HDAC ( IC50 = 27 nM )

Belinostat, at a dose of 10 mg/kg with no effect on body weight, shows significant tumor growth delay in A2780 and A2780/cp70 xenograft.[1] In mouse bladder tumors, belinostat also induces the expression of CDM, HDAC core, and p21WAF1. With a dose of 100 mg/kg, belinastat monotherapy produces dose-proportional antitumor effects in an A2780 xenograft, with a TGI of 47%. Tumor growth could be delayed from 18.6 days to 22.5 days by combining belimostat (100 mg/kg) with carboplatin (40 mg/kg).[3] Belinostat, when combined with bortezomib, causes significant tumor inhibition and gastrointestinal toxicity in mice bearing a xenograft of the bortezomib-resistant UMSCC-11A.[5]

Pelletization of subconfluent cultures is achieved by centrifugation at 200 × g for 5 minutes after they are harvested and twice washed in ice cold PBS. The lyse is performed using three freeze (dry ice) thaw (30 °C water bath) cycles after the cell pellet has been resuspended in two volumes of lysis buffer [60 mM Tris buffer (pH 7.4) containing 30% glycerol and 450 mM NaCl]. The supernatant is kept at -80 °C after cell debris is extracted using centrifugation at 1.2 × 10⁴ g for 5 minutes. Histone H4 peptide (sequence SGRGKGGKGLGKGGAKRHRK, which corresponds to the 20 NH2-terminal residues) is acetylated by a recombinant protein that uses [³H]acetyl CoA as an acetate source and contains the hypoxanthine-aminopterin-thymidine domain of p300. H4 peptide (100 μg) is combined with hypoxanthine-aminopterin-thymidine buffer (50 mM Tris HCl pH 8.0, 5% glycerol, 50 mM KCl, and 0.1 mM EDTA), 1 mM DTT, 1 mM 4-(2-aminoethyl) benzenesulfonylfluoride, 1 × complete protease inhibitors, 50 μL of purified p300, and 1.85 m [³H]acetyl CoA (4.50Ci/mmol) in a final volume of 300 μL. The mixture is then incubated at 30 °C for 45 minutes. Centrifugation and an hour at 4 °C are used to extract the p300 protein from 20 μL of 50% Ni-agaroase beads. After applying the supernatant to a 2 mL Sephadex G15 column, the flow through is gathered. After adding one milliliter of distilled H₂O gently and collecting three drop fractions, this process is repeated until four to five milliliters of distilled H₂O are added and approximately forty fractions are collected. The fractions containing the labeled peptide are identified by diluting three microliters of each fraction in two milliliters of scintillation fluid and counting the results in a scintillation counter. These fractions are combined, and a 1 μL sample is measured to determine the radioactivity in each batch of peptides (3-7×10³ cpm/μL). The reaction for activity assays is conducted in a total volume of 150 μL of buffer [60 mM Tris (pH 7.4) containing 30% glycerol] with 2 μL of cell extract and, if applicable, 2 μL of belinostat added. 20 NH₂-terminal residues' worth of acetylated histone H4 peptide, or 2 μL of [³H] labeled substrate, is added to initiate the reaction. Samples are incubated for 45 minutes at 37 °C, after which the addition of acetic acid and HCl (0.72 and 0.12 M final concentrations, respectively) stops the reaction. Samples are centrifuged at 1.2× 10⁴ g for 5 minutes after released [³H]acetate is extracted into 750 μL of ethyl acetate. After being transferred to 3 milliliters of scintillation fluid, the upper phase (600 μL) is counted.

After seeding tumor cell lines at a density of 8 × 10⁴ cells/25 cm2 flask in 5 mL of medium, they are incubated for 48 hours. For a full day, cells are subjected to varying concentrations of belinostat (0.016 to 10 μM). After the medium is gone, each flask receives 1 mL of trypsin/EDTA. Following their detachment, the cells are resuspended in 1 mL of medium, and the number of cells from the untreated control flask is recorded. Depending on the cell line, three cells are diluted and plated into 6-cm Petri dishes per flask, with a density of 0.5-2× 10³ cells/dish. The drug-treated flasks' cells are diluted and plated similarly to the control flasks. Dishes are incubated at 37 °C for ten to fifteen days. After the cells are fixed in methanol, stained with crystal violet, and rinsed with PBS, colonies containing 50 or more cells are counted. The belinostat concentration needed to lower the number of colonies to 50% of the untreated control cells is known as the IC50, which is used to express sensitivity.

Absorption, Distribution and Excretion
Approximately 40% of the belinostat dose is excreted renally, primarily as metabolites and less than 2% of total dose recovered as unchanged parent drug.
The volume of distribution is 409 ± 76.7 L.
1240 mL/min

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Metabolism / Metabolites
Primarily metabolized by hepatic UGT1A1. Strong UGT1A1 inhibitors are expected to increase exposure to belinostat. Belinostat also undergoes hepatic metabolism by CYP2A6, CYP2C9, and CYP3A4 enzymes to form belinostat amide and belinostat acid. The enzymes responsible for the formation of methyl belinostat and 3-(anilinosulfonyl)-benzenecarboxylic acid, (3-ASBA) are not known

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Biological Half-Life
Displays a three-compartment pharmacokinetic property with elimination half life of 1.1 hours

Hepatotoxicity
In clinical trials of belinostat in patients with PTCL, the rates of serum enzyme elevations during therapy were usually less than 5%, and were above 5 times the ULN in only 1% to 2% of patients. A single instance of severe acute liver injury leading to death from liver failure was reported in an open label trial of belinostat monotherapy in 120 patients with PTCL. The liver injury arose after 10 cycles of treatment and progressed despite drug discontinuation. Specific details were not provided. In another clinical trial, two cases of cholestatic liver injury were reported but without specific details. Thus, belinostat is considered to be a rare cause of acute liver injury but the timing of onset, associated features, clinical course and outcome have not been well defined.
Likelihood score: D (possible cause of clinically apparent liver injury).

