Long-Acting Monoclonal Antibodies Look Promising for COVID-19 Prevention

The randomized, double-blind, placebo-controlled, multicenter PROVENT trial included 5197 participants aged 18 years and older who would benefit from AZD7442.

Positive topline results were announced from a phase 3 study evaluating the efficacy and safety of AZD7442 for the prevention of COVID-19.

AZD7442 is a combination of 2 long-acting monoclonal antibodies, tixagevimab and cilgavimab, derived from B-cells donated by convalescent patients who were infected with the SARS-CoV-2 virus. The investigational antibodies are designed to bind to distinct sites on the SARS-CoV-2 spike protein with an extended half-life and reduced Fc receptor and complement C1q binding. 

The randomized, double-blind, placebo-controlled, multicenter PROVENT trial (ClinicalTrials.gov Identifier: NCT04625725) included 5197 participants aged 18 years and older who would benefit from 2 long-acting antibodies, defined as having increased risk for inadequate response to active immunization or having increased risk of SARS-CoV-2 infection. At the time of screening, participants were unvaccinated and had a negative point-of-care SARS-CoV-2 serology test.

Participants were randomly assigned 2:1 to receive a single intramuscular dose of either 300mg of AZD7442 or saline placebo, administered in 2 separate intramuscular injections. The primary efficacy endpoint was the first case of SARS-CoV-2 reverse transcriptase-polymerase chain reaction positive symptomatic illness occurring post dose prior to day 183. 

Among 5172 evaluable participants, findings showed that AZD7442 met the primary endpoint achieving a 77% (95% CI, 46%-90%) risk reduction of developing symptomatic COVID-19 compared with placebo. There were no cases of severe COVID-19 or COVID-19-related deaths in the AZD7442 treatment arm compared with 3 cases of severe COVID-19 in the placebo arm, including 2 deaths. The safety profile of AZD7224 was found to be well tolerated.

Full trial results will be submitted for publication in a peer-reviewed medical journal and presented at an upcoming medical meeting. The Company will prepare to submit phase 3 trial data from PROVENT and STORM CHASER (ClinicalTrials.gov Identifier: NCT04625972) to health authorities for emergency use authorization or conditional approval for AZD7442.

Myron J. Levin, MD, Professor of Pediatrics and Medicine, University of Colorado School of Medicine, and principal investigator on the trial, noted that the “PROVENT data show that one dose of AZD7442, delivered in a convenient intramuscular form, can quickly and effectively prevent symptomatic COVID-19. With these exciting results, AZD7442 could be an important tool in our arsenal to help people who may need more than a vaccine to return to their normal lives.”


AZD7442 PROVENT phase III prophylaxis trial met primary endpoint in preventing COVID-19. News release. AstraZeneca. Accessed August 20, 2021. https://www.astrazeneca.com/media-centre/press-releases/2021/azd7442-prophylaxis-trial-met-primary-endpoint.html