The results of Phase I trials have shown the drug, also known as Aplidin, had a powerful antiviral activity against all the variants in vitro and a distribution into the lungs of animals tested, resulting in a 99% reduction of viral load in the lungs, the company said.

The results of the trials were released in a paper published in the scientific journal Life Science Alliance, PharmaMar said.

The paper also reported positive effects of Phase I and II trials on patients.

“All data we have seen so far with Plitidepsin corroborate our initial hypothesis of its activity as antiviral,” PharmaMar’s Jose Maria Fernandez Sousa said in a statement.

The drug is being tested in final Phase III trials on patients.

Shares in PharmaMar rose 5.3% in early trading.

Plitidepsin is a drug developed by PharmaMar originally to treat cancer but has an effect as an antiviral.