The endTB project aims to find shorter, less toxic and more effective treatments for ‘multidrug-resistant TB’ (MDR-TB) through:
- access to new drugs
- two clinical trials
- advocacy at national and global levels
Covering 18 countries, the project is a partnership between Partners In Health, Médecins Sans Frontières, Interactive Research & Development and financial partners Unitaid and the Transformational Investment Capacity (TIC) of MSF. This collection contains the final and intermediate results of the studies, advocacy reports, and study presentations. For more information about the endTB project, visit https://endtb.org/.
BACKGROUND
For decades, poor treatment options and low-quality evidence plagued care for patients with rifampin-resistant tuberculosis. The advent of new drugs to treat tuberculosis and enhanced funding now permit randomized, controlled trials of shortened-duration, all-oral treatments for rifampin-resistant tuberculosis.
METHODS
We conducted a phase 3, multinational, open-label, randomized, controlled noninferiority trial to compare standard therapy for treatment of fluoroquinolone-susceptible, rifampin-resistant tuberculosis with five 9-month oral regimens that included various combinations of bedaquiline (B), delamanid (D), linezolid (L), levofloxacin (Lfx) or moxifloxacin (M), clofazimine (C), and pyrazinamide (Z). Participants were randomly assigned (with the use of Bayesian response-adaptive randomization) to receive one of five combinations or standard therapy. The primary end point was a favorable outcome at week 73, defined by two negative sputum culture results or favorable bacteriologic, clinical, and radiologic evolution. The noninferiority margin was -12 percentage points.
RESULTS
Among the 754 participants who underwent randomization, 699 were included in the modified intention-to-treat analysis, and 562 in the per-protocol analysis. In the modified intention-to-treat analysis, 80.7% of the patients in the standard-therapy group had favorable outcomes. The risk difference between standard therapy and each of the four new regimens that were found to be noninferior in the modified intention-to-treat population was as follows: BCLLfxZ, 9.8 percentage points (95% confidence interval [CI], 0.9 to 18.7); BLMZ, 8.3 percentage points (95% CI, -0.8 to 17.4); BDLLfxZ, 4.6 percentage points (95% CI, -4.9 to 14.1); and DCMZ, 2.5 percentage points (95% CI, -7.5 to 12.5). Differences were similar in the per-protocol population, with the exception of DCMZ, which was not noninferior in that population. The proportion of participants with grade 3 or higher adverse events was similar across the regimens. Grade 3 or higher hepatotoxic events occurred in 11.7% of participants overall and in 7.1% of those receiving standard therapy.
CONCLUSIONS
Consistent results across all the analyses support the noninferior efficacy of three all-oral shortened regimens for the treatment of rifampin-resistant tuberculosis. (Funded by Unitaid and others; endTB ClinicalTrials.gov number, NCT02754765.).
BACKGROUND
After a history of poor treatments for rifampin-resistant tuberculosis (RR-TB), recent advances have resulted in shorter, more effective treatments. However, they are not available to everyone and have shortcomings, requiring additional treatment options.
METHODS
endTB is an international, open-label, Phase 3 non-inferiority, randomized, controlled clinical trial to compare five 9-month all-oral regimens including bedaquiline (B), delamanid (D), linezolid (L), levofloxacin (Lfx) or moxifloxacin (M), clofazimine (C) and pyrazinamide (Z), to the standard (control) for treatment of fluoroquinolone-susceptible RR-TB. Participants were randomized to 9BLMZ, 9BCLLfxZ, 9BDLLfxZ, 9DCLLfxZ, 9DCMZ and control using Bayesian response-adaptive randomization. The primary outcome was favorable outcome at week 73 defined by two negative sputum culture results or by favorable bacteriologic, clinical and radiologic evolution. The non-inferiority margin was 12 percentage points.
RESULTS
Of 754 randomized patients, 696 and 559 were included in the modified intention to treat (mITT) and per-protocol (PP) analyses, respectively. In mITT, the control had 80.7% favorable outcomes. Regimens 9BCLLfxZ [adjusted risk difference (aRD): 9.5% (95% confidence interval (CI), 0.4 to 18.6)], 9BLMZ [aRD: 8.8% (95%CI, −0.6 to 18.2)], and 9BDLLfxZ [3.9% (95%CI, −5.8 to 13.6)] were non-inferior in mITT and in PP. The proportion of participants experiencing grade 3 or higher adverse events was similar across the regimens. Grade 3 or higher hepatotoxicity occurred in 11.7% of the experimental regimens overall and in 7.1% of the control.
CONCLUSIONS
The endTB trial increases treatment options for RR-TB with three shortened, all-oral regimens that were non-inferior to a current well-performing standard of care.
