Antibody to prevent malaria reports success in first human trial

A majority of volunteers given an experimental antibody treatment against malaria were reportedly protected from deadly infection. The promising outcome of the monoclonal antibody treatment, dubbed L9LS, highlights its potential to fight the parasitic infection in regions endemic to malaria.

An injection of monoclonal antibodies provides a potent treatment against a targeted pathogen, unlike vaccines which help train the immune system to produce workable antibodies. Monoclonal antibodies are powerfully effective therapeutic tools but are not as long-lasting as vaccines as they degrade over time – monoclonal antibody treatments are often effective for only a few weeks or several months, at best.

The trial for L9LS optimised monoclonal antibodies targeted to a protein used by the malaria parasite to infect hosts: it recruited 17 healthy subjects who tested three different doses of the treatment, with some subjects receiving intravenous administration and others receiving subcutaneous injections.

Between two and six weeks after receiving the antibodies, all volunteers were deliberately exposed to malaria-carrying mosquitos, but only two participants developed malaria in the weeks following exposure. Allegedly, one subject had received the lowest intravenous dose and the other had received a subcutaneous injection.

“The major strengths of monoclonal-antibody therapy are that it can provide a reliable level of antibodies, regardless of the host immune status, and this level can be achieved rapidly after administration,” said infectious disease expert Johanna Daily. “Monoclonal antibodies against malaria may have a distinct role in rapidly controlling infection in areas where there are malaria outbreaks, in locations where antimalarial drug resistance is emerging, and in persons who are unable to mount a protective antibody response to vaccines.”

The team of researchers developing L9LS claim the antibody offers a half-life of 56 days. Protection from a single treatment is hypothesised to last for several months, and in children under the age of five a single subcutaneous injection may deliver at least six months of protection.

The researchers are also quick to add that these newer treatments could be produced affordably. Timothy Wells and Cristina Donini, from non-profit Medicines for Malaria Venture, have agreed that the treatment could be cost-effective depending on effective dosages and manufacturing technologies.

“Current estimates of the cost of production of antibodies obviously depend on individual antibodies, but estimates of USD50 per gram of antibody are certainly feasible. These estimates suggest that these antibodies could be in a similar price range as that of current vaccines, but with the potential to be less expensive as technology develops,” Wells and Donini concluded.

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