The present invention relates to novel compounds and methods for the manufacture of inhibitors of deubiquitylating enzymes (DUBs) and/or desumoylating enzymes. In particular, the invention relates to the inhibition of ubiquitin C-terminal hydrolase 7 or ubiquitin specific peptidase 7 (USP7). The invention further relates to the use of DUB or desumoylating inhibitors in the treatment of cancer. Described herein are compounds of formula (I) or a pharmaceutically acceptable salt thereof, wherein R1a, R1b, R1c and R1d each independently represent hydrogen, optionally substituted C1-C6 alkyl or R1a and R1b together form an optionally substituted C3-C6 cycloalkyl ring, or R1c and R1d together form an optionally substituted C3-C6 cycloalkyl ring; A is a 5 membered nitrogen-containing aromatic ring and is substituted with at least one optionally substituted 5 to 10 membered monocyclic or bicyclic heteroaryl or aryl ring attached through an optional linker.