A potent histone deacetylase (HDAC) inhibitor (ID₅₀ values of 0.01 and 0.07 μM in vitro for HDAC1 and HDAC3, respectively). CBHA also induces apoptosis in nine different neuroblastoma cell lines in culture (0.5-4.0 μM) and completely suppresses neuroblastoma tumor growth in SCID mice at 200 mg/ kg.