Clofazimine improves clinical outcomes in multidrug-resistant tuberculosis: a randomized controlled trial

Bedaquiline and linezolid regimens for multidrug-resistant tuberculosis: a systematic review and meta-analysis

OBJECTIVE

Multidrug-resistant tuberculosis (MDR-TB) remains a global public health challenge, complicating treatment strategies and requiring advanced therapeutic approaches. The persistence of MDR-TB has led to a demand for regimens that are more effective in improving treatment outcomes and controlling transmission. This systematic review and meta-analysis sought to examine the efficacy of linezolid (LZD) and bedaquiline (BDQ) in MDR-TB treatment regimens, evaluating their roles in enhancing therapeutic success and informing optimized management of MDR-TB.

METHODS

A comprehensive search was conducted across MEDLINE (PubMed), EMBASE, the Cochrane Central Register of Controlled Trials, Scopus, and Web of Science for randomized controlled trials assessing the efficacy of LZD and BDQ in MDR-TB patients up to September 14, 2024. We analyzed treatment outcomes, reporting favorable outcomes (cured and treatment completed) and unfavorable outcomes (death, treatment failure, and loss to follow-up) with a 95% confidence interval.

RESULTS

Our analysis included 11 trials, with a total of 1,999 participants. The findings indicate that BDQ+LZD-containing regimens yield significantly higher favorable treatment outcomes (84.5%; 95% CI, 79.8%-88.2%) and lower unfavorable outcomes (15.4%; 95% CI, 11.6%-20.2%). In contrast, regimens lacking either LZD or BDQ show lower efficacy, with favorable outcomes at 66.8% (95% CI, 59.5%-73.4%) and unfavorable outcomes at 33.0% (95% CI, 25.6%-41.4%).

CONCLUSIONS

MDR-TB treatment regimens including BDQ and LZD lead to significantly better patient outcomes. The combined bactericidal and protein synthesis-inhibiting effects of BDQ and LZD create a powerful therapeutic synergy. Adding pretomanid further enhances this effectiveness, highlighting its value in complex cases. Future research should focus on optimizing these regimens for safety and efficacy and explore adjunctive therapies to improve MDR-TB outcomes even further.

Analytical and clinical validation of a volumetric absorptive microsampling (VAMS) - Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the analysis of Clofazimine in whole blood

Monitoring clofazimine blood concentrations is crucial for preventing treatment failure in patients with Multidrug-resistant Tuberculosis (MDR-TB). Volumetric Absorptive Microsampling (VAMS) offers a practical alternative to Conventional Venous Sampling (CVS), enabling remote sampling. Samples collected via VAMS can be conveniently transported to laboratories via courier, enhancing accessibility and patient compliance. In this study, we developed and validated an analytical method for quantifying clofazimine in whole blood collected using VAMS. The study compared the performance and cost-effectiveness of VAMS with CVS. A total of 55 matched finger-prick VAMS and CVS samples were obtained from 39 MDR-TB patients and analyzed using validated UPLC-MS/MS assays. Clofazimine concentrations collected via VAMS and CVS were compared using Passing-Bablok regression, while bias and overall agreement were evaluated through Bland-Altman analysis. Passing-Bablok regression revealed no significant constant difference between VAMS and CVS (95% CI slope: 0.7627-0.9573; 95% CI intercept: -0.02141-0.06482), but systematic difference of 13% lower clofazimine concentrations was observed in VAMS compared to plasma. Bland-Altman analysis demonstrated moderate agreement, with mean plasma/VAMS ratio of 0.9457 (95% CI: 0.88358-1.00775) and 95% Limits of Agreement (LoA) ranging from 0.4956 (95% CI: 0.38881-0.60230) to 1.3858 (95% CI: 1.28903-1.50252). Although statistically significant bias was identified, applying correction factors could improve interchangeability between the two techniques. Furthermore, VAMS was more cost-effective than CVS, with approximate cost difference of 4.45 USD per sample. These findings suggest that VAMS sampling has the potential to replace CVS for routine clinical monitoring of clofazimine, offering a more accessible and economical approach.

In vitro monitoring of drug resistance emergence during stepwise induction of bedaquiline and clofazimine, alone and in combination: a phenotypic and genotypic analysis

OBJECTIVES

The co-resistance between bedaquiline and clofazimine raises significant concerns, as they are commonly co-administered as core drugs in drug-resistant TB regimens. The present study aimed to monitor drug resistance-associated gene mutations and the phenotypic change in Mycobacterium tuberculosis (Mtb) under a stepwise drug resistance induction in vitro using bedaquiline, clofazimine or combined drugs.

METHODS

Drug-resistant Mtb strains were gradually induced in vitro on a drug-containing solid medium with a 2-fold increasing concentration of bedaquiline, clofazimine and their combination. The MIC of the induced drug-resistant Mtb strains was determined. The drug resistance-associated genes, including Rv0678, Rv1979c, atpE and pepQ, were sequenced and analysed.

