Final treatment outcomes of delamanid-containing regimens in patients with MDR-/XDR-TB in South Korea

Identification of fluoroquinolone-resistant Mycobacterium tuberculosis through high-level data fusion of Raman and laser-induced breakdown spectroscopy

Accurate and rapid diagnosis of drug susceptibility of Mycobacterium tuberculosis is crucial for the successful treatment of tuberculosis, a persistent global public health threat. To shorten diagnosis times and enhance accuracy, this study introduces a fusion model combining laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy. This model offers a rapid and accurate method for diagnosing drug-resistance. LIBS and Raman spectroscopy provide complementary information, enabling accurate identification of drug resistance in tuberculosis. Although individual use of LIBS or Raman spectroscopy achieved approximately 90% accuracy in identifying drug resistance, the fusion model significantly improved identification accuracy to 98.3%. Given the fast measurement capabilities of both techniques, this fusion approach is expected to markedly decrease the time required for diagnosis.

Impact of Prior Tuberculosis Treatment With New/Companion Drugs on Clinical Outcomes in Patients Receiving Concomitant Bedaquiline and Delamanid for Multidrug- and Rifampicin-Resistant Tuberculosis

BACKGROUND

There are scarce data on the clinical outcomes of persons retreated with new/companion anti-tuberculosis (TB) drugs for multidrug- and rifampicin-resistant tuberculosis (MDR/RR-TB). We sought to evaluate the efficacy and safety of bedaquiline and delamanid containing regimens among patients with and without prior exposure to the new/companion drugs (bedaquiline, delamanid, linezolid, clofazimine, and fluoroquinolones).

METHODS

We conducted a retrospective cohort study among patients with pulmonary MDR/RR-TB in Georgia who received bedaquiline and delamanid combination as a part of a salvage regimen from November 2017 to December 2020 in a programmatic setting.

RESULTS

Among 106 persons with a median age of 39.5 years, 44 (41.5%) were previously treated with new/companion TB drugs. Patients with prior exposure to new/companion drugs had higher rates of baseline resistance compared to those without exposure to new/companion TB drugs (bedaquiline 15.2% vs 1.8%, linezolid 22.2% vs 16.7%). Sputum culture conversion rates among patients exposed and not exposed to new/companion drugs were 65.9% vs 98.0%, respectively (P < .001). Among patients with and without prior new/companion TB drug use, favorable outcome rates were 41.0% and 82.3%, respectively (P < .001). Treatment adherence in 32 (30.2%) patients was ≤80%. Five of 21 patients (23.8%) who had a baseline and repeat susceptibility test had acquired bedaquiline resistance. QTC/F prolongation (>500 ms) was rare (2.8%).

CONCLUSIONS

Prior exposure to new/companion TB drugs was associated with poor clinical outcomes and acquired drug resistance. Tailoring the TB regimen to each patient's drug susceptibility test results and burden of disease and enhancing adherence support may improve outcomes.

Unraveling Dilemmas and Lacunae in the Escalating Drug Resistance of Mycobacterium tuberculosis to Bedaquiline, Delamanid, and Pretomanid

Delamanid, bedaquiline, and pretomanid have been recently added in the anti-tuberculosis (anti-TB) treatment regimens and have emerged as potential solutions for combating drug-resistant TB. These drugs have proven to be effective in treating drug-resistant TB when used in combination. However, concerns have been raised about the eventual loss of these drugs due to evolving resistance mechanisms and certain adverse effects such as prolonged QT period, gastrointestinal problems, hepatotoxicity, and renal disorders. This Perspective emphasizes the properties of these first-in-class drugs, including their mechanism of action, pharmacokinetics/pharmacodynamics profiles, clinical studies, adverse events, and underlying resistance mechanisms. A brief coverage of efforts toward the generation of best-in-class leads in each class is also provided. The ongoing clinical trials of new combinations of these drugs are discussed, thus providing a better insight into the use of these drugs while designing an effective treatment regimen for resistant TB cases.

