Jennifer Gommerman, a professor of immunology at the University of Toronto, also used the phrase "really promising."
She said that, along with Regeneron's earlier work published in a peer-reviewed journal in August, the additional key takeaway is that the "cocktail" approach is effective.
A cocktail antibody therapy uses two or more lab-engineered antibodies. Regeneron's cocktail includes a monoclonal antibody that targets the spike protein the virus uses to drill into healthy cells, and another antibody that targets a different part of the novel coronavirus. With two, the hope is is to trap and shut down viral replication.
"It appears that they've got positive results and that this antibody cocktail doses reduce the amount of time that the patients are sick, especially the patients that weren't able to mount their own antibody response," Gommerman said. "They're obviously going to have to do much more human experiments and bigger trials to really make sure."
Dr. Richard Besser, a former acting CDC director who now heads the Robert Wood Johnson Foundation, said it makes sense that a treatment that gives a patient antibodies would help the immune system, but he said peer review will find any holes or pitfalls.
"I would withhold judgment on this until we see the data," said Besser. "You know these early results that keep coming out from companies in press releases strike me as being about much more, much more about the stock price than they are about science."
Gommerman, Marrazzo, and Hoyen think antibody treatments could be a real help in patient populations that don't generate a real robust immune response to a vaccine, like patients in nursing homes or other elderly people. The treatment may also be helpful in the transition period, before everyone can get vaccinated.
Regeneron isn't the only company working on an antibody treatment. Eli Lilly is also in late-stage trials with its antibody treatment. There are at least 70 different antibody treatments under investigation according to BIO, an association that represents major biotechnology companies.
Regeneron said that there will be more data to come from this trial, from a trial involving hospitalized patients, and one that is testing the antibody cocktail as a prevention for people who have contact with someone in their household who has Covid-19.
Schleifer said Regeneron is in talks with regulators about these results to see if the US Food and Drug Administration would consider an emergency authorization of the drug. They have additional data the company will submit for formal approval.
Regeneron co-founder George Yancopoulous said during a call with shareholders Tuesday that it is up to regulators to decide if this is enough information to make this therapeutic intervention available sooner to patients who might need it.
"I think that this deserves to be discussed with regulatory authorities, because of all of the societal implications," Yancopoulous said.
"We think that there's a lot of evidence here to suggest that this is a therapeutic solution that could really benefit quite a number of individuals and patients."