Method of treating cancer with quinolone carboxylic acid derivatives

A method of treating a mammalian hyper-proliferative disorder comprising the administration to a patient in need thereof of an effective amount of a compound of Formula I

• wherein
• X represents a N atom or a group of the formula C—H, C—F or C—Cl;
• A represents phenyl, naphthyl, pyridyl, pyrimidyl or pyrazinyl, each of which is optionally substituted with one, two or three substituents each independently selected from NO2, CF3, CN, OH, halo, (C1-C8)alkyl, (C1-C8)alkoxy, (C1-C8)acyl and (C1-C8)alkythio;
• R1 represents H or (C1-C6)alkyl;
• R2 represents H or halo;
• R3 and R4 each independently represent H, benzyloxycarbonyl, (C1-C8)alkyl, or (C1-C8)acyl, or
• R3 and R4 together with the nitrogen atom to which they are attached form a 6-membered saturated heterocycle which additionally can optionally contain a further heteroatom selected from N, S or O;
• or a pharmaceutically acceptable salt or ester thereof.