Engineered IgM Antibody Administered Intranasally May Be More Potent at Inhibiting SARS-CoV-2 and Its Variants than Current Antibody Therapies

An IgM version of an anti-SARS-CoV-2 IgG monoclonal antibody is being developed as an intranasally administered agent for the treatment and prevention of COVID-19.

IGM Biosciences, Inc. (Mountain View, CA, USA), a clinical-stage biotechnology company focused on creating and developing engineered IgM antibodies, has expanded its IgM antibody platform into infectious diseases, with the anticipated advancement of a new pipeline candidate, IGM-6268, into the clinic in the third quarter of 2021. IGM-6268, an engineered human IgM monoclonal antibody designed for the treatment and prevention of COVID-19, has been shown in preclinical studies to be highly effective in preventing and treating COVID-19 after intranasal administration.


Due to its ability to bind to SARS-CoV-2 with greater strength, IGM-6268 offers advantages over current IgG treatments, including 100x to 1,000x greater neutralizing potency than comparable IgG antibodies, and the ability to effectively neutralize all evaluated mutant Variants of Concern (VoC) and Variants of Interest (VoI). Results from a recent study found that, among the anti-SARS-CoV-2 IgG, IgA, and IgM antibodies screened, IgM antibodies were in all cases significantly more potent than IgG and IgA antibodies in neutralizing virus.

IGM-6268 was shown to be effective for prophylaxis and treatment in animal models when administered intranasally, and also demonstrated significantly increased potency against wild type SARS-CoV-2 and emerging natural viral variants, such as the current UK, South African and Brazilian VoC strains, VoIs, as well as the antibody escape mutants for the current Emergency Use Authorized antibodies. In the company’s in vivo models, IGM-6286 appeared to be well-tolerated, did not appear to present any adverse safety signals, and demonstrated good persistence in the sinus following intranasal administration.

“The ability to transform IgG antibodies into potently neutralizing IgM antibodies for the possible prevention and treatment of COVID-19 with broad coverage of VoCs, VoIs and viral escape mutants is a very exciting application of our IgM platform that could address an urgent unmet medical need,” said Fred Schwarzer, CEO of IGM Biosciences. “We look forward to advancing IGM-6268 as quickly as possible and plan to initiate a clinical study in the third quarter of this year, marking the expansion of our IgM antibody platform from oncology into infectious diseases.”

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