Covid-19: scientists seek therapies for those who cannot be vaccinated

When U.S. President Donald Trump was diagnosed with covid-19, the treatment applied was a cocktail of monoclonal antibodies that will be the basis of the disease’s prophylaxis: therapies with immune cells for those who cannot be vaccinated.

Hunting the virus

One of the therapies, called AZD7442, is in phase 3 of clinical testing. Developed by University College Hospital (UCLH) with the AstraZeneca laboratory (the same that works with the Jenner Institute, of the University of Oxford, in the development of a vaccine against covid-19), the research was divided into two studies.

One of them is called Storm Chaser. “Tests should prove that this treatment leads to immediate protection against the development of covid-19 in those who have been exposed to the disease – when it would be too late to be vaccinated,” said virologist Catherine Houlihan, who leads the research.

Antibodies introduced into the body attack infected cells, but treatment does not induce an immune response in the body.Source: Shutterstock / Christoph Burgstedt / Reproduction

Therapy will not replace the coronavirus vaccine: unlike immunizers, prophylaxis does not teach the immune system to produce antibodies against Sars-CoV-2.

The other study developed by UCLH, called Provent, aims to find out whether this same therapy can be used by those who are vaccinated and not develop antibodies (for example those with compromised immune systems, such as cancer patients) or at risk, such as the elderly and people with comorbidities. The researchers hope that the protection provided by AZD7442 will extend from 6 to 12 months after just 1 dose.

Exclusivity

This type of therapy, however, is expensive. The antibodies used are the so-called monoclonal antibodies, which only recognize an antigen, so they are specific for a pathogen and are produced through a single clone of a parental B lymphocyte. The cell is said to be immortalized, reproduced countless times in large bioreactors for about 10 days, generating a lineage of immune cells specific to a single pathogen.

From a single B lymphocyte, an entire monoclonal cell line is created.From a single B lymphocyte, an entire monoclonal cell line is created.Source: NIAID / Disclosure

The antibodies are purified and marketed at prices ranging from $ 95 to $ 200 per gram. There are just over a hundred types of licensed monoclonal antibodies; of these, only seven are used in the prevention and treatment of infectious diseases.

Previous learning

On the other side of the Atlantic, a hospital began its clinical testing program with a therapy that also uses antibodies, but polyclonal, originating from multiple cells of the immune system, and not just B lymphocytes. Called Covid-19 Human Hyperimmune Globulin (Globulin Human Hyperimmune to covid-19, COVID-HIG), it was administered to phase 1 clinical trial volunteers.

Developed by the Monte Sinai Group and Emergent BioSolutions, the therapy uses plasma from donors who have recovered from covid-19. As in the British study, the research will assess whether prophylaxis with COVID-HIG (a solution composed of high levels of antibodies against the disease) can protect those exposed to high loads of Sars-CoV-2.

Other companies are looking for prophylactic treatments. In November, the Food and Drug Administration (FDA) approved in the United States, for emergency use, monoclonal antibody therapies by pharmaceutical companies Regeneron (which developed the cocktail administered at Trump) and Eli Lilly.

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