Kinase inhibitors, prodrug forms thereof and their use in therapy

The invention provides kinase inhibitors of Formula I: wherein either: (1) R1 is H, and (a) R2 is (3-chlorobenzyl)oxy-and R3 is chloro; (b) R2 and R3, together with the carbon atoms to which they are attached, form 1-(3-fluorobenzyl)-1H-pyrazole; (c) R2 is 2-pyridinylmethoxy and R3 is chloro; (d) R2 and R3 are both chloro; (e) R2 is chloro and R1 is bromo; (f) R2 and R3 are both bromo; (g) R2 is fluoro and R3 is ethynyl; (h) R2 is chloro and R3 is ethynyl; (i) R2 is bromo and R3 is ethynyl; (j) other than when R1 is in the 3-position in combination with R3, in the 4-position, R2 is bromo and R3 is fluoro; (k) R2 is 2-pyridinylmethoxy and R3 is fluoro; or (l) R2 is 2-pyridinylmethoxy and R1 is bromo; or (2) at least one of R1, R2 and R3 is selected from benzyloxy, 3-chlorobenzyloxy and 2-pyridinylmethoxy and when at least one of R1, R2 and R3 is not benzyloxy, 3-chlorobenzyloxy or 2-pyridinylmethoxy, each of the others is independently selected from H, halogen, and C2-C4 alkynyl, with the proviso that when one of R1, R2 and R3 is benzyloxy or 2-pyridinylmethoxy, the other two of R1, R2 and R3 are not H; or (3) two of R1, R2 and R3, together with the carbon atoms to which they are attached, form 1-(3-fluorobenzyl)-1H-pyrazole; and the other is selected from H, halogen and C2-C4 alkynyl. Also provided are reductive prodrugs, comprising a kinase inhibitor as defined above and a reductive trigger linked directly or indirectly to a nitrogen of the kinase inhibitor. Further provided are pharmaceutical compositions, comprising the kinase inhibitors or the prodrugs, and the use of such compositions in therapy, in particular for treating cancer.