A new clinical trial conducted by the World Health Organization and industry is being launched in three African countries.
Moxidectin is being investigated for its potential to kill or sterilize the adult worms of Onchocerca volvulus, which cause
onchocerciasis, or river blindness, a leading cause of blindness in Africa.
A child leading an adult blinded by onchocerciasis is located outside the WHO's headquarters in Geneva, Switzerland (Provided
by WHO/Pierre Virot).
The blackfly that transmits the disease breeds in fast flowing rivers. 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 by the WHO's Special Programme for Research and Training
in Tropical Diseases and Wyeth. They are seeking to develop a formulation for human use, and if the outcome is a positive
scientific opinion from the European Medicines Evaluation Agency, Wyeth will request approval by national regulatory authorities
in the countries where onchocerciasis is endemic.
"The moxidectin data have been promising so far, and as the program moves into larger Phase III studies, we are hopeful that
moxidectin will constitute a significant advance against this devastating disease," said Dr. Henrietta Ukwu, MD, vice president
Scope and goal
About 1500 people will be enrolled at four sites in Ghana, Liberia, and the Democratic Republic of Congo (DRC). Preparation
has been ongoing since 2007, and included building a clinical research center in Lofa County, Liberia, and in Nord-Kivu, DRC.
The trial will take 2.5 years.
Currently, onchocerciasis is controlled by ivermectin, which has been donated for more than 20 years by Merck and reaches
more than 60 million people in Africa annually. Ivermectin kills the O. volvulus larvae but not the adult worms, so annual
treatments for up to 14 years are required to ensure disease control. If moxidectin kills both the larvae and adult worms,
it may be able to interrupt the disease transmission cycle within around six annual rounds of treatment.
The investigator meeting was organized by Wyeth, and principal investigators, other physicians, ophthalmologists, study coordinators,
and clinical monitors. Remote training in database use was given by the company, which is providing satellite-based Internet
access to staff.
"It is very much welcomed that more and more pharmaceutical companies are not only donating medicinal products to Africa but
also are supporting those countries to develop their own research, especially in tropical diseases," said Dr. Jenny Mueller,
PhD, clinical trials support manager at MRC Laboratories, Banjul, The Gambia. "Clinical trials conducted in the countries
where the products will be used have the advantage that the efficacy and safety profile is tested in the ethnic groups that
will use them and under the conditions and in the environment they will be handled in later."
Mueller also finds it encouraging that national regulatory authorities are increasing their involvement in clinical research.
Training and education in clinical research by experienced partners helps build capacity and infrastructure, and leads to
more collaboration with African investigators and institutions, she noted.
The main challenges are the lack of functioning health systems, including precise diagnoses, as well as arranging site visits
by participants in remote villages. The trial organizers must also focus on appropriate informed consent procedures and safety
oversight, including the awareness and reporting of signs and symptoms by participants, said Mueller.—Philip Ward