CUDC-101

Specific for class I and class II HDACs, CUDC-101 does not inhibit class III Sir-type HDACs. CUDC-101 displays weak activity against other protein kinases including KDR/VEGFR2, Lyn, Lck, Abl-1, FGFR-2, Flt-3, and Ret with IC50 of 0.85 μM, 0.84 μM, 5.91 μM, 2.89 μM, 3.43 μM, 1.5 μM, abd 3.2 μM, respectively. CUDC-101 displays broad antiproliferative activity in many human cancer cell types with IC50 of 0.04-0.80 μM, exhibiting a higher potency and combinations of vorinostat in most cases. CUDC-101 potently inhibits cancer cell lines. ^[1] CUDC-101 inhibits the resistant EGFR mutant T790M although its effects are incomplete with an Amax of ~60% of peak enzyme activity after inhibition. CUDC-101 treatment increases the acetylation of histone H3 and H4, as well as the acetylation of non-histone substrates of HDAC such as p53 and α-tubulin, in a dose-dependant manner in various cancer cell lines. CUDC-101 also suppresses HER3 expression, Met amplification, and AKT reactivation in tumor cells. ^[2]

Cancer cell lines are plated at 5000 to 10000 cells per well in 96-well flatbottomed plates with varying concentrations of CUDC-101. The cells are incubated with CUDC-101 for 72 hours in the presence of 0.5% of fetal bovine serum. Growth inhibition is assessed by an adenosine triphosphate (ATP) content assay using the Perkin-Elmer ATPlite kit. Apoptosis is routinely assessed by measuring the activities of Caspase-3 and -7 using Apo-ONE Homogeneous Assay Kit.

Administration of CUDC-101 at 120 mg/kg/day induces tumor regression in the Hep-G2 liver cancer model, which is more efficacious at its maximum tolerated dose (25 mg/kg/day) and vorinostat at an equimolar concentration dose (72 mg/kg/day). CUDC-101 inhibits the growth of -sensitive H358 NSCLC xenografts in a dose-dependent manner. CUDC-101 also shows potent inhibition of tumor growth in the -resistant A549 NSCLC xenograft model. CUDC-101 produces significant tumor regression in the -resistant, HER2-negative, EGFR-overexpressing MDA-MB-468 breast cancer model and the EGFR-overexpressing CAL-27 head and neck squamous cell carcinoma (HNSCC) model. Additionally, CUDC-101 inhibits tumor growth in the K-ras mutant HCT116 colorectal and EGFR/HER2 (neu)-expressing HPAC pancreatic cancer models. ^[1]