4.9. Plitidepsin (Aplidin)
It is a cyclic depsipeptide natural product (Figure S5) that is extracted from Aplidium albicans [186]. It is used for acute lymphoblastic leukemia and, with dexamethasone, for patients with refractory and relapsed multiple myeloma [187]. Recently, the molecule was reported to have in vitro nanomolar potency against the human coronavirus 229E [188]. The mechanism is thought to be similar to its anticancer activity, i.e., targeting eukaryotic translation elongation factor 1-α1, which has been reported to play an unexpected role in the replication and pathogenesis of various RNA viruses [189,190]. The drug is being tested in phase 1 trial in patients with COVID-19 (NCT04382066; n = 27).