Quantification of recurrence risk following successful treatment is crucial to evaluating regimens for multidrug- or rifampicin-resistant (MDR/RR) tuberculosis (TB). However, such analyses are complicated when some patients die or become lost during post-treatment-follow-up.
METHODS
We analyzed data on 1,991 patients who successfully completed a longer MDR/RR-TB regimen containing bedaquiline and/or delamanid between 2015 and 2018 in 16 countries. Using five approaches for handling post-treatment deaths, we estimated the six-month post-treatment TB recurrence risk overall, and by HIV status. We used inverse-probability-weighting to account for patients with missing follow-up and investigated the impact of potential bias from excluding these patients without applying inverse-probability weights.
RESULTS
The estimated TB recurrence risk was 7.4 per 1000 (95% confidence interval (CI): 3.5,12.9) when deaths were handled as non-recurrences, and 7.6 per 1000 (95% CI: 3.6,13.1) when deaths were censored and inverse-probability weights were applied to account for the excluded deaths. The estimated risk of composite recurrence outcomes were 25.5 (95% CI: 15.4,38.1), 11.7 (95% CI: 6.5,18.3), and 8.6 (95% CI: 4.2,14.6) per 1000 for recurrence or 1) any death, 2) death with unknown or TB-related cause, 3) TB-related death, respectively. Corresponding relative risks for HIV status varied in direction and magnitude. Exclusion of patients with missing follow-up without inverse-probability-weighting had a small impact on estimates.
CONCLUSIONS
The estimated six-month TB recurrence risk was low, and the association with HIV status was inconclusive due to few recurrence events. Estimation of post-treatment recurrence will be enhanced by explicit assumptions about deaths and appropriate adjustment for missing follow-up data.
RATIONALE
Treatment outcomes may be compromised among patients with multidrug- or rifampicin-resistant tuberculosis with additional fluoroquinolone resistance. Evidence is needed to inform optimal treatment for these patients.
OBJECTIVES
We compared the effectiveness of longer individualized regimens comprised of bedaquiline for 5 to 8 months, linezolid, and clofazimine to those reinforced with at least 1 third-tier drug and/or longer duration of bedaquiline.
METHODS
We emulated a target trial to compare the effectiveness of initiating and remaining on the core regimen to one of five regimens reinforced with (1) bedaquiline for ≥9 months, (2) bedaquiline for ≥9 months and delamanid, (3) imipenem, (4) a second-line injectable, or (5) delamanid and imipenem. We included patients in whom a fluoroquinolone was unlikely to be effective based on drug susceptibility testing and/or prior exposure. Our analysis consisted of cloning, censoring, and inverse-probability weighting to estimate the probability of successful treatment.
MEASUREMENTS AND MAIN RESULTS
Adjusted probabilities of successful treatment were high across regimens, ranging from 0.75 (95%CI:0.61, 0.89) to 0.84 (95%CI:0.76, 0.91). We found no substantial evidence that any of the reinforced regimens improved effectiveness of the core regimen, with ratios of treatment success ranging from 1.01 for regimens reinforced with bedaquiline ≥9 months (95%CI:0.79, 1.28) and bedaquiline ≥9 months plus delamanid (95%CI:0.81, 1.31) to 1.11 for regimens reinforced by a second-line injectable (95%CI:0.92, 1.39) and delamanid and imipenem (95%CI:0.90, 1.41).
CONCLUSIONS
High treatment success underscores the effectiveness of regimens comprised of bedaquiline, linezolid, and clofazimine, highlighting the need for expanded access to these drugs.
Treatment for fluoroquinolone-resistant multidrug-resistant/rifampicin-resistant tuberculosis (pre-XDR TB) often lasts longer than treatment for less resistant strains, yields worse efficacy results, and causes substantial toxicity. The newer anti-tuberculosis drugs, bedaquiline and delamanid, and repurposed drugs clofazimine and linezolid, show great promise for combination in shorter, less-toxic, and effective regimens. To date, there has been no randomized, internally and concurrently controlled trial of a shorter, all-oral regimen comprising these newer and repurposed drugs sufficiently powered to produce results for pre-XDR TB patients.