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Protein Binding
92.9% and 95.8% of belinostat is bound to protein.

[1]. Mol Cancer Ther . 2003 Aug;2(8):721-8.

[2]. J Transl Med . 2007 Oct 12:5:49.

[3]. Mol Cancer Ther . 2006 Aug;5(8):2086-95.

[4]. J Biol Chem . 2011 Sep 2;286(35):30937-30948.

[5]. Mol Cancer Ther . 2007 Jan;6(1):37-50.

Belinostat is a hydroxamic acid-type histone deacetylase (HDAC) inhibitor with antineoplastic activity. It has a role as an antineoplastic agent and an EC 3.5.1.98 (histone deacetylase) inhibitor. It is a hydroxamic acid, a sulfonamide and an olefinic compound.
Belinostat is a novel agent that inhibits the enzyme histone deacetylase (HDAC) with a sulfonamide-hydroxamide structure. It was developed as an orphan drug to target hematological malignancies and solid tumors by TopoTarget. The safety and efficacy of belinostat is currently being evaluated for use in combination with traditional front-line therapies for the treatment of PTCL. Intravenous administration of the agent is available as Beleodaq as monotherapy and the dosing regimen involves a 21-day cycle. It was US-approved in July 2014 as a therapeutic agent for relapsed or refractory peripheral T-cell lymphoma.
Belinostat is a Histone Deacetylase Inhibitor. The mechanism of action of belinostat is as a Histone Deacetylase Inhibitor.
Belinostat is an intravenously administered histone deacetylase inhibitor and antineoplastic agent that is approved for use in refractory or relapsed peripheral T cell lymphoma. Belinostat is associated with moderate rate of minor serum enzyme elevations during therapy and has been reported to cause clinically apparent fatal, acute liver injury.
Belinostat is a novel hydroxamic acid-type histone deacetylase (HDAC) inhibitor with antineoplastic activity. Belinostat targets HDAC enzymes, thereby inhibiting tumor cell proliferation, inducing apoptosis, promoting cellular differentiation, and inhibiting angiogenesis. This agent may sensitize drug-resistant tumor cells to other antineoplastic agents, possibly through a mechanism involving the down-regulation of thymidylate synthase.

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Drug Indication
Belinostat is indicated for the treatment of patients with relapsed or refractory peripheral T-cell lymphoma (PTCL) with manageable safety profile. It is a potential alternative therapy for patients who did not experience adequate response to first-line drugs for PTCL. It can be used in patients with baseline thrombocytopenia.
FDA Label

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Mechanism of Action
Belinostat inhibits the activity of histone deacetylase (HDAC) thus prevents the removal of acetyl groups from the lysine residues of histones and some non-histone proteins. In vitro, belinostat caused the accumulation of acetylated histones and other proteins, increased the expression of tumor-suppressor genes. It ultimately induces cell cycle arrest, inhibition of angiogenesis and/or apoptosis of some transformed cells.

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Pharmacodynamics
Beleodaq is a histone deacetylase (HDAC) inhibitor that exhibits pan-HDAC inhibition and potent growth inhibitory and pro-apoptotic activities in a variety of tumor cells, including PTCL cells, at nanomolar concentrations. None of the trials show any clinically relevant changes caused by Beleodaq on heart rate, PR duration or QRS duration as measures of autonomic state, atrio-ventricular conduction or depolarization; there were no cases of Torsades de Pointes.

C15H14N2O4S

318.35

318.067

C, 56.59; H, 4.43; N, 8.80; O, 20.10; S, 10.07.

414864-00-9

414864-00-9; 866323-14-0

6918638

White solid powder

1.4±0.1 g/cm3

1.667

2.23

3

5

5

22

492

0

S(C1=C([H])C([H])=C([H])C(/C(/[H])=C(\[H])/C(N([H])O[H])=O)=C1[H])(N([H])C1C([H])=C([H])C([H])=C([H])C=1[H])(=O)=O

NCNRHFGMJRPRSK-MDZDMXLPSA-N

InChI=1S/C15H14N2O4S/c18-15(16-19)10-9-12-5-4-8-14(11-12)22(20,21)17-13-6-2-1-3-7-13/h1-11,17,19H,(H,16,18)/b10-9+

(E)-N-hydroxy-3-[3-(phenylsulfamoyl)phenyl]prop-2-enamide

NSC726630; NSC-726630; PX-105684; PXD 101; PXD101; PXD-101; PX105684; PX 105684; NSC-726630; Trade name: Beleodaq

2934.99.03.00

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)