A new study has found an antibody that prevents malaria
A new research study has provided an effective way to prevent adults from malaria infections.
The clinical trial was done by the National Institutes of Health (NIH), a medical research center in the United States. For the study, healthy, non-pregnant adults in Mali, Africa were given a dose of an antibody drug during a six-month malaria season. The antibody was up to 88% effective at preventing infection over a 24-week period. The treatment demonstrated for the first time ever that a monoclonal antibody could prevent malaria infection within an endemic region, meaning that antibodies from white blood cells could be used to effectively prevent infection in a region that is known to have widespread malaria infection.
The study was published on Oct. 31 in The New England Journal of Medicine.
The effects of malaria and the importance of finding treatment
Malaria is a mosquito-borne disease that infected nearly 241 million people globally in 2020, according to the World Health Organization (WHO). It is caused Plasmodium parasites, which are transmitted when a mosquito injects the parasites in a form called sporozoites, specifically Plasmodium Falciparum parasites (P. falciparum) into the skin and bloodstream of humans. Once there, it travels to the liver, where it multiplies and spreads.
The infection resulted in an estimated 627,000 deaths, mostly in children in sub-Saharan Africa. These cases also included more than 11 million pregnant women in Africa, resulting in an estimated 819,000 newborns with low birthweight, significantly increasing their risk illness and death.
Treatments available and novel medicine
Researchers have been looking for new ways to treat and eradicate malaria. “We need to expand the arsenal of available interventions to prevent malaria infection and accelerate efforts to eliminate the disease,” said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), part of NIH. Currently, the only malaria vaccine recommended by the World Health Organization (WHO) is called Mosquirix (RTS,S). The vaccine provides partial protection against malaria only in children aged 5 to 17 months, given in four doses over a 20-month period.
Another current treatment option is a drug made with chemical compounds that prevents the disease, and is available for children and travelers. However, this drug requires frequent dosages, and the body might build resistance to the treatment.
For years, scientists have been working on developing a new treatment that uses a monoclonal antibody — a laboratory-made antibody — to defuse and destroy the disease-causing insect before it can infect the body.
The clinical trial
NIAID funded the trial, which was led by Dr. Peter D. Crompton, the chief of the Malaria Infection Biology and Immunity Section in the NIAID Laboratory of Immunogenetics, and Dr. Kassoum Kayentao, professor at the University of Sciences, Techniques and Technologies (USTTB) of Bamako, Mali. It is known as the NIAID-USTTB trial and is currently in phase 2 of the trial. The research testing assessed the safety and efficacy, or effectiveness of treatment, of a one-time, intravenous infusion of a monoclonal antibody called CIS43LS. This antibody was once known to defuse the sporozoites from P. falciparum before the parasites could spread and infect the liver.
For the study, Dr. Robert A. Seder, acting chief medical officer and acting associate director of the NIAID Vaccine Research Center (VRC) and chief of the VRC’s Cellular Immunology Section, isolated a naturally occurring form of this antibody from the blood of a volunteer who received a malaria vaccine in the trial. Then, the antibody was modified to expand the length of time it would stay in the bloodstream.
For Phase 2 of the clinical trial, there were 369 participants, all who were healthy adults between the ages of 18 to 55 years old. They lived in Kalifabougou and Torodo, both located in Mali, where there’s usually an extremely high transmission of P. falciparum annually from July through December.
The first part of the study examined the safety of the three different doses of the monoclonal antibody. The doses were 5 milligrams per kilogram of body weight (mg/kg), 10 mg/kg and 40 mg/kg. Each dose was given intravenously.
The second part of the trial reviewed the efficacy of the doses, compared to a placebo. 330 participants received either 10 mg/kg of the antibody, 40 mg/kg, or a placebo by intravenous infusion. Only at the end of the trial, did anyone know who received the dosages or the placebo. Researchers followed the participants for 24 weeks, testing their blood for P. falciparum weekly for the first 28 days, then every two weeks.
The efficacy was tested two ways. Over the 24-week study, participants who received the highest dose (40 mg/kg) of the antibody showed that it was 88.2% effective at preventing infection. The lower dose (10mg/kg) was 75% effective. Overall, participants infected with P. falciparum at any time during the 24 weeks had an outcome that showed the antibody was 76.7% successful at preventing infection for the highest dose and 54.2% successful for the lowest dose.
A second antibody that fights malaria
Dr. Seder and his team developed a second monoclonal antibody to fight malaria called the L9LS. It is said to be more potent than the CIS43LS in this study, according to the researchers, and can be given in much smaller doses due to its potency. It can also be given subcutaneously (under the skin) rather than intravenously with an infusion, as in the current study. An early, albeit smaller, NIAID trial study has already found that the treatment is effective, safe, and prevented malaria for 21 days in 15 out of 17 healthy adults exposed to the P. falciparum parasites.