(Reuters) – An experimental new type of antibody drug from IGM Bioscience Inc may be more potent at inhibiting the coronavirus and its variants than antibody therapies currently in use, research in mice suggests. And it is easier to administer with more direct affect on the lungs.

Current antibody drugs use IgG antibodies, which are bivalent (two-armed) – meaning they can simultaneously attach themselves to two of the spikes the coronavirus uses to break into cells. The new IgM antibody drug is 10-valent (10-armed), so it can bind up to 10 viral spike proteins at the same time, explained Zhiqiang An of Texas Medical Center in Houston and Pei-Yong Shi of University of Texas Medical Branch at Galveston, who are among the authors of a report in Nature.

The IgM antibody can therefore bind more strongly and effectively to the virus, they added in an email to Reuters.

The IgM antibody showed broad coverage of variants of concern, the researchers said.

Furthermore, it can be given via nasal spray, whereas conventional antibody drugs require intravenous infusions. The IV-infused IgG antibody must be given in high doses because most of it stays in the blood, with very limited anti-viral effects in the respiratory tract. Nasal delivery would allow for lower doses and direct access to the respiratory tract and lung. In addition, the drug could be self-administered without medical supervision, researchers said.

The drug must still be tested in humans to gauge its actual impact on COVID-19 treatment, An noted.

SOURCE: https://go.nature.com/34ZYiGV Nature, online June 3, 2021.

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