CROI plenary highlights TB progress, urges care in use of new drugs

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Science Speaks is in Atlanta, Georgia this week and will be live-blogging from the 20th CROI — Conference on Retroviruses and Opportunistic Infections from Sunday to Wednesday, covering breaking developments from investigators on cure research, new antiretroviral agents, hepatitis, tuberculosis and treatment as prevention.

ATLANTA, GA — Andreas Diacon from Stellenbosch University in Cape Town updated the audience at the 2013 CROI  on Wednesday about the status and challenges in TB drug development.  The good news is that while still inadequate, the TB drug pipeline is larger than it has been in decades.

He reminded his audience that before effective TB drugs, tuberculosis was associated with a 70 percent fatality rate.  In some respects, TB’s toll hasn’t changed much in his part of the world—South Africa, the epicenter of the HIV and TB epidemics.  In Cape Town today, there are 28,000 cases of tuberculosis every year; HIV prevalence in TB patients is 51 percent and the fatality rate in an ever-growing numbers of patients with extensively drug resistant or X-DR TB is 60 percent over 3 years.

With 50 years of neglected TB research and development, an urgent need for a better biomarker for a cure, which could dramatically streamline and expedite drug development, remains.  Right clinical trial patients must remain in studies for a year after completion to confirm results – adding greatly to the cost of research.

The greatest current medical need is for better treatments for drug-resistant tuberculosis, which Diacon noted, has been steadily increasing over the last 10 years.  The hospital where he works began as a care center for drug-susceptible TB, became a clinical center for MDR-TB and now is a place where X-DR patients are treated, he said.  He challenged the widely held view in the TB field that resistance is always about patients not taking the drug, and argued that non-adherence alone does not explain MDR-TB.

He referenced research conducted by Dr. Tawanda Gumbo, et al that used a hollow fiber apparatus to simulate TB dosing and its impact on resistance.  Dosing regimens that simulated various dosing patterns of less-than –perfect adherence did not produce resistant strains.  There is a great deal of variability in the way and at what levels the drugs are absorbed by TB patients, based on many factors including the number of TB-induced cavities in their bodies.  “With normal dosing and 100 percent compliance we will have patients that do not get enough drug in their blood, “said Diacon.

He urged caution in the use of the new drugs that will soon come on line to preserve their punch against the centuries-old infectious disease killer—still second only to HIV – in its death toll.


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