Sunday , March 7 2021

19 – How does an antibody drug work and when is it useful?

The federal government has bought a new antibody-based drug Covid-19 for Germany. According to the Ministry of Health, these are preparations from the American companies Regeneron and Eli Lilly, which will initially be used in university hospitals. How do these media work and when are they useful? We answer the most important questions.

What are antibodies

Antibodies are proteins, that is, proteins, that arise as part of the body’s immune response. In other words, if you become infected with a pathogen (e.g. a virus), the body’s defense system activates and produces defense molecules directed against the characteristic structures of that pathogen: antibodies. They occur in large quantities during the course of the infection and are able to bind the pathogen, neutralize it, and make it harmless. After infection, the body “remembers” the appearance of the pathogen so that it can react more quickly in the event of a second infection.
In the case of a Sars-CoV-2 infection, antibodies can be detected about two weeks after infection, in case of illness, approximately one week after the onset of symptoms. According to new findings published in the journal Science, another type of antibody can be detected in the blood of people who have recovered for another six to eight months.
In addition to the formation of antibodies, there are other parts of the immune response that help fight the pathogen. Other types of immune system cells are involved.

What are monoclonal antibodies?

“Monoclonal” means that all antibodies come from a cell clone, that is, they are the same. They are made in the laboratory and are targeted very specifically against a characteristic trait of the pathogen, such as part of the “ear” protein that Sars-CoV-2 uses to penetrate certain cells in the body. In contrast, patients recovered from Covid-19 have a mixture of different antibodies against parts of the virus in their blood; there is talk of polyclonal antibodies. Each type of antibody is targeted against a particular feature of the virus, so it can bind to different sites.

How are antibodies used as a medicine against Covid-19?

The principle is to give the body an advance in time: by giving antibodies, it skips the phase of the immune response in which the body is busy recognizing the characteristic structures of the virus and producing suitable antibodies itself. In connection with the crown pandemic, two US preparations are known, which received emergency approval there in November. They come from the companies Regeneron and Eli Lilly. The main difference: Eli Lilly’s drug contains one type of monoclonal antibody, while Regeneron’s drug contains a mixture of two monoclonal antibodies. The advantage of a mix is ​​that additional attack points increase the likelihood of effectiveness. Former US President Trump was treated, among other things, with the preparation of Regeneron, which at the time was not yet approved in the US.

What are the side effects?

In general, antibody therapies are well researched because they are also used to treat other diseases such as cancer and rheumatism. In a clinical study, people treated with the drug Regeneron did not experience an increase in the number of serious side effects compared to the control group. According to the U.S. Food and Drug Administration (FDA), Eli Lilly’s drug had serious side effects in two of the 850 cases examined. The following applies to both preparations: There is a risk of hypersensitivity reactions. In addition, there is not yet enough data to make a definitive statement on this issue. Some side effects may not be known yet.

Antibodies and antivirus mutations

Preparations with a mixture of different monoclonal antibodies can help prevent mutations from taking hold. If the virus multiplies, these variants emerge; most have no advantage or are even harmful to the pathogen and disappear again. In rare cases, a mutation or a combination of different mutations may have advantages for the virus, for example because it can spread more quickly, as is the case with virus variants first detected in Britain and South Africa. If the virus only faces a single very specific “weapon,” such as a type of monoclonal antibody, mutants that this antibody does not recognize will prevail. There is talk of selection pressure. Mixing different antibodies will reduce the chance of this happening.

Why not use antibodies as standard therapy against Covid-19?

There are reasons for this. On the one hand, there is currently no European approval for either Regeneron preparation or Eli-Lilly and, according to the European Medicines Agency (EMA), the corresponding application process is not yet in place. executing. Regeneron has announced that it will apply for European approval together with the pharmaceutical company Roche. In addition, antibody therapy is not always helpful. Due to its mode of action, this treatment achieves the best results, especially at the beginning of an illness. It can then prevent the progression of serious diseases. The data from the study available so far show that those who received the drug during the first ten days after infection benefited more from treatment. Patients who already have severe symptoms of Covid 19 (e.g., are in the hospital and are receiving oxygen) cannot receive this medicine. One possible explanation for this is that severe symptoms of a second phase of Covid-19 are caused by the reaction of the immune system. An active anti-virus ingredient would simply arrive too late here. In addition, this drug should be administered by infusion, which in this case takes about an hour and can only be done in clinics. In addition, the production of antibodies is complex and therefore expensive. The cost is estimated at about 2,400 euros per dose.
Another problem: antibodies are foreign proteins and what the body does not know decomposes: the agent would therefore have limited effectiveness and, unlike a vaccine, for example, does not protect against future infections.

Special case of convalescent plasma

Convalescent plasma is nothing more than the blood plasma of convalescent patients. It contains, often depending on the severity of the disease, antibodies that the immune system has produced on its own, that is, a mixture of polyclonal antibodies. If available, it can be given to newly infected people to protect them from the disease or a serious course of the disease. In this case we speak of passive immunization. This type of therapy has already been used several times in epidemics, such as the 2014 Ebola outbreak in West Africa. The Paul Ehrlich Institute considers this treatment to be a possible therapeutic option for Covid-19. However, studies have not yet shown the effectiveness of this.

(Stand 24.01.2021)

More articles on coronavirus

We have created a news blog. Given the large amount of information, it provides an overview of the most important current developments.

+ Current trends: Coronavirus figures in Germany (as of February 20)
+ Drafting Interjection: How to Deal with Crown Pandemic Issues (as of February 17)
+ Extended lock: what rules apply and what are the prospects for openness? (From February 17)
+ New rules: how federal states implement blockade resolutions (as of February 17)
+ Border controls: what to keep in mind (from 15 February)

Test and protection

+ Protection: the vaccination ordinance: who will be vaccinated first, who will be vaccinated later? (As of: February 17)
+ Dates: how, when and where can I get vaccinated? (Status: February 12)
+ Vaccinations: what is known about the side effects of the crown vaccine (from 16 February)
+ Astrazeneca vaccine: reports of side effects and acceptance problems: experts do not agree (17.02.)
+ Protection: therefore, it is the development of coronavirus vaccines (from February 15)
+ Change of strategy: are rapid tests the breakthrough in the fight against pandemics? (From February 16)
+ Patients: new knowledge about drug search (from January 30)
Treatment: How does an antibody drug work and when is it useful? (From January 25)
+ Economy: how the world of work treats the number of infections (from 16 February)

Contagion and transmission

+ Virus variants: to what extent are new coronavirus mutations dangerous? (As of: February 17)
+ Opponents of infection protection measures: what do AFD and lateral thinkers have to do with the spread of coronavirus in Germany (from 9/2)
+ Transfer: what role do aerosols play (from 22 January)
+ Excess mortality: (as of: 05.02.)
+ Travel notice: current list of risk areas (as of February 17)

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