Compounds of the formula (I): wherein A and B together represent an optionally substituted, fused aromatic ring; X can be NRX or CRXRY; if X=NRX then n is 1 or 2 and if X=CRXRY then n is 1; RX is selected from the group consisting of H, optionally substituted C1-20 alkyl, C5-20 aryl, C3-20 heterocyclyl, amido, thioamido, ester, acyl, and sulfonyl groups; RY is selected from H, hydroxy, amino; or RX and RY may together form a spiro-C3-7 cycloalkyl or heterocyclyl group; RC1 and RC2 are both hydrogen, or when X is CRXRY, RC1, RC2, RX and RY, together with the carbon atoms to which they are attached, may form an optionally substituted fused aromatic ring; and R1 is selected from H and halo.