New treatment regimen may help patients with extensively drug-resistant TB

05 Mar 2020

A new combination of drugs could help patients with tuberculosis (TB) that is resistant to most existing anti-TB medicines. This is according to the results of the Nix-TB trial, which were published today in the New England Journal of Medicine.

Drug resistant TB is a major public health problem, according to the World Health Organisation. Around 600,000 people developed multidrug-resistant (MDR) TB in 2016, and 8,000 cases were reported of extensively drug-resistant (XDR) TB, which is resistant to at least four of the core anti-TB drugs. These types of TB are hard to treat, as there are few drugs available, and outcomes are often poor. Treatment can take 18 months or longer, and may include up to eight different drugs.

Nix-TB assessed the safety and efficacy of a new six month, all oral treatment regimen for participants with pulmonary infection of either XDR-TB, pre-XDR-TB or treatment intolerant or non-responsive MDR-TB. The new regimen was made up of three drugs: linezolid plus bedaquiline and pretomanid.

Nix-TB showed that nine out of ten of people taking part in the trial had a favourable outcome. This means they did not suffer treatment failure or relapse within six months of the end of treatment. This is similar to outcomes seen in modern standard of care treatment trials for drug-sensitive tuberculosis. All participants experienced at least one side-effect during the study.

Nix-TB was a single-arm study, so all participants received the new treatment regimen. 109 patients from three sites in South Africa took part.

These findings show that, with the right combination of effective medicines, treatment for highly drug-resistant forms of TB can potentially be shortened to the same amount of time as it takes to treat drug-sensitive TB and achieve similarly high success rates.

We need to build on this achievement and continue to advance complete regimens of newer and better drugs to end the TB pandemic. The ZeNix trial is now testing different doses and durations of the Nix-TB drug regimen in a randomised phase 3 trial in South Africa, Georgia, Moldova and Romania.

Nix-TB was led by TB Alliance, a non-profit TB drug development organization dedicated to improving TB treatment. The MRC CTU at UCL led the statistical work within the trial. The study was funded by the Global Alliance for TB Drug Development.

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