THURSDAY, Aug. 4, 2022 (HealthDay News) — A next-generation antimalarial monoclonal antibody, L9LS, administered intravenously or subcutaneously, shows protective efficacy against controlled malaria infection, without evident safety concerns, according to a study published in the Aug. 4 issue of the New England Journal of Medicine.

Richard L. Wu, M.D., from the National Institutes of Health in Bethesda, Maryland, and colleagues conducted a phase 1 clinical trial to examine the safety and pharmacokinetics of L9LS and its protective efficacy in healthy adults. Participants received L9LS intravenously or subcutaneously at doses of 1, 5, or 20 mg/kg body weight. Participants underwent controlled human malaria infection in which they were exposed to mosquitoes carrying Plasmodium falciparum (3D7 strain) within two to six weeks after administration of L9LS.

The researchers did not identify any safety concerns. The estimated half-life of L9LS was 56 days, and it had dose linearity. Overall, 17 L9LS recipients and six control participants underwent controlled infection with malaria. Fifteen of the 17 participants who received a single dose of L9LS were protected after infection with human malaria. None of the participants who received 5 or 20 mg/kg intravenous L9LS developed parasitemia. One of the five participants who received 1 mg/kg L9LS intravenously, one of five who received 5 mg/kg L9LS subcutaneously, and all six controls developed parasitemia through 21 days after controlled human malaria infection. At serum concentration as low as 9.2 µg/mL, protection conferred by L9LS was seen.

“The current trial provides a proof of principle that prevention of malaria can be achieved with a next-generation monoclonal antibody, L9LS,” the authors write.

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