Deacetylase inhibitors as a novel modality in the treatment of multiple myeloma.

Deacetylase enzymes remove acetyl groups from histone and nonhistone proteins. Dysregulation of deacetylase activity is a hallmark of malignancy, including multiple myeloma (MM). Deacetylase inhibitors (DACi) cause epigenetic modification and inhibition of the aggresome pathway, resulting in death of MM cells. Panobinostat, a pan-DACi, has shown significant clinical benefit and is the first DACi approved for the treatment of MM. It is approved for use in combination with bortezomib and dexamethasone for the treatment of patients with relapsed or relapsed and refractory MM who have received ≥2 prior regimens including bortezomib and an immunomodulatory drug. Ricolinostat and ACY-241, which selectively inhibit HDAC6 and the aggresome pathway, are currently being studied in combination with dexamethasone and bortezomib or an immunomodulatory drug for the treatment of relapsed and refractory MM. In this review, we discuss the data from key clinical trials investigating deacetylase inhibitors as novel treatment options for MM.