Chloroquine, an old drug for the new coronavirus?

It's the story of an old drug that is coming back to the fore. The success, announced on Monday March 16 in Marseilles, of the treatment with chloroquine - a molecule used to fight against malaria - of patients contaminated by Covid-19 caused a lot of noise in this period of galloping epidemic which forced all France containment.

Didier Raoult, director of the Institut hospitalo-universitaire (IHU) Méditerranée Infection de Marseille (Bouches-du-Rhône), explained that he had conducted a clinical trial during which he had treated 25 people contaminated by the coronavirus with chloroquine. After six days, there were only 25% of patients who took this drug which still had the virus in the body, supports this specialist. In contrast, 90% of those who had not taken chloroquine continued to carry Covid-19.

Tested for the Covid-19, after Sras, Mers or Zika

In the wake of this announcement, the Sanofi laboratory offered to offer millions of platelets of Plaquenil (one of the trade names of chloroquine) to continue the tests, while Sibeth Ndiaye, government spokesperson, judged the "promising results" and promised to expand clinical trials of this treatment.

Several media have even reported that pharmacies have been overwhelmed by the demand for this drug in the past two days. Rapidly, the calls for caution multiplied and several experts stressed that clinical results had to be put into perspective. "This is a study that seems promising, but we must be careful before raising hope with a virus as new as this one for which we do not yet have a lot of data", underlines Sarah D ' Alessandro, doctor of molecular medicine at the University of Milan and malaria specialist who worked on chloroquine, contacted by France 24.

Chloroquine is a drug that comes out of the drawers systematically or almost when a new virus appears. Scientists "suspect that this molecule is altering the ability of a virus to attach to a host cell, which could prevent it from entering it to start multiplying," said Robin May, an infectious disease specialist at University of Birmingham. Chloroquine, which has been available and used for a long time, is also "very well known, inexpensive and can be produced in large quantities quickly," notes Sarah D'Alessandro.

Benefits that explain why research has been conducted to test its effectiveness against Zika, SARS (Severe Acute Respiratory Syndrome) or even Seas (Coronavirus of the Middle East Respiratory Syndrome). Didier Raoult is not the first to take an interest in the Covid-19 either. In China, 25 clinical trials have been conducted or are underway to assess the advisability of using this treatment for infected people.

"Contrasting results" in human patients

It is, moreover, a Chinese study published on March 9 which first put the spotlight on this anti-malaria weapon in the context of the current pandemic. Researchers from the University of Beijing demonstrated the effectiveness of this molecule in an in vitro clinical trial, that is to say on cells in the laboratory. This is the whole problem of chloroquine: "Tests on human patients [for viral infections other than malaria, editor's note] have so far always produced contrasting results, difficult to interpret," recalls Sarah D 'Alessandro.

Hence the interest of Didier Raoult's work in Marseille. He is the first to present trials that appear to be conclusive in human patients. But then again, watch out for the runaway. First, because "the precise data of this clinical trial have not yet been published [in a scientific journal, editor's note] and therefore have not yet been able to be evaluated by peers", recalls MedScape, a site at destination of health professionals.

Then, "because the trial was only carried out on few patients", underlines Sarah D'Alessandro. The Chinese study of March 9 had also been criticized by the scientific community because it involved contaminated cells of "only" 100 patients ... four times more than the experiment conducted in Marseille. Sibeth Ndiaye also stressed the importance of conducting trials on a larger scale before concluding on the effectiveness of chloroquine.

But this drug was rightly excluded from the European program of large-scale clinical trial, launched on March 12, and aiming to test the effectiveness of four treatments which have already proven themselves against other viruses, like Ebola. Chloroquine was not chosen, in particular, because it does not work well with other medicines which may be necessary for certain patients with other conditions in addition to Covid-19, in particular certain autoimmune diseases. But this treatment also presents risks of poisoning, and can be fatal if it is incorrectly dosed. Even if this danger is now well under control in a hospital environment, the risk of accident cannot be completely ruled out. Inserm, which is piloting the European clinical trial program, has however recognized that if additional proof in human patients of the efficacy of this molecule is brought, chloroquine could be added to the list of drugs prescribed during the trials Europeans.

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