A Blog by Jonathan Low

 

Jul 2, 2021

Five Monoclonal Antibodies Are Approved For Treating Covid. Are They Effective?

There is no one antibody that works well in every situation from prevention to hospital treatment. But pharma companies are continuing to develop them and there is hope that, eventually, an effective Covid treatment drug will emerge. JL

Leah Rosenbaum reports in Forbes:

One treatment proven to be the most successful is monoclonal antibodies. When people are infected with Covid-19, nearly all of them produce antibodies against the disease, but no two people produce the same antibodies. Pharma companies are studying thousands of antibodies to find one or two that are particularly potent and could serve to treat others. Those antibodies are then manufactured and infused into patients with an IV. Some are only used in severely sick patients. Others prevent patients from getting sick. Some can be used prophylactically. Some are effective against the Delta variant, while others aren’t. Vaccines have rapidly improved the U.S. Covid-19 pandemic, but hundreds of people a day are still dying from the disease. That number could increase soon thanks to the highly infectious Delta variant, which currently makes up about 20% of U.S. cases — and is likely to spread quickly. One thing that’s desperately needed: effective treatments for people who do get Covid-19.

So far, one type of treatment that has proven to be the most successful is one that was designed by nature: monoclonal antibodies. When people are infected with Covid-19, nearly all of them produce antibodies against the disease, but no two people produce the same antibodies, which means that some are better than others at fighting the disease. Pharma companies take advantage of this by studying thousands of antibodies to find one or two that are particularly potent and could serve to treat others. Those antibodies are then manufactured and infused into patients with an IV. 

Hundreds of thousands of people infected with Covid-19 have been treated with antibodies since one was first authorized in the Fall of 2020. Now there are four monoclonal antibody treatments that have been granted Emergency Use Authorization by the FDA — and more are coming. But not all of these therapies are created equal. Some are supposed to only be used in severely sick patients, while others are used to prevent patients from getting that sick. Some can even be used prophylactically. Some are effective against new variants, including the Delta variant, while others aren’t. Here’s how these treatments stack up. 


Bamlanivimab & Etesevimab


Developers:  Eli Lilly, AbCellera, Junshi BioSciences 

FDA Status: Authorized/Paused

Patients: Non-hospitalized kids and adults

Co-developed by Eli Lilly and biotech company AbCellera, Bamlanivimab was the first monoclonal antibody for Covid-19 granted Emergency Use Authorization by the FDA on November 9th, 2020. A combination therapy of bamlanivimab and etesevimab (an antibody licensed to Lilly by Junshi Biosciences) was authorized by the FDA on February 9th, 2021. Despite the early success, these treatments have had a bumpy ride. While it was initially approved to treat non-hospitalized kids and adults who were at risk of progressing to severe Covid-19 disease, researchers quickly realized that it couldn’t stand up to emerging variants of the virus. First, the FDA withdrew the use of it alone, and said it was only authorized in combination with etesevimab. Then on June 25th, 2021, the FDA recommended stopping the use of the combination as well,  which has proven ineffective against variants. This isn’t necessarily the end of the line for Lilly though; the company is also working on another monoclonal antibody drug in partnership with AbCellera. That antibody is currently in clinical trials, but early data suggests it is so potent that it could be administered with a syringe rather than an IV, which could be a gamechanger for countries that don’t have the medical infrastructure to support large scale IV treatment administration.

REGEN-COV


Developers:  Regeneron

FDA Status: Authorized

Patients: Non-hospitalized kids and adults

Regeneron’s Covid-19 treatment, a combo of two monoclonal antibodies called casirivimab and imdevimab, was given emergency authorization by the FDA on November 21st, 2020. This antibody pair came from a patient who survived Covid-19 as well as from a mouse that’s been genetically modified to have a human immune system, and the most famous patient to receive the treatment is probably former President Trump, who received it when he was infected with Covid last October. In early June, the agency issued a revised authorization allowing the company to lower the dose to about half of what was originally authorized when the lower dose was still found to be effective, and also authorized administration by syringe in cases where IV infusion wasn’t practical. The FDA says that it should only be given to non-hospitalized kids and adults with Covid-19 who are at risk of progressing to severe disease or death. In these patients, studies showed that Regen-Cov reduced the risk of hospitalization or death by 70%. So far, it seems to be effective against all known variants of Covid-19, and the company is looking to extend its EUA to include prophylactic use as well for people at higher risk of infection who haven’t been vaccinated.

