BBC – Coronavirus
posted on 01/04/2021 07:59
Since the beginning of the coronavirus pandemic, no less than 2,700 clinical trials of experimental treatments against covid-19 have been registered on the planet. These are tests involving humans.
This is shown by data from an international platform International Clinical Trials Registry Platform, which brings together registrations of studies of this type about to be initiated. To date, around 1,600 trials are actively recruiting volunteers or have already completed this stage of experiments, whether with drugs, some types of vaccines and even alternative therapies.
Clinical trials are required by health agencies to prove the safety and efficacy of a treatment, and its subsequent registration and commercialization.
In Latin America, Brazil is the country with the most clinical trials related to covid-19 planned or running in its territory: 159.
In the world, the leader is the United States, with 532.
In view of these thousands of bets, we present four experimental treatments against covid-19 that have shown advances in the last month, in Brazil and in the world.
1. Serum developed in Brazil
The National Health Surveillance Agency (Anvisa) gave the green light, last Wednesday (3/24), to the beginning of clinical tests with a serum developed by the Butantan institute, linked to the state government of São Paulo.
The serum, an injectable liquid rich in antibodies against the coronavirus, is intended for people already infected and seeks to slow the worsening of the disease, preventing, for example, from attacking the lung.
Guinea pig tests had “extremely” effective results, according to Butantan.
There is still no set date for starting, but the tests with people should start soon, according to BBC News Brazil Ana Marisa Chudzinski Tavassi, biochemist and director of the Institute’s Center for Development and Innovation.
The number of volunteers is also being defined, but due to the nature of the treatment, the scope is smaller than in vaccine tests. They are designed to be applied to the general population and have a preventive function – unlike treating someone already infected, as the serum does.
Butantan is responsible for the production and supply of other serums throughout the country, such as against rabies and snake venoms. In the treatment developed against the new disease, the coronavirus was isolated from a patient, multiplied, inactivated (so as not to trigger an infection) and applied to horses in a safe dose to avoid getting sick.
The animals function as “factories” of antibodies, produced in contact with the virus and then removed to form the serum applicable in humans.
“Mexico, 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”, points out Chudzinski.
“These serums were made to (attack) a piece of the virus’s spike protein. Our difference is that we work with the entire virus. This can be an advantage over variants that are out there, because the great variations are happening precisely in the spike protein. “
Spike is what is called the protein that fits in human cells to promote coronavirus infection.
“We have already worked in vitro with the P.1 and P.2 variants. We also saw, in the tests with guinea pigs, a clear reduction in viral load and the preservation of the lung one day after treatment”, says the director of Butantan, adding that there is still no published study with the results.
Clinical trials will verify, in phase 1, whether the serum is safe to use; in phase 2, what would be the ideal dosage; and in phase 3, if it is effective on a large number of people.
2. Antiviral starts testing
Another treatment under study that advanced to the first phase of clinical trials was an oral drug that is being developed by the pharmaceutical company Pfizer. The company announced on the 23rd that experiments with patients have started in the United States.
According to the company, the antiviral showed a “potent” action in in vitro tests in the laboratory and is designed to be used at the first symptoms of covid-19.
The Pfizer drug is a protease inhibitor – an enzyme essential for the virus to multiply.
“Protease is critical for the virus to develop, and drugs targeting it cut through some of the early stages of the infection – preventing the virus from replicating,” virologist Stephen Griffin of the University of Leeds told BBC News in England.
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 by 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 since research so far has shown that the treatment had little or no effect in reducing the mortality of hospitalized people.
For now, the first phase of clinical trials announced by Pfizer will mainly assess the safety of the drug, monitoring any adverse effects and changes in tests.
3. Cocktail: goals reached in the third phase
In phase 3, involving more than 4,500 participants, the tests with a cocktail developed by the pharmaceutical company Roche had good results announced also on the last day 23.
The cocktail, a combination of substances casirivimab e imdevimab with intravenous application, it sets up a type of treatment called monoclonal antibodies – when antibodies from a person who has recovered from the disease are selected and copied in the laboratory.
The volunteers were people infected with the coronavirus, not hospitalized, but at risk of worsening the disease.
According to the company, the cocktail reduced the risk of hospitalization and death by 70%, when compared to placebo (an innocuous 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. The adverse effects were not statistically significant in 1% of the patients.
There are several other experiments underway with the casirivimab e imdevimab, including in the Recovery project, a large-scale test suite in the United Kingdom with potential treatments for covid-19.
In a statement, Roche said it would share the results with American and European health agencies, indicating its intention to see the product registered and marketed. The pharmaceutical company also intends to disclose the data in a scientific publication.
4. Antiviral can accelerate virus elimination
In early March, on the 6th, the pharmaceutical companies MSD and Ridgeback presented preliminary results of a phase 2 clinical trial with the oral antiviral molnupiravir, involving 202 people infected with the coronavirus in the United States and not hospitalized.
According to a statement, after the fifth day of treatment, the viral load was reduced among those who received treatment. In addition, adverse effects were considered irrelevant and unrelated to the drug. Details and more results from phase 2, including the main objectives, will be released soon, according to the consortium.
Other phase 2 and 3 trials with the antiviral are also being carried out.
Molnupiravir inhibits the replication of RNA viruses such as SARS-CoV-2, and 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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