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Trial Testing 3-Drug Combo for Drug Resistant TB

Tuberculosis bacteria

Tuberculosis bacteria (

14 May 2015. A new clinical trial is underway in South Africa testing a regimen of three drugs to treat extensively drug-resistant tuberculosis, a form of the disease that does not respond to normal or even back-up treatments. The trial is sponsored by Global Alliance for TB Drug Development, or TB Alliance, an international consortium of government agencies and foundations.

Extensively drug-resistant tuberculosis is a strain of TB that is airborne and infectious, and develops a resistance to both the normal medications to treat the disease, as well as second-line drugs that are more expensive and come with serious side effects. When faced with extensively drug-resistant TB, patients and physicians face long treatment times trying out drugs that may be more toxic or those not designed to treat TB, often resulting in more serious side-effects and limited chances for success, as well as high rates of death.

While cases of extensively drug-resistant TB are considered rare, TB Alliance says cases have been reported in 100 countries. Centers for Disease Control and Prevention considers extensively drug-resistant TB a risk in the U.S., although a low risk, especially for people with HIV or others with compromised immune systems.

The trial is testing three drugs believed to work differently than earlier medications:

  • Bedaquiline, marketed as Sirturo by Janssen Pharmaceuticals
  • Pretomanid, a generic anti-bacterial compound
  • Linezolid, another antibacterial compound, marketed as Zyvox by Pfizer, but also in generic form

Janssen, a division of Johnson & Johnson,  granted a royalty-free license to TB Alliance in 2009 for bedaquiline, which received regulatory approval in some regions as a treatment for TB. Pretomanid is being tested in clinical trials, while linezolid is being used off-label to treat some cases of TB, according to TB Alliance.

The late-stage clinical trial is recruiting 200 patients, age 14 or older, at 3 sites in South Africa with extensively drug-resistant TB or multi-drug resistant TB that does not respond to treatment. The trial is looking primarily at the ability of the drug combination to prevent TB bacteria from reappearing in cultures taken up to 24 months following the treatments. The study is also tracking serious adverse effects of the drugs and activity of the drugs in the body.

TB Alliance is funded by contributions from health, foreign affairs, and assistance agencies in the U.S., Australia, Ireland, U.K., and European Commission, as well as the Bill and Melinda Gates Foundation, UNITAID, and Global Health Innovative Technology Fund. The organization says the new trial is funded by its current donors, but is still seeking contributions to expand the study to more sites.

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