Trial identifies new all-oral drug regimens for rifampin-resistant TB
Key takeaways:
- Three all-oral 9-month treatments for drug-resistant tuberculosis were found to be noninferior to standard treatment.
- Just two in five people with resistant TB receive treatment for the infection.
Researchers identified three new all-oral drug regimens that include at least one of two new drugs for treatment of rifampin-resistant tuberculosis, according to a study.
The study tested five all-oral 9-month regimens combining two relatively new drugs — bedaquiline and delamanid — with older ones to find shorter, less toxic treatments for resistant TB, Carole D. Mitnick, ScD, professor of global health and social medicine at Harvard Medical School, and colleagues wrote in the study.
TB is the leading cause of death globally from a single infectious agent, according to WHO. In 2023, roughly 10.8 million people had TB globally, leading to 1.25 million deaths, WHO reported, and just two in five people with resistant TB received treatment that year.
According to the CDC, there were 9,633 TB cases in the United States in 2023, although the agency estimates that up to 13 million people in the country may have inactive TB.
To test the new treatments, Mitnick and colleagues conducted a phase 3 randomized, controlled noninferiority trial among 699 participants comparing standard therapy for fluoroquinolone-susceptible, rifampin-resistant TB with five 9-month oral regimens. The regimens included combinations of bedaquiline (B), delamanid (D), linezolid (L), levofloxacin (Lfx) or moxifloxacin (M), clofazimine (C) and pyrazinamide (Z). The primary endpoint of the study was a favorable outcome by week 73 with a noninferiority margin of –12 percentage points, according to the study.
The researchers reported that 80.7% of patients in the standard-therapy group achieved favorable outcomes.
Among the five experimental drug regimens, three were determined to be noninferior to standard treatment: BCLLfxZ, at 9.8 percentage points (95% CI, 0.9-18.7); BLMZ, at 8.3 percentage points (95% CI, –0.8 to 17.4); and BDLLfxZ, at 4.6 percentage points (95% CI, –4.9 to 14.1).
Two others, DCLLfxZ, at –1.9 percentage points (95% CI, –12.1 to 8.4), and DCMZ, at 2.5 percentage points (95% CI, –7.5 to 12.5), were deemed not noninferior by the researchers.
Healio asked Mitnick about the regimens, whether they are in use and what the study’s findings could mean for TB treatment.
Healio: WHO endorsed these three all-oral drug regimens for resistant TB in August 2024. Are they in use?
Mitnick: The endTB results are part of a sea change in treatment of multidrug-resistant TB (MDR-TB). WHO has already recommended the three highly effective endTB regimens in rapid communication and will include them in upcoming full guidance.
The regimens are already being used in many places, for example, in Peru, Haiti, Lesotho and Kazakhstan. We will be working with our endTB trial funding partner — Unitaid — to further facilitate scale-up efforts of the effective endTB regimens, and other all-oral shortened regimens, among the more than 400,000 people who newly develop rifampin-resistant TB each year.
Healio: Have these regimens been looked at in other studies?
Mitnick: I’m not aware of other trials examining these regimens, [although] operational research studies are reporting on the use of these and similar all-oral regimens for rifampin-resistant TB. We are pursuing research to compare the endTB regimens with other recommended regimens, without additional prospective studies.
In addition, the world desperately needs research on treatment of more resistant forms of TB. New drugs being explored primarily in treatment of drug-susceptible TB need to be made available for studies of novel treatments for “extensively resistant” TB and for compassionate use in people who are not eligible for those studies.
Healio: What is the main takeaway for clinicians?
Mitnick: The endTB trial has provided clinicians with a significant advance in their efforts to treat rifampin-resistant TB. endTB brings evidence of incontrovertible efficacy of all-oral regimens containing five or fewer drugs delivered for 9 months, which can be used in all age groups and during pregnancy. It means that treatment can be shorter than the historical standard, regardless of age, [and] two of the highly effective endTB regimens can be purchased for $400 or less, a far cry from the $1 million price tag treat rifampin-resistant TB in the 1990s in New York City.
Big picture, it’s important to note that the endTB trial was possible only because of the foundation of trust cultivated over decades among investigators, collaborating institutions — Partners in Health, Doctors Without Borders, Interactive Research and Development and Harvard Medical School — and the communities from which trial volunteers come. That trust is being destroyed by the abrupt elimination of USAID and the precipitous halt of scores of clinical trials and the care they afford to people who generously volunteer to participate for the greater good.
References:
- Mitnick CD, et al. N Eng J Med. 2025;doi:10/1056/NEJMoa2400327.
- CDC. Tuberculosis (TB): About tuberculosis. https://www.cdc.gov/tb/about/index.html. Updated Jan. 17, 2025. Accessed Feb. 11, 2025.
- WHO. Tuberculosis. https://www.who.int/news-room/fact-sheets/detail/tuberculosis. Published Oct. 29, 2024. Accessed Feb. 11, 2025.
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