Orally bioavailable BET inhibitor
BI 894999
BI 894999 (amredobresib) is a potent inhibitor of the interaction between a histone H4-derived peptide with acetylated lysines and the bromodomains BRD4BD1 (IC50 5 ± 3 nM) and BRD4BD2 (IC50 41 ± 30 nM). It only inhibits BET family members and is selective versus 24 other bromodomains. It complements the BET PROTAC MZ1 which is also available on opnMe. Please note that due to its potency, BI 894999 should be handled with great caution.
More information
BI 894999 is a low molecular weight compound which inhibits bromodomain 4 (BRD4) as well as other members of the bromo- and extra-terminal domain (BET) family (BRD2, BRD3 and BRDT) with high selectivity and potency. BRD4 activates transcriptional elongation, thereby contributing to gene expression, at least partially by activating P-TEFb (consisting of CDK9 and CyclinT1). In this process, BRD4 functions as an antagonist of a ribonucleoprotein complex (7SK/HEXIM-1, LARP7, MEPCE), which binds to P-TEFb and functionally inhibits it. BRD4 activates P-TEFb, which then can phosphorylate Ser2 on paused RNA Pol II, leading to transcriptional elongation.
BRD4 is considered to be a general transcriptional regulator. However, pharmacological inhibition of BET proteins has shown therapeutic activity in different models of cancer (mouse xenografts).
BI 894999 has been developed as an oral formulation for investigation in patients with malignancies. Its potency was determined on tumor cells in vitro and in vivo. The closely related molecule BI-6953 can be used as a negative control.
X-ray of BI 894999 in BRD-BD1 (PDB code: 8PIQ).
Competitive displacement of a histone peptide (acetyl-histone H4 Lys5, 8, 12, 16) from human bromodomain by the test-compounds is measured by using the AlphaLISA® bead-based proximity assay.
BI 894999 inhibited the binding of:
- Bromodomain BRD4BD1 to acetylated Histone (Lys5, 8, 12, 16) with an IC50 of 5 ± 3 nM
- Bromodomain BRD4BD2 to acetylated Histone (Lys5, 8, 12, 16) with an IC50 of 41 ± 30 nM
- Bromodomain BRD2BD1 to acetylated Histone (Lys5, 8, 12, 16) with an IC50 of 33 ± 12 nM
The effect of the BET inhibitor BI 894999 was also tested on numerous malignant cell lines of various origin and ranged from single digit nM to µM1-3.
The cellular potency of BI 894999 was determined in cell proliferation assays. A panel consisting of >50 acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), multiple myeloma (MM), diffuse large B-cell lymphoma (DLBCL, ABC and GCB-type), and T-cell lymphoma (TCL) cell lines was tested. All cell lines showed an GI50 <100 nM, with most of the cell lines displaying single digit nM GI50 values.
NUT carcinoma cell lines, carrying BRD-NUT fusions, were exquisitely sensitive to BI 894999 with GI50 values in the single digit nM range (geomean from 0.9 to 2.6 nM).
No data were generated for the negative control BI-6953.
| PROBE NAME / NEGATIVE CONTROL | BI 894999 |
| MW [Da, free base]a | 467.6 |
| BRD4BD1 ALPHA LO (IC50) [nM]b | 6 |
| BRD4BD2 ALPHA LO (IC50) [nM]b | 39 |
| BRD2BD1 ALPHA LO (IC50) [nM]b | 33 |
| BRD9 AS LO ECHO (IC50) [nM]b | 3,059 |
| BRD7 AS LO ECHO (IC50) [nM]b | 81,199 |
| MV-4-11 MYC (EC50) [nM]b | 3 |
| ALAMAR BRD4 MV-4-11 (EC50) [nM]b | 9 |
| MYC_MOLP-8 (EC50) [nM]b | 5 |
| ALA HCT116 (EC50) [nM]b | >250 |
a For the salt form you will get, please refer to the label on the vial and for the molecular weight of the salt, please refer to the FAQs
b For assay conditions see reference 1
BI 894999 is a highly potent BET inhibitor with overall good DMPK properties. No data were generated for the negative control BI-6953.
