The present invention relates to the use of the compound according to formula(I), below for the treatment of tumors, cancer and hyperproliferativediseases, among other conditions or disease states: Where X is H or F； R1 andR2 are independently H, an acyl group, a C1 - C20 alkyl or ether group, aphosphate, diphosphate, triphosphate or a phosphodiester group, a (A) or (B)group； Where Nu is a radical of a biologically active compound such as ananticancer, antiviral or antihyperproliferative compound such that an aminogroup or hydroxyl group from said biologically active agent forms a phosphate,phosphoramidate, carbonate or urethane group with the adjacent moiety； each R8is independently H, or a C1-C20 alkyl or ether group, preferably a C1-C12alkyl group； k is 0-12, preferably, 0-2； and pharmaceutically acceptable saltsthereof.
