Quabodepistat in combination with delamanid and bedaquiline in participants with drug-susceptible pulmonary tuberculosis: protocol for a multicenter, phase 2b/c, open-label, randomized, dose-finding trial to evaluate safety and efficacy.

BACKGROUND: Delamanid and bedaquiline are two of the most recently developed antituberculosis (TB) drugs that have been extensively studied in patients with multidrug-resistant TB. There is currently a need for more potent, less-toxic drugs with novel mechanisms of action that can be used in combination with these newer agents to shorten the duration of treatment as well as prevent the development of drug resistance. Quabodepistat (QBS) is a newly discovered inhibitor of decaprenylphosphoryl-ß-D-ribose-2'-oxidase, an essential enzyme for Mycobacterium tuberculosis to synthesize key components of its cell wall. The objective of this study is to evaluate the safety, efficacy, and appropriate dosing of a 4-month regimen of QBS in combination with delamanid and bedaquiline in participants with drug-susceptible pulmonary TB in comparison with the 6-month standard treatment (i.e., rifampicin, isoniazid, ethambutol, and pyrazinamide). METHODS: This phase 2b/c, open-label, randomized, parallel group, dose-finding trial will enroll approximately 120 participants (including no more than 15% with human immunodeficiency virus [HIV] coinfection) aged ≥ 18 to ≤ 65 years at screening with newly diagnosed pulmonary drug-sensitive TB from ~8 sites in South Africa. Following a screening period of up to 14 days, eligible participants will be randomized in a ratio of 1:2:2:1 to one of four arms. Randomization will be stratified by HIV status and the presence of bilateral cavitation on a screening chest x-ray. After the end of the treatment period, participants will be followed until 12 months post randomization. The primary efficacy endpoint is the proportion of participants achieving sputum culture conversion in Mycobacteria Growth Indicator Tube by the end of the treatment period. The safety endpoints consist of adverse events, clinical laboratory tests, vital signs, physical examination findings, and electrocardiographic changes. DISCUSSION: QBS's potent bactericidal activity and distinct mechanism of action (compared with other TB drugs currently available for human use) may make it an ideal candidate for inclusion in a novel treatment regimen to improve efficacy and potentially prevent resistance to concomitant TB drugs. This trial will assess the effectiveness, safety, and dosing of a new, shorter, QBS-based, combination anti-TB treatment regimen. TRIAL STATUS: ClinicalTrials.gov NCT05221502. Registered on February 3, 2022.

Phase I Single Ascending Dose and Food Effect Study in Healthy Adults and Phase I/IIa Multiple Ascending Dose Study in Patients with Pulmonary Tuberculosis to Assess Pharmacokinetics, Bactericidal Activity, Tolerability, and Safety of OPC-167832.

OPC-167832, an inhibitor of decaprenylphosphoryl-ß-d-ribose 2'-oxidase, demonstrated potent antituberculosis activity and a favorable safety profile in preclinical studies. This report describes the first two clinical studies of OPC-167832: (i) a phase I single ascending dose (SAD) and food effects study in healthy participants; and (ii) a 14-day phase I/IIa multiple ascending dose (MAD; 3/10/30/90 mg QD) and early bactericidal activity (EBA) trial in participants with drug-susceptible pulmonary tuberculosis (TB). OPC-167832 was well tolerated at single ascending doses (10 to 480 mg) in healthy participants and multiple ascending doses (3 to 90 mg) in participants with TB. In both populations, nearly all treatment-related adverse events were mild and self-limiting, with headache and pruritus being the most common events. Abnormal electrocardiograms results were rare and clinically insignificant. In the MAD study, OPC-167832 plasma exposure increased in a less than dose-proportional manner, with mean accumulation ratios ranging from 1.26 to 1.56 for Cmax and 1.55 to 2.01 for area under the concentration-time curve from 0 to 24 h (AUC0-24h). Mean terminal half-lives ranged from 15.1 to 23.6 h. Pharmacokinetics (PK) characteristics were comparable to healthy participants. In the food effects study, PK exposure increased by less than ~2-fold under fed conditions compared to the fasted state; minimal differences were observed between standard and high-fat meals. Once-daily OPC-167832 showed 14-day bactericidal activity from 3 mg (log10 CFU mean ± standard deviation change from baseline; -1.69 ± 1.15) to 90 mg (-2.08 ± 0.75), while the EBA of Rifafour e-275 was -2.79 ± 0.96. OPC-167832 demonstrated favorable pharmacokinetic and safety profiles, as well as potent EBA in participants with drug-susceptible pulmonary TB.

