A compound of the formula (I): wherein: A and B together represent an optionally substituted, fused aromatic ring; D is selected from: (i) where Y1 is selected from CH and N, Y2 is selected from CH and N, Y3 is selected from CH, CF and N; and (ii) where Q is O or S; RD is: wherein RN1 is selected from H and optionally substituted C1-10 alkyl; X is selected from a single bond, NRN2, CRC3RC4 and C═O; RN2 is selected from H and optionally substituted C1-10 alkyl; RC3 and RC4 are independently selected from H, R, C(═O)OR, where R is optionally substituted C1-10 alkyl, optionally substituted C5-20 aryl or optionally substituted C3-20 heterocyclyl; Y is selected from NRN3 and CRC1RC2. RC1 and RC2 are independently selected from H, R, C(═O)OR, where R is optionally substituted C1-10 alkyl, optionally substituted C5-20 aryl or optionally substituted C3-20 heterocyclyl; RC1 and RC2 together with the carbon atom to which they are attached may form an optionally substituted spiro-fused C5-7 carbocylic or heterocyclic ring; and when X is a single bond RN1 and RC2 may together with the N and C atoms to which they are bound, form an optionally substituted C5-7 heterocylic ring; and when X is CRC3RC4, RC2 and RC4 may together form an additional bond, such that there is a double bond between the atoms substituted by RC1 and RC3.