METHODS
endTB-Q is a phase III, multi-country, randomized, controlled, parallel, open-label clinical trial evaluating the efficacy and safety of a treatment strategy for patients with pre-XDR TB. Study participants are randomized 2:1 to experimental or control arms, respectively. The experimental arm contains bedaquiline, linezolid, clofazimine, and delamanid. The control comprises the contemporaneous WHO standard of care for pre-XDR TB. Experimental arm duration is determined by a composite of smear microscopy and chest radiographic imaging at baseline and re-evaluated at 6 months using sputum culture results: participants with less extensive disease receive 6 months and participants with more extensive disease receive 9 months of treatment. Randomization is stratified by country and by participant extent-of-TB-disease phenotype defined according to screening/baseline characteristics. Study participation lasts up to 104 weeks post randomization. The primary objective is to assess whether the efficacy of experimental regimens at 73 weeks is non-inferior to that of the control. A sample size of 324 participants across 2 arms affords at least 80% power to show the non-inferiority, with a one-sided alpha of 0.025 and a non-inferiority margin of 12%, against the control in both modified intention-to-treat and per-protocol populations.
DISCUSSION
This internally controlled study of shortened treatment for pre-XDR TB will provide urgently needed data and evidence for clinical and policy decision-making around the treatment of pre-XDR TB with a four-drug, all-oral, shortened regimen.
Evidence of the effectiveness of the WHO-recommended design of longer individualized regimens for multidrug- or rifampicin-resistant TB (MDR/RR-TB) is limited.
OBJECTIVES
To report end-of-treatment outcomes for MDR/RR-TB patients from a 2015–2018 multi-country cohort that received a regimen consistent with current 2022 WHO updated recommendations and describe the complexities of comparing regimens.
METHODS
We analyzed a subset of participants from the endTB Observational Study who initiated a longer MDR/RR-TB regimen that was consistent with subsequent 2022 WHO guidance on regimen design for longer treatments. We excluded individuals who received an injectable agent or who received fewer than four likely effective drugs.
RESULTS
Of the 759 participants analyzed, 607 (80.0%, 95% CI 77.0–82.7) experienced successful end-of-treatment outcomes. The frequency of success was high across groups, whether stratified on number of Group A drugs or fluoroquinolone resistance, and ranged from 72.1% to 90.0%. Regimens were highly variable regarding composition and the duration of individual drugs.
CONCLUSIONS
Longer, all-oral, individualized regimens that were consistent with 2022 WHO guidance on regimen design had high frequencies of treatment success. Heterogeneous regimen compositions and drug durations precluded meaningful comparisons. Future research should examine which combinations of drugs maximize safety/tolerability and effectiveness.
Effectiveness of bedaquiline use beyond six months in patients with multidrug-resistant tuberculosis
Current recommendations for the treatment of rifampin- and multidrug-resistant tuberculosis include bedaquiline used for six months or longer. Evidence is needed to inform the optimal duration of bedaquiline.
OBJECTIVES
We emulated a target trial to estimate the effect of three bedaquiline duration treatment strategies (6 months, 7-11 months, ≥ 12 months) on the probability of successful treatment among patients receiving a longer individualized regimen for multidrug-resistant tuberculosis.
METHODS
To estimate the probability of successful treatment, we implemented a three-step approach comprising cloning, censoring, and inverse-probability weighting.
MAIN RESULTS
The 1,468 eligible individuals received a median of four (IQR: 4-5) likely effective drugs. In 87.1% and 77.7%, this included linezolid and clofazimine, respectively. The adjusted probability of successful treatment (95% CI) was 0.85 (0.81, 0.88) for 6 months of BDQ, 0.77 (0.73, 0.81) for 7-11 months, and 0.86 (0.83, 0.88) for > 12 months. Compared with 6 months of bedaquiline, the ratio of treatment success (95% CI) was 0.91 (0.85, 0.96) for 7-11 months and 1.01 (0.96, 1.06) for > 12 months. Analyses that did not account for immortal time bias found a higher probability of successful treatment with > 12 months: ratio 1.09 (1.05, 1.14).
CONCLUSIONS
Bedaquiline use beyond six months did not increase the probability of successful treatment among patients receiving longer regimens that commonly included new and repurposed drugs. When not properly accounted for, immortal person-time can bias estimate of effects of treatment duration. Future analyses should explore the effect of duration of bedaquiline and other drugs in subgroups with advanced disease and/or receiving less potent regimens.
endTB Observational Study had sites in 17 countries. In each country, sites enrolled patients on treatment with bedaquiline and delamanid according to National TB Program guidelines, while collecting clinical and bacteriological data on efficacy and safety. Because many of the endTB Observational Study tools were found to be useful for clinicians and programs that were starting to use the new TB drugs and regimens, we made them freely available at the endTB website. This Technical Basis document provides the rationale for clinical decision-making, screening tools and data definitions that are used at the endTB Observational Study sites.
