Compounds of formula (I) inhibit HDAC activity, wherein A, B and D independently represent ═C— or ═N—; W is a divalent radical —CH═CH— or CH
2
CH
2
—; R
1
is a carboxylic acid group (—COOH), or an ester group which is hydrolysable by one or more intracellular carboxyesterase enzymes to a carboxylic acid group; R
2
is the side chain of a natural or non-natural alpha amino acid; z is 0 or 1; and Y, L
1
, and X
1
are as defined in the claims.
The present invention relates to CDK inhibitors and their use in the treatment of cell proliferative diseases such as cancer. The compounds of the invention may further act as HDAC inhibitors.