RESULTS

Unlike exposure to bedaquiline alone or the combination of these two drugs, clofazimine alone resulted in drug resistance gene mutations occurring later, specifically in the fourth round of induction as opposed to the second round of induction. Besides, nucleotide deletion or insertion in Rv0678 was the main mutation type for induction under the two-drug combination, while single-nucleotide polymorphisms (SNPs) in Rv0678 were the major mutation types when induced by bedaquiline or clofazimine alone. Rv0678 mutation happened at a relatively lower bedaquiline concentration exposure alone, while atpE mutation occurred at a higher bedaquiline concentration. Regardless of the drug exposure manner, a strong correlation between bedaquiline MICs and clofazimine MICs was observed in all drug resistance strains.

CONCLUSIONS

Combined exposure to bedaquiline and clofazimine developed Rv0678 mutation as early as exposure to bedaquiline alone. However, rather than SNPs, deletion and insertion were the dominant mutation types in dual-drug exposure strain.

Mucormycosis and COVID-19: Unraveling the Interplay of Fungal Infection in a Global Health Crisis: An Overview

The healthcare system has been greatly affected by the COVID-19 pandemic, resulting in an increase in secondary and co-infections among patients. Factors like pulmonary damage and weakened immune systems make patients more susceptible to fungal infections. Mucormycosis, an opportunistic fungal infection, prospers in environments with limited oxygen, and elevated glucose levels due to conditions such as diabetes and steroid use, as well as in acidic environments from metabolic acidosis and diabetic ketoacidosis, where it demonstrates heightened germination ability. Recognizing these complications is critical to minimize harm to patients. The insights gained from this review can improve our understanding of how fungal infections develop in connection to COVID-19, leading to better predictive algorithms, tailored care plans, enhanced antifungal treatments, quicker diagnostics, and improved management strategies.

Sodium, Potassium-Adenosine Triphosphatase as a Potential Target of the Anti-Tuberculosis Agents, Clofazimine and Bedaquiline

Multidrug-resistant tuberculosis (MDR-TB) patients are treated with a standardised, short World Health Organization (WHO) regimen which includes clofazimine (CFZ) and bedaquiline (BDQ) antibiotics. These two antibiotics lead to the development of QT prolongation in patients, inhibiting potassium (K+) uptake by targeting the voltage-gated K+ (Kv)11.1 (hERG) channel of the cardiomyocytes (CMs). However, the involvement of these antibiotics to regulate other K+ transporters of the CMs, as potential mechanisms of QT prolongation, has not been explored. This study determined the effects of CFZ and BDQ on sodium, potassium-adenosine triphosphatase (Na+,K+-ATPase) activity of CMs using rat cardiomyocytes (RCMs). These cells were treated with varying concentrations of CFZ and BDQ individually and in combination (1.25-5 mg/L). Thereafter, Na+,K+-ATPase activity was determined, followed by intracellular adenosine triphosphate (ATP) quantification and cellular viability determination. Furthermore, molecular docking of antibiotics with Na+,K+-ATPase was determined. Both antibiotics demonstrated dose-response inhibition of Na+,K+-ATPase activity of the RCMs. The greatest inhibition was demonstrated by combinations of CFZ and BDQ, followed by BDQ alone and, lastly, CFZ. Neither antibiotic, either individually or in combination, demonstrated cytotoxicity. Molecular docking revealed an interaction of both antibiotics with Na+,K+-ATPase, with BDQ showing higher protein-binding affinity than CFZ. The inhibitory effects of CFZ and BDQ, individually and in combination, on the activity of Na+,K+-ATPase pump of the RCMs highlight the existence of additional mechanisms of QT prolongation by these antibiotics.

Fragment-based development of small molecule inhibitors targeting Mycobacterium tuberculosis cholesterol metabolism

Mycobacterium tuberculosis (Mtb) is the world's most deadly infectious pathogen and new drugs are urgently required to combat the emergence of multi- (MDR) and extensively- (XDR) drug resistant strains. The bacterium specifically upregulates sterol uptake pathways in infected macrophages and the metabolism of host-derived cholesterol is essential for Mtb's long-term survival in vivo. Here, we report the development of antitubercular small molecules that inhibit the Mtb cholesterol oxidases CYP125 and CYP142, which catalyze the initial step of cholesterol metabolism. An efficient biophysical fragment screen was used to characterize the structure-activity relationships of CYP125 and CYP142, and identify a non-azole small molecule 1a that can bind to the heme cofactor of both enzymes. A structure-guided fragment-linking strategy was used to optimize the binding affinity of 1a, yielding a potent dual CYP125/142 inhibitor 5m (KD CYP125/CYP142 = 0.04/0.16 μM). Compound 5m potently inhibits the catalytic activity of CYP125 and CYP142 in vitro (KI values < 0.1 μM), and rapidly depletes Mtb intracellular ATP (IC50 = 0.15 μM). The compound has antimicrobial activity against both drug susceptible and MDR Mtb (MIC99 values 0.4 - 1.5 μM) in extracellular assays, and inhibits the growth of Mtb in human macrophages (MIC = 1.7 μM) with good selectivity over mammalian cytotoxicity (LD50 ≥ 50 μM). The combination of small molecule inhibitors and structural data reported here provide useful tools to study the role of cholesterol metabolism in Mtb and are a promising step towards novel antibiotics targeting bioenergetic pathways, which could be used to help combat MDR-TB.