The WHO provides standardized outcome definitions for rifampicin-resistant (RR) and multidrug-resistant (MDR) TB. However, operationalizing these definitions can be challenging in some clinical settings, and incorrect classification may generate bias in reporting and research. Outcomes calculated by algorithms can increase standardization and be adapted to suit the research question. We evaluated concordance between clinician-assigned treatment outcomes and outcomes calculated based on one of two standardized algorithms, one which identified failure at its earliest possible recurrence (i.e., failure-dominant algorithm), and one which calculated the outcome based on culture results at the end of treatment, regardless of early occurrence of failure (i.e., success-dominant algorithm).
METHODS
Among 2,525 patients enrolled in the multi-country endTB observational study, we calculated the frequencies of concordance using cross-tabulations of clinician-assigned and algorithm-assigned outcomes. We summarized the common discrepancies.
RESULTS
Treatment success calculated by algorithms had high concordance with treatment success assigned by clinicians (95.8 and 97.7% for failure-dominant and success-dominant algorithms, respectively). The frequency and pattern of the most common discrepancies varied by country.
CONCLUSION
High concordance was found between clinician-assigned and algorithm-assigned outcomes. Heterogeneity in discrepancies across settings suggests that using algorithms to calculate outcomes may minimize bias.
BACKGROUND
Conversion of sputum culture from positive to negative for M. tuberculosis is a key indicator of treatment response. An initial positive culture is a pre-requisite to observe conversion. Consequently, patients with a missing or negative initial culture are excluded from analyses of conversion outcomes. To identify the initial, or “baseline” culture, researchers must define a sample collection interval. An interval extending past treatment initiation can increase sample size but may introduce selection bias because patients without a positive pre-treatment culture must survive and remain in care to have a culture in the post-treatment interval.
METHODS
We used simulated data and data from the endTB observational cohort to investigate the potential for bias when extending baseline culture intervals past treatment initiation. We evaluated bias in the proportion with six-month conversion.
RESULTS
In simulation studies, the potential for bias depended on the proportion of patients missing a pre-treatment culture, proportion with conversion, proportion culture positive at treatment initiation, and proportion of patients missing a pre-treatment culture who would have been observed to be culture positive, had they had a culture. In observational data, the maximum potential for bias when reporting the proportion with conversion reached five percentage points in some sites.
CONCLUSION
Extending the allowable baseline interval past treatment initiation may introduce selection bias. If investigators choose to extend the baseline collection interval past treatment initiation, the proportion missing a pre-treatment culture and the number of deaths and losses to follow up during the post-treatment allowable interval should be clearly enumerated.
However, since the onset of the pandemic, more effective and patient-friendly treatments and regimens for adults and children have become available to the TB community. Now more than ever there is a need to accelerate treatment and save more lives.
This Issue Brief – the eighth in this series – by Médecins Sans Frontières (MSF)’s Access Campaign, examines the current landscape and trends of DR-TB drug pricing and patents, and highlights challenges and opportunities to accelerate people’s access to lifesaving regimens that are shorter, all-oral and make use of the most effective medicines.
Concomitant use of bedaquiline (Bdq) and delamanid (Dlm) for multi-drug/rifampicin resistant tuberculosis (MDR/RR-TB) has raised concerns about a potentially poor risk-benefit ratio. Yet, this combination is an important alternative for patients infected with strains of TB with complex drug resistance profiles or who cannot tolerate other therapies. We assessed safety and treatment outcomes of MDR/RR-TB patients receiving concomitant Bdq and Dlm, along with other second-line anti-TB drugs.
METHODS
We conducted a multi-centric, prospective observational cohort study across 14 countries among patients receiving concomitant Bdq-Dlm treatment. Patients were recruited between April 2015 and September 2018 and were followed until the end of treatment. All serious adverse events and adverse events of special interest (AESI), leading to a treatment change, or judged significant by a clinician, were systematically monitored and documented.
RESULTS
Overall, 472 patients received Bdq and Dlm concomitantly. A large majority also received linezolid (89.6%) and clofazimine (84.5%). Nearly all (90.3%) had extensive disease; most (74.2%) had resistance to fluoroquinolones. The most common AESI were peripheral neuropathy (134, 28.4%) and electrolyte depletion (94, 19.9%). Acute kidney injury and myelosuppression were seen in 40 (8.5%) and 24 (5.1%) of patients, respectively. QT prolongation occurred in 7 (1.5%). Overall, 78.0% (358/458) had successful treatment outcomes, 8.9% died and 7.2% experienced treatment failure.
CONCLUSIONS
Concomitant use of Bdq and Dlm, along with linezolid and clofazimine, is safe and effective for MDR/RR-TB patients with extensive disease. Using these drugs concomitantly is a good therapeutic option for patients with resistance to many anti-TB drugs.
Safety of treatment for multidrug-resistant tuberculosis (MDR/RR-TB) can be an obstacle to treatment completion.
OBJECTIVES
Evaluate safety of longer MDR/RR-TB regimens containing bedaquiline and/or delamanid.
