Study Reports Promising Results from In Vitro Combination Therapy Against COVID-19

A team of researchers has reported promising results from an in vitro combination therapy against COVID-19.

Researchers at the Karolinska Institutet (Stockholm, Sweden) have shown that a combination of Gilead Sciences’ (Foster City, CA, USA) antiviral drug remdesivir that is approved against COVID-19, and hrsACE2, a medicine currently in Phase 2 trials for COVID-19 treatment, reduced the viral load of SARS-CoV-2 and inhibited viral replication in cell cultures and organoids.


Remdesivir, the only approved drug against COVID-19 disease, works by inhibiting an enzyme that prevents the virus from multiplying. In high doses, however, it can cause damage to the liver and the lungs. Human recombinant soluble ACE2 (hrsACE2) is a genetically modified variant of the cell membrane protein angiotensin converting enzyme 2 (ACE2) that the coronavirus uses to enter our cells. Previous laboratory studies have shown that hrsACE2 lures the coronavirus to attach itself to the enzyme copy, hrsACE2, instead of to the actual cells, thereby reducing the viral load in cells.

In this study, the researchers tested combining remdesivir and hrsACE2 in cell cultures from monkeys, liver spheroids and 3D kidney replicas, so-called organoids grown from human stem cells. By combining these two substances, the researchers were able to achieve a dual effect: reduced viral load and reduced viral proliferation to nearby cells. In addition, they achieved this effect with comparably low doses of each substance, which lowered their toxicity and made them safer to use.

“By targeting different aspects of the viral cycle simultaneously, we may be able to increase the effectiveness of the treatment while reducing the risk for potential side-effects,” said Ali Mirazimi, corresponding author and adjunct professor in the Department of Laboratory Medicine, Karolinska Institutet. “Combination therapy is a model that has been used successfully in HIV therapeutics. So far, we have only tested our combination therapy in cell cultures and engineered tissues, but we hope that it can pave the way for clinical trials.”

Related Links:
Karolinska Institutet
Gilead Sciences