Developing the First Novel Drug Regimen from TB Alliance...

TB Alliance’s push to test new drugs in combination has been done to produce a regimen that not only would be faster and easier for patients, but also would tackle two other challenges as a major step in stopping the spread of drug-resistant TB—the complexity and high cost of treatment. This promising regimen eliminates the use of injectables and projects to reduce the cost of MDR-TB therapy by as much as 90 percent.

The study, NC-001, or New Combination 1, was a two-week trial successfully completed at two centers in South Africa. It involved the new combination therapy called PaMZ, consisting of the novel TB drug candidate, PA-824 (see below structure left); moxifloxacin (right structure), an established antibiotic not yet approved for use in first-line TB therapy and being developed in partnership with Bayer Healthcare AG; and pyrazinamide, an existing TB drug.

“Treating drug-sensitive and drug-resistant TB with the same regimen can simplify the delivery of TB treatment worldwide,” said Andreas Diacon, MD, the trial’s principal investigator and lead author of the Lancet study. “The results of this study give healthcare providers on the front lines of the TB epidemic hope for better, faster tools needed to stop this disease.”

 (Pyrazinamide)

Newscenter | Global Alliance for TB Drug Development

PA-824 - Aerosol: New Tool Against Tuberculosis?

We know the epidemic rates of HIV/TB coinfection as well as emerging multidrug-resistant  (MDR) and extensively drug-resistant (XDR) TB strains those are contributing to increased TB-associated deaths worldwide. 

Now PA-824 (see structure), a compound capable of being formulated into a dry powder, has not only shown promising activity against MDR (multidrug-resistant tuberculosis) and XDR (extensively drug-resistant tuberculosis, or latent TB) but has also proven safe and effective in patients coinfected with HIV and TB. Previous studies showed that PA-824 was well-tolerated in tablet form, however, side effects such as headache and stomach discomfort were reported. Aerosol delivery of PA-824 directly to the primary site of infection would limit systemic exposure and ultimately eliminate potentially bothersome side effects.

About  PA-824 :

Nitroimidazoles are widely used drugs in humans for a variety of primarily anaerobic microbial infections. Metronidazole, a 5-nitroimidazole, is an important bactericidal agent for the treatment of anaerobic infections  and shows excellent selective toxicity toward anaerobic bacterial and protozoal pathogens. This class of compounds has only recently begun to be explored for Mtb, because only anaerobic activity of metronidazole against Mtb has been reported. Bicyclic 4-nitroimidazoles such as PA-824 (a nitroimidazo-oxazine) and CGI-17341 (a nitroimidazo-oxazole) have inhibitory activity against aerobically growing and nonreplicating anaerobic Mtb. Although anaerobic conditions have not been demonstrated during TB disease in humans, various authors have suggested that an anaerobic microenvironment may contribute to a nonreplicating state that may be linked with latent disease in humans. Thus, PA-824 has been developed, in part, because it may be a promising lead for therapy against latent disease that may be linked to anaerobically persisting bacilli. The Global Alliance for TB Drug Development has recently initiated phase-I clinical trials with PA-824 

Researchers from the University of North Carolina School of Pharmacy, Chapel Hill, North Carolina; and Harvard School of Engineering and Applied Sciences, Cambridge, Massachusetts, lead by  Dr. Anthony J Hickey  have achieved this interesting finding, i.e., potential use of PA-824 dry powder aerosols in the treatment of TB.

In the study guinea pigs were used to evaluate the effects of PA-824 aerosols on TB infection. One month following infection with TB some guinea pigs received high daily aerosol treatments while others received low daily treatments for 4 weeks. Lung and spleen analysis of guinea pigs receiving the high dose of aerosol PA-284 showed less inflammation, bacterial burden and tissue damage.

"The present studies indicate the potential use of PA-824 dry powder aerosols in the treatment of TB,” say the researchers".

Ref : http://aac.asm.org/cgi/content/abstract/54/4/1436.