OST-01

**OST-01** is a novel natural product extracted from the plant *Baccharis coridifolia*, traditionally known as "mío-mío" in Uruguay. It exhibits potent antileukemic activity, particularly against acute myeloid leukemia (AML) blasts and leukemia stem cells (LSCs), by disrupting c-Myc-dependent ribosome biogenesis through inhibition of the deubiquitinase USP36, leading to ubiquitination and degradation of c-Myc and nucleolar proteins like NPM1 and nucleostemin. OST-01 inhibits proliferation, colony formation, and induces apoptosis in AML cell lines and primary LSC-enriched cells while sparing normal hematopoietic stem cells; it also shows efficacy in multiple AML mouse models and synergizes with venetoclax. Broader preclinical anticancer activity has been observed in glioblastoma, lung, colorectal, triple-negative breast, ovarian, and pancreatic cancers, targeting cancer stem cells via suppression of "stemness" signaling, with ongoing purification identifying active compounds like (2E)-21-Hydroxy-2-henicosenoic acid.[1][2][3][5][10]