A method of treating a patient suffering from lymphoma comprising administering to said patient a therapeutically active amount of a compound formula I, or pharmaceutically acceptable salt or solvate thereof, wherein: the dotted lines indicate the optional presence of a double bond between C1 and C2 or C2 and C3 R2 and R3 are independently selected from H, =O, =CH2, -CN, -R, OR, halo, =CH-R, O-SO2-R, CO2R and COR R6, R7 and R9 are independently selected from H, R, OH, OR, SH, SR, NH2, NHR, NRR, nitro, Me3Sn and halo where R and R are independently selected from optionally substituted C1-12alkyl, C3-20heterocyclyl and C5-20aryl groups R" is a C3-12 alkylene group, which chain may be interrupted by one or more heteroatoms, e.g. O, S, NH, and/or aromatic rings, e.g. benzene or pyridine, and each X is independently selected from O, S, or NH R2, R3, R6, R7 and R9 are all independently selected from the same lists as previously defined for R2, R3, R6, R7 and R9 respectively.