Antitubercular drugs: possible role of natural products acting as antituberculosis medication in overcoming drug resistance and drug-induced hepatotoxicity

Mycobacterium tuberculosis (Mtb) is a pathogenic bacterium which causes tuberculosis (TB). TB control programmes are facing threats from drug resistance. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mtb strains need longer and more expensive treatment with many medications resulting in more adverse effects and decreased chances of treatment outcomes. The World Health Organization (WHO) has emphasised the development of not just new individual anti-TB drugs, but also novel medication regimens as an alternative treatment option for the drug-resistant Mtb strains. Many plants, as well as marine creatures (sponge; Haliclona sp.) and fungi, have been continuously used to treat TB in various traditional treatment systems around the world, providing an almost limitless supply of active components. Natural products, in addition to their anti-mycobacterial action, can be used as adjuvant therapy to increase the efficacy of conventional anti-mycobacterial medications, reduce their side effects, and reverse MDR Mtb strain due to Mycobacterium's genetic flexibility and environmental adaptation. Several natural compounds such as quercetin, ursolic acid, berberine, thymoquinone, curcumin, phloretin, and propolis have shown potential anti-mycobacterial efficacy and are still being explored in preclinical and clinical investigations for confirmation of their efficacy and safety as anti-TB medication. However, more high-level randomized clinical trials are desperately required. The current review provides an overview of drug-resistant TB along with the latest anti-TB medications, drug-induced hepatotoxicity and oxidative stress. Further, the role and mechanisms of action of first and second-line anti-TB drugs and new drugs have been highlighted. Finally, the role of natural compounds as anti-TB medication and hepatoprotectants have been described and their mechanisms discussed.

Molecular mechanisms of resistance and treatment efficacy of clofazimine and bedaquiline against Mycobacterium tuberculosis

Clofazimine (CFZ) and bedaquiline (BDQ) are currently used for the treatment of multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) strains. In recent years, adding CFZ and BDQ to tuberculosis (TB) drug regimens against MDR Mtb strains has significantly improved treatment results, but these improvements are threatened by the emergence of MDR and extensively drug-resistant (XDR) Mtb strains. Recently, CFZ and BDQ have attracted much attention for their strong clinical efficacy, although very little is known about the mechanisms of action, drug susceptibility test (DST), resistance mechanisms, cross-resistance, and pharmacokinetics of these two drugs. In this current review, we provide recent updates on the mechanisms of action, DST, associated mutations with individual resistance and cross-resistance, clinical efficacy, and pharmacokinetics of CFZ and BDQ against Mtb strains. Presently, known mechanisms of resistance for CFZ and/or BDQ include mutations within the Rv0678, pepQ, Rv1979c, and atpE genes. The cross-resistance between CFZ and BDQ may reduce available MDR-/XDR-TB treatment options. The use of CFZ and BDQ for treatment in the setting of limited DST could allow further spread of drug resistance. The DST and resistance knowledge are urgently needed where CFZ and BDQ resistance do emerge. Therefore, an in-depth understanding of clinical efficacy, DST, cross-resistance, and pharmacokinetics for CFZ and BDQ against Mtb can provide new ideas for improving treatment outcomes, reducing mortality, preventing drug resistance, and TB transmission. Along with this, it will also help to develop rapid molecular diagnostic tools as well as novel therapeutic drugs for TB.

Efficacy and safety of bedaquiline and delamanid in the treatment of drug-resistant tuberculosis in adults: A systematic review and meta-analysis

Multi and extensively drug-resistant tuberculosis is a grave cause of global public health concern due to its high mortality and limited treatment options. We conducted this systemic review and meta-analysis to evaluate the efficacy and safety of bedaquiline and delamanid, which have been added to the WHO-recommended regimen for treating drug-resistant tuberculosis. Electronic databases were searched from their inception until December 1st, 2021, for eligible studies assessing the efficacy and safety of bedaquiline and delamanid for treating drug-resistant tuberculosis. Binary outcomes were pooled using a DerSimonian-Laird random-effects model and arcsine transformation and reported on a log scale with a 95% confidence interval (CIs). Twenty-one studies were shortlisted in which bedaquiline, delamanid, and a combination of both were administered in 2477, 937, and 169 patients. Pooled culture conversion at 6 months was 0.801 (p < 0.001), 0.849 (p = 0.059) for bedaquiline and delamanid, respectively, and 0.823 (p = 0.017), concomitantly. In the bedaquiline cohort, the pooled proportion of all-cause mortality at 6 months was reported as 0.074 (p < 0.001), 0.031 (p = 0.372) in the delamanid cohort, and 0.172 in the combined cohort. The incidence of adverse events in the bedaquiline cohort ranged from 11.1% to 95.2%, from 13.2% to 86.2% in the delamanid cohort, and 92.5% in a study in the combined cohort. The incidence of QTC prolongation reported in each cohort is as follows: bedaquiline 0.163 (p < 0.001), delamanid 0.344 (p = 0.272) and combined 0.340 (p < 0.001). Our review establishes the efficacy of delamanid, bedaquiline, and their combined use in treating drug-resistant tuberculosis with reasonable rates of culture conversion, low mortality rates, and safety of co-administration, as seen with their effect on the QTc interval.

