HNHA exhibited the most potent anti-tumor effects in RCC xenografts. HNHA induced more potent inhibition of tumor progression than the established HDAC inhibitors and resulted in the greatest prolongation of survival in Caki-1 (A, B) and A-498 (C, D) xenografts. ‘No tumor’ indicates HNHA-, TSA- and SAHA-treated mice without a xenograft in panels (E) and (F). Each group = 10 mice, survival curves for 63 days. Mean body weights on days 1, 3, 5, 7, 9, 11, 13, 15, 17 and 19 of mice treated with HNHA, TSA and SAHA on Caki-1 (G) and A-498 (H) xenografts (Each group = 10 mice). *P < 0.05 vs. Control, **P < 0.01 vs. Control, ***P < 0.005 vs. Control.