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]

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]

• HDAC, EGFR and HER2 inhibition assays

  The activities of Class I and II HDACs are assessed using the Biomol Color de Lys system. Briefly, HeLa cell nuclear extracts are used as a source of HDACs. Different concentrations of CUDC-101 are added to HeLa cell nuclear extracts in the presence of a colorimetric artificial substrate. Developer is added at the end of the assay and enzyme activity is measured in the Wallac Victor II 1420 microplate reader at 405 nM. EGFR and HER2 kinase activity are measured using HTScan EGF receptor and HER2 kinase assay kits. Briefly, the GST-EGFR fusion protein is incubated with synthetic biotinylated peptide substrate and varying concentrations of CUDC-101 in the presence of 400 mM ATP. Phosphorylated substrate is captured with strapavidin-coated 96-well plates. The level of phosphorylation is monitored by antiphospho-tyrosine- and europium-labeled secondary antibodies. The enhancement solution is added at the end of the assay and enzyme activity is measured in the Wallac Victor II 1420 microplate reader at 615 nM.

• Cell lines

  HCC827, H358, H460, HepG2, Hep3B2, Sk-Hep-1, Capan1, BxPc3, MCF-7, MDA-MB-231, and Sk-Br-3

• Concentrations

  Dissolved in DMSO, final concentrations ~10 μM

• Incubation Time

  72 hours

• Method

  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.

• Animal Models

  Female athymic mice (nude nu/nu CD-1) inoculated with Hep-G2, H358, A549, MDA-MB468, HCT116, CAL-27, HepG2, or HPAC

• Dosages

  ~120 mg/kg/day

• Administration

  Administered via i.v.