Development of a HPLC Method for Analysis of a Combination of Clofazimine, Isoniazid, Pyrazinamide, and Rifampicin Incorporated into a Dermal Self-Double-Emulsifying Drug Delivery System

We describe the development and validation of a new high performance liquid chromatography (HPLC) method for analysis of a combination of the first-line anti-tubercular drugs isoniazid, pyrazinamide, and rifampicin together with clofazimine. This is a unique challenge since clofazimine and rifampicin are relatively highly lipophilic drugs, whereas isoniazid and pyrazinamide are considerably more hydrophilic. Thus, clear separation of peaks and quantification of four individual drugs can present difficulties during the development of an analytical method. Detection was established at two wavelengths-254 nm for isoniazid and pyrazinamide and 320 nm for clofazimine and rifampicin. Gradient elution was employed using 0.1% aqueous formic acid (A) and acetonitrile (B); clear separation of the four drugs was achieved within 10 min. A linear relationship was indicated by a correlation coefficient (r2) of 0.9999 for each anti-tubercular drug, respectively. The limit of detection (LOD) for the individual drugs was 0.70 µg/mL (isoniazid), 0.30 µg/mL (pyrazinamide), 0.20 µg/mL (rifampicin) and 0.20 µg/mL (clofazimine). Precision experiments rendered a mean recovery percentage of 101.25% (isoniazid), 98.70% (pyrazinamide), 99.68% (rifampicin) and 97.14% (clofazimine). This HPLC method was validated and is reliable, repeatable, and accurate for the purpose of conducting simultaneous HPLC analyses of the four anti-tubercular drugs.

Clofazimine for the treatment of tuberculosis

Shorter (6-9 months), fully oral regimens containing new and repurposed drugs are now the first-choice option for the treatment of drug-resistant tuberculosis (DR-TB). Clofazimine, long used in the treatment of leprosy, is one such repurposed drug that has become a cornerstone of DR-TB treatment and ongoing trials are exploring novel, shorter clofazimine-containing regimens for drug-resistant as well as drug-susceptible tuberculosis. Clofazimine's repurposing was informed by evidence of potent activity against DR-TB strains in vitro and in mice and a treatment-shortening effect in DR-TB patients as part of a multidrug regimen. Clofazimine entered clinical use in the 1950s without the rigorous safety and pharmacokinetic evaluation which is part of modern drug development and current dosing is not evidence-based. Recent studies have begun to characterize clofazimine's exposure-response relationship for safety and efficacy in populations with TB. Despite being better tolerated than some other second-line TB drugs, the extent and impact of adverse effects including skin discolouration and cardiotoxicity are not well understood and together with emergent resistance, may undermine clofazimine use in DR-TB programmes. Furthermore, clofazimine's precise mechanism of action is not well established, as is the genetic basis of clofazimine resistance. In this narrative review, we present an overview of the evidence base underpinning the use and limitations of clofazimine as an antituberculosis drug and discuss advances in the understanding of clofazimine pharmacokinetics, toxicity, and resistance. The unusual pharmacokinetic properties of clofazimine and how these relate to its putative mechanism of action, antituberculosis activity, dosing considerations and adverse effects are highlighted. Finally, we discuss the development of novel riminophenazine analogues as antituberculosis drugs.

Impacts of clofazimine on the treatment outcomes of drug-resistant tuberculosis

BACKGROUND

The purpose of this research was to evaluate the effect of clofazimine on drug-resistant tuberculosis treatment outcomes.

METHODS

A systematic search was conducted in the PubMed, Web of Science and EMBASE databases to identify eligible studies published up to July 10, 2021. The search terms were as follows: "clofazimine," "tuberculosis," "multidrug resistant tuberculosis" or "extensively drug resistant tuberculosis" and their synonyms or similar words. Two researchers independently screened the titles, abstracts, and full texts for inclusion. Meta-analysis was performed with Stata version 16.0 (Stata Corp., College Station, Texas, USA). Risk ratios (RRs) with 95% CIs were calculated to evaluate the treatment outcome.

