A compound of formula I: a thiol form of the compound of formula I having a reduced S-S bond, a pharmaceutically acceptable salt of the compound of formula I, a hydrate of the compound of formula I, an anhydrous form of the compound of formula I, an acetylated form of the compound of formula I, a stereoisomer of the compound of formula I, or a mixture of said stereoisomers, for use in treatment of malignant fibrous histocytoma, liposarcoma, rhabdomyosarcoma, leiomyosarcoma, fibrosarcoma, malignant schwannoma, angiosarcoma or clear cell sarcoma.
