Experimental Monoclonal Antibody May Prevent Malaria Infection

One injectable dose of an experimental monoclonal antibody was 77% effective in preventing Plasmodium falciparum malaria infection in Malian children during the country’s six-month rainy season, according to recent findings published in the New England Journal of Medicine. The trial, conducted by researchers from the National Institute of Allergy and Infectious Diseases (NIAID) in partnership with Malian investigators, builds upon a previous phase 1 trial, which found that the experimental monoclonal antibody (L9LS) protected adults against controlled P. falciparum infection.

After completing a safety assessment (consisting of three dose levels in adults and two dose levels in children), investigators randomized 225 children aged 6-10 years to receive either 150 mg of L9LS, 300 mg of L9LS or placebo. The primary endpoint was the first P. falciparum infection, as detected on a blood smear (performed at least every 2 weeks for 24 weeks). A secondary efficacy endpoint was the first episode of clinical malaria.

P. falciparum infection occurred in 36 participants (48%) in the 150-mg group, in 30 (40%) in the 300-mg group and in 61 (81%) in the placebo group. In the placebo group, 59% had clinical malaria. With regards to safety, local and systemic adverse events within 7 days after administration or placebo were uncommon, were mild to moderate in severity, were similar in frequency across the trial groups and resolved without intervention.

According to the authors, the trial demonstrated – for the first time – that a single dose of a monoclonal antibody given by subcutaneous injection can provide high-level protection against malaria in children in an area of intense malaria transmission. Additionally, they noted that results support the development of antimalarial monoclonal antibodies in other high-risk populations, including infants and young children, children with severe anemia after hospital discharge and pregnant people. Additional research among these patient populations is underway.