Drugs for treating infections caused by non-tubercular mycobacteria: a narrative review from the study group on mycobacteria of the Italian Society of Infectious Diseases and Tropical Medicine

BACKGROUND

Non-tuberculous mycobacteria (NTM) are generally free-living organism, widely distributed in the environment, with sporadic potential to infect. In recent years, there has been a significant increase in the global incidence of NTM-related disease, spanning across all continents and an increased mortality after the diagnosis has been reported. The decisions on whether to treat or not and which drugs to use are complex and require a multidisciplinary approach as well as patients' involvement in the decision process.

METHODS AND RESULTS

This review aims at describing the drugs used for treating NTM-associated diseases emphasizing the efficacy, tolerability, optimization strategies as well as possible drugs that might be used in case of intolerance or resistance. We also reviewed data on newer compounds highlighting the lack of randomised clinical trials for many drugs but also encouraging preliminary data for others. We also focused on non-pharmacological interventions that need to be adopted during care of individuals with NTM-associated diseases CONCLUSIONS: Despite insufficient efficacy and poor tolerability this review emphasizes the improvement in patients' care and the needs for future studies in the field of anti-NTM treatments.

Efficacy and safety of bedaquiline containing regimens in patients of drug-resistant tuberculosis: An updated systematic review and meta-analysis

Background

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis and leads to serious complications if left untreated. Some strains of Mycobacterium tuberculosis are multi-drug resistant and require treatment with newer drugs. Bedaquiline based treatment regimens have been used in patients who are diagnosed with drug resistant tuberculosis. The aim of this study is to assess the efficacy and safety profile of bedaquiline-based treatment regimens using a systematic review of existing literature and meta-analysis.

Methods

In this study, an electronic search was carried out on PubMed, ScienceDirect, and Cochrane library to find relevant literature from March 2021 onwards. Random-effects model was used to assess pooled treatment success rate and 95 % CIs. p-value of <0.05 was suggestive of publication bias. The review is registered with PROSPERO: CRD42023432748.

Results

A total of 543 articles were retrieved by database searching, out of which 12 new studies met the inclusion criteria. The total number of articles included in the review was 41 including 36 observational studies (having a total of 9,934 patients) and 5 experimental studies (having a total of 468 patients). The pooled treatment success rate was 76.9 % (95 % CI, 72.9-80.4) in the observational studies and 81.7 % (95 % CI, 67.2-90.7) in the experimental studies. Further subgroup analysis was done on the basis of treatment regimens containing bedaquiline only and treatment regimens containing bedaquiline and delamanid. The pooled treatment success rate in the studies consisting of patients who were treated with regimens containing bedaquiline only was 78.4 % (95 % CI, 74.2-82.1) and 73.6 % (95 % CI, 64.6-81.0) in studies consisting of patients who were treated with regimens containing bedaquiline and delamanid. There was no evidence of publication bias.

Conclusions

In patients of drug resistant tuberculosis having highly resistant strains of Mycobacterium tuberculosis undergoing treatment with bedaquiline-based regimen demonstrate high rates of culture conversion and treatment success. Moreover, the safety profile of bedaquiline-based regimens is well-established in all studies.

A bedaquiline, pyrazinamide, levofloxacin, linezolid, clofazimine second line regimen for tuberculosis displays similar early bactericidal activity as the standard rifampin based first line regimen

BACKGROUND

In 2018 the World Health Organization (WHO) recommended a switch to an all oral bedaquiline based second line regimen for treatment of drug resistant (DR) tuberculosis (TB). How these new second line regimens fare in comparison to first line regimens for treatment of drug sensitive (DS) tuberculosis is not well known.

METHODS

In this study, we contemporaneously enrolled subjects with DS (n = 31) and DR (n = 23) TB and assessed their response to therapy with first-line (rifampin, isoniazid, ethambutol, pyrazinamide) or second-line (bedaquiline, pyrazinamide, levofloxacin, linezolid, clofazimine) regimens, respectively.

RESULTS

We found that the early bactericidal activity of first and second line regimens was similar during the first two weeks of therapy as determined by BACTEC MGIT, colony forming units (CFU), and a liquid limiting dilution (LD) assays capable of detecting differentially detectable/culturable Mtb (DD Mtb). Further, an identical percentage (77.8%) of subjects from the DS and DR cohorts converted to culture negative after two months of therapy.

CONCLUSIONS

Despite presenting with more advanced disease at time of treatment, subjects with DR TB receiving an all oral bedaquiline based second line treatment regimen displayed a similar microbiological response to therapy as subjects with DS TB receiving a first-line treatment regimen.

Outcomes of bedaquiline-containing regimen in the treatment of adults with drug-resistant tuberculosis in a tertiary care center in Rajasthan

The emergence of drug-resistant strains of Mycobacterium tuberculosis has become a significant public health problem and has led to a setback in the efforts to end tuberculosis (TB) worldwide. The longer duration, heavier pill load, and higher toxicity profile of drug-resistant TB regimens compared to those for drug-susceptible TB lead to reduced adherence and worse treatment results, including mortality. This study was conducted to estimate treatment outcomes and adverse effects in patients with drug-resistant TB on a bedaquiline-containing regimen. Patients after the pre-treatment evaluation were enrolled in a bedaquiline-containing regimen. These patients were followed up for 18 months, and the final outcome was assessed along with the adverse effects. It was found that 49 (84.4%) patients achieved culture conversion by 3 months, 54 (93.1%) achieved culture conversion by 6 months, 52 (83.81%) had favorable outcomes (cured, treatment completed), and 10 had unfavorable outcomes (died, lost to follow-up, failed). Coupled with gradually increasing trends in success rates since 2012, lesser failure rates and fewer concerns regarding grave adverse effects are a silver lining in the cloud of increasing burden and widening resistance patterns. More funding has to be directed towards ensuring adherence and finding high-risk individuals to expedite the achievement of sustainable development goals.

QT Interval Prolongation with One or More QT-Prolonging Agents Used as Part of a Multidrug Regimen for Rifampicin-Resistant Tuberculosis Treatment: Findings from Two Pediatric Studies

Rifampicin-resistant tuberculosis (RR-TB) involves treatment with many drugs that can prolong the QT interval; this risk may increase when multiple QT-prolonging drugs are used together. We assessed QT interval prolongation in children with RR-TB receiving one or more QT-prolonging drugs. Data were obtained from two prospective observational studies in Cape Town, South Africa. Electrocardiograms were performed before and after drug administration of clofazimine (CFZ), levofloxacin (LFX), moxifloxacin (MFX), bedaquiline (BDQ), and delamanid. The change in Fridericia-corrected QT (QTcF) was modeled. Drug and other covariate effects were quantified. A total of 88 children with a median (2.5th-to-97.5th range) age of 3.9 (0.5 to 15.7) years were included, of whom 55 (62.5%) were under 5 years of age. A QTcF interval of >450 ms was observed in 7 patient-visits: regimens were CFZ+MFX (n = 3), CFZ+BDQ+LFX (n = 2), CFZ alone (n = 1), and MFX alone (n = 1). There were no events with a QTcF interval of >500 ms. In a multivariate analysis, CFZ+MFX was associated with a 13.0-ms increase in change in QTcF (P < 0.001) and in maximum QTcF (P = 0.0166) compared to those when other MFX- or LFX-based regimens were used. In conclusion, we found a low risk of QTcF interval prolongation in children with RR-TB who received at least one QT-prolonging drug. Greater increases in maximum QTcF and ΔQTcF were observed when MFX and CFZ were used together. Future studies characterizing exposure-QTcF responses in children will be helpful to ensure safety with higher doses if required for effective treatment of RR-TB.

Advances of new drugs bedaquiline and delamanid in the treatment of multi-drug resistant tuberculosis in children

Tuberculosis (TB) is a major public health problem, with nearly 10 million new cases and millions of deaths each year. Around 10% of these cases are in children, but only a fraction receive proper diagnosis and treatment. The spread of drug-resistant (DR) strain of TB has made it difficult to control, with only 60% of patients responding to treatment. Multi-drug resistant TB (MDR-TB) is often undiagnosed in children due to lack of awareness or under-diagnosis, and the target for children's DR-TB treatment has only been met in 15% of goals. New medications such as bedaquiline and delamanid have been approved for treating DR-TB. However, due to age and weight differences, adults and children require different dosages. The availability of child-friendly formulations is limited by a lack of clinical data in children. This paper reviews the development history of these drugs, their mechanism of action, efficacy, safety potential problems and current use in treating DR-TB in children.

