NEW early clinical trial results have indicated that an injection of a candidate monoclonal antibody known as L9LS is both safe and highly protective against the malaria parasite. “These early clinical trial results demonstrating that a monoclonal antibody administered subcutaneously can protect people from malaria are highly encouraging,” stated Anthony D. Fauci, Director of the National Institute of Allergy and Infectious Diseases (NIAID), North Bethseda, Maryland, USA.
Malaria is a mosquito-borne disease caused by Plasmodium parasites. Malaria disproportionately impacts sub-Saharan Africa, where 80% of all malaria deaths are in children under the age of 5 years. Current vaccines have variable efficacy, leaving a need for high efficacy prophylaxis offering high levels of protection.
L9LS is a synthetic version of the naturally occurring antibody L9. The L9 antibody was derived from the blood of a volunteer who had received an investigational malaria vaccine. The antibody works by neutralising the parasite in the skin and blood before it can reach and infect the liver cells. L9LS has a high potency, allowing it to be delivered through subcutaneous injections.
The safety and efficacy of L9LS was assessed in Phase 1 clinical trials, with 18 participants receiving varied doses subcutaneously or intravenously. Following treatment, participants were exposed to malaria-carrying mosquitoes in a carefully controlled setting. Close analysis over 6 weeks revealed that L9LS fully protected 88% of the participants, with four of the five participants who only received low, subcutaneous doses still protected from malaria.
This trial represents the first demonstration that subcutaneous treatment with a monoclonal antibody can provide protection against malaria, a huge step forward for researchers in their goal of eliminating malaria. Additional clinical trials are now underway assessing how L9LS can prevent malaria over 6–12 months in countries where the diseases is endemic, such as Mali and Kenya.