Plitidepsin (also known as dehydrodidemnin B, marketed by PharmaMar, S.A. under the trade name Aplidin) is a chemical compound extracted from the ascidian Aplidium albicans.

[citation needed] Like all didemnin compounds, plitidepsin exhibits antitumor, antiviral and immunosuppressive activities.

[4] In July 2003, plitidepsin was granted orphan drug status by the European Medicines Agency for treating acute lymphoblastic leukemia.

[5] In December 2017, the EMA's Committee for Medicinal Products for Human Use (CHMP) adopted a negative opinion, recommending the refusal of the marketing authorization for the treatment of multiple myeloma.

In October 2018, PharmaMar appealed against this decision, alleging a lack of impartiality on the part of certain members of the Scientific Advisory Group that had advised the CHMP.