First promising TB drug in decades, say researchers

Mycobacterium tuberculosis
Flickr/AJC1
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The first new tuberculosis drug in 40 years has successfully treated multidrug-resistant tuberculosis (MDR-TB) patients in a clinical trial in South Africa.
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Diarylquinoline TMC207 works differently from other anti-tuberculosis drugs by targeting an enzyme of Mycobacterium tuberculosis, the agent that causes TB.
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"This is an exciting new development and the first new TB drug in over forty years," says Alexander Pym, one of the researchers and a chief specialist scientist at the South African Medical Research Council's Clinical and Biomedical TB Research Unit based in Durban, South Africa.
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The researchers gave the drug to 20 patients in addition to standard therapy for MDR-TB for eight weeks.
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Twenty-one patients received a placebo plus standard treatment.
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About half the patients on TMC207 were successfully treated compared to about ten per cent on the placebo. The patients are being monitored to see if treatment remains effective.
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TMC207 was discovered using an old method of drug discovery that has not been used in the last 40 years.
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Modern approaches use computer software to identify drug targets and then design the desired drug, while this approach tests compounds on a rapidly growing relative of M. tuberculosis.
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"What we saw over the eight weeks was a significant difference in the rate in which tuberculosis disappeared," Andreas Diacon, one of the researchers, and the director of the Centre of Clinical Tuberculosis Research at the University of Stellenbosch, told SciDev.Net.
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The drug works on both drug-susceptible and drug-resistant TB in the laboratory and the implications are that this new drug might shorten treatment time for all tuberculosis patients, says Diacon.
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MDR-TB patients take five drugs for up to 18 months and patients with standard tuberculosis take four drugs for six months.
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Diacon adds that because this is a new drug with a new way of working patients will not have developed a resistance — potentially increasing the proportion of people who could be cured.
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A second group of MDR-TB patients is now undergoing a longer, six-month trial of TCM207 in South Africa.
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The research was published in the New England Journal of Medicine this month (4 June).
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Sharon Davis
CAPE TOWN
SciDev
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full abstract

http://content.nejm.org/cgi/content/full/360/23/2397

Promising microbicide can be produced by plants

Fields of genetically modified tobacco could produce large quantities of microbicide
Flickr/perrykm5
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Scientists have developed an anti-HIV microbicide that can be mass-produced in plants — in quantities large enough to make it affordable for people in developing countries, they say.
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The microbicide, which has been found to prevent HIV transmission in cells, is a combination of two promising microbicide compounds — monoclonal antibody b12 and the protein cyanovirin-N.
Together the compounds are "more potent at neutralising HIV than its single components", Amy Sexton, lead author of the study and a researcher at the University of Melbourne, Australia, told SciDev.Net.
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The researchers also showed that the microbicide can be mass-produced by transferring the gene constructed for the microbicide into tobacco plant cells.
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"This way the plant expresses the gene and produces the microbicide in the same way it produces its own proteins," says Sexton.
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Scaling-up production simply requires growing acres of the plants from genetically modified seeds, she adds.
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Microbicide gels and creams are a great hope for female-initiated protection from HIV/AIDS but so far trials have had mixed results
(see Drugs may be the next frontier for HIV prevention and
Anti-HIV gel fails to prevent infection).
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In February this year, research suggested that the anti-HIV gel PRO 2000 might protect against infection
(see Microbicide hope at last, say researchers)
but the results were not completely certain.
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The results of a larger PRO 2000 study are due in December 2009.
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"The success of microbicides depends not only on the identification of a broad-acting effective product, but also on the issue of cheap and easy production at a huge scale for global availability.
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We have demonstrated the potential for overcoming both of these hurdles," says Sexton.
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But Morad Ahmed Morad, a professor of medicine at Tanta University, Egypt, is more cautious, saying that potential health issues such as allergic reaction to a plant-produced microbicidal cream and environmental concerns about the spread of the inserted gene to other plants need to be considered.
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He adds that developing countries may not be able to produce such a microbicide themselves because its production will be controlled by patents.
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The research was published online in The FASEB Journal.

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Link to abstract in The FASEB Journal

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Wagdy Sawahel
SciDev