RESULTS

Eight studies including 3219 participants were included in the meta-analysis. The meta-analysis found that the rates of treatment completion was higher in patients receiving clofazimine-containing regimens than in those not receiving clofazimine-containing regimens (RR: 1.185 (1.060-1.325), P = 0.003). Significant reduction in treatment failure (RR: 0.598 (0.473-0.756), P < 0.001) was found in the clofazimine treatment group. The subgroup analyses of randomized controlled trials (RCTs) found a higher rates of favorable outcomes, treatment completion and cure in the clofazimine group than in the control group (RR: 1.203 (1.029-1.407), P = 0.020; RR: 3.167 (2.043-4.908), P < 0.001; and RR: 1.251 (1.031-1.518), P = 0.023, respectively). Patients receiving clofazimine had a lower risk of treatment failure than those not receiving clofazimine (RR: 0.529 (0.454-0.616), P < 0.001). However, clofazimine treatment did not have a statistically significant effect on all-cause mortality in RCTs.

CONCLUSIONS

This study demonstrated that compared with patients who do not receive clofazimine, this drug has the potential to achieve a higher favorable outcome, treatment completion and cure rates, and a lower treatment failure risk among drug-resistant tuberculosis cases.

Characterization of Clofazimine Metabolism in Human Liver Microsomal Incubation In Vitro

Clofazimine [N,5-bis(4-chlorophenyl)-3-[(propane-2-yl)rimino]-3,5-dihydrophenazin-2-amine] is an antimycobacterial agent used as a second-line antituberculosis (anti-TB) drug. Nonetheless, little information is known about the metabolic routes of clofazimine, and the enzymes involved in metabolism. This study aimed to characterize the metabolic pathways and enzymes responsible for the metabolism of clofazimine in human liver microsomes. Eight metabolites, including four oxidative metabolites, three glucuronide conjugates, and one sulfate conjugate were identified, and their structures were deduced based on tandem mass spectrometry (MS/MS) spectra. Hydroxylated clofazimine and hydrated clofazimine was generated even in the absence of the NADPH generating system presumably via a nonenzymatic pathway. Hydrolytic-dehalogenated clofazimine was catalyzed mainly by CYP1A2 whereas hydrolytic-deaminated clofazimine was formed by CYP3A4/A5. In case of glucuronide conjugates, UGT1A1, UGT1A3, and UGT1A9 showed catalytic activity toward hydroxylated and hydrated clofazimine glucuronide whereas hydrolytic-deaminated clofazimine glucuronide was catalyzed by UGT1A4, UGT1A9, UGT1A3, and UGT2B4. Our results suggested that CYP1A2 and CYP3A are involved in the formation of oxidative metabolites while UGT1A1, 1A3, 1A4, 1A9, and 2B4 are involved in the formation of glucuronide conjugates of oxidative metabolites of clofazimine.

The Correlations of Minimal Inhibitory Concentration Values of Anti-TB Drugs with Treatment Outcomes and Clinical Profiles in Patients with Multidrug-Resistant Tuberculosis (MDR-TB) in China

Objective

It is a challenge to obtain satisfactory treatment outcomes for patients with multidrug-resistant/rifampicin-resistant tuberculosis (MDR/RR-TB); the study aims to correlate the Minimum Inhibitory Concentration (MIC) value of drugs with the outcome of patients with MDR/RR-TB to obtain an understanding for better regimens and optimal outcomes.

Methods

The patients diagnosed with MDR/RR-TB were retrospectively enrolled from January 1, 2018 to December 31, 2019, recorded clinical characteristics, MIC DST (Drug Susceptibility Test) results, and followed the treatment outcome. The data were analyzed on the correlations of MIC DST values with outcomes and clinical characteristics.

Results

A total of 276 patients with MDR/RR-TB were included, containing 98 cases (35.5%) with newly treated patients and 178 cases (64.5%) with re-treated patients. A total of 220 cases recorded treatment success (79.7%) and 49 cases recorded treatment failure or died. MIC values of isoniazid (H), moxifloxacin (Mfx), and ethionamide (Eto) in newly treated patients were lower than those in retreated patients, and resistance levels of Mfx and H were closely associated with the treatment outcome (P < 0.05) while those of other drugs had no close association with treatment outcome.

Conclusions

MIC values of some anti-TB drugs, such as fluoroquinolones (FQs) and H, can reflect the treatment outcome for patients with MDR/RR-TB, which can contribute to making regimens for better treatment outcomes.

