We designed and synthesized hydroxamic acid derivatives bearing a 4-(3-pyridyl) phenyl group as a cap structure, and found that they exhibit potent histone deacetylase (HDAC) inhibitory activity. A representative compound, 17a, showed more potent growth-inhibitory activity against pancreatic cancer cells and greater upregulation of p21WAF1/CIP1 expression than the clinically used HDAC inhibitor suberoylanilide hydroxamic acid ( ...