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Monoclonal antibodies, ivermectin, Xenothera: update on treatments against covid-19 – Coronavirus

The vast majority of people with covid-19 have recovered with rest, proper hydration, and medication for pain and fever. Unfortunately, a significant proportion of patients can be the victim of a serious form and be taken to hospital, sometimes in intensive care. To avoid getting there, treatments exist, and others are being evaluated. However, the miracle pill has yet to be discovered. For most scientists, vaccination remains the only hope to eradicate the pandemic and prevent millions of deaths.

A “significant advance” with dexamethasone

Validated by the health authorities of several countries, dexamethasone, a corticosteroid, has become the routine treatment for covid-19 in a specific setting: it is prescribed to hospitalized people who need respiratory assistance. They undergo, in fact, an overreaction of their immune system with damage to the lungs and other organs that can lead to death. The evidence for the anti-inflammatory efficacy of dexamethasone was provided during the Recovery study which involved more than 6,000 patients. Those who received it were less likely to die within 28 days than those who received standard treatment. Another advantage of this drug is that it is readily available and inexpensive. The independent journal Prescrire considers that it represents “significant progress” in the management of severe forms.

Tocilizumab, the other remedy for severe forms

After dexamethasone, tocilizumab was the second treatment recognized by the World Health Organization (WHO) to treat severe cases of covid-19. Again, it is recommended for patients who need supplemental oxygen or mechanical ventilation. Already approved against several autoimmune diseases, tocilizumab is a monoclonal antibody. How does it work ? A covid patient may experience an overreaction of their body’s immune system. During this “cytokine storm”, a protein involved in inflammation, interleukin-6 (IL-6), is produced in excess in lung cells. Tocilizumab blocks the action of IL-6 and thus attenuates the exaggerated immune response. Clinical trials have shown that the combination of this drug with corticosteroids reduced the risk of death or to be placed on a ventilator. The length of stay in hospital is also shortened. The price of an injection? 800 euros.

Monoclonal antibodies, expensive but promising

Since March 15, the French drug agency, ANSM, has authorized access to two dual monoclonal antibody therapies (casirivimab / imdevimab) from Roche and bamlanivimab / etesevimab from Lilly France) to treat adult patients at high risk of developing a severe form of covid-19. This, within the framework of a temporary authorization of use. And since June 11, they can be offered to children over 12 years old. In addition, the European Commission announced at the end of July that it had signed a contract with the GSK laboratory for the supply of 220,000 Sotrovimab monoclonal antibody treatments.

The administration of these treatments must be done within a maximum of five days after the onset of symptoms, in the form of a single infusion given in a health establishment. The price of an injection is around 1,500 euros.

These synthetic monoclonal antibodies are similar to the antibodies our bodies naturally produce to fight invaders. The treatments authorized in France attack the spike protein of the coronavirus.

Among the evidence for effectiveness, a publication from the Regeneron laboratory, Roche partner, dated June 2021. It has shown an advantage for hospital patients who have not been able to develop their own immune response, reducing the risk of death by 20%. The use of these treatments remains convincing against the Delta variant: in a study published in early July, the Institut Pasteur has established that three of the four antibodies tested remained effective against this strain. One of them – bamlanivimab -, on the other hand, was losing its antiviral activity.

Our live on covid-19

Ivermectin, miracle treatment or false hope?

Ivermectin is an antiparasitic treatment that is the subject of a veritable rush to pharmacies in several countries which are experiencing a lightning wave of covid-19. In Indonesia, South Africa, Brazil, the phenomenon is fueled by the anti-vaccine movement and conspiracy theories circulating on the Internet. The manufacturer, Merck, however indicated that the possibility of a “potential therapeutic effect against covid-19 has no scientific basis” and warned of possible risks if the drug was not correctly administered. Many scientists, the WHO and health agencies in several countries have all pointed to the lack of credible evidence of a positive impact of ivermectin against the coronavirus. The World Health Organization has formally recommended that this drug be administered only in clinical trials. Researchers from the Institut Pasteur have nevertheless shown that it would protect from symptoms of covid-19 in an animal model. Scientists have observed that its intake is associated with a limitation of the inflammation of the respiratory tract and the symptoms which result from it, but it does not show any effect on the replication of the virus.

A polyclonal antibody “made in Nantes”

In France, one of the greatest hopes for the discovery of an effective treatment rests on the Nantes-based biotech Xenothera, which is working on “XAV-19”, a polyclonal antibody. Unlike monoclonal antibodies which target a single antigen on the virus, polyclonal antibodies target several. The results of the phase 2 trials are expected in the next few weeks, while those of phase 3 are expected in six to eight months. The European Medicines Agency, AEM, has globally validated the XAV-19 protocol, and a marketing authorization is expected within 12 to 18 months. The French government has pre-ordered 30,000 first doses and if the Haute Autorité de santé decides to grant early access authorization, XAV-19 could be offered to French patients from October 2021.

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