Tasidotin hydrochloride

Tasidotin hydrochloride is a peptide analog of the antimitotic depsipeptide dolastatin 15, as an inhibitor of microtubule assembly and microtubule dynamics. IC50 & Target: Microtubule^[1] In Vitro: Compared with other breast carcinoma lines, relatively low amounts of Tasidotin enters NCI/ADR-RES cells, consistent with Tasidotin's also being a P-glycoprotein substrate. Of the remaining lines, the greatest difference in sensitivity to Tasidotin is between the more sensitive MDA-MB-435 line and the less sensitive HS 578-T line. The IC₅₀ values in the two lines are 4 and 200 nM, respectively^[1]. The IC₅₀ in Ewing's sarcoma, rhabdomyosarcoma, osteosarcoma, and synovial sarcoma lines ranges from 2 to 320 nM. In the SK-ES1 and RH30 cell lines, Tasidotin induces a G₂-M arrest that persists for 48 h after Tasidotin is washed from the cells. In vitro, more than half the cells are in the early or late phase of apoptosis 48 h after treatment with Tasidotin. Following treatment for 24 h with 160 nM Tasidotin, the RH30 line and SK-ES1 line each shows an accumulation of cells in the G₂-M phase. At hour 24, nearly all the RH30 cells are in the G₂-M phase^[2]. In Vivo: In vivo, a significant increase in apoptotic nuclei is apparent in xenograft tumors harvested within 24 h after a 5-day course of Tasidotin. Mice treated with 100 mg/kg have a mean weight loss of >20% with no return to their baseline starting weight, and one mouse dies before the second treatment course. The mice treated with 90 mg/kg/d Tasidotin have a mean weight loss of <16% following each 5-day treatment of Tasidotin^[2].