Substituted quinazolines

A compound of Formula (I) or a pharmaceutically acceptable salt or solvate thereof

• wherein:
• R1, R2, R3 and R4 independently represent hydrogen or a blocking group which functions to prevent metabolic reaction at the position of substitution;
• or wherein R1 and R2, and/or R3 and R4 together with the carbon to which they are attached form a blocking group which functions to directly or indirectly prevent metabolic reaction at the 3-position, the remainder of groups R1 to R4 being hydrogen;
• R5 is selected from the group comprising:
• fluoro, chloro, bromo and iodo;
• R6 is selected from the group comprising:
• fluoro, chloro, bromo and iodo;
• R7 and R8 are independently selected from the group comprising:
• H;
• halo;
• cyano;
• C1-6 alkyl, C1-6 haloalkyl, C1-6 alkoxy, and C1-6 haloalkoxy;
• and
• R9 is H, C1-6 alkyl, or a Group I metal ion;
• provided always that R1, R2, R3 and R4 are not all hydrogen, or that when one of R1 and R2 is methyl and R3 and R4 are hydrogen then other of R1 and R2 is not hydrogen.