19-nor-vitamin D compounds

A method for treating leukemia which comprises administering to a patient having leukemia at least one 19-nor-vitamin D compound in an amount sufficient to induce the differentiation of the malignant cells characteristic of leukemia to non-malignant macrophages, said 19-nor-vitamin D compound having the formula ##STR9## where X.sup.1 and X.sup.2 are each selected from hydrogen, acyl, alkylsilyl and alkoxyalkyl, and where R is selected from alkyl, hydrogen, hydroxyalkyl, fluoroalkyl and a side chain of the formula ##STR10## wherein R.sup.1 represents hydrogen, hydroxy or O-acyl, R.sup.2 and R.sup.3 are each selected from alkyl, hydroxyalkyl and fluoroalkyl, or, when taken together represent the group--(CH.sub.2).sub.m --where m is an integer having a value of from 2 to 5, R.sup.4 is selected from hydrogen, hydroxy, fluorine, O-acyl, alkyl, hydroxyalkyl and fluoroalkyl, R.sup.5 is selected from hydrogen, fluorine, alkyl, hydroxyalkyl and fluoroalkyl, or R.sup.4 and R.sup.5 taken together represent double-bonded oxygen, R.sup.6 and R.sup.7 are each selected from hydrogen, hydroxy, O-acyl, fluorine and alkyl, or, R.sup.6 and R.sup.7 taken together form a carbon-carbon double bond, and wherein n is an integer having a value of from 1 to 5 and wherein any of the groups --CH(CH.sub.3)--, --CH(R.sup.7)--, or --CH(R.sup.6)-- at positions 20, 22 and 23, respectively, may be replaced by an oxygen atom, with the proviso that when n is 2 to 5 each R.sup.4 is independently selected from hydrogen, hydroxy, fluorine, O-acyl, alkyl, hydroxyalkyl and fluoroalkyl, and each R.sup.5 is independently selected from hydrogen, fluorine, alkyl, hydroxyalkyl and fluoroalkyl.