New clinical trial for extensively drug resistant TB (XDR-TB)

Simon Collins, HIV i-Base

On 14 May 2015, the TB Alliance announced the launch of a new clinical trial to test a new all-oral regimen for extensively drug-resistant TB in South Africa. [1]

The Nix-TB study is important for the development of a universal treatment for all types of TB. The study also has the potential to shorten, simplify, and improve treatment for XDR-TB.

XDR-TB is defined as being resistant to four commonly used anti-TB drugs. XDR-TB has been reported in 100 countries. Treatment is complicated, taking two years or longer, is associated with high rates of side effects and low rates of success. There are currently no regulatory-approved drugs to treat XDR-TB. In a recent review, only 16% of people with XDR-TB were cured after two years of treatment in South Africa. [2]

The three drugs being tested in Nix-TB are:

  • Bedaquiline (B), which received conditional regulatory approval in several high-TB disease burden countries.
  • Pretomanid (Pa), a new antibacterial drug compound, currently in clinical trials.
  • Linezolid, an oxazolidinone, which has been used off-label to treat TB.

The TB Alliance is sponsoring the trial, collaborating with and Janssen, the manufacturer of bedaqualine. In 2009 Janssen granted a royalty-free license to the TB Alliance for the development and marketing of bedaquiline in the field of drug-susceptible TB.

The cost for the initial phase of Nix-TB is covered by a group of long standing TB Alliance donors. TB Alliance is starting to bring together additional funding to expand the study and the number of sites.


  1. TB Alliance press release. TB Alliance launches “Nix-TB” clinical trial to test new XDR-TB treatment. (14 May 2015).
  2. Pietersen E et al. Long-term outcomes of patients with extensively drug-resistant tuberculosis in South Africa: a cohort study. The Lancet, Volume 383, No. 9924, p1230–1239, 5 April 2014.

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