METHODS
Multicentre (16 countries), prospective, observational study, reporting incidence and frequency of clinically relevant adverse events of special interest (AESI) amongst patients who received MDR/RR-TB treatment containing bedaquiline and/or delamanid. The AESIs were defined a priori as important events caused by bedaquiline, delamanid, linezolid, injectables, and other commonly used drugs. Occurrence of these events was also reported by exposure to the likely causative agent.
RESULTS
Among 2296 patients, the most common clinically relevant AESIs were: peripheral neuropathy in 26.4%, electrolyte depletion in 26.0%, and hearing loss in 13.2% of patients. Per 1000 person-months of treatment, the incidence of these events was 21.5 (95% confidence interval [CI]: 19.8-23.2), 20.7 (95% CI: 19.1-22.4), and 9.7 (95% CI: 8.6-10.8), respectively. QT interval was prolonged in 2.7% or 1.8 (95% CI: 1.4-2.3)/1000 person-months of treatment. Patients who received injectables (N=925) and linezolid (N=1826) were most likely to experience events during exposure: Hearing loss, acute renal failure, or electrolyte depletion occurred in 36.8% or 72.8 (95%CI: 66.0-80.0) times/1000 person-months of injectable drug exposure. Peripheral neuropathy, optic neuritis and/or myelosuppression occurred in 27.8% or 22.8 (95% CI: 20.9-24.8) times/1000 patient-months of linezolid exposure.
CONCLUSIONS
Adverse events often related to linezolid and injectable drugs were more common than those frequently attributed to bedaquiline and delamanid. MDR-TB treatment monitoring schedules and individual drug durations should reflect expected safety profiles of drug combinations.
CLINICAL TRIALS REGISTRATION
NCT02754765
Drug-resistant tuberculosis (DR-TB) carries significant morbidity and mortality risk. Care of DR-TB in pregnancy is even more challenging. A recent meta-analysis examining the impact of DR-TB on pregnancy outcomes found a higher than expected rate of maternal death, pregnancy loss, and a significant prevalence of low-birthweight infants. Anti-tubercular drugs such as bedaquiline and clofazimine have long half-lives and the impact of in-utero exposure is largely unknown. There is little information to help women, their family members, and clinicians make informed decisions about DR-TB treatment during pregnancy.
METHODS
Data on pregnancy outcomes were systematically collected as part of a pharmacovigilance programme supporting a clinical trial (TB-PRACTECAL; N=552) and a prospective cohort (endTB; N=2,906). We present the birth outcomes as reported to investigators by participants.
ETHICS
The endTB and TB-PRACTECAL studies were both approved by the local ethics committees in all recruiting countries and by the MSF Ethics Review Board. endTB was approved by the Partners Healthcare Human Research Committee, Boston, USA, and TB-PRACTECAL was approved by the London School of Hygiene and Tropical Medicine Ethics Committee, UK.
RESULTS
Between 01 April 2015 and 31 December 2021, 58 pregnancies in 53 women were notified from 10 different countries, predominantly Uzbekistan (14), Kazakhstan (13) and Pakistan (9). In 13 cases, pregnancy occurred after completion of tuberculosis treatment. Patients became pregnant a median of 260.5 (range, 0-727) days from treatment start; five women were 5-32 weeks pregnant at treatment start. There were no maternal deaths. 17.0% (9/53) of mothers changed or interrupted treatment during pregnancy. Treatment outcome was successful in 97.3% (36/37) of others in endTB and 100% (7/7) of mothers who completed follow-up in TB-PRACTECAL. Pregnancy outcome was known in 52 cases: 20 elective abortions, three miscarriages and 30 live births (one twin pregnancy). There were no stillbirths. Of the 30 live births, 29 occurred in mothers ever exposed to bedaquiline, 16 to clofazimine, 11 to a second-line injectable, 10 to pretomanid, and 7 to delamanid. Birth weight was known in 24/30 (80.0%) babies. Median weight was 3,015 (range, 1,270 to 4,200) grams. Two babies were born prematurely at 30 and 31 weeks. Low birthweight was reported in seven (29.2%; 7/24) babies. One low-birthweight baby died within four months of birth from complications unrelated to tuberculosis. One baby was treated for DR-TB. There were no reported birth malformations.
CONCLUSION
These results support evidence that effective DR-TB treatments may improve maternal outcomes and prevent perinatal transmission. How these perinatal outcomes compare to other cohorts not affected by TB in these settings or exposed to different TB treatments needs exploration. The factors contributing to low birthweight in babies born to mothers with DR-TB requires further research. A global registry is urgently needed to assist parents and clinicians with decision-making.