| PROBE NAME / NEGATIVE CONTROL | BI 894999 |
| logP @ pH 11 | 3.5 |
| Solubility @ pH 6.8 [µg/mL] | 54 |
| MDCK permeability PappAB @ 1 µM [10-6 cm/s] | 7.9 |
| MDCK efflux ratio | 14 |
| Microsomal stability (human/mouse/rat) [% QH] | 32 / 44 / <23 |
| Hepatocyte stability (human/mouse/rat) [% QH] | 12 / 51 / 7 |
| Plasma Protein Binding (human/mouse/rat) [%] | 65.6 / 54.2 / 74.7 |
| hERG [inh. % @ 1 µM] | 8.9 |
| CYP 3A4 (IC50) [µM] | >50 |
| CYP 2C8 (IC50) [µM] | >50 |
| CYP 2C9 (IC50) [µM] | >50 |
| CYP 2C19 (IC50) [µM] | >50 |
| CYP 2D6 (IC50) [µM] | >50 |
BI 894999 is a highly potent BET inhibitor with oral bioavailability in mice and rats.
| BI 894999 | Mouse | RAT |
| Clearance [% QH]a | 71 | 28 |
| Mean residence time after i.v. dose [h] | 0.5 | 5.4 |
| tmax [h]b | 0.5 | 3 |
| Cmax [nM]b | 300 | 1,500 |
| F [%] | 23 | 40 |
| Vss [L/kg] | 1.9 | 6.1 |
a i.v. dose mouse: 0.5 mg/kg; i.v. dose rat: 1 mg/kg
b p.o. dose mouse: 2 mg/kg; p.o. dose rat: 10 mg/kg
BI 894999 was also tested in several tumor cell line derived xenografts (CDX) as well as patient-derived xenografts (PDX). The results of these in vivo experiments were supportive to initiate a clinical trial (NCT02516553). BET pathway modulation markers HEXIM1 and HIST2H2BF have been used preclinically and throughout the clinical trial.
BI-6953 features a substitution of a NH group by a N-Methyl group, resulting in a molecular weight of 481.6 Da. Due to this substitution, BI-6953 is no longer able to bind to the different bromodomains and therefore serves as a good negative control.
2D structure of BI-6953, which serves as a negative control
| SELECTIVITY DATA AVAILABLE | BI-894999 | BI-6953 |
SafetyScreen44™ with kind support of  | Yes | ongoing |
| Invitrogen® | No | No |
| DiscoverX® | No | No |
Only BZD/CENTR/R is hit > 50% inhibition (51%) in the SafetyScreen 44. In addition to BRD2-4 (0-1% ctrl), TAF1 (9% ctrl), BRDT (21% ctrl) and CREBBP (25% ctrl) are hit in the DiscoverX panel.
Download selectivity data:
BI894999_selectivityData.xlsx
BI 894999 is potentially similar or inferior to JQ1, OTX015, CPI-0610 or GSK52576211,12
BI 894999 (amredobresib) is a small molecule oral BET inhibitor suitable for in vitro and in vivo studies. BET family proteins are key regulators of transcription.
The novel BET bromodomain inhibitor BI 894999 represses super-enhancer-associated transcription and synergizes with CDK9 inhibition in AML
Gerlach D., Tontsch-Grunt U., Baum A., Popow J., Scharn D., Hofmann M. H., Engelhardt H., Kaya O., Beck J., Schweifer N., Gerstberger T., Zuber J., Savarese F., Kraut N.
Oncogene. 2018, 37(20):2687-2701.
Bromodomain and extra-terminal (BET) bromodomain inhibition activate transcription via transient release of positive transcription elongation factor b (P-TEFb) from 7SK small nuclear ribonucleoprotein
Bartholomeeusen K., Xiang Y., Fujinaga K., Peterlin B. M.
J Biol Chem. 2012, 287(43):36609-16.
Selective inhibition of BET bromodomains
Filippakopoulos P., Qi J., Picaud S., Shen Y., Smith W. B., Fedorov O., Morse E. M., Keates T., Hickman T. T., Felletar I., Philpott M., Munro S., McKeown M. R., Wang Y., Christie A. L., West N., Cameron M. J., Schwartz B., Heightman T. D., La Thangue N., French C. A., Wiest O., Kung A. L., Knapp S., Bradner J. E.
Nature 2010, 468(7327):1067-73.
Transcriptional plasticity promotes primary and acquired resistance to BET inhibition
Rathert P., Roth M., Neumann T., Muerdter F., Roe J. S., Muhar M., Deswal S., Cerny-Reiterer S., Peter B., Jude J., Hoffmann T., Boryń L. M., Axelsson E., Schweifer N., Tontsch-Grunt U., Dow L. E., Gianni D., Pearson M., Valent P., Stark A., Kraut N., Vakoc C. R., Zuber J.
Nature. 2015, 525(7570):543-547.
When you plan a publication, please use the following acknowledgement:
BI 894999 was kindly provided by Boehringer Ingelheim via its open innovation platform opnMe, available at https://www.opnme.com.