical trials and could simulate future therapeutics.

Development of New Tuberculosis Drugs: Translation to Regimen Composition for Drug-Sensitive and Multidrug-Resistant Tuberculosis

Tuberculosis (TB) kills more people than any other infectious disease. Challenges for developing better treatments include the complex pathology due to within-host immune dynamics, interpatient variability in disease severity and drug pharmacokinetics-pharmacodynamics (PK-PD), and the growing emergence of resistance. Model-informed drug development using quantitative and translational pharmacology has become increasingly recognized as a method capable of drug prioritization and regimen optimization to efficiently progress compounds through TB drug development phases. In this review, we examine translational models and tools, including plasma PK scaling, site-of-disease lesion PK, host-immune and bacteria interplay, combination PK-PD models of multidrug regimens, resistance formation, and integration of data across nonclinical and clinical phases.We propose a workflow that integrates these tools with computational platforms to identify drug combinations that have the potential to accelerate sterilization, reduce relapse rates, and limit the emergence of resistance.

Evaluation of pharmacokinetic-pharmacodynamic relationships and selection of drug combinations for tuberculosis

AIMS

Despite evidence of the efficacy of anti-tubercular drug regimens in clinical practice, the rationale underpinning the selection of doses and companion drugs for combination therapy remains empirical. Novel methods are needed to optimise the antibacterial activity in combination therapies. A drug-disease modelling framework for rational selection of dose and drug combinations in tuberculosis is presented here.

METHODS

A model-based meta-analysis was performed to assess the antibacterial activity of different combinations in infected mice. Data retrieved from the published literature were analysed using a two-state bacterial growth dynamics model, including fast- and slow-growing bacterial populations. The contribution of each drug to the overall antibacterial activity of the combination was parameterised as relative change to the potency of the backbone drug (EC₅₀ -F and/or EC₅₀ -S). Rifampicin and bedaquiline were selected as paradigm drugs to evaluate the predictive performance of the modelling approach.

RESULTS

Pyrazinamide increased the potency (EC₅₀ -F and EC₅₀ -S) of rifampicin (RZ) and bedaquiline (BZ) by almost two-fold. By contrast, pretomanid and isoniazid were found to worsen the antibacterial activity of BZ and RZ, respectively. Following extrapolation of in vivo pharmacokinetic-pharmacodynamic relationships, the dose of rifampicin showing maximum bactericidal effect in tuberculosis patients was predicted to be 70 mg·kg^-1 when given in combination with pyrazinamide.

CONCLUSIONS

The use of a drug-disease modelling framework may provide a more robust rationale for extrapolation and selection of dose and companion drugs in humans. Our analysis demonstrates that RZ and BZ should be considered as a backbone therapy in prospective novel combination regimens against tuberculosis.

Longitudinal Pharmacokinetic-Pharmacodynamic Biomarkers Correlate With Treatment Outcome in Drug-Sensitive Pulmonary Tuberculosis: A Population Pharmacokinetic-Pharmacodynamic Analysis

Background

This study aims to explore relationships between baseline demographic covariates, plasma antibiotic exposure, sputum bacillary load, and clinical outcome data to help improve future tuberculosis (TB) treatment response predictions.

Methods

Data were available from a longitudinal cohort study in Malawian drug-sensitive TB patients on standard therapy, including steady-state plasma antibiotic exposure (154 patients), sputum bacillary load (102 patients), final outcome (95 patients), and clinical details. Population pharmacokinetic and pharmacokinetic-pharmacodynamic models were developed in the software package NONMEM. Outcome data were analyzed using univariate logistic regression and Cox proportional hazard models in R, a free software for statistical computing.

Results

Higher isoniazid exposure correlated with increased bacillary killing in sputum (P < .01). Bacillary killing in sputum remained fast, with later progression to biphasic decline, in patients with higher rifampicin area under the curve (AUC)_0-24 (P < .01). Serial sputum colony counting negativity at month 2 (P < .05), isoniazid C_MAX (P < .05), isoniazid C_MAX/minimum inhibitory concentration ([MIC] P < .01), and isoniazid AUC_0-24/MIC (P < .01) correlated with treatment success but not with remaining free of TB. Slower bacillary killing (P < .05) and earlier progression to biphasic bacillary decline (P < .01) both correlate with treatment failure. Posttreatment recurrence only correlated with slower bacillary killing (P < .05).

Conclusions

Patterns of early bacillary clearance matter. Static measurements such as month 2 sputum conversion and pharmacokinetic parameters such as C_MAX/MIC and AUC_0-24/MIC were predictive of treatment failure, but modeling of quantitative longitudinal data was required to assess the risk of recurrence. Pooled individual patient data analyses from larger datasets are needed to confirm these findings.