The Changing Paradigm of Drug-Resistant Tuberculosis Treatment: Successes, Pitfalls, and Future Perspectives

Drug-resistant tuberculosis (DR-TB) remains a global crisis due to the increasing incidence of drug-resistant forms of the disease, gaps in detection and prevention, models of care, and limited treatment options. The DR-TB treatment landscape has evolved over the last 10 years. Recent developments include the remarkable activity demonstrated by the newly approved anti-TB drugs bedaquiline and pretomanid against Mycobacterium tuberculosis. Hence, treatment of DR-TB has drastically evolved with the introduction of the short-course regimen for multidrug-resistant TB (MDR-TB), transitioning to injection-free regimens and the approval of the 6-month short regimens for rifampin-resistant TB and MDR-TB. Moreover, numerous clinical trials are under way with the aim to reduce pill burden and shorten the DR-TB treatment duration. While there have been apparent successes in the field, some challenges remain. These include the ongoing inclusion of high-dose isoniazid in DR-TB regimens despite a lack of evidence for its efficacy and the inclusion of ethambutol and pyrazinamide in the standard short regimen despite known high levels of background resistance to both drugs. Furthermore, antimicrobial heteroresistance, extensive cavitary disease and intracavitary gradients, the emergence of bedaquiline resistance, and the lack of biomarkers to monitor DR-TB treatment response remain serious challenges to the sustained successes. In this review, we outline the impact of the new drugs and regimens on patient treatment outcomes, explore evidence underpinning current practices on regimen selection and duration, reflect on the disappointments and pitfalls in the field, and highlight key areas that require continued efforts toward improving treatment approaches and rapid biomarkers for monitoring treatment response.

Linezolid resistance in multidrug-resistant mycobacterium tuberculosis: A systematic review and meta-analysis

Introduction: Linezolid (LNZ) is an effective antibiotic to treat patients with multidrug-resistant tuberculosis (MDR-TB) treatment failure. M. tuberculosis strains resistant to isoniazid and rifampin are defined as MDR-TB. In recent years, resistance to LNZ among MDR-TB cases has been reported in several different countries. In this study, we performed a systematic review and meta-analysis to investigate the prevalence of LNZ resistance among MDR-TB isolates.

Methods: The databases of Embase, PubMed/Medline, and Web of Science were searched systematically from January 2000 to April 2021. Statistical analyses were performed by using Comprehensive Meta-Analysis software. Heterogeneity was reported by using the t-squared statistic and Q-statistic. Begg’s rank correlation in combination with the funnel plot were used to evaluate any possible publication bias.

Results: In total, 25 studies were selected for meta-analysis from 14 different countries; the majority was from China (n = 5) and Turkey (n = 4). Moreover, 7,366 patients were infected with MDR M. tuberculosis. Among the study population, 98 patients were co-infected with HIV, and 18 patients with hepatitis C virus (HCV). Furthermore, 28 cases had diabetes, and139 cases were alcohol abuser. Overall, 4,956 MDR M. tuberculosis strains were isolated from TB patients. The pooled frequency of LNZ resistance among the clinical isolates of MDR M. tuberculosis was 4.2% (95%). Begg’s (p = 0.72) test showed no evidence of publication bias.

Conclusion: LNZ resistance among MDR M. tuberculosis isolates is increasing. On the other hand, long-term treatment of MDR-TB cases with LNZ alone is associated with several adverse effects. Thus, it is recommended that newer anti-TB drugs, including bedaquiline and delamanid, in combination with linezolid could increase its effectiveness and decrease toxicities. However, more studies should be done in this field.

Pediatric Tuberculosis Management: A Global Challenge or Breakthrough?

Managing pediatric tuberculosis (TB) remains a public health problem requiring urgent and long-lasting solutions as TB is one of the top ten causes of ill health and death in children as well as adolescents universally. Minors are particularly susceptible to this severe illness that can be fatal post-infection or even serve as reservoirs for future disease outbreaks. However, pediatric TB is the least prioritized in most health programs and optimal infection/disease control has been quite neglected for this specialized patient category, as most scientific and clinical research efforts focus on developing novel management strategies for adults. Moreover, the ongoing coronavirus pandemic has meaningfully hindered the gains and progress achieved with TB prophylaxis, therapy, diagnosis, and global eradication goals for all affected persons of varying age bands. Thus, the opening of novel research activities and opportunities that can provide more insight and create new knowledge specifically geared towards managing TB disease in this specialized group will significantly improve their well-being and longevity.

The efficacy of bedaquiline versus kanamycin in multi-drug resistant tuberculosis: A systematic scoping review

Background

Drug-resistant tuberculosis (DR-TB) has become a serious cause of concern both on a global scale and in South Africa. It is associated with a lower successful treatment rate, thus creating a hurdle in achieving good treatment outcomes for patients.

Aim

The aim of this study was to compare the efficacy of the drug kanamycin, an injectable aminoglycoside, to bedaquiline, a newer oral drug used to treat DR-TB.

Methods

PubMed and Google Scholar, both of which are online databases, were extensively searched using the necessary keywords so that studies that were relevant to the scoping review were retrieved. A data-charting list was developed to extract the needed data for this scoping review.

Results

The main findings of the scoping review showed that bedaquiline was highly efficacious in the treatment of DR-TB, and that it was a valuable addition in the treatment of DR-TB. The findings of the study also showed that kanamycin does not have good efficacy against DR-TB. and its use extends the treatment of DR˗TB.

Conclusion

It stands to reason that bedaquiline replaces kanamycin in the DR-TB drug regimen as it was shown to be more efficacious and patients experienced better treatment outcomes in a shorter period of time. There were also fewer adverse effects associated with bedaquiline as compared to kanamycin.

Contribution

Bedaquiline-based DR-TB therapy is more efficacious than aminoglycoside-based regimens which include kanamycin.

Comparative Efficacy of the Novel Diarylquinoline TBAJ-876 and Bedaquiline against a Resistant Rv0678 Mutant in a Mouse Model of Tuberculosis

Bedaquiline (BDQ, B) is the first-in-class diarylquinoline to be approved for treatment of tuberculosis (TB). Recent guidelines recommend its use in treatment of multidrug- and extensively drug-resistant tuberculosis (MDR/XDR-TB). The newly approved regimen combining BDQ with pretomanid and linezolid is the first 6-month oral regimen proven to be effective against MDR/XDR-TB. However, the emergence of BDQ resistance, primarily due to inactivating mutations in the Rv0678 gene encoding a repressor of the MmpS5-MmpL5 transporter, threatens to undermine the efficacy of new BDQ-containing regimens. Since the shift in MIC due to these mutations is relatively small (2–8×), safer, and more potent, diarylquinoline analogues may be more effective than BDQ. TBAJ-876, which is in phase 1 trials, has more potent in vitro activity and a superior pre-clinical safety profile than BDQ. Using a murine model of TB, we evaluated the dose-dependent activity of TBAJ-876 compared to BDQ against the wild-type H37Rv strain and an isogenic Rv0678 loss-of-function mutant. Although the mutation affected the MIC of both drugs, the MIC of TBAJ-876 against the mutant was 10-fold lower than that of BDQ. TBAJ-876 at doses ≥6.25 mg/kg had greater efficacy against both strains compared to BDQ at 25 mg/kg, when administered alone or in combination with pretomanid and linezolid. Likewise, no selective amplification of BDQ-resistant bacteria was observed at TBAJ-876 doses ≥6.25 mg/kg. These results indicate that replacing BDQ with TBAJ-876 may shorten the duration of TB treatment and be more effective in treating and preventing infections caused by Rv0678 mutants.

Baseline assessment of pharmacovigilance activities in four sub-Saharan African countries: a perspective on tuberculosis

Background

New medicines have become available for the treatment of drug-resistant tuberculosis (DR-TB) and are introduced in sub-Saharan Africa (SSA) by the national TB programs (NTPs) through special access schemes. Pharmacovigilance is typically the task of national medicines regulatory agencies (NMRAs), but the active drug safety monitoring and management (aDSM) recommended for the new TB medicines and regimens was introduced through the NTPs.

