Positive results for US Malaria vaccine, trial shows 

A monoclonal antibody (mAb) treatment for the prevention of Malaria has shown encouraging results in a US Phase I clinical trial.  

The mAb, known as L9LS, was developed by scientists at the National Institutes of Health’s (NIH) Vaccine Research Centre (VRC). L9LS is a laboratory-made version of a naturally occurring antibody called L9, developed from the blood of a volunteer who had received an investigational malaria vaccine. L9LS works by neutralising the Plasmodium parasites deposited by mosquitos before they can infect liver cells.  

In the Phase I clinical trial1, one injection of L9LS was found to be safe and highly protective in US adults exposed to the malaria parasite. The trial involved 18 volunteers who received various doses of L9LS subcutaneously or intravenously. 

Some two to six weeks after receiving a dose, and having reported no safety concerns, participants were bitten five times by mosquitoes carrying the malaria parasite. Volunteers were monitored for any adverse effects in a carefully controlled setting known as controlled human malaria infection (CHMI).  

L9LS fully protected 15 of 17 (88%) participants from malaria infection during the 21-day challenge period. More so, four of the five participants who received a low, subcutaneous dose of the mAb were protected from malaria. 

The trial was conducted at the NIH Clinical Center in Bethesda, Maryland, and the Walter Reed Army Institute of Research (WRAIR) in Silver Spring, Maryland. 

Additional clinical trials evaluating if L9LS can prevent malaria over six to 12 months against seasonal and perennial transmission are underway in infants and children in Mali and Kenya, where malaria is endemic.  

Official comments  

“These early clinical trial results demonstrating that a monoclonal antibody administered subcutaneously can protect people from malaria are highly encouraging,” said NIAID Director Anthony S. Fauci, M.D. “A one-time intervention that protects against malaria for six months to a year could significantly reduce morbidity and mortality among children in malaria-endemic regions and offer an effective preventive tool for health care workers, military personnel and travellers to these areas.”   

“This is the first demonstration that a monoclonal antibody can provide protection when given by the subcutaneous route, with important implications for widespread clinical use and reaching the goal of eliminating malaria,” said Robert Seder, M.D., Chief of the Cellular Immunology Section in the VRC, who led the development of L9LS. “We look forward to results in larger field studies that will help establish an effective dose.”  


1: https://clinicaltrials.gov/ct2/show/NCT05019729  


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