Update on AZD7442 STORM CHASER trial in post-exposure prevention of symptomatic COVID-19

AstraZeneca today announced results from the STORM CHASER trial assessing the safety and efficacy of AZD7442, a long-acting antibody (LAAB) combination, for the prevention of symptomatic COVID-19 in participants recently exposed to the SARS-CoV-2 virus. The trial did not meet the primary endpoint of post-exposure prevention of symptomatic COVID-19 with AZD7442 compared to placebo.

Trial participants were unvaccinated adults 18 years and over with confirmed exposure to a person with a case of the SARS-CoV-2 virus within the past eight days. In the overall trial population, AZD7442 reduced the risk of developing symptomatic COVID-19 by 33% (95% confidence interval (CI): -26, 65) compared to placebo, which was not statistically significant (Table 1).

The trial included 1,121 participants in a 2:1 randomisation AZD7442 to placebo, with 23 cases of symptomatic COVID-19 accrued in the AZD7442 arm (23/749) and 17 cases accrued in the placebo arm (17/372). All participants had a negative SARS-CoV-2 antibody test on the day of dosing to exclude prior infection, and a nasopharyngeal swab was also collected and subsequently analysed for SARS-CoV-2 by RT-PCR to detect virus.

Given the importance of finding therapies for COVID-19 and to help interpret trial results during the pandemic, additional analyses were performed and are being communicated (Table 1).

In a pre-planned analysis of SARS-CoV-2 PCR positive (detectable virus) and PCR negative (no detectable virus) participants, AZD7442 reduced the risk of developing symptomatic COVID-19 by 73% (95% CI: 27, 90) compared with placebo, in participants who were PCR negative at time of dosing. In a post-hoc analysis, in participants who were PCR negative at baseline, AZD7442 reduced the risk of developing symptomatic COVID-19 by 92% (95% CI: 32, 99) versus placebo more than seven days following dosing, and by 51% (95% CI: -71, 86) up to seven days following dosing.

Myron J. Levin, MD, Professor of Pediatrics and Medicine, University of Colorado School of Medicine, US, and principal investigator on the trial, said: “The results of STORM CHASER suggest that AZD7442 may be useful in preventing symptomatic COVID-19 in individuals not already infected. The PROVENT trial will give us more clarity in this patient population. While COVID-19 vaccination efforts have been successful, there is still a significant need for prevention and treatment options for certain populations, including those unable to be vaccinated or those who may have an inadequate response to vaccination.”

Mene Pangalos, Executive Vice President, BioPharmaceuticals R&D, said: “While this trial did not meet the primary endpoint against symptomatic illness, we are encouraged by the protection seen in the PCR negative participants following treatment with AZD7442. We await results from PROVENT, our pre-exposure prevention trial and TACKLE, our treatment trial in preventing more severe disease, to understand the potential role of AZD7442 in protecting against COVID-19.”

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