Application of Next Generation Sequencing for Diagnosis and Clinical Management of Drug-Resistant Tuberculosis: Updates on Recent Developments in the Field

The World Health Organization’s End TB Strategy prioritizes universal access to an early diagnosis and comprehensive drug susceptibility testing (DST) for all individuals with tuberculosis (TB) as a key component of integrated, patient-centered TB care. Next generation whole genome sequencing (WGS) and its associated technology has demonstrated exceptional potential for reliable and comprehensive resistance prediction for Mycobacterium tuberculosis isolates, allowing for accurate clinical decisions. This review presents a descriptive analysis of research describing the potential of WGS to accelerate delivery of individualized care, recent advances in sputum-based WGS technology and the role of targeted sequencing for resistance detection. We provide an update on recent research describing the mechanisms of resistance to new and repurposed drugs and the dynamics of mixed infections and its potential implication on TB diagnosis and treatment. Whilst the studies reviewed here have greatly improved our understanding of recent advances in this arena, it highlights significant challenges that remain. The wide-spread introduction of new drugs in the absence of standardized DST has led to rapid emergence of drug resistance. This review highlights apparent gaps in our knowledge of the mechanisms contributing to resistance for these new drugs and challenges that limit the clinical utility of next generation sequencing techniques. It is recommended that a combination of genotypic and phenotypic techniques is warranted to monitor treatment response, curb emerging resistance and further dissemination of drug resistance.

HIV-Negative Rifampicin Resistance/Multidrug-Resistant Extrapulmonary Tuberculosis in China from 2015 to 2019: A Clinical Retrospective Investigation Study from a National Tuberculosis Clinical Research Center

Background

China is the region with a high global burden of rifampicin resistance/multidrug-resistant tuberculosis (RR/MDR-TB) and low HIV incidence. Our aim was to assess the clinical and demographic characteristics of RR/MDR-extrapulmonary tuberculosis (EPTB) from 2015 to 2019 to provide evidence for the prevention and control of the disease in high TB burden areas.

Methods

We investigated the clinical and demographic data of all MDR/RR-EPTB cases in a TB specialized hospital from China and compared the cases with the MDR/RR-pulmonary tuberculosis (PTB) patients over the same period.

Results

Of the RR/MDR-TB patients enrolled, 15.4 were EPTB. The most common anatomical site was pleural/chest wall (25.9%). Compared with RR/MDR-PTB, females were more likely to be susceptible to RR/MDR-EPTB (OR 1.65, 95% CI 1.52–1.77); the risk of RR/MDR-EPTB for 25–44 years group increased (OR 1.61, 95% CI 1.52–1.77), and then decreased with the increasing age (OR 1.48, 95% CI 0.74–1.69 for 44–65 years group and OR 2.23, 95% CI 0.98–2.71 for ≥65 years group); more likely to be newly diagnosed (p < 0.01) and less likely to to combine with diabetes (P < 0.01), more dependent on GeneXpert MTB/RIF (Xpert, 90.9%) for diagnosis, with significantly higher rates of pre-XDR/XDR and significantly lower favorable treatment outcomes (both p < 0.01).

Conclusion

There are clinical and demographic differences between RR/MDR-PTB and RR/MDR-PTB. Xper should be recommended at an early stage for suspected patients, and fluoroquinolones should be used cautiously for anti-infective therapy in this population.

MDR Tuberculosis Treatment

Multidrug-resistant (MDR) tuberculosis (TB), resistant to isoniazid and rifampicin, continues to be one of the most important threats to controlling the TB epidemic. Over the last few years, there have been promising pharmacological advances in the paradigm of MDR TB treatment: new and repurposed drugs have shown excellent bactericidal and sterilizing activity against Mycobacterium tuberculosis and several all-oral short regimens to treat MDR TB have shown promising results. The purpose of this comprehensive review is to summarize the most important drugs currently used to treat MDR TB, the recommended regimens to treat MDR TB, and we also summarize new insights into the treatment of patients with MDR TB.

A highly effective and inexpensive standardized treatment of multidrug-resistant tuberculosis: a multicenter prospective study in China

BACKGROUND

To verify the efficacy and safety of an inexpensive standardized regimen for multidrug-resistant tuberculosis (MDR-TB) with low resistance to isoniazid (INH), a multicenter prospective study was conducted in eastern China.

METHODS

Patients diagnosed as MDR-TB with low concentration INH resistance and rifampicin resistance, second-line/injectable agents sensitive were prospectively enrolled, given the regimen of Amikacin (Ak)-Fluoroquinolones (FQs)-Cycloserine (Cs)-Protionamide (Pto)-PasiniaZid (Pa)-Pyrazinamide (Z) for 6 months followed by 12 months of FQs-Cs-Pto-Pa-Z, and then followed up for treatment outcomes and adverse events (AEs).

RESULTS

A total of 114 patients were enrolled into the study. The overall favorable treatment rate was 79.8% (91/114). Among 91 cases with favorable treatment, 75.4% (86/114) were cured and 4.4% (5/114) were completed treatment. Regarding to unfavorable outcomes, among 23 cases, 8.8% (10/114) had failures, 8.8% (10/114) losing follow up, 0.9% (1/114) had treatment terminated due to intolerance to drugs and 1.8% (2/114) died. Treatment favorable rate was significantly higher in newly treated MDR-TB (91.7%, 33/36) than that in retreated MDR-TB (74.4%, 58/78, p 0.03). The investigators recorded 42 AEs occurrences in 30 of 114 patients (26.3%). Clinicians rated most AEs as mild or moderate (95.24%, 40/42).