Evaluation of 2,3-dihydroimidazo[2,1-b]oxazole and imidazo[2,1-b]oxazole derivatives as chemotherapeutic agents

Imidazo[2,1-b]oxazole and 2,3-dihydroimidazo[2,1-b]oxazole ring systems are commonly employed in therapeutically active molecules. In this article, the authors review the utilization of these core scaffolds as chemotherapeutic agents from 2018 to 2022. These scaffolds possess many important biological activities including antimicrobial and anticancer, among others. This review covers their biological activities and structure-activity relationships. One of the most important drugs in this class of compounds is the antitubercular agent delamanid. In this paper, the compounds structure-activity relationship and preclinical and clinical trial data are thoroughly presented.

Global treatment outcomes of extensively drug-resistant tuberculosis in adults: A systematic review and meta-analysis

INTRODUCTION

Historically, extensively drug-resistant tuberculosis has been notoriously difficult to treat with devasting outcomes. As we are coming to the end of an era where the 2006 extensively drug-resistant tuberculosis definitions and old treatment regimens are being replaced, we aimed to estimate the proportion of extensively drug-resistant tuberculosis patients globally who achieved successful treatment outcomes.

METHODS

We conducted a systematic review of PubMed/MEDLINE, Scopus, Web of Science, and Embase from January 1, 2005, through April 3, 2023. Included studies reported WHO treatment outcomes, or adaptions hereof, for pre-extensively and/or extensively drug-resistant tuberculosis patients according to the 2006 WHO definition. Eligible studies included cohorts of at least 10 adults (aged>18 years) that were not pregnant. Using a random-effects model, we calculated pooled proportions of treatment outcomes and performed sensitivity and subgroup analyses. PROSPERO registration number: CRD42022340961.

RESULTS

Among 5056 studies reviewed, we identified 94 studies from 26 countries, involving 10,223 extensively drug-resistant tuberculosis patients. The pooled proportion of successful treatment outcomes was 44.2% (95%CI: 38.3-50.3). Sensitivity analyses consistently produced similar estimates. A slight improvement in treatment outcomes was observed after 2013. Furthermore, 25 studies reported outcomes for 3564 individuals with pre-extensively drug-resistant tuberculosis, of which 63.3% achieved successful treatment (95%CI: 43.1-72.5).

CONCLUSION

Globally, the success rate of extensively drug-resistant tuberculosis treatment is 44.2%, far below the WHO's target rate of 75%. These results may serve as a reference for future studies assessing extensively drug-resistant tuberculosis treatment outcomes under the 2021 definition treated with better treatment regimens available. Comprehensive surveillance data of extensively drug-resistant tuberculosis outcomes from the whole world are desirable to monitor treatment progress.

Delamanid-containing regimens and multidrug-resistant tuberculosis: A systematic review and meta-analysis

INTRODUCTION

Multidrug-resistant tuberculosis (MDR-TB) is a life-threatening condition needing long poly-chemotherapy regimens. As no systematic reviews/meta-analysis is available to comprehensively evaluate the role of delamanid (DLM), we evaluated its effectiveness and safety.

METHODS

We reviewed the relevant scientific literature published up to January 20, 2022. The pooled success treatment rate with 95% confidence intervals (CI) was assessed using a random-effect model. We assessed studies for quality and bias, and considered P<0.05 to be statistically significant.

RESULTS

After reviewing 626 records, we identified 25 studies that met the inclusion criteria, 22 observational and 3 experimental, with 1276 and 411 patients, respectively. In observational studies the overall pooled treatment success rate of DLM-containing regimens was 80.9% (95% CI 72.6-87.2) with no evidence of publication bias (Begg's test; P >0.05). The overall pooled treatment success rate in DLM and bedaquiline-containing regimens was 75.2% (95% CI 68.1-81.1) with no evidence of publication bias (Begg's test; P >0.05). In experimental studies the pooled treatment success rate of DLM-containing regimens was 72.5 (95% CI 44.2-89.8, P <0.001, I²: 95.1%) with no evidence of publication bias (Begg's test; P >0.05).

CONCLUSIONS

In MDR-TB patients receiving DLM, culture conversion and treatment success rates were high despite extensive resistance with limited adverse events.

