Monoclonal antibodies from Regeneron (NASDAQ:REGN) and Eli Lilly (NYSE:LLY) designed to bind to the novel coronavirus have delivered solid clinical trial data suggesting they can help patients with COVID-19. In this Fool Live video, Healthcare and Cannabis Bureau Chief Corinne Cardina and longtime Motley Fool contributor Brian Orelli discuss the difference between monoclonal and polyclonal antibodies. They also talk about how positive data for the monoclonal antibodies could be good news for companies developing coronavirus vaccines.

Corinne Cardina: What is the difference between a polyclonal versus a monoclonal approach? Is one of these more promising than the other?

Brian Orelli: Polyclonal antibodies is just a mixture of antibodies that have more than one antibody in the mixture. The plasma would be quite a few different kinds of the antibodies because you're taking it from different patients and mixing them all together. That's a very broad polyclonal idea, where monoclonal will just be one antibody. You can have two monoclonals together, this is what Regeneron is doing. I don't know if I really call that a polyclonal approach or two monoclonal. I would call it two monoclonal approach just because it's a little more clear what they're doing. Polyclonal usually implies that you're just taking all the antibodies from an animal or a human so I would call this a two monoclonal approach. I think two is probably going to be better than one in general because if they're binding on different parts of the virus, you can see that that might help. Then also, if there was a mutation in the virus, it would have a harder time escaping two antibodies compared to just one.

Corinne Cardina: Great. At the end of September, Regeneron released the first data from its descriptive analysis included. This was looking at the first 275 patients who are enrolled in the trial. I'm just going to go over some highlights and then I have a question for you at the end. This is specific to the trial of nonhospitalized COVID-19 patients. Here's what the company said. The treatment reduced viral load and the time to alleviate symptoms in nonhospitalized patients with COVID-19. The antibody treatment also showed positive trends in reducing medical visits. Regeneron's president, Dr. George Yancopoulos, said the greatest treatment benefit was in patients who had not mounted their own effective immune response, suggesting that the treatment could provide a therapeutic substitute for the naturally occurring immune response. These patients were less likely to clear the virus on their own and were at greater risk for prolonged symptoms. He then said these data also support the promise of vaccines targeting the coronavirus spike protein. Could you elaborate on this connection that he's talking about? What can we learn from antibody treatment trials that informs what we know about a coronavirus vaccine?

Brian Orelli: Yes. The spike is one of the proteins on the outside code of the virus and it uses that spike to attach to the cell and inject its genetic material into the cell. Maybe all, but certainly most of the vaccines are developing vaccines for that spike protein. So they put that protein in either by putting protein directly in or by inserting DNA or RNA into the cells that make that protein. But either way, you end up with spike protein in the body and the patient that got the vaccine develops antibodies to that protein. So if Regeneron's putting in antibodies that can then bind to that protein and it seems to be helping patients, in theory, if the patients are making their own antibodies because they got the vaccine with the spike protein, then that should mean that those vaccines are likely to work.

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