The invention concerns benzamide compounds of formula (I), wherein R1 is a C-linked pyrazole ring, which is optionally substituted by one or more groups selected from C1-4alkyl, C3-4cycloalkyl, C1-4alkoxy and C3-4cycloalkoxy; or a pharmaceutically acceptable salt or pro-drug form thereof. The invention also concerns processes for the preparation of such compounds, pharmaceutical compositions containing them and their use in the manufacture of a medicament for use as an antiproliferative agent in the prevention or treatment of tumors or other proliferative conditions, which are sensitive to the inhibition of histone deacetylase (HDAC).