CONCLUSIONS

The regimen was proved to be effective, safe and inexpensive. It is suitable for specific drug resistant population, especially for newly-treated patients, which could be expected to be developed into a short-course regimen. Clinical trials registration China Clinical Trial Registry ChiCTR-OPC-16009380.

Clofazimine as a Treatment for Multidrug-Resistant Tuberculosis: A Review

Multidrug-resistant tuberculosis (MDR-TB) is an infectious disease caused by Mycobacterium tuberculosis which is resistant to at least isoniazid and rifampicin. This disease is a worldwide threat and complicates the control of tuberculosis (TB). Long treatment duration, a combination of several drugs, and the adverse effects of these drugs are the factors that play a role in the poor outcomes of MDR-TB patients. There have been many studies with repurposed drugs to improve MDR-TB outcomes, including clofazimine. Clofazimine recently moved from group 5 to group B of drugs that are used to treat MDR-TB. This drug belongs to the riminophenazine class, which has lipophilic characteristics and was previously discovered to treat TB and approved for leprosy. This review discusses the role of clofazimine as a treatment component in patients with MDR-TB, and the drug’s properties. In addition, we discuss the efficacy, safety, and tolerability of clofazimine for treating MDR-TB. This study concludes that the clofazimine-containing regimen has better efficacy compared with the standard one and is also well-tolerated. Clofazimine has the potential to shorten the duration of MDR-TB treatment.

Treatment Outcome of a Shorter Regimen Containing Clofazimine for Multidrug-resistant Tuberculosis: A Randomized Control Trial in China

BACKGROUND

The emergence of multidrug-resistant tuberculosis (MDR-TB) poses a serious obstacle to global TB control programs.

METHODS

We carried out a prospective, randomized, multicenter study in China that was focused on the potential of a shorter regimen containing clofazimine (CFZ) for the treatment of MDR-TB. There were 135 MDR-TB cases that met eligibility requirements and were randomly stratified into either the control group or experimental group. Patients in the control group received an 18-month treatment regimen, whereas patients in the experimental group received a 12-month treatment regimen containing CFZ.

RESULTS

At the completion of the treatment period, the difference in sputum-culture conversion rates between the experimental group and the control group was not significant. Notably, by the end of 3 months of treatment, 68.7% patients receiving the experimental regimen had sputum-culture conversion, as compared with 55.9% of those receiving the control regimen; this was a significant difference, suggesting an early sputum conversion (P = .04). There were 67 adverse events reported in 56 patients in this study, including 32 in the control group and 35 in the experimental group. No significant difference in the overall incidences of adverse events was observed between the 2 groups.

CONCLUSIONS

The MDR-TB patients treated with the shorter regimen containing CFZ had a comparable successful outcome rate when compared to those with the standard regimen. The patients assigned to the experimental group achieved more rapid sputum-culture conversion, reflecting superior antimicrobial activity against MDR-TB.

CLINICAL TRIALS REGISTRATION

Chinese Clinical Trial Registry ChiCTR 1800020391.

A review of recent advances in anti-tubercular drug development

Tuberculosis is a global threat but in particular affects people from developing countries. It is thought that nearly a third of the population of the world live with its causative bacteria in a dormant form. Although tuberculosis is a curable disease, the chances of cure become slim as the disease becomes multidrug-resistant and the situation gets even worse as the disease becomes extensively drug-resistant. After approximately 5 decades without any new TB drug in the pipeline, there has been some good news in the recent years with the discovery of new drugs such as bedaquiline and delamanid as well as the discovery of new classes of anti-tubercular drugs. Some old drugs such as clofazimine, linezolid and many others which were not previously indicated for tuberculosis have been also repurposed for tuberculosis and they are performing well.

Early outcome and safety of bedaquiline-containing regimens for treatment of MDR- and XDR-TB in China: a multicentre study

OBJECTIVES

Bedaquiline treatment significantly improves multidrug-resistant tuberculosis (MDR-TB) patient treatment outcomes. However, safety and efficacy data are lacking for bedaquiline used with background regimens to treat Chinese TB patients. Here, we describe our initial clinical experience for bedaquiline treatment of a large multicentre cohort of MDR-TB and extensively drug-resistant tuberculosis (XDR-TB) patients in China.

METHODS

Patients (177) received 24-week bedaquiline treatment combined with personalized anti-TB drug background regimens. As primary efficacy endpoints, times to initial sputum culture conversion were measured.

