On Thursday, the White House took notice.
President Donald Trump said he had directed the Food and Drug Administration to investigate whether chloroquine, which is available by prescription only, should be given to patients with the virus. Bayer, the international drugmaker, then noted in a press release that it would donate 3 million tablets of the drug Resochin, or chloroquine phosphate, to U.S. patients. Trump also pointed to another existing drug, remdesivir, an anti-viral developed by drugmaker Gilead, which is already being used in China to treat COVID-19.
Neither drug is currently approved by the FDA to treat the coronavirus. So it is important "not to provide false hope," FDA Commissioner Stephen Hahn said at the White House’s daily press briefing. But Trump has "asked us to be aggressive" and "break through exciting, lifesaving treatment, and we’re doing that at the FDA," he added.
Early promising data
So what is chloroquine, and why is it considered so promising by the scientific community?
The drug has been around since the 1940s and is known for being generally safe and well tolerated in mild to moderate doses, although it can be toxic in high doses. It has been used to treat malaria, in addition to some autoimmune disorders. It is available as a generic, which means it could be a scalable and potentially affordable treatment.
"Nothing is definitive yet, but chloroquine is a drug used for more than 70 years with minimal side effects at a modest dosage," said Pellini.
Malaria is caused by a parasite, not a virus. But some studies have found that chloroquine has been effective at treating a virus that causes severe acute respiratory syndrome, or SARS, a close relative of COVID-19. It is also being studied at research labs throughout the world as a way to alleviate symptoms for patients diagnosed with COVID-19.
"It has been found in mice to be effective to treat a variety of viruses," noted Dr. Kristian Olson, an associate professor at Harvard Medical School and internal medicine physician at Massachusetts General Hospital. "It also appears it’s active in vitro (via test tube experiments) against COVID-19."
Some of the early data is promising. A group of researchers in France are testing a less toxic derivative of the chloroquine drug called hydroxychloroquine on a few dozen patients with COVID-19, and early reports of the trial indicate that the drug might help shorten the amount of time that people with the disease are infectious.
Because of these early signs, some biotech experts say it’s worth putting more research dollars into studying the drug.
"I don’t see Trump’s willingness to jump into humans quickly (to test the drug) as a panicked response," said Vas Bailey, a life sciences-focused investor at Artis with a Ph.D. in biomedical engineering from the Johns Hopkins School of Medicine. "It could be a potentially efficient way of using real-world evidence to help us triage which of these safe drugs will work in alleviating symptoms and treating COVID-19."
Lack of concrete evidence and lots of unknowns
But we’re still far from having an approved treatment for COVID-19, and the evidence behind chloroquine is not firm.
As Bailey points out, there is no data yet from a randomized clinical trial, which is considered the gold standard to minimize the possibility of bias in the findings. One of the biggest problems, scientists say, is that the tests have not been blinded. If physicians have prior knowledge of the intervention, that might influence how to treat the patient. That introduces other variables that are hard to separate from the effect of the drug.
There’s also further work needed to understand whether the drug reduces hospital time and mortality rates, and whether it impacts ventilation use. There are also some big unknowns about when, how and to whom the drug should be administered.
"What I don’t know, and I don’t think anyone knows is the degree of anti-viral activity and if it can be used to treat the most critical patients," said Olson.
"We still also don’t understand the optimal dose treatment for covid-19, and whether it might be used at a lower dose for prophylaxis (meaning to take preventatively) than for treatment."
As Olson points out, there are still side effects, like nausea and vision issues, and it remains to be seen whether the drug will be tolerated well in very sick patients. Furthermore, overdosing on the drug in high doses can cause serious health outcomes.
Because of these gaps in understanding, the World Health Organization said last month that there is "no proof" the drug is effective in treating the coronavirus.
Overall, however, some biotech experts say there’s some reason for optimism that the drug can help. "You wouldn’t see qualified medical professionals from China, France, and Korea looking into this if there wasn’t something to it," Bailey said.