We assessed the strengths and challenges of pharmacovigilance systems in Eswatini, Ethiopia, Nigeria and Tanzania, focusing on their capacity to monitor safety of medicines registered and not registered by the NMRAs for the treatment of DR-TB.

Methods

Assessment visits were conducted to all four countries by a multidisciplinary team. We used a pharmacovigilance indicator tool derived from existing tools, interviewed key stakeholders, and visited health facilities where DR-TB patients were treated with new medicines. Assessment results were verified with the local NMRAs and NTPs.

Results

Most countries have enabling laws, regulations and guidelines for the conduct of pharmacovigilance by the NMRAs. The relative success of NTP-NMRA collaboration is much influenced by interpersonal relationships between staff. Division of roles and responsibilities is not always clear and leads to duplication and unfulfilled tasks (e.g. causality assessment). The introduction of aDSM has increased awareness among DR-TB healthcare providers.

Conclusion

aDSM has created awareness about the importance of pharmacovigilance among NTPs. In the future, a push for conducting pharmacovigilance through public health programs seems useful, but this needs to coincide with increased collaboration with between public health programs and NMRAs with clear formulation of roles and responsibilities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-021-07043-6.

Efficacy of bedaquiline in the treatment of drug-resistant tuberculosis: a systematic review and meta-analysis

Background

Drug-resistant tuberculosis (DR-TB) remains a major public health concern worldwide. Bedaquiline, a novel diarylquinoline, was added to the WHO-recommended all-oral regimen for patients with multidrug-resistant tuberculosis. We performed a systematic review and meta-analysis to determine the effect of bedaquiline on tuberculosis treatment outcomes.

Methods

We searched the PubMed, Web of Science and EMBASE databases for relevant studies published up to March 12, 2021. We included studies in which some participants received bedaquiline and others did not. Stata version 16.0 (Stata Corp., College Station, Texas, USA) was used to analyze the results of the meta-analysis. Risk ratios (RRs) with 95% confidence intervals (95% CIs) were calculated to evaluate the effect of bedaquiline on drug-resistant tuberculosis. Between-study heterogeneity was examined by the I-squared test. Randomized controlled trials were assessed for quality using the Jadad scale, and cohort studies were assessed using the Newcastle–Ottawa scale.

Results

Eight studies, including 2 randomized controlled trials and 6 cohort studies involving a total of 21,836 subjects, were included. When compared with the control, bedaquiline treatment was associated with higher rates of culture conversion (risk ratio (RR):1.272 (1.165–1.389), P < 0.001). We found substantial evidence of a significant reduction in all-cause death (RR: 0.529 (0.454–0.616), P < 0.001)) in the bedaquiline treatment group. There was no significant reduction in treatment success (RR = 0.980 (0.948–1.013, P = 0.234)).

Conclusions

This study demonstrated that compared with patients who do not receive bedaquiline, this drug has the potential to achieve a higher culture conversion rate and a lower mortality risk among drug-resistant tuberculosis cases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06666-8.

Insignificant difference in culture conversion between bedaquiline-containing and bedaquiline-free all-oral short regimens for multidrug-resistant tuberculosis

BACKGROUND

Multidrug-resistant tuberculosis (MDR-TB) patients have been suffering long, ineffective, and toxic treatment until short-course injectable-free regimens emerged. However, the new WHO-recommended regimens might be less feasible in the real-world setting. Here, we evaluated two optimized all-oral short-course regimens in China.

METHODS

From April 2019 to August 2020, we conducted a prospective nonrandomized controlled trial and consecutively included 103 MDR-TB patients diagnosed with pulmonary MDR-TB in Shenzhen, China. A 4-5 drug regimen of 9-12 months was tailored to the strain's resistance patterns, patients' affordability, and tolerance to drugs. This was an interim analysis, focusing on the early treatment period.

RESULTS

53.4% (55/103) of patients were prescribed linezolid, fluoroquinolone (FQ), clofazimine, cycloserine, and pyrazinamide, followed by a regimen in which clofazimine was replaced by bedaquiline (35/103, 34.0%). The culture conversion rate was 83.1% and 94.4% at two and four months, respectively, with no significant difference between bedaquiline-free and bedaquiline-containing cases and between FQ-susceptible and FQ-resistant cases. Among 41 patients who completed treatment, 40 (97.6%) patients had a favorable outcome and no relapse was observed. Peripheral neuropathy and arthralgia/myalgia were the most frequent AEs (56.3%, 58/103). 18 AEs caused permanent discontinuation of drugs, mostly due to pyrazinamide and linezolid.

CONCLUSION

Optimized all-oral short-course regimens showed satisfactory efficacy and safety in early treatment stage. Further research is needed to confirm these results.

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.

Tuberculosis: An Update on Pathophysiology, Molecular Mechanisms of Drug Resistance, Newer Anti-TB Drugs, Treatment Regimens and Host- Directed Therapies

Human tuberculosis (TB) is primarily caused by Mycobacterium tuberculosis (Mtb) that inhabits inside and amidst immune cells of the host with adapted physiology to regulate interdependent cellular functions with intact pathogenic potential. The complexity of this disease is attributed to various factors such as the reactivation of latent TB form after prolonged persistence, disease progression specifically in immunocompromised patients, advent of multi- and extensivelydrug resistant (MDR and XDR) Mtb strains, adverse effects of tailor-made regimens, and drug-drug interactions among anti-TB drugs and anti-HIV therapies. Thus, there is a compelling demand for newer anti-TB drugs or regimens to overcome these obstacles. Considerable multifaceted transformations in the current TB methodologies and molecular interventions underpinning hostpathogen interactions and drug resistance mechanisms may assist to overcome the emerging drug resistance. Evidently, recent scientific and clinical advances have revolutionised the diagnosis, prevention, and treatment of all forms of the disease. This review sheds light on the current understanding of the pathogenesis of TB disease, molecular mechanisms of drug-resistance, progress on the development of novel or repurposed anti-TB drugs and regimens, host-directed therapies, with particular emphasis on underlying knowledge gaps and prospective for futuristic TB control programs.

Impact of bedaquiline on treatment outcomes of multidrug-resistant tuberculosis in a high-burden country

BACKGROUND

Evaluation of novel anti-tuberculosis (TB) drugs for the treatment of multidrug-resistant (MDR)-TB continues to be of high interest on the TB research agenda. We assessed treatment outcomes in patients with pulmonary MDR-TB who received bedaquiline-containing treatment regimens in the Republic of Moldova, a high-burden MDR-TB country.

METHOD

We systematically analysed the SIMETB national electronic TB database and performed a retrospective propensity score-matched comparison of treatment outcomes in a cohort of patients with MDR-TB who started treatment during 2016-2018 with a bedaquiline-containing regimen (bedaquiline cohort) and a cohort of patients treated without bedaquiline (non-bedaquiline cohort).

RESULTS

Following propensity score matching, 114 patients were assigned to each cohort of MDR-TB patients. Patients in the bedaquiline cohort had a higher 6-month sputum culture conversion rate than those in the non-bedaquiline cohort (66.7% versus 40.3%; p<0.001). Patients under bedaquiline-containing regimens had a higher cure rate assessed by both World Health Organization (WHO) and TBnet definitions (55.3% versus 24.6%; p=0.001 and 43.5% versus 19.6%; p=0.004, respectively), as well as a lower mortality rate (8.8% versus 20.2%; p<0.001 and 10.9% versus 25.2%; p=0.01, respectively). In patients who previously failed on MDR-TB treatment, >40% of patients achieved a cure with a bedaquiline-containing regimen.

CONCLUSIONS

Bedaquiline-based MDR-TB treatment regimens result in better disease resolution when compared with bedaquiline-sparing MDR-TB treatment regimens under programmatic conditions in a country with a high burden of MDR-TB.

