Monoclonal Antibody ADG20 Neutralizes COVID-19 Variants

“Monoclonal antibodies” became 2 of the most buzzed-about words during the COVID-19 pandemic. Though proven to be less effective at neutralizing the Omicron variant, monoclonal antibodies are still an exciting treatment option with untapped potential for past and future variants.

One study, accepted as an abstract for the Making a Difference in Infectious Diseases (MAD-ID) 2022 Annual Meeting, examined ADG20, an investigational fully human IgG1 monoclonal antibody, for the treatment of COVID-19. The investigators assessed the in vitro neutralizing activity of ADG20 against circulating COVID-19 variants.

The study included the COVID-19 variants and variants of concern as of November 18, 2021. Utilizing a lentiviral pseudovirus assay, the investigators tested ADG20 against circulating variants. For the variants associated with reduced susceptibility to some or all currently authorized monoclonal antibodies, the investigators used a non-replicative vesicular stomatitis virus pseudovirus system to test ADG20’s efficacy.

In an exploratory analysis of ADG20 administration in healthy adults, investigators determined sVNA titers with a plaque reduction assay for authentic SARS-CoV-2 BavPat (D614G) and variants of concern. These were then compared with antibody titers in a second adult cohort 7-30 days after they received their second dose of an authorized COVID-19 vaccine.

The investigators found that ADG20 successfully neutralized all COVID-19 variants tested, with 50% inhibitory concentrations within 0.4- to 5.1-fold of the reference D614G strain. ADG20 also demonstrated potent in vitro activity against COVID-19 variants that had shown resistance to some authorized monoclonal antibodies.

At 6 months after administration, ADG20 sVNA titers were comparable to peak antibody responses after Moderna mRNA vaccination. sVNA titers from the phase 1 study suggest the potential of a single 300 mg IM injection of ADG20 to protect against symptomatic or severe COVID-19 disease for at least 6 months.

This study, “ADG20, a half-life–extended monoclonal antibody in development for the prevention and treatment of COVID-19, demonstrates potent neutralization against SARS-CoV-2 variants,” was accepted as an abstract for the Making a Difference in Infectious Diseases (MAD-ID) 2022 Annual Meeting.