A compound having the Formula I: or a pharmaceutically acceptable salt thereof, wherein: A is N or CR 15; R 1 is H; or Ci-s alkyl, C 2-8 alkenyl, C 3-8 cycloalkyl, aryl or heteroaryl optionally substituted by any one, two or three of the following groups: halo, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, and halo C 1- C 6 alkyl; R 2 is a heterocyclic group, an aryl or a heteroaryl optionally substituted by any one, two, three or four of the following groups: C 1 -C 6 alkyl, C 1 -C 6 acyl, heterocyclic group, halo, oxy group, nitro and C 1 -C 6 alkylamino, wherein the C 1 -C 6 alkyl, the C 1 -C 6 acyl, the heterocyclic group, the oxy group and the C 1 -C 6 alkylamino are optionally substituted by 1-4 groups selected from the following groups: C 1 -C 6 alkyl, C 1 -C 6 acyl, a heterocyclic group optionally substituted by 1-4 of C 1 -C 6 alkyl, halo, -NR a R b and hydroxy, wherein R a and R b are independently H and C 1 -C 6 alkyl; R 3 -R 7 and R 15 are independently H, halo, amino, alkoxy, C 1-10 alkyl, haloalkyl, alkenyl, alkynyl, hydroxyalkyl, aminoalkyl, carboxyalkyl, nitro, cyano, acylamido, hydroxy, thiol, acyloxy, azido, carboxy, ethylenedioxo, hydroxyacylamino or alkylthiol; wherein the aryl is a C 6 -C 14 aryl; the heteroaryl is a group having 5 to 14 ring atoms, 6, 10 or 14 π electrons shared in a cyclic array, and containing, as ring atom, carbon atoms and 1-3 heteroatoms selected from oxygen, nitrogen and sulfur; and the heterocyclic group is a saturated or partially saturated 3-7 membered monocyclic, or 7-10 membered bicyclic ring system, which consists of carbon atoms and one to four heteroatoms independently selected from the group consisting of O, N and S; with the proviso that the compound is not 6-(2,6-dimethylphenyl)-2-((4-(4-methylpiperazin-1-yl)phenyl)amino)-8,9-dihydroimidazo[1,2-a]pyrimido[5,4-e]pyrimidin-5 -one. A is N or CR 15; R 1 is H; or Ci-s alkyl, C 2-8 alkenyl, C 3-8 cycloalkyl, aryl or heteroaryl optionally substituted by any one, two or three of the following groups: halo, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, and halo C 1- C 6 alkyl; R 2 is a heterocyclic group, an aryl or a heteroaryl optionally substituted by any one, two, three or four of the following groups: C 1 -C 6 alkyl, C 1 -C 6 acyl, heterocyclic group, halo, oxy group, nitro and C 1 -C 6 alkylamino, wherein the C 1 -C 6 alkyl, the C 1 -C 6 acyl, the heterocyclic group, the oxy group and the C 1 -C 6 alkylamino are optionally substituted by 1-4 groups selected from the following groups: C 1 -C 6 alkyl, C 1 -C 6 acyl, a heterocyclic group optionally substituted by 1-4 of C 1 -C 6 alkyl, halo, -NR a R b and hydroxy, wherein R a and R b are independently H and C 1 -C 6 alkyl; R 3 -R 7 and R 15 are independently H, halo, amino, alkoxy, C 1-10 alkyl, haloalkyl, alkenyl, alkynyl, hydroxyalkyl, aminoalkyl, carboxyalkyl, nitro, cyano, acylamido, hydroxy, thiol, acyloxy, azido, carboxy, ethylenedioxo, hydroxyacylamino or alkylthiol; wherein the aryl is a C 6 -C 14 aryl; the heteroaryl is a group having 5 to 14 ring atoms, 6, 10 or 14 π electrons shared in a cyclic array, and containing, as ring atom, carbon atoms and 1-3 heteroatoms selected from oxygen, nitrogen and sulfur; and the heterocyclic group is a saturated or partially saturated 3-7 membered monocyclic, or 7-10 membered bicyclic ring system, which consists of carbon atoms and one to four heteroatoms independently selected from the group consisting of O, N and S; with the proviso that the compound is not 6-(2,6-dimethylphenyl)-2-((4-(4-methylpiperazin-1-yl)phenyl)amino)-8,9-dihydroimidazo[1,2-a]pyrimido[5,4-e]pyrimidin-5 -one.