A cyclopenta[g]quinazoline derivative, containing an L-Glu-γ-D-Glu dipeptide group, of formula (I): wherein R1 is amino, C1-4 hydroxyalkyl, C1-4 fluoroalkyl or methoxy-C1-4-alkyl； R2 is hydrogen, C1-4 alkyl, C3-4 alkenyl, C3-4 alkynyl, C2-4 hydroxyalkyl C2-4 halogenoalkyl or C1-4 cyanoalkyl； and Ar is phenylene, thiophenediyl, thiazolediyl, pyridinediyl or pyrimidinediyl which may optionally bear one or two substituents selected from halogeno, hydroxy, amino, nitro, cyano, trifluoromethyl, C1-4 alkyl and C1-4 alkoxy, the compound (I) optionally being in the form of a pharmaceutically acceptable salt or ester； may be used for the treatment of rheumatoid arthritis or acute myeloid leukaemia.