Treatment of Multidrug-Resistant and Extensively Drug-Resistant Tuberculosis in Children: The Role of Bedaquiline and Delamanid

Multidrug-resistant (MDR) tuberculosis (TB) has been emerging at an alarming rate over the last few years. It has been estimated that about 3% of all pediatric TB is MDR, meaning about 30,000 cases each year. Although most children with MDR-TB can be successfully treated, up to five years ago effective treatment was associated with a high incidence of severe adverse effects and patients with extensively drug-resistant (XDR) TB had limited treatment options and no standard regimen. The main objective of this manuscript is to discuss our present knowledge of the management of MDR- and XDR-TB in children, focusing on the characteristics and available evidence on the use of two promising new drugs: bedaquiline and delamanid. PubMed was used to search for all of the studies published up to November 2020 using key words such as "bedaquiline" and "delamanid" and "children" and "multidrug-resistant tuberculosis" and "extensively drug-resistant tuberculosis". The search was limited to articles published in English and providing evidence-based data. Although data on pediatric population are limited and more studies are needed to confirm the efficacy and safety of bedaquiline and delamanid, their use in children with MDR-TB/XDR-TB appears to have good tolerability and efficacy. However, more evidence on these new anti-TB drugs is needed to better guide their use in children in order to design effective shorter regimens and reduce adverse effects, drug interactions, and therapeutic failure.

Comparative Efficacy of the Novel Diarylquinoline TBAJ-587 and Bedaquiline against a Resistant Rv0678 Mutant in a Mouse Model of Tuberculosis

Since its conditional approval in 2012, bedaquiline (BDQ) has been a valuable tool for treatment of drug-resistant tuberculosis. More recently, a novel short-course regimen combining BDQ with pretomanid and linezolid won approval to treat highly drug-resistant tuberculosis. Clinical reports of emerging BDQ resistance have identified mutations in Rv0678 that derepress the expression of the MmpL5/MmpS5 efflux transporter as the most common cause. Because the effect of these mutations on bacterial susceptibility to BDQ is relatively small (e.g., 2 to 8× MIC shift), increasing the BDQ dose would increase antibacterial activity but also pose potential safety concerns, including QTc prolongation. Substitution of BDQ with another diarylquinoline with superior potency and/or safety has the potential to overcome these limitations. TBAJ-587 has greater in vitro potency than BDQ, including against Rv0678 mutants, and may offer a larger safety margin. Using a mouse model of tuberculosis and different doses of BDQ and TBAJ-587, we found that against wild-type M. tuberculosis H37Rv and an isogenic Rv0678 mutant, TBAJ-587 has greater efficacy against both strains than BDQ, whether alone or in combination with pretomanid and either linezolid or moxifloxacin and pyrazinamide. TBAJ-587 also reduced the emergence of resistance to diarylquinolines and pretomanid.

Bedaquiline: Current status and future perspectives

The development of drug-resistant tuberculosis (TB) is a major threat worldwide. Based on World Health Organization (WHO) reports, it is estimated that more than 500 000 new cases of drug-resistant TB occur annually. In addition, there are alarming reports of increasing multidrug-resistant TB (MDR-TB) and the emergence of extensively drug-resistant TB (XDR-TB) from different countries of the world. Therefore, new options for TB therapy are required. Bedaquiline (BDQ), a novel anti-TB drug, has significant minimum inhibitory concentrations (MICs) both against drug-susceptible and drug-resistant TB. Moreover, BDQ was recently approved for therapy of MDR-TB. The current narrative review summarises the available data on BDQ resistance, describes its antimicrobial properties, and provides new perspectives on clinical use of this novel anti-TB agent.

Changes in treatment for multidrug-resistant tuberculosis according to national income

The aim of this study was to analyse temporal changes in treatments for and outcomes of multidrug-resistant (MDR)/rifampin-resistant (RR)-tuberculosis (TB) in the context of national economic status.We analysed data collected by the Collaborative Group for the Meta-Analysis of Individual Patient Data in MDR-TB Treatment on MDR/RR-TB patients from 37 countries. The data were stratified by three national income levels (low-/lower-middle, upper-middle and high) and grouped by time of treatment initiation (2001-2003, 2004-2006, 2007-2009, 2010-2012 and 2013-2015). Temporal trends over the study period were analysed. The probability of treatment success in different income groups over time was calculated using generalised linear mixed models with random effects.In total, 9036 patients were included in the analysis. Over the study period, use of group A drugs (levofloxacin/moxifloxacin, bedaquiline and linezolid) recommended by the World Health Organization increased and treatment outcomes improved in all income groups. Between 2001-2003 and 2013-2015, treatment success rates increased from 60% to 78% in low-/lower-middle-income countries, from 40% to 67% in upper-middle-income countries, and from 73% to 81% in high-income countries. In earlier years, the probability of treatment success in upper-middle-income countries was lower than that in low-/lower-middle-income countries, but no difference was observed after 2010. However, high-income countries had persistently higher probability of treatment success compared to upper-middle income countries.Improved treatment outcomes and greater uptake of group A drugs were observed over time for patients with MDR/RR-TB at all income levels. However, treatment outcomes are still unsatisfactory, especially in upper-middle-income countries.

Multidrug-resistant tuberculosis in children and adolescents: current strategies for prevention and treatment

INTRODUCTION

An estimated 30,000 children develop multidrug-resistant (MDR) tuberculosis (TB) each year, with only a small proportion diagnosed and treated. This field has historically been neglected due to the perception that children with MDR-TB are challenging to diagnose and treat. Diagnostic and therapeutic developments in adults have improved pediatric management, yet further pediatric-specific research and wider implementation of evidence-based practices are required.

AREAS COVERED

This review combines the most recent data with expert opinion to highlight best practice in the evaluation, diagnosis, treatment, and support of children and adolescents with MDR-TB disease. A literature search of PubMed was carried out on topics related to MDR-TB in children. This review provides practical advice on MDR-TB prevention and gives updates on new regimens and novel treatments. The review also addresses host-directed therapy, comorbid conditions, special populations, psychosocial support, and post-TB morbidity, as well as identifying outstanding research questions.

EXPERT OPINION

Increased availability of molecular diagnostics has the potential to aid with the diagnosis of MDR-TB in children. Shorter MDR-TB disease treatment regimens have made therapy safer and shorter and further developments with novel agents and repurposed drugs should lead to additional improvements. The evidence base for MDR-TB preventive therapy is increasing.

Malaria and tuberculosis as diseases of neglected populations: state of the art in chemotherapy and advances in the search for new drugs

Malaria and tuberculosis are no longer considered to be neglected diseases by the World Health Organization. However, both are huge challenges and public health problems in the world, which affect poor people, today referred to as neglected populations. In addition, malaria and tuberculosis present the same difficulties regarding the treatment, such as toxicity and the microbial resistance. The increase of Plasmodium resistance to the available drugs along with the insurgence of multidrug- and particularly tuberculosis drug-resistant strains are enough to justify efforts towards the development of novel medicines for both diseases. This literature review provides an overview of the state of the art of antimalarial and antituberculosis chemotherapies, emphasising novel drugs introduced in the pharmaceutical market and the advances in research of new candidates for these diseases, and including some aspects of their mechanism/sites of action.

Challenge to treat pre-extensively drug-resistant tuberculosis in a low-income country: A report of 12 cases

Setting: Democratic Republic of the Congo is a high-burden TB country. Its capital, Kinshasa, reports annually about one-third of all MDR-TB cases in the country; thus, pre-XDRTB management is warranted.

Objectives

To describe the main challenges in treating pre- XDR TB in this low resources setting and possible solutions.

Method

This is a retrospective study of all pre-XDR TB patients diagnosed in Kinshasa in 2018. A personalized regimen was applied according to the clinical profile, drug availability, and the Drug susceptibility testing (DST). Treatment was administered by hospitalization during the intensive phase and in ambulatory care in the continuation phase except in emergencies. Monthly follow up included evaluating clinical and bacteriological features, renal and liver functions, QT interval on ECG, and audiometry for those under aminoglycosides.

Results

Among the 236 MDR-TB patients identified in 2018, 14 had pre-XDR. Two died before treatment initiation. Of the remaining 12. 75% were male, 50% were aged 25-44 years, 66.7% had previous anti-tuberculosis treatment, 75% had a body mass index < 18.5 kg/m², and 1 patient was HIV positive. On radiography, all the patients had cavities. The median time from the diagnosis to treatment initiation was 48.5 days (range: 14-105). A favorable outcome occurred in 10 cases (83.3%), one patient died, and anotherwas lost to follow up. Nine (75%) patients reported adverse reactions, which were mild or moderate in 6 cases and severe in 2 cases. The severe reactions were psychosis (1 case) and ototoxicity (1 case).

