A Key Drug in Fighting Covid Is Now at Risk

(Bloomberg) -- Monoclonal antibodies were one of the earliest and most effective drugs for fighting Covid-19. Continued production of them is at risk though — jeopardizing the availability of a key tool in fighting the virus.

Some new antiviral pills appear to be extremely effective, which has relegated antibody drugs to niche corners of the market. Funding for U.S. government orders of antibody drugs is also in danger of running out. The Senate announced $10 billion in repurposed Covid spending this week. However, the deal still needs to pass and the White House said that number was not high enough to meet the continued demands of the pandemic. 

For many patients, antiviral simply pills make more sense, as some current antibody drugs have been rendered ineffective by new Covid variants. Antibodies also require infusions or injections in medical settings as opposed to simply popping a pill at home. But a halt to the development of monoclonal antibodies is not without its risks. It would weaken efforts to combat Covid while cases in many parts of the world are on the rise yet again as the virus continues to evolve rapidly.

If drugmakers stop making new antibodies, “you’re removing a weapon against Covid that has proven to be very useful,” said Michael Kinch, director of the Center for Drug Discovery at Washington University in St. Louis.

Without monoclonal antibodies, some populations would be left far more vulnerable to Covid-19.  For people on some medications — like those for autoimmune or transplant patients — antiviral pills could cause harmful drug interactions. And for immunocompromised people, for whom vaccines are not fully protective, antibody drugs can be used to prevent infection before or after exposure. There’s also the potential to test antibodies in combination with antivirals to try to prevent drug resistance, which can occur with continued use of one drug over time. 

Experts like Kinch contend that it’s too soon for drugmakers to let their guards down and stop production of a tool that might be useful in containing the spread of the virus or preventing hospitalizations. 

“I recognize there are finite resources, but we can’t declare victory too soon,” he said. 

Since new antibodies can be developed quickly, they can serve as the first mode of defense and buy time as more complex drugs are developed, Kinch said. That could be critical in fighting new variants of Covid as they inevitably arise.

There’s already been a general shift toward antiviral pills as the go-to treatment for high-risk outpatients, particularly Pfizer Inc.’s pill that’s shown high efficacy. Countries around the world have ordered far fewer antibody drugs than antiviral pills. The total number of antibody regimens purchased globally is equal to just 20% of the total number of antiviral courses that have been bought, according to analytics firm Airfinity Ltd.

If government funding for Covid drugs runs out and private insurers have to pay for them, demand for antibodies will likely fall even more. The therapies are more expensive to produce and administer than pills, making insurers less likely to cover them, said Damien Conover, director of health-care equity research at Morningstar Inc.

As new variants have emerged, antibodies have already started to fall out of favor. The Food and Drug Administration halted usage of antibody drugs from Eli Lilly & Co. and Regeneron Pharmaceuticals Inc. over concerns they didn’t work against omicron. The agency also doubled the size of the initial dose of AstraZeneca Plc’s prophylactic antibody, as data show it may be less active against certain omicron subvariants.

Then this week, the antibody made by by Vir Biotechnology Inc. and GlaxoSmithKline Plc — which withstood omicron when others didn’t — had its authorization pulled in the U.S., since the drug is unlikely to fight the BA.2 subvariant.

A new antibody from Eli Lilly has appeared effective against BA.2 in lab tests, but so far it has not gained widespread usage, said Phyllis Tien, professor of medicine at University of California, San Francisco. That may be because the FDA said it should only be used when other treatments are not an option and because there is only limited data about its efficacy. 

While companies that make antibody drugs could keep updating their therapies to fight new variants, few have done this so far. Companies risk yet another new variant coming along quickly to render their therapy ineffective again. Antibody drugs are more vulnerable to viral mutations because they target the frequently mutating spike protein of the virus, while antiviral pills target the virus’ ability to replicate.

Drugmakers including Eli Lilly and Regeneron are waiting to see what happens with Covid before investing further in new antibody drugs. Regeneron has a series of new candidates, but President and Chief Scientific Officer George Yancopoulos said the company is waiting to see if cases rise again before testing the drugs in large trials, or seeing if the FDA will expedite authorization based on small trials.

Vir said it plans to work on a range of drugs with GSK. It has one Covid antibody drug that’s being tested in an early-stage trial and said it’s preparing for future pandemics with different types therapies in the pipeline, including antibodies. 

If these drugs do soon become less available, it will mean trouble for a notable subset of patients. Alfred Kim, an assistant professor of medicine at Washington University in St. Louis, estimates that about a quarter of his hospital’s high-risk patients would have to hold or adjust dosing of their medications to be able to take Pfizer’s favored pill. About 3% of patients, he said, can’t take the pill at all.

“Of course people want to develop a drug that a large number of people would benefit from, but there’s always going to be pockets of people that just cannot take any of the more common medications,” said Tien of UCSF. “What are the options for them?”

Losing antibody drugs would also leave the world less prepared for future disease outbreaks, said Kinch, of Washington University.

“It’s having that strategy ready for the next thing, and that next thing might be a new variant of Covid or the next thing might be a brand new bug that we haven’t even thought of,” he said. “If we let our guard down prematurely, we will pay the price for it.” 

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