Neutrophil Elastase inhibitor
BI-5524
BI-5524 in an inhibitor of human neutrophil elastase (hNE), which dysregulation is associated with inflammatory and fibrotic diseases. It inhibits the neutrophil-derived serine protease elastase by binding to its catalytic site with high potency and selectivity. Its excellent PK properties allow for the investigation of suitable disease models in rodent species. The distomer BI-5525 can be used as negative control.
Background information
The serine protease neutrophil elastase (NE) is expressed in bone marrow precursor cells and is stored in the granules of peripheral blood neutrophils at high concentrations. Upon neutrophil activation, NE is secreted causing degradation of the extracellular matrix components, like elastin, fibronectin, laminin, collagen and proteoglycans3. In addition, NE activity is implicated in the activation of proinflammatory pathways4.
While normal NE function is required for microbial clearance and an appropriate innate immune response, NE dysregulation is described to play a major role in a number of chronic inflammatory and fibrotic diseases in different organs5. As part of various research approaches NE Inhibitors have been associated with a potential role in several diseases such as idiopathic pulmonary fibrosis as well as other inflammatory and fibrotic diseases of the lung2.
Significant protection or resistance against experimental lung emphysema6, pulmonary hypersension7, pulmonary fibrosis8 and myocarditis9 could also be shown in murine elastase knock-out models.
Structure of hNE in complex with dihydropyrimidone inhibitor BAY-678 (PDB ID 5A0A)1
BI-5524 shows sub-nanomolar potency in representative in vitro assays.
| Probe name / negative control | BI-5524 | BI-5525 |
| MW [Da, free base]a | 512.5 | 512.5 |
| hNE inhibitor assay (IC50) [nM]b | 0.5 | >30 |
| Mouse NE inhibitor assay (IC50) [nM] | 12 | N/A |
| Zymosan assay plasma (EC50) [nM]c | 0.4 | N/A |
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 Inhibition of hNE was tested in a biochemical assay using purified commercial hNE and a fluorescent peptide substrate10
c Inhibition of zymosan-stimulated NE activity in human plasma10,11
BI-5524 shows good solubility and permeability as well as metabolic stability in vitro.
| Probe name / negative control | BI-5524 | BI-5525 |
| logP @ pH 11 | 2.7 | 2.7 |
| Solubility @ pH 6.8 [µg/mL] | 79.0 | 47 |
| Caco-2 permeability AB @ pH 7.4 [*10-6 cm/s] | 11.1 | 17 |
| Caco-2 efflux ratio | 6.8 | 3.2 |
| Microsomal stability (human/mouse/rat) [% QH] | <23 / <23 / 37 | n.a. |
| Hepatocyte stability (human/mouse/rat) [% QH] | 0/0/50 | n.a. |
| Plasma Protein Binding (human/mouse/rat) [%] | 73/75/58 | n.a. |
| hERG [inh. % @ 10 µM] | 27.4 | n.a. |
| CYP 3A4 (IC50) [µM] | >50 | >50 |
| CYP 2C8 (IC50) [µM] | >50 | >50 |
| CYP 2C9 (IC50) [µM] | >50 | >50 |
| CYP 2C19 (IC50) [µM] | >50 | >50 |
| CYP 2D6 (IC50) [µM] | >50 | >50 |
BI-5524 shows excellent PK properties in rodent species and is suited for in vivo studies.
| BI-5524 | Mouse | Rat |
| Clearance [% QH]a | 19 | 52 |
| Mean residence time after iv dose [h]a | 2.0 | 1.4 |
| tmax [h] | 1.0b | 2.0c |
| Cmax [nM] | 2,280b | 247,696c |
| F [%] | 100b | 100c |
| Vss [l/kg] | 2.0 | 3.1 |
a mouse i.v. dose: 0.5 mg/kg, rat i.v. dose: 0.5 mg/kg
b mouse p.o. dose: 5 mg/kg
c mouse p.o. dose: 100 mg/kg
BI-5525 is the distomer of the active probe BI-5524. It has an at least 75-fold lower activity in hNE inhibitor assays and it is virtually inactive.
BI-5525 which serves as a negative control
BI-5524 displays a high selectivity for hNE (Inhibition of closely related proteases, like proteinase 3 and cathepsin G @ >100 nM and >10 µM, respectively).
BI-5524 was also tested on 96 targets in a selectivity panel and showed ≥1,000-fold selectivity for all targets (≤ 50% inhibition @ 10 µM).
BI-5525 was tested on 44 targets in a selectivity panel and showed ≥1,000-fold selectivity for all targets (≤ 50% inhibition @ 10 µM).
| SELECTIVITY DATA AVAILABLE | BI-5524 | BI-5525 |
SafetyScreen44™ with kind support of  | Yes | Yes |
| Invitrogen® | No | No |
| DiscoverX® | No | No |
| Dundee | No | No |
Download selectivity data:
BI-5524_selectivityData.xlsx
BI-5525_selectivityData.xlsx
BAY-678
BI-5524 is a highly potent and selective inhibitor of human neutrophil elastase with a favorable pharmacokinetic (PK) profile suited for in vivo studies. The distomer BI-5525 is available as a negative control.
Freezing the Bioactive Conformation to Boost Potency: The Identification of BAY 85-8501, a Selective and Potent Inhibitor of Human Neutrophil Elastase for Pulmonary Diseases
von Nussbaum F., Li V. M-J., Allerheiligen S., Anlauf S., Bärfacker L., Bechem M., Delbeck M., Fitzgerald M. F., Gerisch M., Gielen-Haertwig H., Haning H., Karthaus D., Lang D., Lustig K., Meibom D., Mittendorf J., Rosentreter U., Schäfer M., Schäfer S., Schamberger J., Telan L. A., Tersteegen A.
Chem Med Chem 2015, 10(7), 1163-73.
Substituted bicyclic dihydropyrimidinones and their use as inhibitors of neutrophil elastase activity
Gnamm C., Oost T., Peters S., Hoesch H., Ries U. J.
WO2014122160A1 2014.
When you plan a publication, please use the following acknowledgement:
BI-5524 was kindly provided by Boehringer Ingelheim via its open innovation platform opnMe, available at https://www.opnme.com.