CONFLICTS OF INTEREST
The endTB project was funded by UNITAID (Geneva, Switzerland). Provision of delamanid within the endTB project was partially funded through a donation from Otsuka Company (Kyoto, Japan).
Treatment of multidrug- and rifampin-resistant tuberculosis (MDR/RR-TB) is expensive, labour-intensive, and associated with substantial adverse events and poor outcomes. While most MDR/RR-TB patients do not receive treatment, many who do are treated for 18 months or more. A shorter all-oral regimen is currently recommended for only a sub-set of MDR/RR-TB. Its use is only conditionally recommended because of very low-quality evidence underpinning the recommendation. Novel combinations of newer and repurposed drugs bring hope in the fight against MDR/RR-TB, but their use has not been optimized in all-oral, shorter regimens. This has greatly limited their impact on the burden of disease. There is, therefore, dire need for high-quality evidence on the performance of new, shortened, injectable-sparing regimens for MDR-TB which can be adapted to individual patients and different settings.
METHODS
endTB is a phase III, pragmatic, multi-country, adaptive, randomized, controlled, parallel, open-label clinical trial evaluating the efficacy and safety of shorter treatment regimens containing new drugs for patients with fluoroquinolone-susceptible, rifampin-resistant tuberculosis. Study participants are randomized to either the control arm, based on the current standard of care for MDR/RR-TB, or to one of five 39-week multi-drug regimens containing newly approved and repurposed drugs. Study participation in all arms lasts at least 73 and up to 104 weeks post-randomization. Randomization is response-adapted using interim Bayesian analysis of efficacy endpoints. The primary objective is to assess whether the efficacy of experimental regimens at 73 weeks is non-inferior to that of the control. A sample size of 750 patients across 6 arms affords at least 80% power to detect the non-inferiority of at least 1 (and up to 3) experimental regimens, with a one-sided alpha of 0.025 and a non-inferiority margin of 12%, against the control in both modified intention-to-treat and per protocol populations.
DISCUSSION
The lack of a safe and effective regimen that can be used in all patients is a major obstacle to delivering appropriate treatment to all patients with active MDR/RR-TB. Identifying multiple shorter, safe, and effective regimens has the potential to greatly reduce the burden of this deadly disease worldwide.
TRIAL REGISTRATION
ClinicalTrials.gov Identifier NCT02754765.
Recent World Health Organisation guidance on drug-resistant tuberculosis treatment de-prioritised injectable agents, in use for decades, and endorsed all-oral longer regimens. However, questions remain about the role of the injectable agent, particularly in the context of regimens using new and repurposed drugs. We compared the effectiveness of an injectable-containing regimen to that of an all-oral regimen among patients with drug-resistant tuberculosis who received bedaquiline- and/or delamanid as part of their multidrug regimen.
METHODS
Patients with a positive baseline culture were included. Six-month culture conversion was defined as two consecutive negative cultures collected >15 days apart. We derived predicted probabilities of culture conversion and relative risk using marginal standardisation methods.
RESULTS
Culture conversion was observed in 83.8% (526/628) of patients receiving an all-oral regimen and 85.5% (425/497) of those receiving an injectable-containing regimen. The adjusted relative risk comparing injectable-containing regimens to all-oral regimens was 0.96 (95%CI: 0.88–1.04). We found very weak evidence of effect modification by HIV status: among patients living with HIV, there was a small increase in the frequency of conversion among those receiving an injectable-containing regimen, relative to an all-oral regimen, which was not apparent in HIV-negative patients.
CONCLUSIONS
Among individuals receiving bedaquiline and/or delamanid as part of a multidrug regimen for drug-resistant tuberculosis, there was no significant difference between those who received an injectable and those who did not regarding culture conversion within 6 months. The potential contribution of injectable agents in the treatment of drug-resistant tuberculosis among those who were HIV positive requires further study.
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.
Tuberculosis (TB) is the world’s deadliest infectious disease, and drug-resistant (DR) TB is a global health emergency. The World Health Organization (WHO) has estimated that only 1 in 3 people with DR-TB is started on treatment, and those treated have faced exceedingly poor cure rates of 56% for multidrug- resistant TB (MDR-TB) and 39% for extensively drug-resistant TB (XDR-TB), as of 2018. Before the innovations in TB over the last few years, the best DR-TB treatment entailed long regimens with painful injections, severe side effects and poor outcomes. Safer and more effective DR-TB drugs are now available for use in all- oral regimens recommended by WHO.