Delamanid Added to an Optimized Background Regimen in Children with Multidrug-Resistant Tuberculosis: Results of a Phase I/II Clinical Trial.

Delamanid has been demonstrated to be safe and effective for treatment of adult multidrug-resistant tuberculosis (MDR-TB) and has been approved by the European Commission for treatment of pediatric MDR-TB patients at least 10 kg in weight, making the drug no longer limited to adults. A 10-day phase I age deescalation study was conducted, followed by a 6-month phase II extension study, to assess the pharmacokinetics, safety, tolerability, and preliminary efficacy of delamanid when combined with optimized background regimen (OBR) in children (birth to 17 years) with MDR-TB. Delamanid administered at 100 mg twice-daily (BID), 50 mg BID, and 25 mg BID resulted in exposures in 12- to 17- (n = 7), 6- to 11- (n = 6), and 3- to 5-year-olds (n = 12), respectively, comparable with those in adults at the approved adult dosage (100 mg BID). Exposures in 0- to 2-year-olds (n = 12) following a weight-based dosing regimen (5 mg once daily [QD] to 10 mg BID) were lower than predicted from pharmacokinetic modeling of the older three age groups and below target exposures in adults. Overall, the safety profile of delamanid in children 0 to 17 years of age was similar to the adult profile. At 24 months after the first delamanid dose, 33/37 children (89.2%) had favorable treatment outcomes, as defined by the World Health Organization (15/37 [40.5%] cured and 18/37 [48.6%] completed treatment). A new pediatric delamanid formulation used in 0- to 2-year-olds and 3- to 5-year-olds was palatable per child/parent and nurse/investigator reports. Data from initial phase I/II studies inform our understanding of delamanid use in children and support its further assessment in the setting of pediatric MDR-TB. (This study has been registered at ClinicalTrials.gov under identifiers NCT01856634 [phase I trial] and NCT01859923 [phase II trial].).

Population Pharmacokinetic and Concentration-QTc Analysis of Delamanid in Pediatric Participants with Multidrug-Resistant Tuberculosis.

A population pharmacokinetic analysis of delamanid and its major metabolite DM-6705 was conducted to characterize the pharmacokinetics of delamanid and DM-6705 in pediatric participants with multidrug-resistant tuberculosis (MDR-TB). Data from participants between the ages of 0.67 and 17 years, enrolled in 2 clinical trials, were utilized for the analysis. The final data set contained 634 delamanid and 706 DM-6705 valid plasma concentrations from 37 children. A transit model with three compartments best described the absorption of delamanid. Two-compartment models for each component with linear elimination were selected to characterize the dispositions of delamanid and DM-6705, respectively. The covariates included in the model were body weight on the apparent volume of distribution and apparent clearance (for both delamanid and DM-6705); formulation (dispersible versus film-coated tablet) on the mean absorption time; age, formulation, and dose on the bioavailability of delamanid; and age on the fraction of delamanid metabolized to DM-6705. Based on the simulations, doses for participants within different age/weight groups that result in delamanid exposure comparable to that in adults following the approved adult dose were calculated. By concentration-QTc (QTcB [QT corrected by Bazett's formula]) analysis, a significant positive correlation was detected with concentrations of DM-6705. However, the model-predicted upper bounds of the 90% confidence intervals of ΔQTc values were <10 ms at the simulated maximum concentration (Cmax) of DM-6705 following the administration of the maximum doses simulated. This suggests that the effect on the QT interval following the proposed dosing is unlikely to be clinically meaningful in children with MDR-TB who receive delamanid.

Compassionate use of delamanid in adults and children for drug-resistant tuberculosis: 5-year update.

BACKGROUND: Although delamanid has been approved for the treatment of multidrug-resistant TB (MDR-TB) in numerous regions, in areas where it is not yet registered it can be accessed as part of salvage therapy (in particular for those patients with limited treatment options) via the Otsuka compassionate use programme. Here we present the analysis of interim treatment outcomes by 24 weeks of more than 200 MDR-TB patients globally who received delamanid under this programme. METHODS: We evaluated treatment efficacy with respect to culture negativity at 24 weeks, as well as the safety profile of delamanid, in an MDR-TB patient cohort treated under compassionate use between 2014 and 2019. RESULTS: Among patients who received delamanid as part of a multidrug regimen, 123 (61%) out of 202 had extensively drug-resistant TB (XDR-TB), 66 (33%) out of 202 had HIV co-infection and 34 (17%) out of 202 were children aged between 6 and 17 years. Of those patients who were culture positive at delamanid treatment initiation and who completed 24 weeks of delamanid treatment in combination with other anti-tuberculosis (TB) drugs, culture negativity was achieved in 116 (79%) out of 147 cases. The corresponding rates of culture negativity for patients with XDR-TB and HIV co-infection, as well as the paediatric subgroup were 69 (77%) out of 90, 44 (92%) out of 48 and 20 (80%) out of 25, respectively. QT interval prolongation was the most frequently observed serious adverse event and was reported in 8% of patients receiving delamanid. Overall, treatment safety outcomes did not reveal any new or unidentified risks. CONCLUSIONS: The use of delamanid combined with other active drugs has the potential to achieve high rates of culture negativity in difficult-to-treat drug-resistant TB cases, with a favourable safety profile.