Mechanism of Action, Resistance, Synergism, and Clinical Implications of Delamanid Against Multidrug-Resistant Mycobacterium tuberculosis

Multidrug-resistant (MDR) isolates of Mycobacterium tuberculosis (MTB) remain a primary global threat to the end of tuberculosis (TB) era. Delamanid (DLM) is a nitro-dihydro-imidazooxazole derivative utilized to treat MDR-TB. DLM has distinct mechanism of action, inhibiting methoxy- and keto-mycolic acid (MA) synthesis through the F420 coenzyme mycobacteria system and generating nitrous oxide. While DLM resistance among MTB strains is uncommon, there are increasing reports in Asia and Europe, and such resistance will prolong the treatment courses of patients infected with MDR-TB. In this review, we address the antimycobacterial properties of DLM, report the global prevalence of DLM resistance, discuss the synergism of DLM with other anti-TB drugs, and evaluate the documented clinical trials to provide new insights into the clinical use of this antibiotic.

Novel treatments in multidrug-resistant tuberculosis

The management of multidrug-resistant tuberculosis (TB) is associated with low treatment success, high mortality and failure rates. New drugs and novel short-therapeutic regimens have only recently helped overcome these obstacles. We carried out a narrative literature review aimed at summarizing the scientific evidence on the recent therapeutic advances in the field of drug-resistant TB. Experimental and observational studies on novel (i.e. bedaquiline, delamanid, pretomanid) drugs and novel regimens and the main pharmacological characteristics of the newest compounds are described. We also highlight the main scientific evidence on therapeutic strategies complementary to standard chemotherapy (i.e. new approaches to drug delivery, host-directed therapy, surgery, new collapse therapy, rehabilitation, and palliative care).

Outcomes of multidrug-resistant tuberculosis treated with bedaquiline or delamanid

BACKGROUND

Since September 1, 2016, bedaquiline and delamanid have been administered for treatment of patients with multidrug-resistant/rifampicin-resistant tuberculosis after the official approval in South Korea. This study aimed to assess and compare the final treatment outcomes of patients who received bedaquiline with those of patients who received delamanid.

METHODS

This is a nationwide cohort study of patients with multidrug-resistant/rifampicin-resistant tuberculosis in whom bedaquiline or delamanid was administered from September 1, 2016, to February 28, 2018, after receiving the official approval in South Korea. Patients were classified into the bedaquiline and delamanid group according to the first used drug. We evaluated and compared the final treatment outcomes between the groups.

RESULTS

During the study period, 284 patients with multidrug-resistant/rifampicin-resistant tuberculosis were approved to use bedaquiline or delamanid and 260 were included in the final analysis; 119 (45.8%) and 141 patients (54.2%) were classified into bedaquiline and delamanid groups, respectively. Among them, 30 patients (11.5%) exhibited additional resistance to second-line injectable drugs, 94 patients (36.2%) had additional resistance to fluoroquinolones, and 37 patients (14.2%) had resistance to both drugs. The overall treatment success rate was 79.2%. Initiation of bedaquiline rather than delamanid was not associated with treatment success (adjusted odds ratio = 0.671, 95% confidence interval = 0.350-1.285). Frequencies of adverse events were not significantly different between the two groups.

CONCLUSIONS

Initial choice of bedaquiline or delamanid did not make any significant difference in the final treatment outcome or the frequencies of adverse events among patients with multidrug-resistant/rifampicin-resistant tuberculosis.

Treatment outcomes of patients with multidrug and extensively drug-resistant tuberculosis in Zhejiang, China

Background

The aim of this study was to assess the treatment outcomes of multidrug and extensively drug-resistant tuberculosis (M/XDR-TB) in Zhejiang, China and to evaluate possible risk factors associated with poor outcomes of M/XDR-TB.

Methods

Two-hundred-and-sixty-two patients having M/XDR-TB who received the diagnosis and treatment at nine referral hospitals from 1 January 2016 to 31 December 2016 in Zhejiang, China were included. All patients received second-line regimens recommended by WHO under the DOTS-Plus strategy.

