Treatment of malignancies

A method for treating cancer comprising administering a compound of formula I, or a salt thereof, to an animal in need thereof:

• wherein:
• R1 is alkylaryl or arylalkylene, optionally substituted with one to three (1-3) alkyl, alkoxy, halide, or CF3 groups;
• R2 is phenyl or -phenyl-N(R4)2, wherein each R4 is independently hydrogen, acyl, alkyl, aminoalkyl, formimideamide, thioalkyl, alkylenethiol, aminosulfonyl, sulfonylamine, sulfonylaminoalkyl, aryl, arylalkylene, arylsulfonyl, sulfonylalkylenearyl, cycloalkyl, alkylenecycloalkyl, cycloalkylalkyl, cycloalkylsulfonyl or sulfonylcycloalkyl, wherein the aryl or cycloalkyl is optionally substituted with one to three (1-3) hydroxy, alkoxy or halide groups or
• R4, and the nitrogen to which it is attached, form a guinidinyl group;
• R3 is phenyl or benzyl optionally substituted with halide or alkoxy;
• R5 is phenyl;
• and
• R6 is alkoxy.