A compound of formula: wherein: ▪ R 1 represents: - a hydrogen atom, or - a -CO-R 4 unit or a -CO 2 -R 4 unit wherein R 4 represents a radical (C 1 -C 10)alkyl, (C 2 -C 10)alkylene, (C 3 -C 14)cycloalkyl, heterocycloalkyl, aryl, heteroaryl, (C 1 -C 6)alkyl-(C 3 -C 14)cycloalkyl, (C 1 -C 6)alkyl-heterocycloalkyl, (C 1 -C 6)alkyl-(C 3 -C 14)cycloalkyloxy, (C 1 -C 6)alkyl-heterocycloalkyloxy, (C 1 -C 6)alkyl-aryl, (C 1 -C 6)alkyl-aryloxy, (C 1 -C 6)alkyl-heteroaryl, or (C 1 -C 6)alkyl-heteroaryloxy, said radicals being optionally substituted by at least one (C 1 -C 6)alkyl group, one hydroxy group, one ketone, one (C 1 -C 6)alkoxy group, one carboxylic acid group eventually substituted by a (C 1 -C 6)alkyl group, one -NR 5 R 6 unit wherein R 5 and R 6 represent a hydrogen atom or a (C 1 -C 6)alkyl group, one halogen atom, one cyano group, or one nitro group; ▪ R 2 represents a hydrogen atom or a (C 1 -C 6)alkyl chain, preferably a hydrogen atom; and ▪ R 3 represents a hydrogen atom, or a (C 1 -C 6)alkyl chain, or (C 2 -C 6)alkylene, said chains being optionally substituted by at least one (C 1 -C 6)alkyl group, one hydroxy group, one -O-CO-(C 1 -C 6)alkyl unit, one ketone, one carboxylic acid group eventually substituted by a (C 1 -C 6)alkyl group, one -NR 5 R 6 unit wherein R 5 and R 6 represent H or a (C 1 -C 6)alkyl group, one halogen atom, one cyano group or one nitro group; or one of its pharmaceutically acceptable salts, for use in the treatment of cancer. ▪ R 1 represents: - a hydrogen atom, or - a -CO-R 4 unit or a -CO 2 -R 4 unit wherein R 4 represents a radical (C 1 -C 10)alkyl, (C 2 -C 10)alkylene, (C 3 -C 14)cycloalkyl, heterocycloalkyl, aryl, heteroaryl, (C 1 -C 6)alkyl-(C 3 -C 14)cycloalkyl, (C 1 -C 6)alkyl-heterocycloalkyl, (C 1 -C 6)alkyl-(C 3 -C 14)cycloalkyloxy, (C 1 -C 6)alkyl-heterocycloalkyloxy, (C 1 -C 6)alkyl-aryl, (C 1 -C 6)alkyl-aryloxy, (C 1 -C 6)alkyl-heteroaryl, or (C 1 -C 6)alkyl-heteroaryloxy, said radicals being optionally substituted by at least one (C 1 -C 6)alkyl group, one hydroxy group, one ketone, one (C 1 -C 6)alkoxy group, one carboxylic acid group eventually substituted by a (C 1 -C 6)alkyl group, one -NR 5 R 6 unit wherein R 5 and R 6 represent a hydrogen atom or a (C 1 -C 6)alkyl group, one halogen atom, one cyano group, or one nitro group; - a hydrogen atom, or - a -CO-R 4 unit or a -CO 2 -R 4 unit wherein R 4 represents a radical (C 1 -C 10)alkyl, (C 2 -C 10)alkylene, (C 3 -C 14)cycloalkyl, heterocycloalkyl, aryl, heteroaryl, (C 1 -C 6)alkyl-(C 3 -C 14)cycloalkyl, (C 1 -C 6)alkyl-heterocycloalkyl, (C 1 -C 6)alkyl-(C 3 -C 14)cycloalkyloxy, (C 1 -C 6)alkyl-heterocycloalkyloxy, (C 1 -C 6)alkyl-aryl, (C 1 -C 6)alkyl-aryloxy, (C 1 -C 6)alkyl-heteroaryl, or (C 1 -C 6)alkyl-heteroaryloxy, said radicals being optionally substituted by at least one (C 1 -C 6)alkyl group, one hydroxy group, one ketone, one (C 1 -C 6)alkoxy group, one carboxylic acid group eventually substituted by a (C 1 -C 6)alkyl group, one -NR 5 R 6 unit wherein R 5 and R 6 represent a hydrogen atom or a (C 1 -C 6)alkyl group, one halogen atom, one cyano group, or one nitro group; ▪ R 2 represents a hydrogen atom or a (C 1 -C 6)alkyl chain, preferably a hydrogen atom; and ▪ R 3 represents a hydrogen atom, or a (C 1 -C 6)alkyl chain, or (C 2 -C 6)alkylene, said chains being optionally substituted by at least one (C 1 -C 6)alkyl group, one hydroxy group, one -O-CO-(C 1 -C 6)alkyl unit, one ketone, one carboxylic acid group eventually substituted by a (C 1 -C 6)alkyl group, one -NR 5 R 6 unit wherein R 5 and R 6 represent H or a (C 1 -C 6)alkyl group, one halogen atom, one cyano group or one nitro group;