Cabazitaxel-d9 is intended for use as an internal standard for the quantification of cabazitaxel (Item No. 22262) by GC- or LC-MS. Cabazitaxel is a second generation semisynthetic taxane derived from 10-deacetylbaccatin III (Item No. 22261).1 It stabilizes microtubule assembly by reducing lag time for tubulin assembly (LT50 = 100 nM) and the rate of cold-induced microtubule depolymerization (IC50s = 100-250 nM) in vitro. Cabazitaxel inhibits proliferation of P388, HL-60, Calc18, and KB cells (IC50s = 4-41 nM), as well as P-glycoprotein-expressing, drug-resistant versions of these cell lines (IC50s = 16-414 nM). In vivo, cabazitaxel dose-dependently reduces tumor growth in docetaxel-susceptible N87 human gastric carcinoma and docetaxel-resistant UISO BCA-1 breast cancer mouse xenograft models. Formulations containing cabazitaxel have been used in combination with prednisone in the treatment of hormone-refractory metastatic prostate cancer.WARNING This product is not for human or veterinary use.