Cumulative Fraction of Response for Once- and Twice-Daily Delamanid in Patients with Pulmonary Multidrug-Resistant Tuberculosis.

Pharmacokinetic (PK) and pharmacodynamic (PD) analyses were conducted to determine the cumulative fraction of response (CFR) for 100 mg twice-daily (BID) and 200 mg once-daily (QD) delamanid in patients with multidrug-resistant tuberculosis (MDR-TB), using a pharmacodynamic target (PDT) that achieves 80% of maximum efficacy. First, in the mouse model of chronic TB, the PK/PD index for delamanid efficacy was determined to be area under the drug concentration-time curve over 24 h divided by MIC (AUC0-24/MIC), with a PDT of 252. Second, in the hollow-fiber system model of tuberculosis, plasma-equivalent PDTs were identified as an AUC0-24/MIC of 195 in log-phase bacteria and 201 in pH 5.8 cultures. Third, delamanid plasma AUC0-24/MIC and sputum bacterial decline data from two early bactericidal activity trials identified a clinical PDT of AUC0-24/MIC of 171. Finally, the CFRs for the currently approved 100-mg BID dose were determined to be above 95% in two MDR-TB clinical trials. The CFR for the 200-mg QD dose, evaluated in a trial in which delamanid was administered as 100 mg BID for 8 weeks plus 200 mg QD for 18 weeks, was 89.3% based on the mouse PDT and >90% on the other PDTs. QTcF (QTc interval corrected for heart rate by Fridericia's formula) prolongation was approximately 50% lower for the 200 mg QD dose than the 100 mg BID dose. In conclusion, while CFRs of 100 mg BID and 200 mg QD delamanid were close to or above 90% in patients with MDR-TB, more-convenient once-daily dosing of delamanid is feasible and likely to have less effect on QTcF prolongation.

Efficacy and safety of delamanid in combination with an optimised background regimen for treatment of multidrug-resistant tuberculosis: a multicentre, randomised, double-blind, placebo-controlled, parallel group phase 3 trial.

BACKGROUND: Delamanid is one of two recently approved drugs for the treatment of multidrug-resistant tuberculosis. We aimed to evaluate the safety and efficacy of delamanid in the first 6 months of treatment. METHODS: This randomised, double-blind, placebo-controlled, phase 3 trial was done at 17 sites in seven countries (Estonia, Latvia, Lithuania, Moldova, Peru, the Philippines, and South Africa). We enrolled eligible adults (>18 years) with pulmonary multidrug-resistant tuberculosis to receive, in combination with an optimised background regimen developed according to WHO and national guidelines, either oral delamanid (100 mg twice daily) for 2 months followed by 200 mg once daily for 4 months or placebo (same regimen). Patients were centrally randomised (2:1) and stratified by risk category for delayed sputum culture conversion. Primary outcomes were the time to sputum culture conversion over 6 months and the difference in the distribution of time to sputum culture conversion over 6 months between the two groups, as assessed in the modified intention-to-treat population. The trial is registered at ClinicalTrials.gov, number NCT01424670. FINDINGS: Between Sept 2, 2011, and Nov 27, 2013, we screened 714 patients, of whom 511 were randomly assigned (341 to delamanid plus optimised background regimen [delamanid group] and 170 to placebo plus optimised background regimen [placebo group]) and formed the safety analysis population. 327 patients were culture-positive for multidrug-resistant tuberculosis at baseline and comprised the efficacy analysis population (226 in the delamanid group and 101 in the placebo group). Median time to sputum culture conversion did not differ between the two groups (p=0·0562; modified Peto-Peto), with 51 days (IQR 29-98) in the delamanid group and 57 days (43-85) in the placebo group; the hazard ratio was 1·17 (95% CI 0·91-1·51, p=0·2157). 501 (98·0%) of 511 patients had at least one treatment-emergent adverse event. 136 (26·6%) of 511 patients had at least one serious treatment-emergent adverse event; the incidence was similar between treatment groups (89 [26·1%] of 341 patients for delamanid and 47 [27·6%] of 170 for placebo). Deaths related to treatment-emergent adverse events were similar between groups (15 [4·4%] of 341 for delamanid and six [3·5%] of 170 for placebo). No deaths were considered to be related to delamanid. INTERPRETATION: The reduction in median time to sputum culture conversion over 6 months was not significant in the primary analysis. Delamanid was well tolerated with a highly characterised safety profile. Further evaluation of delamanid is needed to determine its role in a rapidly evolving standard of care. FUNDING: Otsuka Pharmaceutical.

