INCB057643 is a novel, orally bioavailable BET inhibitor that has been tested in preclinical models of hematologic malignancies. INCB057643 is an analog of INCB054329 but with longer plasma half time which enables once a day dosing, while INCB054329 has to be dosed twice a day. INCB057643 inhibited binding of BRD2/BRD3/BRD4 to an acetylated histone H4 peptide in the low nM range, and was selective against other bromodomain containing proteins. In vitro analyses showed that INCB057643 inhibited proliferation of human AML, DLBCL, and multiple myeloma cell lines, with a corresponding decrease in MYC protein levels. Cell cycle analyses indicated that G1 arrest and a concentration-dependent increase in apoptosis were seen within 48 hours of treatment with INCB057643. Production of several cytokines, including IL-6, IL-10 and MIP-1α, was repressed by INCB057643 in human and mouse whole blood stimulated ex vivo with LPS. Consistent with these effects, analyses of gene expression in cells treated with INCB057643 revealed that pathways involved in cell cycle progression, apoptosis, and IL-6 were among the most significantly altered in vitro. Oral administration of INCB057643 resulted in significant anti-tumor efficacy in xenograft models of AML, myeloma, and DLBCL. Additionally, combining INCB057643 with standard of care agents used for the treatment of DLBCL including rituximab and bendamustine resulted in enhanced anti-tumor efficacy relative to that achieved with single agent therapies at doses that were well tolerated. In addition, many B cell malignancies are reliant on the PI3Kδ pathway for proliferation and survival, suggesting that the combination of INCB057643 with the clinical stage PI3Kδ specific inhibitor INCB050465 may be a rational therapeutic strategy for DLBCL. Compared with single agent BETi or PI3Kδi therapy, the combination significantly potentiated tumor growth inhibition in DLBCL models representative of the ABC subtype (HBL-1), and the double hit GCB subtype (WILL2). These data suggest that clinical exploration of INCB057643 as a monotherapy or in combination in hematologic malignancies is warranted.

Physicochemical Properties

Molecular Formula	C20H21N3O5S
Molecular Weight	415.46284365654
Exact Mass	415.12
CAS #	1820889-23-3
Related CAS #	1820889-23-3
PubChem CID	118467751
Appearance	White to off-white solid powder
LogP	0.8
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	5
Rotatable Bond Count	2
Heavy Atom Count	29
Complexity	862
Defined Atom Stereocenter Count	0
SMILES	O1C2=C(C3=CN(C)C(=O)C4NC=CC=43)C=C(S(C)(=O)=O)C=C2N(C)C(=O)C1(C)C
InChi Key	VZSAMEOETVNDQH-UHFFFAOYSA-N
InChi Code	InChI=1S/C20H21N3O5S/c1-20(2)19(25)23(4)15-9-11(29(5,26)27)8-13(17(15)28-20)14-10-22(3)18(24)16-12(14)6-7-21-16/h6-10,21H,1-5H3
Chemical Name	2,2,4-trimethyl-8-(6-methyl-7-oxo-6,7-dihydro-1H-pyrrolo[2,3-c]pyridin-4-yl)-6-(methylsulfonyl)-2H-benzo[b][1,4]oxazin-3(4H)-one
Synonyms	INCB057643; INCB-057643; INCB 057643
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

ln Vitro	INCB-057643 is a new, orally accessible BET inhibitor. INCB-057643 inhibits binding of BRD2/BRD3/BRD4 to an acetylated histone H4 peptide in the low nM range, and is selective against other bromodomain containing proteins. In vitro tests demonstrate that INCB -057643 inhibits proliferation of human AML, DLBCL, and multiple myeloma cell lines, with a commensurate drop in MYC protein levels. Cell cycle studies suggest that G1 arrest and a concentration-dependent increase in apoptosis are detected within 48 hours of treatment with INCB- 057643[1].
ln Vivo	When LPS is induced ex vivo in human and mouse whole blood, INCB-057643 inhibits the production of many cytokines, including as IL-6, IL-10, and MIP-1α. In xenograft models of AML, myeloma, and DLBCL, oral treatment of INCB-057643 has a strong anti-tumor efficacious effect. Additionally, at well-tolerated doses, INCB-057643 enhances anti-tumor activity compared to single agent therapy when combined with standard of care medicines for the treatment of DLBCL, such as bendamustine and rituximab[1].
Animal Protocol	Oral Mouse xenograft models of AML, myeloma, and DLBCL
References	[1]. Abstract 5071: Preclinical characterization of the potent and selective BET inhibitor INCB057643 in models of hematologic malignancies. AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5071.
Additional Infomation	INCB-057643 is under investigation in clinical trial NCT02959437 (Azacitidine Combined With Pembrolizumab and Epacadostat in Subjects With Advanced Solid Tumors (ECHO-206)). BET Inhibitor INCB057643 is an inhibitor of the Bromodomain (BRD) and Extra-Terminal (BET) family of BRD-containing proteins, with potential antineoplastic activity. Upon administration, the BET inhibitor INCB057643 binds to the acetylated lysine recognition motifs found in the BRD of BET proteins, thereby preventing the interaction between the BET proteins and acetylated lysines on histones. This disrupts chromatin remodeling and gene expression. Prevention of the expression of certain growth-promoting genes, such as c-Myc-dependent target genes, may lead to an inhibition of tumor cell growth. BET proteins are transcriptional regulators that are overexpressed in certain tumor cells and play an important role in cellular growth.

Solubility Data

Solubility (In Vitro)

DMSO: >60 mg/mL Water:N/A Ethanol:N/A

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 2.08 mg/mL (5.01 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 2.08 mg/mL (5.01 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Solubility in Formulation 3: ≥ 2.08 mg/mL (5.01 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	2.4070 mL	12.0349 mL	24.0697 mL
	5 mM	0.4814 mL	2.4070 mL	4.8139 mL
	10 mM	0.2407 mL	1.2035 mL	2.4070 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.