AstraZeneca Says Antibody Cocktail Can Treat COVID, Too

The monoclonal antibody cocktail AZD7442 (tixagevimab and cilgavimab) reduced the risk of severe COVID-19 and death in high-risk patients by half, becoming the first long-acting monoclonal antibody to show effectiveness at both treating and preventing COVID, manufacturer AstraZeneca said Monday.

Topline results of the phase III TACKLE trial found that the cocktail reduced risk of severe COVID-19 and all-cause mortality in non-hospitalized adults with mild to moderate COVID-19 randomized to the intervention compared with those randomized to placebo within 7 days of symptom onset.

For the primary endpoint, a composite of severe COVID-19 or death through day 29, there were 18 cases in the intervention group and 37 in the placebo group among 822 participants enrolled in the trial (4.4% vs 9.9%, respectively), AstraZeneca said.

“These positive results show that a convenient intramuscular dose of AZD7442 could play an important role in helping combat this devastating pandemic,” said TACKLE principal investigator Hugh Montgomery, MD, of University College London, in a statement.

AstraZeneca also touted the results of a prespecified analysis of patients treated within 5 days of symptom onset, noting that AZD7442 reduced risk of the primary outcome by 67%, with nine events in 253 participants in the intervention group and 27 events in 251 participants in the placebo arm. (While not highlighted in the release, this suggests little difference between groups for patients treated after 5 days of symptom onset.)

The manufacturer already unveiled positive topline results in August from PROVENT, a study using the cocktail as pre-exposure prophylaxis, and recently presented more detailed trial results at IDWeek. AstraZeneca said the cocktail reduced symptomatic COVID-19 by 77% in high-risk populations. The company recently filed for emergency use authorization with the FDA to use the cocktail for COVID prevention in these populations.

TACKLE was an international multicenter trial in which outpatients ages 18 and up with laboratory-confirmed SARS-CoV-2 infection at 96 sites in 13 countries, including the U.S. and the U.K., were randomized to receive either a 600-mg intramuscular dose of the cocktail or saline placebo in two separate injections. About 13% of participants were ages 65 and up, and 90% had baseline comorbidities. About 62% were white, 4% were Black, 6% were Asian, and 24% were either American Indian or Alaskan Native. Of these, 52% were also of Hispanic/Latino ethnicity.

Participants will continue to be followed for 15 months, AstraZeneca said, and they plan to submit their results to a peer-reviewed medical journal.