Home News & Events Experimental malaria prevention proves effective; The latest health stories from around the...

Experimental malaria prevention proves effective; The latest health stories from around the world

A single dose of an experimental antibody drug protects children from malaria for up to 6 months, according to a clinical study published today in The New England Journal of Medicine. www.science.org/content/article/injectable-antibody-drug-protects-children-malaria-mali-trial?

The therapy, an injectable monoclonal antibody called L9LS that has already shown success in adults, reduced infections and clinical disease in 6- to 10-year-olds in Mali. Although the drug is still undergoing clinical testing, the results suggest monoclonal antibodies could be an important addition to the arsenal against this deadly disease, researchers say.

Malaria caused an estimated 608,000 deaths in 2022, about three-quarters of them among African children under 5 years old. There are various strategies to try to stall the mosquito-borne disease, including insecticide-treated bed nets, vaccination—which got its first large-scale rollout in Cameroon this year and is now part of childhood immunization programs in eight African countries—and preventative treatment with antimalarial drugs. However, no approach is 100% effective and all carry practical limitations. Some antimalarials, for example, have to be taken for several days each month to be protective.

Monoclonal antibodies, which can stop pathogens invading cells by binding to proteins on their surface, offer another approach, says Peter Crompton, a malaria researcher with the U.S. National Institute of Allergy and Infectious Diseases. In 2022, he and his colleagues reported that one dose of a lab-produced antibody called CIS43LS protected adults from infection throughout Mali’s high malaria season, which runs from July through December. That drug was cumbersome to deliver, having to be infused directly into a person’s bloodstream over about half an hour. So the team developed L9LS, a different, injectable antibody that also protected adults from infection in a small clinical trial.

In the new study, Crompton and colleagues first tested the antibody’s safety on a small group of children and adults. Then, they gave more than 200 children in the Koulikoro region of southwest Mali a high L9LS dose, a low L9LS dose, or a placebo. Over the next 24 weeks, participants were monitored with regular finger-prick tests to look for infection with the malaria parasite Plasmodium falciparum, and given general health check-ups to detect the disease and treat it, if needed.

Infection rates were high across all groups. However, whereas 81% of children who received placebo got the parasite during those 24 weeks, only 48% of the low-dose and 40% of the high-dose children became infected. Smaller numbers in each group developed the actual disease. Using a statistical analysis that compares the time between antibody injection and malaria infection across groups, the team calculated that the high dose of L9LS was 70% efficacious at preventing infection and 77% efficacious at stopping disease. The low dose was a little more than 65% efficacious in both cases.

“We’re really happy with these results, both in terms of efficacy and in terms of safety,” says study co-author Kassoum Kayentao of the University of Sciences, Techniques and Technologies of Bamako. The findings suggest a single dose of monoclonal antibody could replace monthly antimalarial medication programs in places like Mali, he adds.Top of Form

The researchers could also examine L9LS’s effects in areas where malaria rates aren’t quite so high, or in countries such as Gambia where the disease is on the path to being eliminated, says Umberto D’Alessandro, a clinical epidemiologist at the London School of Hygiene & Tropical Medicine and director of the Medical Research Council Unit, The Gambia.

He and others emphasize that L9LS must clear multiple hurdles before it can be widely used. In addition to conducting more safety and efficacy studies, the team will have to establish the correct dosing regimen, says Mwayiwawo Madanitsa, a clinical epidemiologist at the Malawi University of Science and Technology. They’ll also need to assess the feasibility and cost-effectiveness of rolling the drug out on a large scale.

Although the exact cost isn’t yet clear, Crompton says L9LS manufacture could end up at about $50 per gram, giving a single low dose a price tag of about $8. That’s competitive with the cost of treating a child with monthly antimalarial drugs, which comes to about $5 per year, he says, adding that more potent antibodies developed in the future could help make the approach more economically viable.

For now, the researchers are testing L9LS in two further studies: one in Kenya focusing on children between 5 months and 5 years old, and another in Mali among women of childbearing age, in preparation for trials among pregnant people.

Crompton says the team is also planning a trial in infants as young as 4 weeks. Vaccination is only recommended for children 5 months and older, he notes, so perhaps L9LS could help protect kids during the vulnerable first months of their lives.