Anti-malaria drug shows success in lab tests

Infection protection-Dr. Michael Riscoe and colleagues are developing a new drug to treat malaria. (Photo by Michael Moody)

Infection protection—Dr. Michael Riscoe and colleagues are developing a new drug to treat malaria. (Photo by Michael Moody)

Malaria, spread by mosquitoes, kills more than a million people worldwide each year. Treating the disease is difficult because all its strains now resist quinine and chloroquine, two drugs that used to be standard therapy.

Michael Riscoe, PhD, and colleagues at the Portland VA Medical Center and Oregon Health and Science University have been working to develop a new treatment. Their latest report, in the March 2013 issue of Science Translational Medicine, shows they are getting closer to human clinical trials.

Supported by VA, the National Institutes of Health, and the Swiss nonprofit Medicines for Malaria Venture, Riscoe's team has been developing and testing compounds called quinolone-3-diarylethers, designed to kill the mosquito-borne parasites that cause the disease. The drugs kill the parasite by attacking the mitochondria—the energy hubs—of its cells. Importantly, this happens while the parasite is still in the liver, while its numbers are fewer and before it has started reproducing in the bloodstream.

One drug in particular, ELQ-300, shows promise because it appears to be effective in a single low dose, given orally. While the results so far are based only on tests in mice, the researchers are cautiously optimistic. They write, "ELQ-300 has potential as a new drug for the treatment, prevention, and ultimately, eradication of human malaria."

Said Riscoe in an interview, "We believe ELQ-300 has a chance to change the landscape of how we fight malaria across the world." He noted that any new malaria drug would be given as part of a drug cocktail, to check the emergence of resistant strains of the disease.

Malaria accounts for 40 percent of public health spending in Africa, but it's also a threat to U.S. troops in certain areas, such as Afghanistan. Military personnel are prescribed a daily preventive pill for malaria, but if they fail to take it, the disease can strike. In addition to taking the pill, troops are advised to use insect repellent and cover their skin to help ward off mosquito bites in the first place.

Riscoe, who directs the Experimental Chemotherapy Lab at the Portland VA and is a professor of molecular microbiology and immunology at OHSU, said he expects the drug to be ready for human clinical trials within two years.