Conclusion

Successful pre-XDRTB treatment using the new strategy is possible even in a low-income country. The main challenges are diagnosis access, drug availability and follow-up laboratory facilities. These can be included in a global policy review by the NTP to ensure the sustainability of the strategies implemented.

Bedaquiline and delamanid for drug-resistant tuberculosis: a clinician's perspective

Drug-resistant tuberculosis (TB) represents a substantial threat to the global efforts to control this disease. After decades of stagnation, the treatment of drug-resistant TB is undergoing major changes: two drugs with a new mechanism of action, bedaquiline and delamanid, have been approved by stringent regulatory authorities and are recommended by the WHO. This narrative review summarizes the evidence, originating from both observational studies and clinical trials, which is available to support the use of these drugs, with a focus on special populations. Areas of uncertainty, including the use of the two drugs together or for prolonged duration, are discussed. Ongoing clinical trials are aiming to optimize the use of bedaquiline and delamanid to shorten the treatment of drug-resistant TB.

Linezolid-Associated Neurologic Adverse Events in Patients with Multidrug-Resistant Tuberculosis, France

Linezolid is one of the most effective drugs for treating multidrug-resistant tuberculosis (MDR TB), but adverse effects remain problematic. We evaluated 57 MDR TB patients who had received >1 dose of linezolid during 2011–2016. Overall, patients received 600 mg/day of linezolid for a median of 13 months. In 33 (58%) patients, neurologic or ophthalmologic signs developed, and 18 (32%) had confirmed peripheral neuropathy, which for 78% was irreversible at 12 months after the end of TB treatment despite linezolid withdrawal. Among the 19 patients who underwent ophthalmologic evaluation, 14 patients had optic neuropathy that fully reversed for 2. A total of 16 (33%) of 49 patients had a linezolid trough concentration >2 mg/L, and among these, 14 (88%) experienced adverse effects. No significant association was found between trough concentration and neurologic toxicity. These findings suggest the need to closely monitor patients for neurologic signs and discuss optimal duration of linezolid treatment.

Improved Treatment Outcomes With Bedaquiline When Substituted for Second-line Injectable Agents in Multidrug-resistant Tuberculosis: A Retrospective Cohort Study

BACKGROUND

Bedaquiline is used as a substitute for second-line injectable (SLI) intolerance in the treatment of multidrug-resistant (MDR) tuberculosis, but the efficacy and safety of this strategy is unknown.

METHODS

In this retrospective cohort study adults receiving bedaquiline substitution for MDR tuberculosis therapy, plus a matched control group who did not receive bedaquiline, were identified from the electronic tuberculosis register in the Western Cape Province, South Africa. The primary outcome measure was the proportion of patients with death, loss to follow-up, or failure to achieve sustained culture conversion at 12 months of treatment.

RESULTS

Data from 162 patients who received bedaquiline substitution and 168 controls were analyzed; 70.6% were infected with human immunodeficiency virus. Unfavorable outcomes occurred in 35 of 146 (23.9%) patients in the bedaquiline group versus 51 of 141 (36.2%) in the control group (relative risk, 0.66; 95% confidence interval, .46 -.95). The number of patients with culture reversion was lower in those receiving bedaquiline (1 patient; 0.8%) than in controls (12 patients; 10.3%; P = .001). Delayed initiation of bedaquiline was independently associated with failure to achieve sustained culture conversion (adjusted odds ratio for every 30-day delay, 1.5; 95% confidence interval, 1.1-1.9). Mortality rates were similar at 12 months (11 deaths in each group; P = .97).

CONCLUSIONS

Substituting bedaquiline for SLIs in MDR tuberculosis treatment resulted in improved outcomes at 12 months compared with patients who continued taking SLIs, supporting the use of bedaquiline for MDR tuberculosis treatment in programmatic settings.

Early treatment outcome of bedaquiline plus optimised background regimen in drug resistant tuberculosis patients

AIMS

Bedaquiline (BDQ) has been recently approved for drug resistant tuberculosis with active drug safety monitoring under programmatic condition. The present study was conducted to evaluate safety, tolerability and efficacy of bedaquiline plus optimised background regimen.

METHODS

A prospective study was conducted on cohort of pre-extensively drug resistant (XDR) and XDR pulmonary TB patients. Eligible patients were closely monitored for cardiac safety, adverse events (AEs), clinical and microbiological improvement during BDQ (6 months) and post BDQ phase for twelve months.

RESULTS

Of 127 patients enrolled, a significant increase in mean QTc interval was observed on 13th day and 3rd week as compared to baseline (p < 0.0001). Mean maximum increase of QTc was 37.92ms (95% CI, 14.1-61.74ms). Concomitant anti-TB medications, age, gender, low body mass index (BMI) had significant effect on QTc prolongation (p < 0.0001, p < 0.05). However, none of the patient required discontinuation of BDQ. Majority of AEs (86.3%) were non-serious and not preventable 108 (87.1%). The median time for sputum-culture conversion was 40.89 ± 3.5 days (95% CI, 34-48 days) and the treatment outcome was successful in 102 (80.3%) patients with negative sputum culture conversion.

CONCLUSIONS

Bedaquiline containing regimen achieved favourable outcome. Although, bedaquiline along with concomitant anti-TB medications has the potential to prolong QTc interval, the benefit certainly outweighs the risk. This calls for a through pre-treatment cardiovascular and biochemical evaluation as a preventive measure and appropriate selection of patients for safe use of BDQ and successful outcome.

Challenges and controversies in the treatment of spinal tuberculosis

Current guidelines regarding management of spinal TB are mostly extrapolated from trials on pulmonary disease. Since the British Medical Research Council (BMRC) trials in the 1970s, there are not many good quality studies that substantiate best practice guidelines for the management of this entity. Tuberculous infection of the spine behaves much differently from bacterial osteomyelitis and limited data leads to ambiguity in many cases. Although a few studies have been conducted in patients with spinal TB, most were in the era preceding short course chemotherapy and prior to current radiological and surgical advances. While spinal TB is primarily managed medically, surgical intervention may be needed in certain cases. We discuss areas of uncertainty and challenges that exist with regards to medical treatment, diagnosis, therapeutic endpoints, and a few surgical considerations. Substantial delay in diagnosis continues to be common with this disease even in the developed nations, leading to substantial morbidity. In light of limited evidence, there is an emerging recognition of the need to individualize various aspects of its treatment such as duration, frequency and acknowledging the limitations of various diagnostic and radiological modalities. We aim to consolidate potential areas of research in the diagnosis and management of spinal TB and to revisit the latest published evidence on its redressal.

Molecule Property Analyses of Active Compounds for Mycobacterium tuberculosis

Tuberculosis (TB) continues to claim the lives of around 1.7 million people per year. Most concerning are the reports of multidrug drug resistance. Paradoxically, this global health pandemic is demanding new therapies when resources and interest are waning. However, continued tuberculosis drug discovery is critical to address the global health need and burgeoning multidrug resistance. Many diverse classes of antitubercular compounds have been identified with activity in vitro and in vivo. Our analyses of over 100 active leads are representative of thousands of active compounds generated over the past decade, suggests that they come from few chemical classes or natural product sources. We are therefore repeatedly identifying compounds that are similar to those that preceded them. Our molecule-centered cheminformatics analyses point to the need to dramatically increase the diversity of chemical libraries tested and get outside of the historic Mtb property space if we are to generate novel improved antitubercular leads.

Drug-associated adverse events in the treatment of multidrug-resistant tuberculosis: an individual patient data meta-analysis

BACKGROUND

Treatment of multidrug-resistant tuberculosis requires long-term therapy with a combination of multiple second-line drugs. These drugs are associated with numerous adverse events that can cause severe morbidity, such as deafness, and in some instances can lead to death. Our aim was to estimate the absolute and relative frequency of adverse events associated with different tuberculosis drugs to provide useful information for clinicians and tuberculosis programmes in selecting optimal treatment regimens.

METHODS

We did a meta-analysis using individual-level patient data that were obtained from studies that reported adverse events that resulted in permanent discontinuation of anti-tuberculosis medications. We used a database created for our previous meta-analysis of multidrug-resistant tuberculosis treatment and outcomes, for which we did a systematic review of literature published between Jan 1, 2009, and Aug 31, 2015 (updated April 15, 2016), and requested individual patient-level information from authors. We also considered for this analysis studies contributing patient-level data in response to a public call made by WHO in 2018. Meta-analysis for proportions and arm-based network meta-analysis were done to estimate the incidence of adverse events for each tuberculosis drug.

