Regeneron Pharmaceuticals on Tuesday announced that a phase 3 trial still in progress of an antibody cocktail has shown a 100 percent prevention of symptomatic COVID-19 infections.
Interim results also show approximately 50 percent lower overall rates of infection across all patients.
For infections that did take place, peak virus levels were decreased and they had a short duration of viral shedding. None of the individuals who received the cocktail had high viral loads, compared to 62 percent of the infected who were treated with a placebo.
"These data using REGEN-COV as a passive vaccine suggest that it may both reduce transmission of the virus as well as reduce viral and disease burden in those who still get infected," George Yancopoulos, president and chief scientific officer at Regeneron, said in a statement.
"Even with the emerging availability of active vaccines, we continue to see hundreds of thousands of people infected daily, actively spreading the virus to their close contacts. The REGEN-COV antibody cocktail may be able to help break this chain by providing immediate passive immunity to those at high risk of infection, in contrast to active vaccines which take weeks to provide protection."
The New York-based company said adverse events occurred among 12 percent of those who took the cocktail, versus 18 percent who took the placebo. There was one death and one hospitalization in the placebo group, and neither deaths nor hospitalizations in the treatment group.
The trial's interim results were drawn from a group of about 400 volunteers.
The patients receive the cocktail through an injection, rather than infusion.
"It's notable that the few infections that did occur after receiving REGEN-COV were all asymptomatic, and associated with markedly lower viral load and duration of viral shedding, potentially further reducing transmission. We look forward to seeing the full dataset early next quarter and will discuss the current results with regulatory authorities, including the potential to expand the Emergency Use Authorization," David Weinreich, head of global clinical development at the company, said in a statement.
Eli Lilly on Tuesday also reported results from a phase 3 trial. It said its neutralizing antibodies together reduced the risk of COVID-19 hospitalizations and death by 70 percent.
"These exciting results, which replicate positive Phase 2 data in a much larger set of patients, add valuable clinical evidence about the role neutralizing antibodies can play in fighting this pandemic. While the preliminary nature of Phase 2 results from COVID-19 neutralizing monoclonal antibodies may have limited acceptance of treatment, these Phase 3 data further strengthen the available evidence," said Daniel Skovronsky, Lilly's chief scientific officer and president of Lilly Research Laboratories, in a statement.
The trial featured 1,035 patients.
Bamlanivimab was approved for emergency use by drug regulators last year. An application for emergency authorization for bamlanivimab and etesevimab together is still being reviewed.