A therapeutic method is provided to inhibit tumor cell growth in a subject in need of said therapy is provided, comprising parenterally administering a therapeutic amount of a compound in a pharmaceutically acceptable carrier, wherein said compound has the structure: ##STR1## wherein R is selected from the group consisting of: ##STR2## and wherein said tumor cell is sensitive to inhibition by said compound and is selected from the group consisting of a myeloid leukemia cell, a T-cell leukemia cell, a lung carcinoma cell, an ovarian carcinoma cell, and a breast carcinoma cell.