FINDINGS

58 studies were identified, including 50 studies from the updated individual patient data meta-analysis for multidrug-resistant tuberculosis treatment. 35 of these studies, with 9178 patients, were included in our analysis. Using meta-analysis of proportions, drugs with low risks of adverse event occurrence leading to permanent discontinuation included levofloxacin (1·3% [95% CI 0·3-5·0]), moxifloxacin (2·9% [1·6-5·0]), bedaquiline (1·7% [0·7-4·2]), and clofazimine (1·6% [0·5-5·3]). Relatively high incidence of adverse events leading to permanent discontinuation was seen with three second-line injectable drugs (amikacin: 10·2% [6·3-16·0]; kanamycin: 7·5% [4·6-11·9]; capreomycin: 8·2% [6·3-10·7]), aminosalicylic acid (11·6% [7·1-18·3]), and linezolid (14·1% [9·9-19·6]). Risk of bias in selection of studies was judged to be low because there were no important differences between included and excluded studies. Variability between studies was significant for most outcomes analysed.

INTERPRETATION

Fluoroquinolones, clofazimine, and bedaquiline had the lowest incidence of adverse events leading to permanent drug discontinuation, whereas second-line injectable drugs, aminosalicylic acid, and linezolid had the highest incidence. These results suggest that close monitoring of adverse events is important for patients being treated for multidrug-resistant tuberculosis. Our results also underscore the urgent need for safer and better-tolerated drugs to reduce morbidity from treatment itself for patients with multidrug-resistant tuberculosis.

FUNDING

Canadian Institutes of Health Research, Centers for Disease Control and Prevention (USA), American Thoracic Society, European Respiratory Society, and Infectious Diseases Society of America.

Standardised shorter regimens versus individualised longer regimens for rifampin- or multidrug-resistant tuberculosis

We sought to compare the effectiveness of two World Health Organization (WHO)-recommended regimens for the treatment of rifampin- or multidrug-resistant (RR/MDR) tuberculosis (TB): a standardised regimen of 9-12 months (the "shorter regimen") and individualised regimens of ≥20 months ("longer regimens").We collected individual patient data from observational studies identified through systematic reviews and a public call for data. We included patients meeting WHO eligibility criteria for the shorter regimen: not previously treated with second-line drugs, and with fluoroquinolone- and second-line injectable agent-susceptible RR/MDR-TB. We used propensity score matched, mixed effects meta-regression to calculate adjusted odds ratios and adjusted risk differences (aRDs) for failure or relapse, death within 12 months of treatment initiation and loss to follow-up.We included 2625 out of 3378 (77.7%) individuals from nine studies of shorter regimens and 2717 out of 13 104 (20.7%) individuals from 53 studies of longer regimens. Treatment success was higher with the shorter regimen than with longer regimens (pooled proportions 80.0% versus 75.3%), due to less loss to follow-up with the former (aRD -0.15, 95% CI -0.17- -0.12). The risk difference for failure or relapse was slightly higher with the shorter regimen overall (aRD 0.02, 95% CI 0-0.05) and greater in magnitude with baseline resistance to pyrazinamide (aRD 0.12, 95% CI 0.07-0.16), prothionamide/ethionamide (aRD 0.07, 95% CI -0.01-0.16) or ethambutol (aRD 0.09, 95% CI 0.04-0.13).In patients meeting WHO criteria for its use, the standardised shorter regimen was associated with substantially less loss to follow-up during treatment compared with individualised longer regimens and with more failure or relapse in the presence of resistance to component medications. Our findings support the need to improve access to reliable drug susceptibility testing.

Injectable-free regimens containing bedaquiline, delamanid, or both for adolescents with rifampicin-resistant tuberculosis in Khayelitsha, South Africa

BACKGROUND

Limited data exist on the use of bedaquiline and delamanid in adolescents with rifampicin-resistant tuberculosis (RR-TB). We describe RR-TB treatment of adolescents (10-19 years) with injectable-free regimens containing these drugs in Khayelitsha, South Africa.

METHODS

This retrospective study included adolescents initiating injectable-free RR-TB treatment regimens containing bedaquiline and/or delamanid from February 2015 to June 2018. We report adverse events (AEs) of interest, sputum culture conversion (SCC), and final end-of-treatment outcomes.

FINDINGS

Twenty-two patients were included; median age at treatment initiation was 17 years (interquartile range [IQR] 15-18), and six (27%) were HIV-positive (median CD4 count 191 cells/mm3 [IQR 157-204]). Eight (36%) patients had RR-TB with fluoroquinolone resistance; ten (45%), eight (36%), and four (18%) patients received regimens containing bedaquiline, delamanid, or the combination of bedaquiline and delamanid, respectively. The median durations of exposure to bedaquiline and delamanid were 5·6 (IQR 5·5-8·4) and 9·4 (IQR 5·9-14·4) months, respectively. There were 49 AEs of interest which occurred in 17 (77%) patients. Fourteen (64%) patients had pulmonary TB with positive sputum cultures at bedaquiline and/or delamanid initiation; among these SCC at month 6 was 79%. Final end-of-treatment outcomes for the 22 adolescent were: 17 (77%) successfully treated, two (9%) lost-to-follow-up, two (9%) treatment failed, and one (5%) died.

INTERPRETATION

This study found that injectable-free regimens containing bedaquiline and/or delamanid in a programmatic setting were effective and well tolerated in adolescents and should be routinely provided for RR-TB treatment in this age group as recommended by the World Health Organisation.

Safety implications of combined antiretroviral and anti-tuberculosis drugs

Introduction: Antiretroviral and anti-tuberculosis (TB) drugs are often co-administered in people living with HIV (PLWH). Early initiation of antiretroviral therapy (ART) during TB treatment improves survival in patients with advanced HIV disease. However, safety concerns related to clinically significant changes in drug exposure resulting from drug-drug interactions, development of overlapping toxicities and specific challenges related to co-administration during pregnancy represent barriers to successful combined treatment for HIV and TB.Areas covered: Pharmacokinetic interactions of different classes of ART when combined with anti-TB drugs used for sensitive-, drug-resistant (DR) and latent TB are discussed. Overlapping drug toxicities, implications of immune reconstitution inflammatory syndrome (IRIS), safety in pregnancy and research gaps are also explored.Expert opinion: New antiretroviral and anti-tuberculosis drugs have been recently introduced and international guidelines updated. A number of effective molecules and clinical data are now available to build treatment regimens for PLWH with latent or active TB. Adopting a systematic approach that also takes into account the need for individualized variations based on the available evidence is the key to successfully integrate ART and TB treatment and improve treatment outcomes.

Outcomes of Bedaquiline Treatment in Patients with Multidrug-Resistant Tuberculosis

Bedaquiline is recommended by the World Health Organization for the treatment of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB). We pooled data from 5 cohorts of patients treated with bedaquiline in France, Georgia, Armenia, and South Africa and in a multicountry study. The rate of culture conversion to negative at 6 months (by the end of 6 months of treatment) was 78% (95% CI 73.5%-81.9%), and the treatment success rate was 65.8% (95% CI 59.9%-71.3%). Death rate was 11.7% (95% CI 7.0%-19.1%). Up to 91.1% (95% CI 82.2%-95.8%) of the patients experienced >1 adverse event, and 11.2% (95% CI 5.0%-23.2%) experienced a serious adverse event. Lung cavitations were consistently associated with unfavorable outcomes. The use of bedaquiline in MDR and XDR TB treatment regimens appears to be effective and safe across different settings, although the certainty of evidence was assessed as very low.

Bedaquiline in multidrug-resistant tuberculosis treatment: Safety and efficacy in a Korean subpopulation

BACKGROUND

The final treatment outcomes of Korean multidrug-resistant tuberculosis (MDR-TB) patients treated with bedaquiline in the C209 trial have not yet been reported. Therefore, a subgroup analysis of the Korean population from the C209 trial was performed, and the results were compared with those of the overall C209 study population.