In the face of poor cure rates and clear need to scale up DR-TB treatment in high-burden places, improvements in DR-TB management are finally at hand. But to achieve these improvements, the barriers to treatment scale-up must be addressed with haste, so that people with TB can benefit from these shorter, less toxic, more potent therapies. Access to testing and key DR-TB medicines, especially bedaquiline and delamanid, and potentially pretomanid, must be accelerated, including through more affordable pricing and by overcoming patent and licensing hurdles.
Also, the global COVID-19 pandemic has complicated and diverted resources from TB care, amongst other health areas. As the pandemic continues, disruption of TB services must be monitored and minimised.
This Issue Brief by Médecins Sans Frontières (MSF)’s Access Campaign examines the current landscape of DR-TB and TB- prevention drug pricing and patents, and what needs to be done to accelerate people’s access to these lifesaving medicines.
Active pharmacovigilance (PV) is recommended for TB programmes, notably for multidrug-resistant TB (MDR-TB) patients treated with new drugs. Launched with the support of UNITAID in April 2015, endTB (Expand New Drug markets for TB) facilitated treatment with bedaquiline (BDQ) and/or delamanid of >2600 patients in 17 countries, and contributed to the creation of a central PV unit (PVU).
OBJECTIVE
To explain the endTB PVU process by describing the serious adverse events (SAEs) experienced by patients who received BDQ-containing regimens.
DESIGN
The overall PV strategy was in line with the ‘advanced´ WHO active TB drug safety monitoring and management (aDSM) system. All adverse events (AEs) of clinical significance were followed up; the PVU focused on signal detection from SAEs.
RESULTS AND CONCLUSION
Between 1 April 2015 and 31 March 2019, the PVU received and assessed 626 SAEs experienced by 417 BDQ patients. A board of MDR-TB/PV experts reviewed unexpected and possibly drug-related SAEs to detect safety signals. The experts communicated on clusters of risks factors, notably polypharmacy and off-label drug use, encouraging a patient-centred approach of care. Organising advanced PV in routine care is possible but demanding. It is reasonable to expect local/national programmes to focus on clinical management, and to limit reporting to aDSM systems to key data, such as the SAEs.
Bedaquiline and delamanid offer the possibility of more effective and less toxic multidrug-resistant tuberculosis (MDR-TB) treatment. 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/MDR-TB treated in routine care, according to WHO guidance, with delamanid- and/or bedaquiline-containing regimens. We report frequency of sputum culture conversion within six-months of treatment initiation and risk factors for non-conversion.
METHODS
We included patients with a positive baseline culture who initiated a first endTB regimen prior to April 2018. Two consecutive negative cultures collected > 15 days apart constituted culture conversion. We used generalized mixed models to derive marginal predictions for the probability of culture conversion in key subgroups.
FINDINGS
1,109 patients initiated a multidrug treatment containing bedaquiline (63%), delamanid (27%) or both (10%). Of these, 939 (85%) experienced culture conversion within six months. In adjusted analyses, patients with HIV had a lower probability of conversion (0·73 [95% 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/glucose intolerance, and baseline resistance were not associated with conversion.
INTERPRETATION
Frequent sputum conversion in patients with rifampin-resistant/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.
Delamanid should be effective against highly resistant strains of Mycobacteriumtuberculosis, but uptake has been slow globally. In the endTB (expand new drug markets for TB) Observational Study, which enrolled a large, heterogeneous cohorts of patients receiving delamanid as part of a multidrug regimen, 80% of participants experienced sputum culture conversion within 6 months.
Drug resistance is a major public health crisis thwarting the effective treatment and care of people living with tuberculosis (TB) – the world’s leading infectious disease killer. Declared a global health emergency by the World Health Organization (WHO) in 2014 and again in 2017, drug-resistant TB (DR-TB) affected an estimated half million people in 2018 yet only 1 in 3 started treatment.
Until recently, the standard DR-TB treatment regimens recommended by WHO – and still in use by many countries – have a high pill burden, long treatment duration (up to two years), painful daily injections, severe side effects and poor treatment outcomes. These regimens cured only 56% of people with multidrug-resistant TB (MDR-TB), and 39% of people with extensively drug- resistant TB (XDR-TB).
In March 2019, WHO released new DR-TB treatment guidelines, recommending more effective and easier-to-take all- oral drug regimens. In July 2019, WHO Director-General Dr Tedros Adhanom Ghebreyesus called for countries to transition to all-oral DR-TB regimens by World TB Day, 24 March 2020. By this time, 100% of people newly enrolled on treatment should be offered these optimal regimens.
This Issue Brief examines the current landscape of DR-TB drug pricing and access policies, and what needs to be done by governments, policymakers and health care providers to get these lifesaving medicines to the people who need them most.
