A method of inhibiting mammalian topoisomerase II and inhibiting the growth and inducing the regression of malignant cells in mammals by the action of a (S)-3-methyl-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine or -benzothiazine of the formula ##STR1## wherein R.sub.1 is hydrogen or fluoro, R.sub.2 and R.sub.3 each independently is hydrogen or alkyl having 1 to 4 carbon atoms, and X is O, S or S=O; a pharmaceutically acceptable acid-addition salt thereof; or a salt thereof with a pharmaceutically acceptable cation; and certain novel compounds of formula I.
一种通过使用(S)-3-甲基-7-氧代-2,3-二氢-7H-
吡啶[1,2,3-de][1,4]苯并
噁唑或
苯并噻唑来抑制哺乳动物拓扑异构酶II并抑制哺乳动物恶性细胞的生长和诱导其退化的方法,该化合物的
化学式为##STR1##其中R.sub.1为氢或
氟,R.sub.2和R.sub.3各自独立地为1至4个碳原子的氢或烷基,X为O、S或S=O;其药学上可接受的酸加成盐;或其与药学上可接受的阳离子的盐;以及某些新的化合物I的方法。