Ricolinostat (ACY-1215, Rocilinostat) is a selectiveHDAC6inhibitor withIC50of 5 nM in a cell-free assay. It is >10-fold more selective for HDAC6 than HDAC1/2/3 (class I HDACs) with slight activity against HDAC8, minimal activity against HDAC4/5/7/9/11, Si In vitro
ACY-1215 is a hydroxamic acid derivative. ACY-1215 is 12-, 10-, and 11-fold less active against HDAC1, HDAC2, and HDAC3 (class I HDACs), respectively. ACY-1215 has minimal activity (IC50 > 1μM) against HDAC4, HDAC5, HDAC7, HDAC9, HDAC11, Sirtuin1, and Sirtuin2, and has slight activity against HDAC8 (IC50 = 0.1μM). The IC50 values for ACY-1215 for T-cell toxicity is 2.5μM. ACY-1215 overcomes tumor cell growth and survival conferred by BMSCs and cytokines in the BM milieu. ACY-1215 in combination with bortezomib induces synergistic anti-MM activity. ACY-1215 induces potent acetylation of α-tubulin at very low doses and triggers acetylation of lysine on histone H3 and histone H4 only at higher doses, confirming its specific inhibitory effect on HDAC6 activity.
In vivo
ACY-1215 in combination with bortezomib triggered more significant anti-MM activity than either agent alone in suppressing tumor growth and prolonging survival in both plasmacytoma model and disseminated MM model without significant adverse effects. ACY-1215 is readily absorbed by tumor tissue. Moreover, the drug does not accumulate in tumor tissue, as evidenced by the parallel decline of acetylated α-tubulin in blood cells and tumor tissue by 24 hours after dose. Cell Data
