Adagio Therapeutics, Inc. announced positive preliminary clinical results from its Phase 2/3 clinical trials of adintrevimab (ADG20) and is providing an update on the anticipated timing for its Emergency Use Authorization (EUA) request for adintrevimab for the prevention and treatment of COVID-19. The Omicron BA.2 variant, which has shown reduced in vitro susceptibility to monoclonal antibodies, has recently emerged as the current predominant variant of SARS-CoV-2 in the U.S. Adintrevimab, which has demonstrated broadly neutralizing activity in vitro against SARS-CoV-2 variants of concern including Alpha, Beta, Delta, Delta Plus, Gamma and Omicron BA.1, has markedly reduced neutralization activity in vitro against the Omicron BA.2 variant. Based on feedback from the U.S. Food and Drug Administration (FDA) regarding adintrevimab's lack of neutralizing activity against the BA.2 variant, Adagio is pausing the submission of an EUA request.

Adagio intends to continue engaging with the FDA and monitor the evolution of SARS-CoV-2 and the in vitro activity of adintrevimab against predominant variants in the U.S. to determine the optimal timing for its planned EUA request. Adintrevimab Preliminary Clinical Data: Adagio is committed to advancing adintrevimab as a potential future therapeutic option in anticipation of the emergence of new variants. The company is also conducting an ongoing Phase 1 trial evaluating pharmacokinetics and safety of higher doses of adintrevimab in healthy volunteers and is continuing its antibody research efforts, including efforts to modify adintrevimab to improve binding to the Omicron BA.1 and BA.2 subvariants.

Adagio is on-track to have more than one million doses of adintrevimab secured in 2022, in preparation of its potential utility as a prophylaxis and treatment option for COVID-19 in the future. Adintrevimab Preliminary Clinical Data: Preliminary clinical results from the Phase 2/3 clinical trial of adintrevimab for the prevention (EVADE) and treatment (STAMP) of COVID-19 showed that in the pre-Omicron population, adintrevimab administered as a single 300mg intramuscular dose met the primary endpoints with statistical significance across all three indications: 1) pre-exposure prophylaxis (PrEP), 2) post-exposure prophylaxis (PEP), and 3) treatment. Preliminary data from EVADE showed that adintrevimab reduced the risk of symptomatic COVID-19 by 71% compared to placebo in the PrEP cohort and by 75% compared to placebo in PEP cohort.

Preliminary data from STAMP showed that adintrevimab reduced the risk of hospitalization or death by 66% compared to placebo in the primary efficacy analysis population, and by 77% compared to placebo in patients who received treatment within three days of symptom onset. In addition, in a pre-specified exploratory analysis of the PrEP cohort following the emergence of the Omicron (BA.1) variant, a clinically meaningful reduction in cases of symptomatic COVID-19 was observed with adintrevimab, as compared to placebo. Across both trials, administration of adintrevimab was well-tolerated and had a similar safety profile to that of placebo.