Abstract: The metabolism of tumor cells which have .beta.-glucuronidase activity is inhibited by administering to a patient a conjugate of glucuronic acid and a thiocarbamate compound of the formula: ##STR1## wherein R.sup.1 and R.sup.2 are selected from the group consisting of C.sub.1 -C.sub.6 alkyl and C.sub.1 -C.sub.6 cycloaliphatic, and M is selected from the group consisting of hydrogen, an electropositive, ionically bonded metal, and the radical ##STR2## and R.sup.3 and R.sup.4 are selected from the group consisting of C.sub.1 -C.sub.6 alkyl and C.sub.1 -C.sub.6 cycloaliphatic groups.