AstraZeneca antibody cocktail slashes risk of symptomatic COVID-19, setting up regulatory filings and a lifeline for the immunosuppressed

AstraZeneca has caught a break. After enduring a series of struggles in COVID-19, the drugmaker has shown its long-acting antibody cocktail cuts the risk of symptomatic coronavirus infection by 77%, boosting its effort to provide protection to people underserved by vaccines.

The trial enrolled 5,197 people who were expected to respond poorly or be intolerant to COVID-19 vaccines, or who were at increased risk of SARS-CoV-2 infection. Nobody was vaccinated at baseline, and anyone who expected to get jabbed during the follow-up period was excluded from the study. More than 75% of participants had comorbidities such as immunosuppressive disease that put them at increased risk of developing severe COVID-19. Two-thirds of subjects received AZD7442.

AstraZeneca’s primary analysis looked at 25 cases of symptomatic COVID-19 that occurred up to six months after dosing. The analysis found one dose of AZD7442 cut the risk of symptomatic COVID-19 by 77%. There were no cases of severe COVID-19 or deaths related to the virus in the AZD7442 arm. Three people on placebo developed severe COVID-19. Two of those participants died. 

Armed with the data, which include safety analyses showing adverse events were balanced between the AZD7442 and placebo groups, AstraZeneca plans to seek emergency or conditional approvals of its antibody cocktail. The submissions will include results from a study that gave AZD7442 to people who had recently been exposed to the virus. That study missed its primary endpoint, but the results looked better in a preplanned analysis of PCR-negative participants.

RELATED: AstraZeneca’s COVID-19 antibody combination fails post-exposure prevention trial

Just how good the data from the latest study are remains to be seen. AstraZeneca is yet to share much data beyond the headline finding, and the durability of the protection provided by AZD7442 is unknown. Through changes including amino acid substitutions, AstraZeneca has sought to provide up to 12 months of protection but is yet to provide late-phase data to show it has delivered on that goal.

Regardless of whether the protection lasts six or 12 months, the antibody combination could make a big difference to the lives of a group of people who have been unable to benefit from vaccines. As vaccination rates in the West have risen and societies have opened up, people who have immunosuppressive disease, are taking immunosuppressants or are otherwise unable or unlikely to receive a vaccine and mount a significant immune response have remained vulnerable.  

Delta waves around the world have increased the risk of exposure to the virus. The AstraZeneca trial, which involved sites in the U.S., U.K., Spain, France and Belgium, largely took place before the delta waves, but there is in vitro evidence that AZD7442 neutralizes the variant and other emerging threats.