BACKGROUND

Bedaquiline (BDQ) resistance presents a critical challenge in the fight against tuberculosis (TB), particularly multidrug-resistant (MDR) strains. The emergence of resistance to BDQ, a key drug in treating MDR-TB, poses significant threats to TB treatment effectiveness.

METHODS

The National Institute of Tuberculosis and Respiratory Diseases in Delhi and the Médecins Sans Frontières clinic in Mumbai provide BDQ, delamanid, and carbapenem-based regimens for patients with suspected or confirmed treatment failure. BDQ phenotypic drug-susceptibility testing (DST) was performed for all BDQ-exposed patients. Treatment regimens were individualized based on exposure history, comorbidities, drug interactions, prior adverse drug reactions, and DST results.

RESULTS

Of 117 BDQ-exposed patients from December 2020–December 2022, 42 (36%) exhibited a BDQ-resistant strain. Median (IQR) age was 24 (22–32) years, with 63 (54%) females and 94% with pulmonary TB. Patients with a BDQ-resistant strain were older (median age: 27 vs 23 years; P = .04), more likely to have lung cavities (risk ratio [RR]: 1.8; 95%-CI: 1.1–3.1; P = .02), and be resistant to clofazimine (RR: 2.3; 95%-CI: 1.5–3.6; P = .001). Overall, 102 patients initiated treatment. Patients with BDQ-resistance had higher risk of unfavorable outcomes compared with BDQ-susceptible patients (RR:2.1; 95%-CI: 1.5–2.8; P < .001). Overall, 87% (33/38) of patients with BDQ-resistance experienced unfavorable treatment outcomes: 15 (40%) died, 15 (40%) had treatment failure, and 3 (8%) were lost-to-follow-up.

CONCLUSIONS

The study highlights a concerning rate of BDQ-resistance among previously treated patients, resulting in poor treatment outcomes. To prevent treatment failure, we recommend implementing BDQ-DST, developing affordable and accurate rapid tests for BDQ-resistance, and intensifying research and development efforts for newer TB drugs.

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

Tuberculosis (TB) remains a significant cause of mortality globally, with India accounting for 27% of the estimated number of people with TB. Multidrug-resistant TB (MDR-TB) and isoniazid (INH) resistance pose additional challenges to effective treatment. We aimed to describe treatment outcomes of INH mono-resistant TB patients under programmatic conditions in Mumbai, India.

METHODS

This retrospective cohort study was conducted at Shatabdi Hospital in Mumbai between 2019-2021.We described the clinical and demographic characteristics, treatment outcomes, and risk factors for unfavourable outcomes among patients with INH mono-resistant TB treated with rifampicin, ethambutol, pyrazinamide, and levofloxacin (LfxREZ) for a duration of 6 months.

RESULTS

Among 3105 patients with drug-resistant TB initiated on treatment, 217 (7 %) had INH mono-resistant TB. Of these, 54 % (117/217) were female, with a median age of 26 years (interquartile range: 20-40). The majority (88 %; 191/217) presented with pulmonary TB, and most (87 %; 188/217) had favourable treatment outcomes, including treatment completion (52 %; 112/217) and cure (35 %; 76/217). Unfavourable outcomes, including treatment failure (2.3 %; 5/217), loss to follow-up (9.2 %; 20/217), or death (1.8 %; 4/217), were observed in 13 % (29/217) of patients. A total of ten (5 %) patients experienced at least one non-severe adverse drug reaction. Factors associated with unfavourable outcomes included severe thinness (p = 0.019) and male gender (p = 0.012).

CONCLUSION

Treating INH mono-resistant patients with LfxREZ resulted in satisfactory outcomes and low toxicity. It is important to rule out drug resistance to INH while determining the treatment regimen.