METHODS

In the C209 trial, MDR-TB patients were treated with bedaquiline for 24 weeks in combination with background anti-TB drugs, and were followed-up until week 120 after bedaquiline treatment initiation.

RESULTS

With the exception of drug susceptibility patterns, the baseline clinical characteristics of both groups were similar. The proportions of pre-extensively drug-resistant TB to extensively drug-resistant TB (pre-XDR-TB/XDR-TB) were 61.9 and 35.2% in the Korean and the overall C209 populations, respectively. Aminoglycosides, later-generation fluoroquinolones, cycloserine, and linezolid were the most common concomitant drugs used during bedaquiline treatment. The culture conversion rates of both groups were similar at week 24 (end of bedaquiline treatment; 80.0% vs. 79.5%) and 120 (75.0% vs. 72.2%). Additionally, the frequency and type of adverse events during treatment were similar in both groups, and 1 patient (5.0%) died due to a cause unrelated to bedaquiline treatment.

CONCLUSIONS

Bedaquiline showed similar efficacy and safety in Korean patients with MDR-TB, despite their advanced drug-resistance profiles, possibly due to other concomitant drugs such as linezolid.

Effectiveness and safety of bedaquiline under conditional access program for treatment of drug-resistant tuberculosis in India: An interim analysis

BACKGROUND

India accounts for a quarter of the world's multidrug-resistant tuberculosis (MDR-TB); with less than 50% having successful treatment outcomes. Bedaquiline (BDQ) was approved for use under conditional access program in India in 2015.

OBJECTIVE

We evaluate the effectiveness, safety, and tolerability of a BDQ containing regimen used under field settings in India.

METHOD

Interim analysis of a prospective cohort of MDR-TB patients on a BDQ containing regimen at six sites in the country.

RESULTS

Six hundred and twenty MDR-TB patients [349 (56%) males; 554 (89%) between 18 and 50 years and 240 (39%) severely malnourished] were started on BDQ containing regimen between June 2016 and August 2017. There 354 (57%) patients had MDR-TB with additional drug resistance to fluoroquinolone (MDR_FQ); 31 (5%) with additional resistance to second-line injectable (MDR_SLI) and 101 (16%) extensively drug-resistant TB. After 6 months of treatment, culture conversion was achieved in 513 of 620 (83%) patients. The median time to culture conversion was 60 days. Higher body mass index was the only factor associated with faster culture conversion (HR 1.97; 95% CI 1.24-2.9). Around 100 patients (16.3%) experienced a ≥60-ms increase in QTc interval during the treatment. Seventy-three (12%) deaths were reported, the majority of them (56%) occurring within the first 6 months of treatment.

CONCLUSIONS

BDQ with a background regimen has the potential to achieve higher and faster culture conversion rates with a lower toxicity profile among DR-TB patients. Use of BDQ with additional monitoring may be safe and effective even in the field settings.

Integration of drug safety monitoring in tuberculosis treatment programmes: country experiences

New drugs and shorter treatments for drug-resistant tuberculosis (DR-TB) have become available in recent years and active pharmacovigilance (PV) is recommended by the World Health Organization (WHO) at least during the early phases of implementation, with active drug safety monitoring and management (aDSM) proposed for this. We conducted a literature review of papers reporting on aDSM. Up to 18 April, 2019, results have only been published from one national aDSM programme. Because aDSM is being introduced in many low- and middle-income countries, we also report experiences in introducing it into DR-TB treatment programmes, targeting the reporting of a restricted set of adverse events (AEs) as per WHO-recommended aDSM principles for the period 2014-2017. Early beneficial effects of active PV for TB patients include increased awareness about the occurrence, detection and management of AEs during TB treatment, and the increase of spontaneous reporting in some countries. However, because PV capacity is low in most countries and collaboration between national TB programmes and national PV centres remains weak, parallel and coordinated co-development of the capacities of both TB programmes and PV centres is needed.

Clinical Management of Multidrug-Resistant Tuberculosis in 16 European Countries

RATIONALE

Multidrug-resistant tuberculosis (MDR-TB) is a major burden to public health in Europe. Reported treatment success rates are around 50% or less, and cure rates are even lower.

OBJECTIVES

To document the management and treatment outcome in patients with MDR-TB in Europe.

METHODS

We performed a prospective cohort study, analyzing management and treatment outcomes stratified by incidence of patients with MDR-TB in Europe. Treatment outcomes were compared by World Health Organization and alternative simplified definitions by the Tuberculosis Network European Trialsgroup (TBNET).

MEASUREMENTS AND MAIN RESULTS

A total of 380 patients with MDR-TB were recruited and followed up between 2010 and 2014 in 16 European countries. Patients in high-incidence countries compared with low-incidence countries were treated more frequently with standardized regimen (83.2% vs. 9.9%), had delayed treatment initiation (median, 111 vs. 28 d), developed more additional drug resistance (23% vs. 5.8%), and had increased mortality (9.4% vs. 1.9%). Only 20.1% of patients using pyrazinamide had proven susceptibility to the drug. Applying World Health Organization outcome definitions, frequency of cure (38.7% vs. 9.7%) was higher in high-incidence countries. Simplified outcome definitions that include 1 year of follow-up after the end of treatment showed similar frequency of relapse-free cure in low- (58.3%), intermediate- (55.8%), and high-incidence (57.1%) countries, but highest frequency of failure in high-incidence countries (24.1% vs. 14.6%).

CONCLUSIONS

Conventional standard MDR-TB treatment regimens resulted in a higher frequency of failure compared with individualized treatments. Overall, cure from MDR-TB is substantially more frequent than previously anticipated, and poorly reflected by World Health Organization outcome definitions.

Tuberculosis

Tuberculosis remains the leading cause of death from an infectious disease among adults worldwide, with more than 10 million people becoming newly sick from tuberculosis each year. Advances in diagnosis, including the use of rapid molecular testing and whole-genome sequencing in both sputum and non-sputum samples, could change this situation. Although little has changed in the treatment of drug-susceptible tuberculosis, data on increased efficacy with new and repurposed drugs have led WHO to recommend all-oral therapy for drug-resistant tuberculosis for the first time ever in 2018. Studies have shown that shorter latent tuberculosis prevention regimens containing rifampicin or rifapentine are as effective as longer, isoniazid-based regimens, and there is a promising vaccine candidate to prevent the progression of infection to the disease. But new tools alone are not sufficient. Advances must be made in providing high-quality, people-centred care for tuberculosis. Renewed political will, coupled with improved access to quality care, could relegate the morbidity, mortality, and stigma long associated with tuberculosis, to the past.

Early efficacy and safety of Bedaquiline and Delamanid given together in a "Salvage Regimen" for treatment of drug-resistant tuberculosis

BACKGROUND

Drug-Resistant Tuberculosis (DR-TB) patients for whom a WHO recommended regimen along with Bedaquiline (BDQ) cannot be prescribed, Delamanid (DLM) was added along with other drugs to provide a "Salvage Regimen". The experience of the Institute in respect of early efficacy and safety of both drugs given together is presented.

OBJECTIVE

To ascertain the early efficacy, safety and tolerability of Bedaquline and Delamanid given together as a part of salvage regimen.

METHODS

BDQ and DLM were used together to make regimens along with other drugs where four effective anti TB drugs could not be prescribed as per WHO recommendations. Patients were followed up for sputum smear and culture conversion and adverse events during the treatment.

RESULTS

In this cohort study, 53 DR-TB patients (Median age-24) were initiated on regimens containing both BDQ and DLM. Sputum smear conversion was seen in 35% and 94% patients at the end of 1st week and 3rd month respectively. 84% patients had culture conversion at the end of 4th month. 29 adverse events (AE) were reported among 17 patients and there were 11 deaths. QTc prolongation more than 500 MS was seen in only 1 patient.

CONCLUSION

BDQ and DLM given together in a salvage regimen is efficacious with low rate of adverse events. The combination provides hope to DR-TB patients with limited treatment options and should be provided as a life saving option.

Safety, efficacy, and pharmacokinetics of bedaquiline in Japanese patients with pulmonary multidrug-resistant tuberculosis: An interim analysis of an open-label, phase 2 study

BACKGROUND

Bedaquiline, a diarylquinoline with a novel mode of action that specifically inhibits mycobacterial adenosine 5׳-triphosphate (ATP) synthase, has been approved in over 50 countries including the USA and EU for the treatment of pulmonary multidrug-resistant tuberculosis (pMDR-TB) in adults.

