Method of inhibiting neoplastic cells with indole derivatives

A method of treating a mammal having precancerous lesions sensitive to the compounds of formula I comprising administering to said mammal a pharmacologically effective amount of a compound of Formula I:

• wherein R1 to R3 each represent hydrogen, a lower alkyl group, an oxy group, an oxy-lower alkyl group, a lower alkyloxy group, a carbonyl group, a lower alkenyl group, an optionally-substituted imino group, a lower alkylimino group optionally substituted at its nitrogen atom, a thio-lower alkyl group, or a lower alkylthio group, wherein any of said group is optionally substituted by an aryl or a heterocyclic substituent, wherein said substituent optionally is further substituted by any of a halogen atom, a nitro group, a lower alkylamino group, an acylamino group, a lower alkyl group, a lower alkoxy group, a halo-lower alkyl group, a lower cycloalkyl group, or an aryl, heterocyclic, aryl-lower alkyl, heterocyclic-lower alkyl, aryl-lower alkyoxy, heterocyclic-lower alkyloxy, aryl-lower alkenyl or heterocyclic-lower alkynyl group that in turn is optionally substituted by any of a halogen atom or a lower alkyl group, with the proviso that R1 to R3 are not simultaneously hydrogen atoms;
• R4 is selected from the group consisting of hydrogen atom or lower alkyl;
• R5 is selected from the group consisting of carboxyl, an esterified carboxyl group, or an amidated carboxyl group.