Early Tests Show Omicron Tougher for Current COVID Antibody Therapies to Tackle

Not a lot is known about how well vaccines, antiviral drugs and antibody therapies work against the latest “variant of concern” (VOC), Omicron. Early tests of Regeneron Pharmaceuticals' antibody cocktail show it isn’t as effective against Omicron. According to researchers outside the company, separate tests of Eli Lilly's antibody cocktail also demonstrated it wasn’t as effective. Lilly indicated that it is running the tests itself and would not speculate on the data.

In a media statement made today, Regeneron said it is evaluating its antibody cocktail, Regen-Cov (casirivimab and imdevimab), against Omicron, which they routinely do with all new World Health Organization (WHO)-designated VOCs. They point out that the U.S. Food and Drug Administration (FDA) and multiple other analyses have confirmed that Regen-Cov maintains its potency against the main VOCs in the U.S., including Delta.

“To date,” Regeneron stated, “there have been no direct data testing the Omicron variant’s resistance to vaccine-induced and monoclonal antibody-conveyed immunity. Prior in vitro analyses and structural modeling regarding the individual mutations present in the Omicron variant indicate that there may be reduced neutralization activity of both vaccine-induced and monoclonal antibody-conveyed immunity, including the current Regen-Cov antibodies. Further analyses are ongoing to confirm and quantify this potential impact using the actual Omicron variant sequence.”

Omicron was designated a VOC by the WHO over the weekend. It appears to have about 50% of its spike protein mutated from other variants. It was first identified in South Africa. Some evidence suggests that the symptoms are mild — and different — than what has been seen with Delta and other variants. However, some studies suggest it is more contagious. All the major vaccine companies are running tests to determine if their vaccines are effective against Omicron and if not, how quickly they can modify their vaccines. Pfizer-BioNTech, Moderna and Johnson & Johnson have suggested that if they need to modify their vaccines, they would be ready to distribute new shots targeting Omicron in about 90 days. However, it’s not yet known if those new vaccines would require clinical trials.

The new antiviral drugs, Merck and Ridgeback’s molnupiravir and Pfizer's Paxlovid, are likely to be effective against Omicron, although no studies have been run to prove it. The antiviral drugs are not dependent upon the structure of the virus’s spike protein. Gilead Sciences also believes its antiviral drug Veklury (remdesivir) will be effective against Omicron.

Regeneron suggested that the mutations seen in Omicron “indicate that there may be reduced neutralization activity” from their antibody therapies. Still, it is working on several “next generation antibodies” that it believes would be effective against the new VOC.

This is based on research by investigators at the Fred Hutchinson Cancer Research Center in Seattle, who tested Regeneron and Eli Lilly’s antibody therapies and their ability to attach to the Omicron strain. However, they also said more comprehensive tests against the entire variant, not just against the individual mutations, would need to be conducted to thoroughly understand the magnitude of the decreased effectiveness.

Nicole Kallewaard, a virologist with Lilly said, “I think that we need to wait for confirmation of the whole virus. Hopefully, the data will come in the next few weeks.”

Vir and GlaxoSmithKline reported they believe their monoclonal antibody sotrovimab “is likely to maintain activity and potency against this variant,” because it targets a part of the virus that “is less likely to mutate.”

Skip Virgin, chief scientific officer of Vir, said, “Omicron hasn’t become the next Delta.” But “we think the extent of the mutations, the number of them, means that the world needs to take Omicron very seriously.”

Peter Marks, the FDA's lead vaccines official, told an American Medical Association webinar earlier this month, “I actually think we’re in a really good place with the technologies we have, because if a new variant came along, it would probably be a matter of very few months before we would be mass-producing a vaccine against that variant. The spike protein, if it changes, it can be easily then shifted back into the vaccine manufacturing process, not just for the mRNA, but for other vaccines as well. We won’t have to go back to square one and do large scale clinical trials.”