Since the start of the coronavirus pandemic, no less than 2,700 clinical trials of experimental treatments against covid-19 have been registered on the planet. These tests involve humans.
This is what the data of the International Platform for the Registry of Clinical Trials shows, which collects records of studies of this type about to start.
Till the date, around 1,600 trials are recruiting volunteers or have already completed this stage of experiments, either with medications, some types of vaccines and even alternative therapies.
Health agencies require clinical trials to demonstrate the safety and efficacy of a treatment and its subsequent registration and marketing.
In Latin America, Brazil is the country with the most clinical trials related to covid-19 planned or underway in its territory: 159.
In the world, the leader is the United States, with 532.
In view of these hundreds of bets, we present four experimental treatments against covid-19 that have shown progress in the last month in Brazil and in the world, although they are still in different phases of testing to confirm their safety and efficacy.
1. Serum developed in Brazil
The National Health Surveillance Agency (Anvisa) gave the green light, last Wednesday, to the start of clinical tests of a serum developed by the Butantan Institute, linked to the São Paulo state government.
The serum, an injectable liquid rich in antibodies against the coronavirus, is intended for people already infected and seeks to stop the worsening of the disease, preventing, for example, from attacking the lungs.
The guinea pig tests had “extremely” effective results, according to Butantan.
There is no set start date yet, but human trials should start soon, Ana Marisa Chudzinski Tavassi, biochemist and director of the institute’s Center for Development and Innovation, told BBC News Brazil.
The number of volunteers is also being defined, but due to the nature of the treatment, the coverage is lower than in vaccine trials.
Immunizations are designed to be applied to the general population and have a preventive function, different from treating someone already infected, as does serum.
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Butantan is responsible for the production and supply of other serums throughout the country, such as rabies and snake venom serums.
In the treatment developed against the new disease, the coronavirus was isolated from a patient, multiplied, inactivated and applied to horses in a safe dose to prevent them from getting sick.
Animals function as antibody “factories”: that is, once they enter in contact with the virus produce antibodies that later they are extracted for manufacture the serum applicable in humans.
“Mexico and Costa Rica, among other countries, have produced serums. Argentina already has a serum with authorized use for patients in general and with very good results,” says Chudzinski.
“These sera were made to (attack) a part of the spike protein of the virus. Our difference is that we work with the whole virus. This can be an advantage over the variants that exist, because the large variations occur precisely in the spike” , Explain.
Spike is the name for the protein that is embedded in human cells to cause coronavirus infection.
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“We have already worked in vitro with the P.1 and P.2 variants. We also saw, in the guinea pig tests, a clear reduction in viral load and preservation of the lung the day after treatment,” says Chudzinski, but adds that there is not yet a published study with the results.
Clinical trials will verify, in phase 1, if the serum is safe to use; in phase 2, what would be the ideal dose; and in phase 3, if it is effective in a large number of people.
2. Antiviral in tests
Another treatment under evaluation that advanced to the first phase of clinical trials was an oral antiviral that is being developed by Pfizer.
The company announced on March 23 that experiments with patients in the US had begun.
According to the company, the antiviral showed “potent” action in in vitro laboratory tests and is designed to be used at the first symptoms of COVID-19.
Pfizer’s drug is a protease inhibitor, an enzyme essential for the virus to multiply.
“Protease is essential for the virus to grow, and the drugs that attack it stop some of the early stages of infection, preventing the virus from replicating,” explained virologist Stephen Griffin of the University of Leeds, to BBC News .
Protease inhibitors are already used against HIV and hepatitis C viruses. Even one of these drugs, lopinavir-ritonavir, originally used against HIV, was included in a major project of the World Health Organization (WHO ) to test treatments considered promising by the entity against covid-19.
However, a few months after the start of the project, called Solidarity, the WHO announced that it had stopped studies with lopinavir-ritonavir as research did not show that the treatment had an effect on reducing mortality in hospitalized people.
For now, the first phase of clinical trials announced by Pfizer will primarily evaluate the drug’s safety, monitoring any adverse effects.
3. Cocktail: goals achieved in the third phase
In phase 3, in which more than 4,500 people participated, the tests with a cocktail developed by the pharmaceutical company Roche had good results, also announced on March 23.
The cocktail, a combination of substances casirivimab e imdevimab with intravenous application, it is a type of treatment that is based on the so-called monoclonal antibodies, and that applies when the antibodies of a person who has recovered from the disease are isolated and copied in the laboratory.
The volunteers were people infected with the coronavirus, not hospitalized, but at risk of worsening the disease.
According to Roche, the cocktail reduced the risk of hospitalization and death by 70%, compared to placebo (a safe treatment). This was the main objective to be verified by the study.
But secondary goals have also had good results, such as reducing the duration of symptoms from 14 to 10 days. Adverse effects were statistically insignificant, since they only occurred in 1% of patients.
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There are several other ongoing experiments with casirivimab and imdevimab, including the Recovery project, a large-scale test suite in the UK with potential treatments for COVID-19.
In a statement, Roche said it would share the results with US and European health agencies, indicating its intention to register and commercialize the product. The pharmaceutical company also intends to release the data in a scientific publication.
4. The antiviral that can reduce the burden of the virus
On March 6, the pharmaceutical companies MSD and Ridgeback presented the preliminary results of a phase 2 clinical trial with the oral antiviral molnupiravir, which included 202 people infected with the coronavirus in the United States and not hospitalized.
According to a statement, after the fifth day of treatment, viral load dropped among those who received treatment.
Furthermore, adverse effects were considered irrelevant and unrelated to the drug. Details and further results of phase 2, including main objectives, will be released soon, according to the consortium.
Other phase 2 and 3 trials with the antiviral are also underway.
Molnupiravir inhibits the replication of RNA viruses such as SARS-CoV-2, and it has had good results in the laboratory not only with this pathogen, but with others such as SARS-CoV-1 and MERS.
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