HDAC3 inhibitor PT3 is a novel potent, selective, BBB-permeable HDAC3 inhibitor.PT3 exhibited higher selectivity for HDAC3 over HDAC1, HDAC6, and HDAC8 compared to the reference compound CI994.PT3 upregulated H3K9 acetylation, CREB 1, BDNF, TRKB, Nr4a2, c-fos, PKA, GAP 43 and MMP9 expression in mouse neuronal (N2A) cells.PT3 significantly improved the discrimination index in C57/BL6 mice in the novel object recognition (NOR) model, significant increased in H3K9 acetylation in hippocampus.PT3 upregulated CREB 1, BDNF, TRKB, Nr4a2, c-fos, PKA, GAP 43, PSD 95 and MMP9 expression in mice treated with PT3.

IRBM6 (Class I HDAC-IN-6) is a potent, class I selective HDAC inhibitor with EC50 of 50 nM (HeLa cellular), HDAC1/2/3 IC50 of 1.7/2.8/1.1 nM.IRBM6 weakly inhibits HDAC6 (IC50=177 nM) and is inactive at 5 uM against HDACs 4-7.IRBM6 showed a potent inhibitory effect on the growth TC-797s and two additional NUT carcinoma (NC) cell lines, PER-403, and 10-15.IRBM6 induces a transcriptional program of differentiation in NC cells, demonstrated large-scale changes in gene expression that were significantly enriched with differentiation gene sets and depleted of pro-growth gene sets, including those of MYC and E2F targets.IRBM6 repressed growth and induced differentiation of NUT carcinoma (NC) cells in proportion to inhibition of NUT transcriptional activity.

KA2507 (KA-2507, KA 2507) is a potent and selective inhibitor of HDAC6 with IC50 of 2.5 nM, >300-fold selectivity over other HDACs.KA2507 demonstrated cellular potency (IC50=150 nM) in a cellular assay measuring induction of acetylated α-tubulin, a marker of HDAC6 inhibition.KA2507 displays antiproliferative effects against a set of 93 human cancer cells with IC50 of 2-30 uM.KA2507 inhibits tumor growth in the syngeneic B16-F10 mouse melanoma model.

LSH-A54 is a potent, class I selective HDAC inhibitor with IC50 of 26.2 nM (HDAC1) and 59.3 nM (HDAC2); LSH-A54 displays no significant inhibition against HADC3/6 (IC50>10 uM). LSH-A54 exhibits antiproliferative properties against breast cancer cell lines T-47D (IC50=1.58 uM), MCF-7 (IC50=1.32 uM) and BT-474 (IC50=2.55 uM). LSH-A54 attenuates cell migration significantly in wound healing assay and comparably to the pan-HDACi vorinostat, whereas the HDAC1-3 selective HDACi entinostat has no significant effect on cell migration. LSH-A54 reduced the number of colonies significantly in clonogenic survival assay compared to entinostat and showed comparable activity to pan-HDACi vorinostat.

MJM-1 is a small-molecule brain-penetrant HDAC inhibitor that increases the overall level of histone 3 (H3) acetylation in prostate cancer cell line.MJM-1 injected intraperitoneally (i.p.) crossed the BBB in mice and could be detected in the hippocampus, a brain region that mediates memory.MJM-1 (post-training i.p. administration) enhanced hippocampus-dependent spatial memory consolidation in male mice.

NN-390 (NN390) is a potent, selective HDAC6 inhibitor with IC50 of 9.8 nM, >200-550-fold selectivity over other HDAC isoforms.NN-390 inhibits primary cells of treatment-refractory Group 3 MB cells (SU_MB002) with IC50 of 2.33 uM.NN-390 is the first HDAC6-selective inhibitor to show therapeutic potential in metastatic Group 3 medulloblastoma (MB), an aggressive pediatric brain tumor often associated with leptomeningeal metastases and therapy resistance.NN-390 selectively targets cell population with a 44.3-fold therapeutic margin between patient-derived Group 3 MB cells in comparison to healthy neural stem cells.NN-390 demonstrated a 45-fold increased potency over HDAC6-selective clinical candidate citarinostat.

NR-160 (NR160) is a novel potent, selective inhibitor of histone deacetylase 6 (HDAC6) with IC50 of 30 nM, shows SI (75-1847 )over all HDAC class I isoforms.NR-160 induced α-tubulin acetylation (ac-α-tubulin) in treated acute myeloid leukemic (AML) cell line HL60, but not histone H3 (ac-H3) (a marker for the inhibition of class I HDACs).NR-160 enhances the cytotoxicity induction of bortezomib, epirubicin and daunorubicin on a panel of seven leukemia cell lines

PTG-0861 (JG-265) is a novel potent, selective HDAC6 inhibitor with IC50 of 5.92 nM, >36-fold selectivity over other HDACs.PTG-0861 (JG-265) displays HDAC6 cellular target engagement with EC50 of 0.59 uM (ELISA), has in vitro and cellular selectivity superior to HDAC6-selective inhibitor citarinostat (ACY-241).PTG-0861 (JG-265) demonstrates potency against several blood cancer cell lines (e.g. MV4-11, MM1S), whilst showing limited cytotoxicity against non-malignant cells and CD-1 mice.PTG-0861 (JG-265) exihibits promising in vitro pharmacokinetics achieved with good safety profile in cells and in vivo.