Results

Among the 262 patients, the treatment success rate was 55.34% (n = 145) with 53.44% (n = 140) cured and 1.91% (n = 5) who completed treatment, 62 (23.66%) failed, 27 (10.31%) died, 16 (6.11%) defaulted and 12 (4.58%) transferred out. Forty (64.52%) of the 62 M/XDR-TB patients who failed treatment were due to adverse effects in the first 10 months of treatment. Eighteen patients (6.37%) had XDR-TB. Treatment failure was significantly higher among patients with XDR-TB at 50% than that among patients with non-XDR-TB at 21.72% (P = 0.006). Failure outcomes were associated with a baseline weight less than 50 kg (OR, 8.668; 95% CI 1.679–44.756; P = 0.010), age older than 60 years (OR, 9.053; 95% CI 1.606–51.027; P = 0.013), hemoptysis (OR, 8.928; 95% CI 1.048–76.923; P = 0.045), presence of cavitary diseases (OR, 10.204; 95% CI 2.032–52.631; P = 0.005), or treatment irregularity (OR, 47.619; 95% CI 5.025–500; P = 0.001).

Conclusion

Treatment outcomes for M/XDR-TB under the DOTS-Plus strategy in Zhejiang, China were favorable but still not ideal. Low body weight (< 50 kg), old age (> 60 years), severe symptoms of TB including cavitary disease, hemoptysis and irregular treatment were independent prognostic factors for failure outcomes in patients with M/XDR-TB.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-021-00502-0.

Biobank for multidrug-resistant tuberculosis research: importance of sequential samples

Since 2013, Masan National Tuberculosis Hospital has collected standardized specimens from its tuberculosis patients, which include a large number of multidrug-resistant strains. The repository collects matched participants and their bacilli samples, compiling sequential samples from the beginning of treatment. The repository aims to provide resources for in-depth international research.

Culture Conversion in Patients Treated with Bedaquiline and/or Delamanid. A Prospective Multicountry Study

Rationale: Bedaquiline and delamanid offer the possibility of more effective and less toxic treatment for multidrug-resistant (MDR) tuberculosis (TB). With this treatment, however, some patients remain at high risk for an unfavorable treatment outcome. The endTB Observational Study is the largest multicountry cohort of patients with rifampin-resistant TB or MDR-TB treated in routine care with delamanid- and/or bedaquiline-containing regimens according to World Health Organization guidance.

Objectives: We report the frequency of sputum culture conversion within 6 months of treatment initiation and the risk factors for nonconversion.

Methods: We included patients with a positive baseline culture who initiated a first endTB regimen before April 2018. Two consecutive negative cultures collected 15 days or more apart constituted culture conversion. We used generalized mixed models to derive marginal predictions for the probability of culture conversion in key subgroups.

Measurements and Main Results: A total of 1,109 patients initiated a multidrug treatment containing bedaquiline (63%), delamanid (27%), or both (10%). Of these, 939 (85%) experienced culture conversion within 6 months. In adjusted analyses, patients with HIV had a lower probability of conversion (0.73; 95% confidence interval [CI], 0.62–0.84) than patients without HIV (0.84; 95% CI, 0.79–0.90; P = 0.03). Patients with both cavitary disease and highly positive sputum smear had a lower probability of conversion (0.68; 95% CI, 0.57–0.79) relative to patients without either (0.89; 95% CI, 0.84–0.95; P = 0.0004). Hepatitis C infection, diabetes mellitus or glucose intolerance, and baseline resistance were not associated with conversion.

Conclusions: Frequent sputum conversion in patients with rifampin-resistant TB or MDR-TB who were treated with bedaquiline and/or delamanid underscores the need for urgent expanded access to these drugs. There is a need to optimize treatment for patients with HIV and extensive disease.

Treatment Outcomes of Patients with Multidrug-Resistant Tuberculosis: Comparison of Pre- and Post-Public-Private Mix Periods

BACKGROUND

This study compared the treatment outcomes of patients with multidrug-resistant tuberculosis (MDR-TB) before and after the implementation of public-private mix (PPM). Factors affecting treatment success were also investigated.

