Table 3.

List of HDAC inhibitors (HDACi). Columns indicate: structural class (as described in the text); name of the inhibitor (in brackets, alternative name); specificity of inhibition (‘Pan’ indicating an activity against all HDACs); cancer type in which the drug is currently being tested; references (with focus on drug tests in cancer contexts). The following drugs in this table have been approved by the Food & Drug Administration (FDA), as of May 2020: Vorinostat, Belinostat, Panobinostat, Valproic acid and Romidepsin.

Structural Group	Name	Specificity	Cancer	Reference
Group I - Hydroxamic acids
	Trichostatin A (TSA)	Pan	Pancreatic, prostate, NSCLC, gastric	[265,266,267,268]
	Vorinostat (SAHA)	Pan	Ovarian, gastric, leukemia	[221,268,269]
	Belinostat (PXD101)	Pan	T-Cell lymphoma, pancreatic, hepatocellular carcinoma, acute myelogenous leukemia	[270,271,272,273,274]
	Panobinostat (LBH589)	Pan	MLL-ALL, neuroblastoma, esophageal squamous cell carcinoma, NSCLC, ovarian, pontine glioma, DLBCL	[216,223,227,275,276,277,278]
	Givinostat (ITF-2357)	Pan	NSCLC, acute lymphoblastic leukemia, glioblastoma, acute lymphoblastic leukemia	[279,280,281,282]
	Resminostat (RAS2410)	Pan	Prostate, pancreas, NSCLC, hepatocellular carcinoma	[283,284,285,286]
	Abexinostat (PCI-24781)	Pan	breast, gastric, neuroblastoma, DLBCL	[267,287,288,289]
	Quisinostat (JNJ-26481585)	Pan	Lung, multiple myeloma, rhabdomyosarcoma	[290,291,292]
	Pracinostat (SB939)	Pan	Acute lymphoblastic leukemia, myelodysplastic syndromes, myelofibrosis, NSCLC	[222,293,294,295]
	Rocilinostat (ACY-1215)	HDAC6	Esophageal squamous cell carcinoma, DLBCL, multiple myeloma, NSCLC	[229,296,297,298]
	Nanatinostat (CHR-3996)	Class I & II	HCC, multiple myeloma	[228,299,300]
Group II—SCFAs
	Sodium butyrate and derivatives	Class I & IIa	Breast, colorectal, gastric	[235,268,301]
	Valproic acid (VPA)	Class I	CNS, colorectal, prostate cancer, NSCLC, pancreatobiliary tract	[302,303,304,305]
Group III—Benzamides
	Mocetinostat (MGCD0103)	Class I & IV	Pancreatic, Hodgkin’s lymphoma, SHH medulloblastoma, leiomyosarcoma, prostate, glioblastoma, ovarian	[197,306,307,308,309,310,311]
	Entinostat (MS-275)	Class I & IV	Breast, leukemia, ovarian, renal cell carcinoma	[244,245,312,313]
	K560 and derivatives	Class I	N/A	[248,249]
Group IV—Tetrapeptides (depsipeptides)
	Apicidin (OSI-2040)	Class I	Oral squamous cell carcinoma, ovarian, pancreatic	[264,314,315]
	Romidepsin (FK228)	Class I	Germ cell, HCC, T cell lymphoma	[256,257,259]
	Chromopeptide A	Class I	Prostate	[255]
	Largazole	Class I	Colon, lung	[316,317,318]
	Spiruchostatin A	Class I	Bladder, breast	[319,320]
Tetrapeptides ( α 4-cyclotetrapeptides)
	Trapoxin	HDAC8	N/A	[252,261]
	Azumamide A and derivates	Class I	N/A	[321]
	HC-toxin	Class I	Cholangiocarcinoma, breast, neuroblastoma, medulloblastoma	[322,323,324,325]

Molecule structures in Table 3 were obtained from PubChem [326] or from the indicated references, and drawn using MarvinSketch [327].