SS-208 (SS208) is a novel potent, selective inhibitor of histone deacetylase 6 (HDAC6) with IC50 of 12 nM, >100-fold selectivity over HDAC1/4/5/7/8/9/11.SS-208 has minimal effects on the viability of murine SM1 melanoma cells in vitro, significantly reduced in vivo tumor growth in a murine SM1 syngeneic melanoma mouse model.

SW-101 (SW101) is a potent, selective HDAC6 inhibitor with IC50 of 0.7 nM, >200-fold selectivity over HDAC1/2/3.SW-101 possesses excellent HDAC6 potency and selectivity, together with markedly improved metabolic stability and druglike properties compared to SW-100.SW-101 treatment elevates the impaired level of acetylated α-tubulin in the distal sciatic nerve, counteracts progressive motor dysfunction, and ameliorates neuropathic symptoms in a CMT2A mouse model bearing mutant MFN2.

T-518 (T518) is a potent, highly selective, brain penetrant, oral HDAC6 inhibitor with IC50 of 36 nM.T-518 did not obviously inhibit human HDAC1, 4, or 7 at 10 uM, which belongs to Class I or Class IIa HDAC.T-518 showed brain penetration in an oral dose and blocked HDAC6-dependent tubulin deacetylation at Lys40 in mouse hippocampus.T-518 decreased RIPA-insoluble tau accumulation (3-month treatment, 1 and 3 mg/kg), restored impaired axonal transport and novel object recognition in the P301S tau Tg mouse (tauopathy model) by 2-week treatment with dose 1 and 3 mg/kg.

Tucidinostat (Chidamide, HBI-8000, CS055) is a novel histone deacetylase (HDAC) inhibitor with IC50 of 95/160/67/733/78/432 nM for HDAC1/2/3/8/10/11, respectively; shows no activity against Class IIa HDAC4/4/7/9 and HDAC6; demonstrates significant and broad spectrum in vitro and in vivo antitumor activity, induces G1 arrest, ROS-dependent apoptosis and differentiation in human leukaemia cells.

UBD253 (SGC-UBD253) is a potent, selective ubiquitin chemical probe for ubiquitin binding domain of HDAC6 with Kd of 84 nM (SPR), inhibits the HDAC6-ISG15 interaction (EC50=1.9 uM, nanoBRET).UBD253 (SGC-UBD253) displays little to no affinity for other USPs (>100-fold selectivity). SGC-UBD253 potently (<100 nM) binds HDAC6-UBD (ubiquitin binding domain), decreases the interaction between full-length HDAC6 with ISG15.

[18F]-NT160, a Florbetapir (18F)-radiolabeled NT160, is a diagnostic tool for positron emission tomography (PET). NT160 is a brain-penetrant and selective class-IIa HDAC inhibitor with an IC50 of 46 nM. NT160 exhibits a remarkably high inhibition against HDAC4, HDAC5, HDAC7, and HDAC9 with IC50s of 0.08 nM, 1.2 nM, 1.0 nM, and 0.9 nM, respectively.

2-Hexyl-4-pentynoic acid ((±)-2-Hexyl-4-pentynoic acid), valproic acid (VPA) derivative, exhibits potential roles of HDAC inhibition (IC50=13 µM) and HSP70 induction. Potent neuroprotective effects. 2-Hexyl-4-pentynoic acid causes histone hyperacetylation and protect against glutamate-induced excitotoxicity in cultured neurons.

JPS014 is a benzamide-based Von Hippel-Lindau (VHL) E3-ligase proteolysis targeting chimeras (PROTAC). JPS014 degrades class I histone deacetylase (HDAC). JPS014 is potent HDAC1/2 degrader correlated with greater total differentially expressed genes and enhanced apoptosis in HCT116 cells.

JPS016 is a benzamide-based Von Hippel-Lindau (VHL) E3-ligase proteolysis targeting chimeras (PROTAC). JPS016 degrades class I histone deacetylase (HDAC). JPS016 is potent HDAC1/2 degrader correlated with greater total differentially expressed genes and enhanced apoptosis in HCT116 cells.

JPS035 is a benzamide-based Von Hippel-Lindau (VHL) E3-ligase proteolysis targeting chimeras (PROTAC). JPS035 degrades class I histone deacetylase (HDAC). JPS035 is potent HDAC1/2 degrader correlated with greater total differentially expressed genes and enhanced apoptosis in HCT116 cells.

JPS036 is a benzamide-based Von Hippel-Lindau (VHL) E3-ligase proteolysis targeting chimeras (PROTAC). JPS036 degrades class I histone deacetylase (HDAC). JPS036 is potent HDAC1/2 degrader correlated with greater total differentially expressed genes and enhanced apoptosis in HCT116 cells.

GEM144 is a potent and orally active DNA polymerase α (POLA1) and HDAC 11 dual inhibitor. GEM144 induces acetylation of p53, activation of p21, G1/S cell cycle arrest, and apoptosis. GEM144 has significant antitumor activity in human orthotopic malignant pleural mesothelioma xenografts.

HC-Toxin, a cyclic tetrapeptide, is a potent HDAC inhibitor with an IC50 of 30 nM. HC-Toxin induces tumor cell apoptosis and has anticancer effects.

TH-6 is a potent HDAC inhibitor with IC50s of 0.115, 0.135, 0.242, 0.138, 2.120 µM for HDAC1, HDAC2, HDAC3, HDAC6, HDAC8, respectively. TH-6 inhibits cell migration and invasion. TH-6 induces apoptosis and cell cycle arrest at G2/M phase. TH-6 shows anti-tumor activity.