The invention provides a combination therapy. A pharmaceutical combination comprises (a) a compound of formula (I), [Chemical formula should be inserted here as it appears on Abstract in paper form] or pharmaceutically acceptable salts thereof; and (b) one or more at least one compound targeting, decreasing or inhibiting the intrinsic ATPase activity of Hsp90 and/or degrading, targeting, decreasing or inhibiting the Hsp90 client proteins via the ubiquitin proteosome pathway; the uses of such combination in the treatment or prevention of proliferative diseases; and methods of treating a subject suffering from a proliferative disease; and methods of treating a subject suffering from a proliferative disease comprising administering a therapeutically effective amount of such combination.