METHODS

This study was conducted to evaluate the safety, efficacy, and pharmacokinetics of bedaquiline in adult Japanese patients with pMDR-TB. In this study, patients received bedaquiline for 24 weeks or more (maximum 48 weeks) with an individualized background regimen (BR). Efficacy was assessed as the time to sputum culture conversion after the initiation of bedaquiline treatment.

RESULTS

Treatment-emergent adverse events (TEAEs) were reported in 5/6 patients (83.3%) during the investigational phase (bedaquiline treatment + 1 week). The TEAEs observed in >1 patient were hepatic function abnormal (4/6), hypoaesthesia (3/6), nasopharyngitis, acne, and nausea (2/6 each). The TEAEs leading to treatment discontinuation of bedaquiline were none. The time to sputum culture conversion was 14-15 days. Plasma bedaquiline C_max was achieved within 4-6 h of bedaquiline administration and AUC_24h ranged from 50,637 to 107,300 ng*h/mL (5 patients) at week 2 and were 58,513 and 77,148 ng *h/mL (2 patients) at week 24.

CONCLUSIONS

No new safety signals in patients, including those receiving bedaquiline with BR beyond 24 weeks, and the faster culture conversion time indicate that the administration of bedaquiline as part of a multi-drug regimen for at least 24 weeks is a suitable treatment for adult Japanese patients with pMDR-TB.

Treatment outcomes for multidrug-resistant tuberculosis in Eastern Taiwan

Objectives:

The objective of this study is to evaluate the treatment outcomes of patients with multidrug-resistant tuberculosis (MDR-TB) under special programmatic management in Eastern Taiwan over the past 10 years.

Materials and Methods:

All newly diagnosed MDR-TB patients and MDR-TB patients enrolled previously with persistent positive cultures were included in this study, from May 2007 to April 2017, in Eastern Taiwan. A panel of pulmonologists designed the initial MDR-TB regimens. Subsequently, regimens were adjusted according to drug susceptibility test results for second-line drugs. Mobile teams were organized for treatment support, and several measures were adapted to safeguard effective treatment support.

Results:

A total of 178 patients with bacteriological confirmed pulmonary MDR-TB were identified, of whom 167 had treatment outcomes when the study was conducted. Of these 167 patients, 120 (71.9%) were cured, 11 (6.5%) completed therapy (78.4% had successful treatment), 25 (15.0%) died, 9 (5.4%) had treatment failure, none were transferred out, and 2 (1.2%) were lost to follow-up. Surgery was performed on 8 (4.8%).

Conclusions:

This is an analysis of the treatment outcomes after adopting the Directly Observed Treatment, Short-course Plus program to treat MDR-TB patients in Eastern Taiwan. We had a low proportion of loss-to-follow-up, resulting in a high treatment success rate. This program serves as an effective model in providing quality care to patients with MDR-TB.

In Vitro Susceptibility Testing of Bedaquiline against Mycobacterium abscessus Complex

We performed bedaquiline broth microdilution susceptibility testing using Clinical and Laboratory Standards Institute (CLSI) guidelines on 104 nonduplicate isolates of Mycobacterium abscessus complex [M. abscessus subsp. abscessus (76); M. abscessus subsp. massiliense (10); M. abscessus subsp. bolletii (2); and M. abscessus subsp. abscessus-M. abscessus subsp. massiliense hybrid, i.e., M. abscessus subsp. abscessus by rpoB gene and M. abscessus subsp. massiliense by erm(41) gene (16)]. All isolates from patients not known to have been on bedaquiline prior had MIC values of ≤0.25 μg/ml. The bedaquiline MIC₅₀ value for all 76 isolates of M. abscessus subsp. abscessus and 16 isolates of M. abscessus subsp. abscessus-M. abscessus subsp. massiliense hybrid was 0.06 μg/ml. The MIC₅₀ and MIC₉₀ values for 10 isolates of M. abscessus subsp. massiliense were 0.12 μg/ml. Only two isolates of M. abscessus subsp. bolletii were tested with bedaquiline MICs of 0.06 μg/ml. Our study suggests that oral bedaquiline may have potential use in the treatment of disease caused by the M. abscessus complex. Combination therapy with other agents (imipenem, cefoxitin, amikacin, and/or tigecycline) is recommended.

Curving Tuberculosis: Current Trends and Future Needs

Tuberculosis (TB) presents new challenges as a global public health problem, especially at a time of increasing threats to some particular patients due to Human Immunodeficiency Virus (HIV) infection and multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis. The World Health Assembly strives to reduce TB deaths by 95% and to decrease TB incidence by 95% by 2035. However, new approaches are necessary in order to attain these objectives. Such approaches include active ascertainment of cases in high risk populations, increasing the availability of accurate point-of-care testing, rapid detection of drug resistance, novel vaccines, and new prophylaxis and treatment regimens (particularly for MDR and XDR TB). The ultimate objective of those programs is to develop highly effective drug regimens that can achieve high cure rates regardless of strains’ resistance patterns.

Bedaquiline and delamanid in the treatment of multidrug-resistant tuberculosis: Promising but challenging

Improving treatment outcomes in multidrug‐resistant tuberculosis (MDR‐TB) is partly hampered by inadequate effective antitubercular agents. Development of bedaquiline and delamanid has potentially changed the treatment landscape for MDR‐TB. This review provides an update on the progress of these novel antitubercular agents. We review published studies aimed at evaluating clinical efficacy and effectiveness of bedaquiline and delamanid. Five prospective clinical studies and seven retrospective studies on bedaquiline showed that patients treated with a bedaquiline‐containing regimen had a high culture conversion rate ranging from 65 to 100% and a satisfactory treatment outcome. The combined use with linezolid might add to the effectiveness of bedaquiline. Controversies about bedaquiline resistance are discussed. Three clinical trials have reported outcomes on delamanid and showed that introducing delamanid to a background regimen improved culture conversion rate at 2 months from 29.6% to more than 40%. A higher favorable treatment rate was also observed among patients who received delamanid for more than 6 months, but about a quarter of patients defaulted in the control group. Seven retrospective studies were summarized and found a treatment benefit as well. More reliable evidence from randomized clinical trials reporting on the treatment outcomes is needed urgently to support a strong recommendation for the use of delamanid. Advances in the combined use of bedaquiline and delamanid are also reviewed, and the combination may be well tolerated but requires electrocardiograph monitoring.

Inhibitors of energy metabolism interfere with antibiotic-induced death in mycobacteria

Energy metabolism has recently gained interest as a target space for antibiotic drug development in mycobacteria. Of particular importance is bedaquiline (Sirturo), which kills mycobacteria by inhibiting the F₁F₀ ATP synthase. Other components of the electron transport chain such as the NADH dehydrogenases (NDH-2 and NdhA) and the terminal respiratory oxidase bc₁:aa₃ are also susceptible to chemical inhibition. Because antituberculosis drugs are prescribed as part of combination therapies, the interaction between novel drugs targeting energy metabolism and classical first and second line antibiotics must be considered to maximize treatment efficiency. Here, we show that subinhibitory concentration of drugs targeting the F₁F₀ ATP synthase and the cytochrome bc₁:aa₃, as well as energy uncouplers, interfere with the bactericidal potency of isoniazid and moxifloxacin. Isoniazid- and moxifloxacin-induced mycobacterial death correlated with a transient increase in intracellular ATP that was dissipated by co-incubation with energy metabolism inhibitors. Although oxidative phosphorylation is a promising target space for drug development, a better understanding of the link between energy metabolism and antibiotic-induced mycobacterial death is essential to develop potent drug combinations for the treatment of tuberculosis.

The use of bedaquiline to treat patients with multidrug-resistant tuberculosis and end-stage renal disease: A case report

The use of bedaquiline to treat patients with multidrug-resistant tuberculosis (MDR-TB) and end-stage renal disease (ESRD) may raise safety concerns. Currently, no clinical information is available on the use of bedaquiline to treat MDR-TB patients with ESRD. We report the use of bedaquiline to treat two patients with MDR-TB and ESRD. This report highlights the safety and tolerability of bedaquiline as well as the treatment outcome. The use of bedaquiline in patients with ESRD is also discussed.