Antibody Prevents Malaria in New Trial

A new monoclonal antibody discovered and developed at the National Institutes of Health safely prevented malaria for up to 9 months in people who were exposed to the malaria parasite.

The small clinical trial is the first to show an antibody capable of preventing malaria in people. The trial was sponsored and conducted by scientists from the Vaccine Research Center (VRC) of the National Institute of Allergy and Infectious Diseases and was funded by NIAID.

“Malaria continues to be a major cause of illness and death in many regions of the world, especially in infants and young children; therefore, new tools are needed to prevent this deadly disease,” said NIAID Director Anthony Fauci, MD. “The results reported today suggest that a single infusion of a monoclonal antibody can protect people from malaria for at least 9 months. Additional research is needed, however, to confirm and extend this finding.”

The study was published Thursday in The New England Journal of Medicine.

A total of 25 participants received at least one dose of an antibody named CIS43LS, and four of them received a second dose.

Among adults who had never had malaria infection or vaccination, CIS43LS prevented malaria.

In the study, 15 participants were bitten by mosquitoes carrying the parasite. Medical staff watched them closely for several weeks. Nine of the participants received the antibody, and none developed malaria. The other six participants each received a placebo, and five did develop the disease.

A larger phase II clinical trial is underway in Mali to test CIS43LS in adults during a 6-month malaria season.

Malaria is caused by plasmodium parasites, which are transmitted to people through the bite of an infected mosquito. The mosquito injects the parasites into the skin and bloodstream. These travel to the liver, where they mature and multiply. The mature parasite spreads throughout the body via the bloodstream to cause illness. 

An estimated 229 million cases of malaria occurred worldwide in 2019, resulting in an estimated 409,000 deaths, mostly in children in sub-Saharan Africa. So far, no licensed or experimental malaria vaccine that has completed phase III testing provides more than 50% protection from the disease for a year or longer.

VRC scientists are doing more research on CIS43LS in the United States to determine the lowest dose that protects people from malaria infection.

“Monoclonal antibodies may represent a new approach for preventing malaria in travelers, military personnel, and health care workers traveling to malaria-endemic regions,” said Robert Seder, MD, chief of the Cellular Immunology Section of the VRC Immunology Laboratory. “Further research will determine whether monoclonal antibodies can also be used for the seasonal control of malaria in Africa and ultimately for malaria elimination campaigns.”

SOURCES:

National Institutes of Health: “Monoclonal antibody prevents malaria in small NIH trial.”

The New England Journal of Medicine: “A Monoclonal Antibody for Malaria Prevention.”

World Health Organization: “Malaria.”

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