An experimental monoclonal antibody, CIS43LS, protects against malaria for up to nine months among a small group of participants in a study funded by the National Institute of Health (NIH). It is a landmark achievement in what monoclonal antibodies can do. The results will facilitate more advances in malaria research that may generate more feasible endeavours to curb the spread of malaria or even eliminate it through more potent vaccines.
Malaria, a parasitic infection caused by plasmodium parasites, causes significant morbidity and mortality. Plasmodium falciparum accounts for about 409,000 deaths annually, most of which occur in sub-Saharan Africa. Public health specialists and policymakers derived prevention and control measures to curb the effects of the disease, which reduced malaria infections by up to three-quarters between 2000 and 2015. These measures included insecticide-treated mosquito nets, antimalarial drugs, and repellents. Despite the advancement in research and malaria controls measures, the incidence of malaria infections has surged, and we don’t have a licensed potent malaria vaccine yet.
For years, studies have shown that antibodies can prevent P. falciparum sporozoites from causing carnage if the antibodies target them within the skin and blood before they attack the liver cells. After identifying a monoclonal antibody, CIS43, from a Sanaria vaccine recipient, scientists analysed the molecule. They noted that it binds to and neutralises a surface protein on the Plasmodium falciparum parasites (P. falciparum circumsporozoite protein) that aids the parasite to move and invade the liver cells where they mature before causing havoc to the entire body. In the novel study, the scientists modified the monoclonal antibody, CIS43LS, to prolong its half-life.
They then recruited participants in an open-label format who received escalating doses of CIS43LS in two phases. In one of the phases (phase two), the scientists exposed participants to parasite-infected mosquitoes in a controlled environment. In this second phase, some participants had received the antibody, and others had not (to act as controls). By the end of nine months, none of the participants who had received the monoclonal antibody suffered from malaria but, only one of the control participants who had not received the antibody didn’t suffer from malaria. The full details of this study appear in the New England Journal of Medicine.
Monoclonal antibodies have garnered traction in treating cancers and various immune-mediated diseases, and recently, they have had landmark achievements in curbing the deleterious effects of coronavirus disease 2019 (covid-19). However, extending their use to prevent a debilitating infectious disease like malaria is a feat worth celebrating. Though small, the study represents a glimmer of hope in our endeavour to eliminate malaria, a parasitic infection that has crippled the economies of many sub-Saharan Africa. Moreover, it extends opportunities for people who visit malaria-endemic regions, and they have to take prophylactic antimalarial drugs before and during the travel period. If one injection protects one from malaria for up to nine months, the injection becomes a welcome remark. Read about trial details from here at NEJM.