HDAC9 and AL amyloidosis: To date, numerous HDAC inhibitors are in various stages of clinical research; vorinostat (SAHA), beristatin (PXD101), and bilestat (LBH589) are approved for the clinical treatment of cutaneous T cell lymphoma, peripheral T cell lymphoma and multiple myeloma, respectively (Ho et al., 2020), and other HDAC inhibitors have been investigated in clinical trials for the treatment of various cancers (Ono et al., 2018; Xie et al., 2018).