At a time when programs were struggling to design effective regimens for the treatment of multidrug-resistant tuberculosis (MDR-TB), the marketing authorization of bedaquiline and delamanid was a critical development in the MDR-TB treatment landscape. However, despite their availability for routine programmatic use, the uptake of these drugs has remained slow; concerns included a lack of evidence on safety and efficacy and the need to protect the new drugs from the development of acquired resistance. As part of the endTB Project, we aimed to address these barriers by generating evidence on safety and efficacy of bedaquiline or delamanid based MDR-TB regimens.
METHODS
This is a protocol for a multi-center prospective cohort study to enroll 2600 patients from April 2015 through September 2018 in 17 countries. The protocol describes inclusion of patients started on treatment with bedaquiline- or delamanid- containing regimens under routine care, who consented to participate in the endTB observational study. Patient follow-up was according to routine monitoring schedules recommended for patients receiving bedaquiline or delamanid as implemented at each endTB site. Therefore, no additional tests were performed as a part of the study. Data were to be collected in a customized, open-source electronic medical record (EMR) system developed as a part of the endTB Project across all 17 countries.
DISCUSSION
The endTB observational study will generate evidence on safety and efficacy of bedaquiline- and delamanid-containing regimens in a large, extremely heterogeneous group of MDR-TB patients, from 17 epidemiologically diverse countries. The systematic, prospective data collection of repeated effectiveness and safety measures, and analyses performed on these data, will improve the quality of evidence available to inform MDR-TB treatment and policy decisions. Further, the resources available to countries through implementation of the endTB project will have permitted countries to: gain experience with the use of these drugs in MDR-TB regimens, improve local capacity to record and report adverse events (pharmacovigilance), and enhance significantly the body of data available for safety evaluation of these drugs and other novel treatments.
Although tuberculosis (TB) is the number-one infectious disease killer and one of the top ten causes of mortality worldwide, the global response to TB remains off track. 2 The interim 2020 targets set by the World Health Organization (WHO) End TB Strategy – to reduce new TB infections by 20%, reduce TB deaths by 35%, and eliminate catastrophic costs of treatment for families – won’t be reached unless there is a dramatic increase in the pace of the global TB response
Out of Step 2017 includes the results of a 29-country survey on national TB policies and practices. The report was created to identify gaps in implementation and monitor progress towards ending TB. While countries have made progress since the Out of Step 2015 report, much more work needs to be done to make sure that these policies are fully implemented across all communities, so that they will make a real difference to people affected by TB.
Out of Step in EECA is a regional adaptation the Out of Step 2017 report that focuses on TB diagnosis and treatment challenges in Eastern Europe and Central Asia (EECA). An epidemic of drug-resistant TB (DR-TB) is on the rise in EECA, where nearly half of all TB cases are multidrug-resistant and the number of people with DR-TB is increasing by more than 20% each year.
The endTB Medical Committee formulates recommendations for off-label and compassionate use of the new anti-TB drugs for M(X)DR-TB.
It provides advice to any MSF, PIH and IRD projects for individual patient’s management on a case-by-case basis in answer to requests initiated by clinicians from the projects.
This guide is designed to give guidance to the endTB Project site on the use of new TB drugs bedaquiline and delamanid. It is intended to be a resource for physicians and other health care professionals involved in the endTB project. Every effort possible has been made to ensure that the material presented here is accurate, reliable, and in accord with current standards. However, as new research and experience expand our knowledge, recommendations for care and treatment change.
To evaluate the use of Bayesian adaptive randomization for clinical trials of new treatments for multidrug-resistant tuberculosis.
METHODS
We built a response-adaptive randomization procedure, adapting on two preliminary outcomes for tuberculosis patients in a trial with five experimental regimens and a control arm. The primary study outcome is treatment success after 73 weeks from randomization; preliminary responses are culture conversion at 8 weeks and treatment success at 39 weeks. We compared the adaptive randomization design with balanced randomization using hypothetical scenarios.
RESULTS
When we compare the statistical power under adaptive randomization and non-adaptive designs, under several hypothetical scenarios we observe that adaptive randomization requires fewer patients than non-adaptive designs. Moreover, adaptive randomization consistently allocates more participants to effective arm(s). We also show that these advantages are limited to scenarios consistent with the assumptions used to develop the adaptive randomization algorithm.
CONCLUSION
Given the objective of evaluating several new therapeutic regimens in a timely fashion, Bayesian response-adaptive designs are attractive for tuberculosis trials. This approach tends to increase allocation to the effective regimens.
This report – now in its fourth edition – analyses the barriers and factors affecting access to treatment regimens for drug-resistant tuberculosis (DR-TB), including new and repurposed drugs. We provide detailed pricing profiles of key DR-TB drugs, using manufacturer responses to standardised questionnaires and the Global TB Drug Facility website.