RESULTS

Of 177 MDR-TB patients completing the 24-week treatment course, sputum culture conversion occurred for 151/177 (85.3%), while 26 had unfavourable outcomes, including 3/177 (1.7%) deaths and 23/177 (13.0%) non-responders at treatment completion. The median time to sputum culture conversion was 4 (interquartile range 2-8) weeks. Conversion rates were 33/39 (84.6%, 95% confidence interval (CI) 73.3-95.9) for MDR-TB patients, 47/56 (83.9%, 95% CI 74.3-93.6) for pre-XDR-TB patients and 71/82 (86.6%, 95% CI 79.2-94.0) for XDR-TB patients. Multivariate analysis demonstrated that patients with low body mass index (odds ratio 7.356; 95% CI 2.652-20.401) were at significantly high risk of unfavourable outcomes, with serious adverse events noted in 15 (8.5%) patients, including six with corrected QT interval (QTc) prolongation times (>500 ms).

CONCLUSION

Bedaquiline, when included in background regimens for treatment of MDR-TB and XDR-TB patients in China, was safe and associated with a high rate of culture conversion.

Clofazimine: an old drug for never-ending diseases

Clofazimine (CFZ), an old hydrophobic riminophenazine, has a wide range of antimycobacterial activity ranging from leprosy to nontuberculous mycobacterial diseases. CFZ has several advantages such as a favorable pharmacokinetic profile, dose-dependent side effects as well as low price. In this narrative review, we have assessed the clinical development of CFZ, starting from the potential in vitro mechanism of actions, to the spectrum of side effects and potential drug-drug interactions, highlighting its current place in therapy and future possible use in leprosy, nontuberculous mycobacterial diseases and drug-resistant tuberculosis.

Potential anti-TB investigational compounds and drugs with repurposing potential in TB therapy: a conspectus

The latest WHO report estimates about 1.6 million global deaths annually from TB, which is further exacerbated by drug-resistant (DR) TB and comorbidities with diabetes and HIV. Exiguous dosing, incomplete treatment course, and the ability of the tuberculosis bacilli to tolerate and survive current first-line and second-line anti-TB drugs, in either their latent state or active state, has resulted in an increased prevalence of multidrug-resistant (MDR), extensively drug-resistant (XDR), and totally drug-resistant TB (TDR-TB). Although a better understanding of the TB microanatomy, genome, transcriptome, proteome, and metabolome, has resulted in the discovery of a few novel promising anti-TB drug targets and diagnostic biomarkers of late, no new anti-TB drug candidates have been approved for routine therapy in over 50 years, with only bedaquiline, delamanid, and pretomanid recently receiving tentative regulatory approval. Considering this, alternative approaches for identifying possible new anti-TB drug candidates, for effectively eradicating both replicating and non-replicating Mycobacterium tuberculosis, are still urgently required. Subsequently, several antibiotic and non-antibiotic drugs with known treatment indications (TB targeted and non-TB targeted) are now being repurposed and/or derivatized as novel antibiotics for possible use in TB therapy. Insights gathered here reveal that more studies focused on drug-drug interactions between licensed and potential lead anti-TB drug candidates need to be prioritized. This write-up encapsulates the most recent findings regarding investigational compounds with promising anti-TB potential and drugs with repurposing potential in TB therapy.

Towards tailored regimens in the treatment of drug-resistant tuberculosis: a retrospective study in two Italian reference Centres

Background

The increased incidence of drug-resistant TB is a major challenge for effective TB control. Limited therapeutic options and poor treatment outcomes of DR-TB may increase drug-resistance rates. The objective of the study is to retrospectively compare MDR-TB and pre-XDR-TB treatment regimens and outcomes in two large TB reference centres in Italy from January 2000 to January 2015.

Methods

A retrospective, multicentre study was conducted at the Regional TB Reference Centre Villa Marelli Institute (Milan) and at the Reference Center for MDR-TB and HIV-TB, Eugenio Morelli Hospital (Sondalo). The supra-national Reference Laboratory in Milan performed DST. Inclusion criteria were: age ≥ 18 and culture-confirmed diagnosis of MDR- or pre-XDR TB. Chi-square or Fisher exact test was used to detect differences in the comparison between treatment outcomes, therapeutic regimens, and drug-resistances. Computations were performed with STATA 15.

Results

A total of 134 patients were selected. Median (IQR) age at admission was 33 (26–41) years and 90 patients (67.2%) were male. Pulmonary TB was diagnosed in 124 (92.5%) patients. MDR- and pre-XDR-TB cases were 91 (67.9%) and 43 (32.1%), respectively. The WHO shorter MDR-TB regimen could have been prescribed in 16/84 (19.1%) patients. Treatment success was not statistically different between MDR- and pre-XDR-TB (81.3% VS. 81.4%; P = 0.99). Mortality in MDR-TB and pre-XDR-TB groups was 4.4 and 9.3%, respectively (P = 0.2). Median duration of treatment was 18 months and a total of 110 different regimens were administered. Exposure to linezolid, meropenem, and amikacin was associated with a better outcome in both groups (P = 0.001, P < 0.001, and P = 0.004, respectively).

Conclusions

Tailored treatment regimens based on DST results can achieve successful outcomes in patients with pre-XDR-TB.