ansamitocin P3

**Ansamitocin P3** is a natural ansamycin macrolide and maytansine analog, originally isolated from the bacterium **Actinosynnema pretiosum** and identified in some plant sources. It is a potent antitumor agent, well-known for its use as a cytotoxic "payload" in certain antibody-drug conjugates (ADCs), such as trastuzumab emtansine, for targeted cancer therapy. Mechanistically, ansamitocin P3 binds to **β-tubulin** in eukaryotic cells at the maytansine-binding site, thereby inhibiting microtubule assembly, causing microtubule disassembly, and leading to disruption of mitosis, cell cycle arrest, and apoptosis. It also acts as a maturation inducer of dendritic cells and has immunomodulatory effects that can synergize with immune checkpoint blockade therapies. In bacteria, its cytotoxicity relates to binding to **FtsZ**, an important cell division protein structurally analogous to β-tubulin[1][2][3][4][5][6][7][10].

Other names

ansamitocin P3ansamitocin P-3Ansamitomicin P-3Antibiotic C 15003P3Maytansinol isobutyrateNSC-292222NSC292222NSC 292222