One dose of an antibody drug safely protected healthy, non-pregnant adults from malaria infection during an intense six-month malaria season in Mali, Africa.
The antibody was up to 88.2% effective at preventing infection over a 24-week period, demonstrating for the first time that a monoclonal antibody can prevent malaria infection in an endemic region.
The findings were published in The New England Journal of Medicine and presented at the American Society of Tropical Medicine & Hygiene 2022 Annual Meeting in Seattle.
“We need to expand the arsenal of available interventions to prevent malaria infection and accelerate efforts to eliminate the disease,” said Anthony S Fauci, Director of the National Institute of Allergy and Infectious Diseases (NIAID), part of NIH.
“These study results suggest that a monoclonal antibody could potentially complement other measures to protect travellers and vulnerable groups such as infants, children, and pregnant women from seasonal malaria and help eliminate malaria from defined geographical areas.”
Urgent need for new interventions
An estimated 241 million cases of malaria occurred worldwide in 2020, according to the World Health Organization, resulting in an estimated 627,000 deaths, mostly in children in sub-Saharan Africa.
There is an urgent need for new, fast-acting, infrequently dosed interventions that safely provide strong protection against malaria infection.
The Phase II NIAID-USTTB trial evaluated a one-time, intravenous infusion of a monoclonal antibody called CIS43LS.
“These first field results demonstrating that a monoclonal antibody safely provides high-level protection against intense malaria transmission in healthy adults pave the way for further studies to determine if such an intervention can prevent malaria infection in infants, children, and pregnant women,” said Dr Richard Seder, lead researcher and Chief of the NIAID Vaccine Research Center Cellular Immunology Section. “We hope monoclonal antibodies will transform malaria prevention in endemic regions.”
Trials in more potent antibody
The researchers have developed a second antimalarial monoclonal antibody, L9LS, that is much more potent than CIS43LS and can be administered in a smaller dose as an injection.
An early-phase NIAID trial of L9LS in the United States found that the antibody was safe and prevented malaria infection for 21 days in 15 out of 17 healthy adults. Two Phase II trials assessing L9LS in infants, children and adults are underway in Mali and Kenya.