Phase II results from a novel anti-tuberculosis drug cocktail—PA-824, moxifloxacin and pyrazinamide—show the elimination of 99% of the Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), found in patients’ saliva following just two weeks of treatment.
The study, funded by the non-profit TB Alliance, provides a stark contrast to the six-month treatment regimen of TB therapies currently on the market. Compliance problems with patients prescribed current TB-related therapy have resulted in the emergence of drug-resistant TB strains, including multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB). A shorter course of therapy is likely to decrease treatment costs while increasing patient compliance.
TB strains resistant to rifampicin and isoniazid are a growing concern, but the new cocktail consists of drugs with different mechanisms of action from both rifampicin and isoniazid, giving it therapeutic leverage against MDR-TB and XDR-TB. The cocktail was effective against both treatment-sensitive and drug-resistant TB in the phase II trial, but more detailed studies in larger patient populations are required to assess its safety and toxicity profile and efficacy against drug-resistant TB.
An ongoing phase IIb trial to study the drug cocktail in a larger population over a two-month treatment regimen is being conducted in South Africa, Brazil and Tanzania. If the trial produces similar results to the phase II trial, developers will likely attempt to fast-track FDA approval via the GAIN Act, which prioritizes antimicrobial therapies for indications with pressing medical need.