Here is some background as it appears to be entering Phase III.
An unexpected COVID-19 drug derived from a rare sea animal and historically used to treat cancer is found to be 27.5 times more effective than the Gilead Sciences’ popular coronavirus drug remdesivir, a study published in the journal Science on Monday revealed. The treatment, known as Aplidin or Plitidepsin, is developed by the Spanish drug company PharmaMar. It has clinical approval in some countries, such as Australia, for treating multiple myeloma, a form of bone marrow cancer. The drug was identified as a potential COVID-19 treatment in March 2020 by a team of scientists at the University of California, San Francisco. Since then, it has completed phase 1 and phase 2 clinical trials and is expected to enter a phase 3 trial before seeking regulatory approval. Last week, a related study (yet to be peer-reviewed) on Aplidin by scientists at University College London found that the drug is equally effective at combating the new COVID-19 variant recently discovered in Britain. Lab tests showed that Aplidin was effective when used against two different human lung and epithelial cells infected with the new viral strain.