London: British-Swedish biopharmaceutical company AstraZeneca on Tuesday stated that its monoclonal antibody treatment failed to prevent the Covid-19 symptoms in individuals already exposed to the virus.
The Covid-19 antibody therapy -- AZD7442 -- was only 33 per cent effective in reducing the risk of symptoms, when compared to a placebo, according to the results of a Phase 3 trial.
"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," Executive Vice President, BioPharmaceuticals R&D, Mene Pangalos, said in a statement.
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The Phase 3 trial included 1,121 participants, from the UK and the US. The participants were unvaccinated adults 18 years and above with confirmed exposure to a person with a case of the SARS-CoV-2 virus within the past eight days.
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.
The results are not peer reviewed yet.
"The results of the study suggest that AZD7442 may be useful in preventing symptomatic Covid-19 in individuals not already infected," said principal investigator on the trial Myron J Levin, Professor at University of Colorado School of Medicine, US.
AZD7442 is a combination of two LAABs - tixagevimab (AZD8895) and cilgavimab (AZD1061) - derived from B cells donated by convalescent patients after SARS-CoV-2 virus. Discovered by Vanderbilt University Medical Center and licensed to AstraZeneca in June 2020, the human monoclonal antibodies bind to distinct sites on the SARS-CoV-2 spike protein2 and were optimised by AstraZeneca with half-life extension and reduced Fc receptor binding.
The therapy is currently being tested in several additional Covid prevention and treatment trials: Phase 3 trial of over 5,000 participants in pre-exposure prophylaxis; Phase 3 treatment trial in outpatient setting; and collaborator treatment trials in outpatient and hospitalised settings.