New drug being tested in Africa for river blindness

The World Health Organization reports that a clinical trial is being launched in three African countries of a drug that could eliminate onchocerciasis, or river blindness, one of the leading infectious causes of blindness across Africa. The drug, moxidectin, is being investigated for its potential to kill or sterilize the adult worms of Onchocerca volvulus, which cause onchocerciasis.

Currently, the disease is controlled by ivermectin, which has been donated for more than 20 years by the pharmaceutical company Merck & Co. for use in onchocerciasis endemic countries. Treatment with ivermectin has enabled significant progress in the control of onchocerciasis, and currently reaches more than 60 million people in Africa annually. However, ivermectin kills the O. volvulus larvae but not the adult worms, so annual treatments for an extended period of time (at least 11-14 years) are required to ensure disease control.

If moxidectin kills not only the larvae but also sterilizes or kills the adult worms, it has the potential to interrupt the disease transmission cycle within around 6 annual rounds of treatment. The drug could be distributed through the community-directed mechanisms set up in collaboration among APOC, African control programmes, and NGOs for the distribution of ivermectin.

“This is a devastating illness that has plagued 30 African countries for centuries, in particular the populations in the most remote areas ‘beyond the end of the road’,” says Dr Uche Amazigo, Director of the African Programme for Onchocerciasis Control (APOC). “Over 100 million people are at risk of infection with onchocerciasis in Africa and a few small areas in the Americas and Yemen.”

The development of moxidectin for onchocerciasis is being conducted through a collaboration of the Special Programme for Research and Training in Tropical Diseases (TDR), which is administered by WHO, with Wyeth Pharmaceuticals. The work ranges from the development of a formulation for human use and initial studies in healthy volunteers, to clinical studies and community studies in Africa.

TDR is building the capacity and managing the clinical trials in Africa. If the development is successful and results in a positive scientific opinion from the European Medicines Evaluation Agency, Wyeth with the assistance of WHO will request approval by regulatory authorities in the countries where onchocerciasis is endemic.

The trial will take place over the next two and a half years.