An experimental monoclonal antibody developed at the U.S. National Institutes of Health (NIH) prevented malaria for up to nine months in volunteers exposed to the disease-causing parasite in a small trial, researchers reported on Wednesday in the New England Journal of Medicine.
Malaria is a preventable disease caused by parasites transmitted to people through bites from infected mosquitoes. According to the World Health Organization, malaria caused an estimated 409,000 deaths worldwide in 2019, with 67 percent being children under 5.
The only licensed malaria vaccine, Mosquirix, developed by GlaxoSmithKline, is around 30 percent effective.
NIH’s early-stage study, which enrolled 40 healthy adults, tested whether a monoclonal antibody called CIS43LS could safely provide a high level of protection from malaria following controlled exposure to mosquitoes carrying the disease-causing Plasmodium falciparum parasite.
Fifteen volunteers were exposed to bites from the mosquitoes. None of the nine who received CIS43LS developed malaria, compared with five of the six who did not receive the drug.
Monoclonal antibodies are manufactured copies of disease-fighting proteins called antibodies. They have been approved or authorized for emergency use for inflammatory diseases, cancer, and viral infections such as COVID-19. NIH’s latest study is the first to show monoclonal antibodies can prevent malaria.
The findings indicate that one dose of CIS43LS can prevent malaria for up to nine months, and no safety concerns were identified, the NIH said.
“Monoclonal antibodies may represent a new approach for preventing malaria in travelers, military personnel, and healthcare workers traveling to malaria-endemic regions,” said study coauthor Robert Seder, chief of the Cellular Immunology Section of the NIH’s Vaccine Research Center Immunology Laboratory.
Preventing malaria for several months with a single dose of CIS43LS could also be valuable in regions where malaria cases increase during rainy seasons, the NIH said in January.
Results of a larger, mid-stage trial being conducted to assess CIS43LS during a six-month malaria season in Mali are expected in 2022.
