Baccatin III, which is the precursor for the semisynthesis of paclitaxel,exerts anti-tumor immunomodulatory activity in very low doses (0.05-0.5mg/kg),it reduces tumor progression by inhibiting the accumulation and suppressive function of MDSCs. Baccatin III also exerts immunomodulatory activities in vivo as well as in vitro on the MHC-restricted antigen presentation. Baccatin III is a tetracyclic diterpenoid isolated from plant species of the genus Taxus. It has a role as a plant metabolite. It is a benzoate ester, an acetate ester and a tetracyclic diterpenoid. It derives from a hydride of a taxane.