METHODS

Data from culture-confirmed pulmonary MDR-TB patients who commenced MDR-TB treatment at Pusan National University Hospital between January 2003 and December 2017 were retrospectively reviewed. Patients were divided into two groups in terms of PPM status: pre-PPM period, patients who commenced MDR-TB treatment between 2003 and 2010; and post-PPM period, patients treated between 2011 and 2017.

RESULTS

A total of 176 patients were included (64 and 112 in the pre- and post-PPM periods, respectively). 36.9% of the patients were resistant to a fluoroquinolone or a second-line injectable drug, or both. The overall treatment success rate was 72.7%. The success rate of post-PPM patients was higher than that of pre-PPM patients (79.5% vs. 60.9%, p=0.008). Also, loss to follow-up was lower in the post-PPM period (5.4% vs. 15.6%, p=0.023). In multivariate regression analysis, age ≥65 years, body mass index ≤18.5 kg/m2, previous TB treatment, bilateral lung involvement, and extensively drug-resistant (XDR)- or pre-XDR-TB were associated with poorer treatment outcomes. However, the use of bedaquiline or delamanid for ≥1 month increased the treatment success.

CONCLUSION

The treatment success rate in MDR-TB patients was higher in the post-PPM period than in the pre-PPM period, particularly because of the low rate of loss to follow-up. To ensure comprehensive patient-centered PPM in South Korea, investment and other support must be adequate.

Diagnosis and treatment of multidrug-resistant tuberculosis

Tuberculosis (TB) is still a major health problem worldwide. Especially, multidrug-resistant TB (MDR-TB), which is defined as TB that shows resistance to both isoniazid and rifampicin, is a barrier in the treatment of TB. Globally, approximately 3.4% of new TB patients and 20% of the patients with a history of previous treatment for TB were diagnosed with MDR-TB. The treatment of MDR-TB requires medications for a long duration (up to 20-24 months) with less effective and toxic second-line drugs and has unfavorable outcomes. However, treatment outcomes are expected to improve due to the introduction of a new agent (bedaquiline), repurposed drugs (linezolid, clofazimine, and cycloserine), and technological advancement in rapid drug sensitivity testing. The World Health Organization (WHO) released a rapid communication in 2018, followed by consolidated guidelines for the treatment of MDR-TB in 2019 based on clinical trials and an individual patient data meta-analysis. In these guidelines, the WHO suggested reclassification of second-line anti-TB drugs and recommended oral treatment regimens that included the new and repurposed agents. The aims of this article are to review the treatment strategies of MDR-TB based on the 2019 WHO guidelines regarding the management of MDR-TB and the diagnostic techniques for detecting resistance, including phenotypic and molecular drug sensitivity tests.

Interim treatment outcomes in multidrug-resistant tuberculosis using bedaquiline and/or delamanid in South Korea

PURPOSE

The Korea Centers for Disease Control & Prevention has implemented a review process for the approval of new drugs used to treat patients with multidrug-resistant tuberculosis (MDR-TB) since September 2016. Therefore, this study aimed to evaluate the efficacy and safety of these new drugs bedaquiline (Bdq) and delamanid (Dlm).

METHODS

A total of 318 patients with MDR-TB were reviewed by the committee from September 2016 to February 2018; 282 (88.7%) of them were treated with the new drugs (Bdq, 107 patients; Dlm, 108 patients; and both concurrently or sequentially, 67 patients) and retrospectively evaluated. Culture conversion rates, interim treatment outcomes at 12 months, and predictors of unfavorable outcomes were analyzed. Treatment efficacy was also compared between Bdq and Dlm.

RESULTS

The mean age of the patients was 49.3 years, and 197 (69.9%) were male. Three patients were HIV seropositive and 151 (53.5%) were quinolone resistant. The culture conversion rates at 2 and 6 months were 57.4% (81/141) and 89.4% (126/141), respectively. A favorable outcome at 12 months was achieved in 84.8% of patients (239/282). Differences in the culture conversion rate or interim treatment outcomes were not statistically significant among the drug susceptibility test patterns or new drugs used. Multivariable analysis showed that age >60 years and body mass index of <18.5 kg/m² were significant risk factors for unfavorable outcomes at 12 months.

CONCLUSIONS

The use of new drugs resulted in satisfactory interim treatment results, without significant differences between them.