Delamanid: From discovery to its use for pulmonary multidrug-resistant tuberculosis (MDR-TB).

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), is the leading cause of death from an infectious disease globally. The widespread and ever-increasing resistance to TB drugs is reducing the effectiveness of treatment and jeopardizing TB control. New effective drugs with acceptable safety profiles are needed to turn the tide. Since the early 1990s, Otsuka Pharmaceutical Co., Ltd. has had a TB drug development program that resulted in the selection and development of delamanid (OPC-67683, Deltyba®), a first-in-class bicyclic nitroimidazole. Delamanid was initially approved by the European Medicines Agency (EMA) in 2014 for the treatment of adult pulmonary multi-drug resistant (MDR)-TB when an effective treatment regimen cannot otherwise be composed for reasons of resistance or tolerability. It has since been approved by several other countries/regions. In this review, we describe the history of delamanid's development, including the screening process, in vitro and in vivo characterization, as well as various clinical studies. Delamanid possesses potent activity against replicating, dormant, and intracellular MTB bacilli, and is bactericidal in mouse and guinea pig TB models. Delamanid resistance mechanisms have been attributed to genes in the F420-dependent deazaflavin nitroreductase bio-activation pathway, found in mycobacterium species but not in common bacterial or mammalian cells. Published susceptibility testing results from 744 clinical isolates from delamanid-naïve patients indicate that the natural resistance rate to delamanid is very low (1.3%). Delamanid is largely metabolized by albumin in serum, and to a much less extent by cytochrome P450 enzymes. Furthermore, it neither inhibits nor induces P450 enzymes. In terms of efficacy, delamanid demonstrated activity in an early bactericidal activity trial in drug susceptible pulmonary TB patients and increased 2-month sputum culture conversion rates when added to an optimized background regimen in MDR-TB patients in a phase 2b global clinical trial. In addition, recent results outside clinical studies show favourable responses in highly resistant TB patients including extensively drug resistant (XDR)-TB when treated with delamanid-containing regimens in routine programmatic settings. The primary safety concern with delamanid is QTcF interval prolongation, although this observation has thus far not been associated with any clinical cardiac events. Overall, delamanid appears to be a well-tolerated and safe anti-TB drug when compared to other drugs used to treat MDR-TB.

Drug-resistant tuberculosis in sub-saharan Africa.

Drug-resistant tuberculosis (DRTB) is an emerging infectious disease threat to sub-Saharan Africa (SSA), particularly in the regions hit hardest by the HIV epidemic. Numerous challenges face clinicians and public health officials tasked with combating DRTB in SSA. These include difficulties providing effective diagnosis, treatment, and prevention of this illness. Furthermore, combating DRTB requires addressing various legal and ethical complexities. A sustained commitment to investigating as well as implementing new diagnostic, therapeutic, and preventative interventions is essential to defeating this threat.

Infections in lung transplantation: new insights.

PURPOSE OF REVIEW: Infections represent a major source of complications in lung transplant recipients (LTR), especially when compared with recipients of other solid organ transplants. Within the past year, new data on the impact and prevention of specific pathogens in the setting of lung transplant have been published. Specifically, this review will assess the effect of Burkholderia infection on cystic fibrosis (CF) patients following lung transplant (LTx), the role that Gram-negative bacilli (GNB) play in the development of bronchiolitis obliterans syndrome (BOS), and the optimal duration of cytomegalovirus (CMV) prophylaxis in LTR. RECENT FINDINGS: Recent data support the hypothesis that certain Burkholderia species, potentially B. gladioli and specific B. cenocepacia subtypes, pose a greater risk for death in CF LTR than do other Burkholderia species. Additionally, recent data suggest that colonization with GNB, particularly Pseudomonas species, may play a role in the pathogenesis of BOS, the leading cause of late-term mortality in LTR. Finally, recent studies suggest that extended prophylactic regimens may be more efficacious in reducing CMV-related events. SUMMARY: Recent data have broadened our understanding of the role that infections play in affecting LTR outcomes. Prospective multicenter studies are needed to further optimize pathogen specific prevention strategies.