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A Covid Treatment That Promises to Fight Off Omicron

A Covid Treatment That Promises to Fight Off Omicron

GlaxoSmithKline Plc has delivered some good news amid mounting concerns about the omicron variant. Its research showed that sotrovimab, the Covid-19 antibody treatment it developed with Vir Biotechnology Inc., is effective against the full combination of mutations seen in the new variant. Will this make it easier to live with omicron? Bloomberg Opinion’s Therese Raphael talks to Sam Fazeli, senior pharmaceutical analyst for Bloomberg Intelligence, about the development. 

Therese Raphael: Let’s start with the basics. Sotrovimab is a monoclonal antibody treatment — what are these and how are they used against the virus?

Sam Fazeli: The idea is to reduce the risk of hospitalization by giving people antibodies that stick to the virus and stop it from infecting cells. Vaccines do the same thing by stimulating the person’s own immune system to make antibodies. With vaccines, you get a polyclonal response — that is, lots of different antibodies — whereas here, as the “monoclonal” name suggests, you’re only getting one antibody. This makes it more susceptible to mutations in the virus, which is why these drugs (and vaccines) have to be tested against each variant.

There are two settings in which a monoclonal would be the treatment of choice. One is when subjects have weaker immune systems that do not respond well to vaccines and need to be given prolonged protection. The other setting where a longer-acting therapy would be better is preventively, where someone who is immune-compromised has been exposed to the virus but not yet tested positive for Covid. 

TR: GSK says lab studies show that sotrovimab, which goes under the trade name Xevudy, would be effective against omicron — meaning it would help prevent the most serious illnesses. How sure should we be?

SF: While we haven’t seen the actual data yet, the company said in a press release that sotrovimab had three-fold less neutralizing ability  — the ability to block the path of the virus into a cell — against omicron than against other variants. Now that sounds bad, but it is unlikely to impact efficacy significantly and is actually a lot better than the reduction in neutralization that I expect to see for antibody treatments from Eli Lilly-AbCellera and Regeneron-Roche. If an increased dose level from sotrovimab can compensate for this drop in neutralization, however, that would mean fewer overall doses available for global use.

TR:  Who would receive this treatment and how does it have to be administered? 

SF:  Most monoclonal antibody treatments are used within 10 days of symptoms appearing in patients with a high risk of developing severe disease. That’s quite a big window, especially when compared with antiviral treatments that have to be administered within the first few days of getting an infection. But most of these treatments cannot be used once a patient is hospitalized because by that time the disease is much less driven by the virus itself than the overreaction of the immune system. 

Sotrovimab has been granted emergency use authorization in the U.S. It has also been approved in the U.K. and several other countries as a 500mg dose given as an intravenous infusion over 30 minutes. So it needs to be given at an infusion center. However, GSK recently reported data showing that an intramuscular injection performs just as well. This means it can be administered by any qualified professional and even at home.

TR:  How does this compare to other monoclonal antibodies that have been approved or are in the works? 

SF:  They all try to do the same thing. But, as noted above, other antibody treatments are at risk of evasion by new variants. Some, such as those made by AstraZeneca and Adagio, may also be less impacted by the omicron variant. This is because the region to which these antibodies bind, called the epitope, is not affected by omicron’s mutations. 

The problem with antibody drugs is that they are not as easy to manufacture at volume and administer as pills the way Pfizer’s paxlovid or Merck’s molnupiravir  (two antiviral treatments) are. While the number of doses is far lower with antibody treatments, they are about three times more expensive.

But antibody treatments have one very important characteristic: longevity. Data from Regeneron showed that one injection was effective in reducing the risk of disease for up to eight months. AstraZeneca’s monoclonal antibody AZD7442 has also been designed to have an even longer-term effect. So the two types of therapy are complementary.

TR:  How do doctors decide between these antibody treatments and antivirals? 

SF:  The decision between antibody treatments and, say, molnupiravir is simple given the latter’s relatively weak efficacy, as we discussed recently. Generally, if a patient can be given a monoclonal, that’s the preference. Pfizer’s paxlovid has so far shown efficacy that appears on a par with monoclonal antibodies, however. If that remains the case after data in a larger population is published, then paxlovid may be the first choice since it is administered in pill form and is a cheaper treatment.

TR: We’ve been talking a lot about vaccine equity, especially since the omicron variant emerged in a country, South Africa, with a 24% vaccination rate. Can treatments like sotrovimab be easily deployed in developing countries where vaccination rates are low?

SF: Given the fairly low volume that these monoclonals can be manufactured at and their cost, I do not think they will be as equitably distributed as the antiviral pills, which are cheaper and easier to manufacture. In fact, both Merck and Pfizer have provided licenses to others to manufacture their drugs at generic prices for low-middle-income countries.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Therese Raphael is a columnist for Bloomberg Opinion. She was editorial page editor of the Wall Street Journal Europe.

Sam Fazeli is senior pharmaceuticals analyst for Bloomberg Intelligence and director of research for EMEA.

©2021 Bloomberg L.P.