Sotrovimab 


Developers:  GlaxoSmithKline and Vir

FDA Status: Authorized

Patients: Non-hospitalized kids and adults

On May 26th 2021, the FDA granted Emergency Use Authorization to GSK and Vir’s monoclonal antibody sotrovimab for treating non-hospitalized kids and adults with mild to moderate Covid-19. This antibody was derived from patients who had SARS in 2003 and targets a part of the virus that SARS-CoV-2 has in common with the original SARS virus, which suggests that part is less likely to mutate and the antibody should likely prove to work against new variants. The FDA says that it should only be given to people who have tested positive for Covid-19 and are also at risk of progressing to severe disease. Data from the clinical trials was promising: studies showed that patients who got sotrovimab had a 79% reduction in the risk of hospitalization or death compared to high-risk adult patients who took a placebo. But some questions about the drug still remain — like which doctors and patients can actually get their hands on it. Luckily, however, so far it seems to be effective against all known variants of the disease. GSK and Vir are also developing another antibody against Covid, which the companies say could serve not only as a treatment, but as a T-cell vaccine that provides durable immunity to Covid.

Actemra


Developer: Genentech

FDA Status: Authorized

Patients: Hospitalized kids and adults

Actemra (tocilizumab) was granted Emergency Use Authorization on June 24th 2021 for the treatment of severe Covid-19 in hospitalized kids and adults. Unlike some of the other antibody therapies, it’s not a Covid-specific antibody. Instead, it acts by preventing the severe inflammatory response seen in the lungs of some hospitalized patients. The drug is already approved by the FDA for rheumatoid arthritis and other severe inflammatory conditions. When it comes to Covid, Actemra is only authorized for use in patients who are already receiving steroids and require breathing support, either in the form of supplemental oxygen or ventilation. The FDA said that it based its decision on four trials that studied Actemra in more than 5,500 hospitalized patients. But the ruling is controversial: almost a year ago, a huge study found that the drug failed to meaningfully help hospitalized patients. Two more recent studies, however, showed that it can prevent a small number of Covid-related deaths: after 28 days, the proportion of patients who died after taking Actemra was 12.2%, compared to 19.3% in patients who took a placebo. This modest improvement was enough for the FDA, especially since this group of patients has few other treatment options.

Lenzilumab


Developer: Humanigen

FDA Status: Application Submitted

Patients: Hospitalized kids and adults

Humanigen’s monoclonal antibody, lenzilumab, hasn’t yet been granted Emergency Use Authorization by the FDA — but the decision could come any day. On May 28th, the company announced that it had submitted an application for the drug to get FDA authorization for use as a treatment in hospitalized adults and kids. Like Actemra, lenzilumab is not specifically an anti-Covid body. It’s another anti-inflammatory antibody, which is being developed as a treatment for cytokine storms that can affect patients who are undergoing treatments like CAR-T cell therapy, as well as Covid-19.  Unlike Actemra, which is used for hospitalized patients that are already on ventilation, Humanigen’s drug is used for patients who are newly hospitalized with Covid-19, but not yet on mechanical ventilators. In clinical trials, patients who took lenzilumab had a 54% relative improvement in the likelihood of surviving without ventilation compared to patients who got a placebo medication. Paired with other drugs, including steroids and remdesivir, the chance of avoiding ventilation was even higher. If authorized, this treatment could prove to do a lot to keep people from dying from a Covid infection.

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