This invention relates to compositions including a compound of Formula I wherein R is selected from a C.sub.1-C.sub.6 alkyl, unsubstituted phenyl or phenyl substituted by one or more halo, C.sub.1-C.sub.6 alkyl or C.sub.1-C.sub.6 alkoxy, combinations of a compound of formula I with other chemotherapeutic agents, and the use of the compositions or combinations for the treatment of cellular proliferative disorders.