Real-time monitoring of live mycobacteria with a microfluidic acoustic-Raman platform

Tuberculosis (TB) remains a leading cause of death worldwide. Lipid rich, phenotypically antibiotic tolerant, bacteria are more resistant to antibiotics and may be responsible for relapse and the need for long-term TB treatment. We present a microfluidic system that acoustically traps live mycobacteria, M. smegmatis, a model organism for M. tuberculosis. We then perform optical analysis in the form of wavelength modulated Raman spectroscopy (WMRS) on the trapped M. smegmatis for up to eight hours, and also in the presence of isoniazid (INH). The Raman fingerprints of M. smegmatis exposed to INH change substantially in comparison to the unstressed condition. Our work provides a real-time assessment of the impact of INH on the increase of lipids in these mycobacteria, which could render the cells more tolerant to antibiotics. This microfluidic platform may be used to study any microorganism and to dynamically monitor its response to different conditions and stimuli.

Baron et al. describe a microfluidic system that acoustically traps live mycobacteria and acquires label-free optical measurements over time using wavelength modulated Raman spectroscopy. Using acoustically trapped live M. smegmatis, they show that under stressed conditions produced by an antibiotic, bacteria displayed an increase in lipids which could render the cells more tolerant to antibiotics.

Efficacy of Moxifloxacin plus Treatment of Physician's Choice in Patients with Metastatic Breast Cancer

LESSONS LEARNED

Moxifloxacin plus continuation of the previous treatment of physician's choice shows promising efficacy in patients with metastatic breast cancer. The addition of moxifloxacin shows well-tolerated toxicities.

BACKGROUND

Recent studies have confirmed bacterial infection as an important contributor in cancer. Elimination of tumor-associated microbes may lead to a reduction in tumors and improved survival. Moxifloxacin is an orally administrated fourth-generation quinolone with broad-spectrum coverage against tumor-associated bacteria.

METHODS

In this study, we assessed the efficacy and safety of moxifloxacin in combination with treatment of physician's choice (TPC) in patients with metastatic breast cancer (MBC). In this single-arm, phase II study, we recruited 30 patients with MBC who had a trend toward disease progression (stable disease [SD] with increased tumor size) during TPC before enrollment at Sun Yat-sen University Cancer Center between January 1 and July 30, 2018. Eligible patients were given moxifloxacin once daily at a dose of 400 mg from days 1 to 7 of a 28-day cycle, in addition to continuing to receive the therapy previously selected by their physicians. Tumor response was determined according to RECIST (version 1.1). Progression-free survival (PFS) was calculated using the Kaplan-Meier method.

RESULTS

The concomitant use of moxifloxacin and previous TPC yielded a median PFS of 6.6 months (95% confidence interval [CI]: 4.0-9.1) and a 1-year PFS of 25.9% (95% CI: 10.0%-41.9%). Objective responses were achieved in seven (23.3%, 95% CI: 7.3%-39.4%) patients. The clinical benefit rate was 46.7% (95% CI: 27.7%-65.6%). No grade 4 adverse events (AEs) and four grade 3 AEs were observed, none of which were considered to have definite relation to moxifloxacin.

CONCLUSION

The combination of moxifloxacin with previous TPC shows promising efficacy and well-tolerated toxicities in patients with MBC.

The Growing Importance of Tuberculosis Preventive Therapy and How Research and Innovation Can Enhance Its Implementation on the Ground

Ending the tuberculosis (TB) epidemic by 2030 requires two key actions: rapid diagnosis and effective treatment of active TB and identification and treatment of latent TB infection to prevent progression to active disease. We introduce this perspective by documenting the growing importance of TB preventive therapy on the international agenda coupled with global data showing poor implementation of preventive activities in programmatic settings. We follow this with two principal objectives. The first is to examine implementation challenges around diagnosis and treatment of active TB. Within this, we include recent evidence about the continued morbidity and heightened mortality that persists after TB treatment is successfully completed, thus elevating the importance of TB preventive therapy. The second objective is to outline how current TB preventive therapy activities have been shaped and are managed and propose how these can be improved through research and innovation. This includes expanding and giving higher priority to certain high-risk groups including those with fibrotic lung lesions on chest X-ray, showcasing the need to develop and deploy new biomarkers to more accurately predict risk of disease and making shorter treatment regimens, especially with rifapentine-isoniazid, more user-friendly and widely available. Ending the TB epidemic requires not only cure of the disease but preventing it before it even begins.

New drugs to treat difficult tuberculous and nontuberculous mycobacterial pulmonary disease

PURPOSE OF REVIEW

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.

RECENT FINDINGS

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.

SUMMARY

Treatment of Drug-Susceptible Tuberculosis

Mycobacterium tuberculosis is a major public health concern and requires prompt treatment. Goals of treatment include curing the individual patient and protecting the community from ongoing tuberculosis transmission. To achieve durable cure, regimens must include multiple agents given concurrently and in a manner to ensure completion of therapy. This article focuses on preferred regimens of drug-susceptible tuberculosis under current guidelines by the American Thoracic Society, Centers for Disease Control and Prevention, and Infectious Diseases Society of America and World Health Organization. In addition, topics including patient centered care, poor treatment outcomes, and adverse effects are also discussed.