Oral drug for sleeping sickness passes early tests

The first oral drug candidate designed specifically for easy treatment of sleeping sickness was shown to be safe and effective in pre-clinical trials, a conference heard this week.

Sleeping sickness, or human African trypanosomiasis, is caused by the parasite Trypanosoma brucei, transmitted by tsetse flies, and is fatal without effective treatment. The disease infects around 30,000 people a year but is a threat to millions in Sub-Saharan Africa.

Most existing treatments were developed decades ago, are expensive and are either toxic or difficult to administer. Few are effective in the late stages of the disease, when the parasite infects the brain, and parasites are already developing resistance to a newer combination therapy introduced in 2009.

Now, Anacor Pharmaceuticals has teamed up with drug-discovery company Scynexis to screen its library of boron-based compounds, known to be effective against a range of pathogens, for activity against sleeping sickness parasites.

The Drugs for Neglected Diseases Initiative (DNDi), a non-profit organisation based in Switzerland, has supported the research with US$14.8 million, secured mainly from the Bill & Melinda Gates Foundation.

One compound, SCYX-7158, successfully treated both early and late stages of the disease in mice, and could be delivered as an oral, rather than intravenous, liquid. If human trials, expected to start later this year are also successful, the drug could provide a safer, shorter and easier-to-administer treatment for both stages of the disease within the next five years, according to the DNDi.

The results were unveiled at the BIO International Convention, a global conference for biotechnology industry, in Washington DC, United States, this week (27–30 June) and published in PLoS Neglected Tropical Diseases on Tuesday (28 June).

Drug development for neglected diseases is hampered by a lack of financial incentives for pharmaceutical companies. DNDi was formed in 1999 to address the issue by collaborating with industry, academia and non-governmental organisation to speed up research and development for such drugs.

"Developing a new oral drug for sleeping sickness is an important demonstration that we can bring the best science to the most neglected diseases and patients," said Bernard Pécoul, executive director of DNDi.

Chris Schofield, who studies infectious diseases at the London School of Hygiene & Tropical Medicine and is a member of the African Union’s Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC), told SciDev.Net: "Obviously this is still at an early stage, but it sounds very promising, and DNDi is doing sterling work getting companies on board to fight neglected tropical diseases."

But this is only the start of the process, Schofield warned. "The real problem is getting the drugs to the people who need them, which is a big challenge in remote areas, plus getting rid of the flies, something the African Union, through PATTEC, has begun to appreciate and is already committing funds to."

Link to full article in PLoS Neglected Tropical Diseases