COVID-19: New drug candidates, treatments offer reasons for hope

In this Special Feature, we investigate the latest scientific findings that may provide a glimmer of hope among the COVID-19 crisis.

close up of scientist in PPE working with a blood sample

What are the new drug candidates?

A team of Chinese-based researchers found a new candidate drug against SARS-CoV-2, the coronavirus that causes COVID-19. The so-called protease of the virus — that is, a type of enzyme without which the virus cannot survive — was the starting point of the scientists’ efforts.

Using two compounds, which they dubbed 11a and 11b, the team managed to inhibit this protease. Then, they monitored the antiviral activity of these two compounds and found that the substances successfully fought the infection.

Finally, experiments in mice suggested that scientists could safely administer the two compounds via several routes, including an IV drip. However, final animal tests in rats and Beagle dogs revealed that 11a is less toxic, so the scientists focused on this one compound.

There is no human equivalent to the enzyme that the compound targets. And this, the researchers explain, minimizes the likelihood of severe side effects in humans.

Rather than developing new compounds from scratch, researchers led by Prof. Nevan J. Krogan, from the University of California San Francisco (UCSF) took another route and looked at existing drugs in search of suitable candidates for the fight against SARS-CoV-2.

These researchers used a special technique that helped them map all the human proteins that the new coronavirus needs to interact with to survive.

Next, the team looked at existing drugs that already target these proteins — be they FDA-approved or drugs that are in clinical or preclinical stages.

This interactive mapping technique yielded some antibiotics, some antimalarials (although these have dangerous toxic side effects), and, most importantly, a promising anticancer drug called PB28.

The scientists say that PB28, which is an experimental drug, was 20 times more potent than the antimalarial hydroxychloroquine at deactivating SARS-CoV-2. Furthermore, it may be a lot safer at higher doses.

However, Prof. Krogan and the team stress the importance of testing these compounds in animals and then in extensive clinical studies. They also note the limitations of their research, which they conducted in cell cultures.

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