Cathepsin C inhibitor
BI-9740
BI-9740 is a very potent inhibitor of the enzymatic activity of Cathepsin C (CatC). It is highly selective versus the related proteases CatB, CatF, CatH, CatK, CatL and CatS, and has very good in vitro and in vivo PK profiles in several animal species. The production of active neutrophil elastase was fully inhibited in human U937 cells treated with BI-9740, as well as in peripheral neutrophils of mice treated with an oral formulation of BI-9740 for 11 days. BI-9740 has very good in vitro and in vivo PK properties in several animal species (mouse, rat, minipig). Treatment of mice with an oral formulation of BI-9740 for 11 consecutive days eliminates active neutrophil elastase in peripheral neutrophils with an ED50 of 0.05 mg/kg q.d. The levels of active Cathepsin G and Proteinase 3 are similarly reduced1. Its diasteoisomer BI-1821 is available as negative control.
More information
Cathepsin C (CatC or CTSC) is a lysosomal cysteine protease. It is expressed at high levels in lung, kidney, and placenta and at moderate to low levels in many other organs. Among immune/inflammatory cells, the mRNA is expressed at high levels in polymorphonuclear leukocytes and alveolar macrophages and their precursor cells2.
In the bone marrow, CatC activates neutrophil serine proteases (NSPs) during myelopoiesis of neutrophils. Inhibition of CatC leads to a decrease in neutrophil elastase (NE), cathepsin G (CG), proteinase 3 (PR3) and NSP4 activities in circulating neutrophils. Inhibition of Cathepsin C can therefore be used to target pathophysiological processes triggered by enhanced or uncontrolled activity of these proteases3.
The active sites of CatC from human, rat, mouse, hamster and minipig are mostly conserved. Some non-conserved residues at the outer rim of the active site are not expected to largely influence inhibitor binding between species.
BI-9740, 3D conformation
BI-9740 displays an IC50 = 1.8 nM in a biochemical human CatC assay and inhibits NE activity in U937 cell-lysate with an IC50 = 5.4 nM. BI-9740 possesses excellent selectivity toward CatK, CatS, CatL, CatB, CatH, CatF.
| Probe name / negative control | BI-9740 | BI-1821 |
| MW [Da]a | 432.5 | 432.5 |
| Human CatC + BSA (IC50) [nM]b | 1.8 | 818 |
| NE activity in U937 cell-lysate (IC50) [nM] | 5.4 | n.d. |
| Mouse Cat C + BSA (IC50) [nM] | 0.6 | n.d. |
| Rat Cat C + BSA (IC50) [nM] | 2.6 | n.d. |
| Human CatK + BSA (IC50) [µM] | 3.5 | n.d. |
| Human CatS + BSA (IC50) [µM] | 32.6 | n.d. |
| Human CatL + BSA (IC50) [µM] | >30.0 | n.d. |
| Human CatH + BSA (IC50) [µM] | >100 | n.d. |
| Human CatB + BSA (IC50) [µM] | >100 | n.d. |
| Human CatF - BSA (IC50) [µM] | >100 | n.d. |
aFor 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
bAssay conditions for CatC assay are available in the patent WO2014140075. For CatK, CatS, CatH, CatB and CatF the assay conditions are identical except for the enzyme nature, concentration, buffer and substrates.
- For CatC, substrate is Gly-Arg-AMC
- For CatK, substrate is Z-Gly-Pro-Arg-AMC
- For CatS, substrate is Z-Val-Val-Arg-AMC
- For CatL, substrate is Z-Phe-Arg-AMC
- For CatH, substrate is H-Arg-AMC
- For CatB, substrate is Z-Arg-Arg-AMC
- For CatF, substrate is Z-Leu-Arg-AMC
BI-9740 has high solubility at pH 2.2, 4.5 and 7. BI-9740 has very good in vitro PK properties in several animal species (mouse, rat, minipig). The negative control BI-1821 is also highly soluble.
| Probe name / negative control | BI-9740 | BI-1821 |
| logP @ pH 11 | 3.1 | n.a. |
| logD @ pH 2 / pH 11 | 1.0 / 3.0 | 1.0 / 2.9 |
| Solubility @ pH 6.8 [µg/mL] | 25 | 54 |
| Caco-2 permeability AB @ pH 7.4 [*10-6 cm/s] | 38 | 41 |
| Caco-2 efflux ratio | 1 | 2 |
| MDCK permeability PappAB @ 1µM [10-6 cm/s] | 6.1 | n.a. |
| MDCK efflux ratio | 9.6 | n.a. |
| Microsomal stability (human/mouse/rat) [% QH] | <23 / 39 / 80 | n.a. |
| Hepatocyte stability @ 5% plasma (human/mouse/rat) [% QH] | <1 / 19 / 13 | n.a. |
| Plasma Protein Binding (human/mouse/rat) [%] | 98.5 / 97.7 / 99.9 | n.a. |
| hERG [inh. % @ 10 µM] | 39 | n.a. |
| CYP 3A4 (IC50) [µM] | >50 | >50 |
| CYP 2C8 (IC50) [µM] | >50 | n.a. |
| CYP 2C9 (IC50) [µM] | >50 | n.a. |
| CYP 2C19 (IC50) [µM] | >50 | n.a. |
| CYP 2D6 (IC50) [µM] | 37 | n.a. |
BI-9740 has in vivo PK properties in several animal species (mouse, rat, minipig) allowing its testing in most of in vivo acute and chronic models.
BI-9740 | MOUSEb | RATb | MINI PIGc |
| Clearance [% QH]a | 5 | 0.6 | 4 |
| Mean residence time after i.v. dose [h] | 2 | 5 | 3.7 |
| tmax [h] | 0.3 (natrosol) | 1.4 (suspension) | 2.5 |
| Cmax [nM] | 655 | 5,590 | 283 |
| Bone marrow exposure [nM] | 15 | 205 | - |
| F [%] | 100 | 72 | 30 |
| Vss [L/kg] | 0.54 | 0.12 | 0.38 |
ai.v. dose: 0.43 mg/kg
bp.o. dose: 2.1 mg/kg
cp.o. dose: 4.3mg/kg (SUS/ADF)
A mouse model was used to demonstrate in vivo activity. In consideration of neutrophil homeostasis, animals were treated with BI-9740 once daily for 11 consecutive days. On day 12, animals were compound treated, followed by a LPS challenge by inhalation. Four hours later, bronchioalveolar lavage (BAL) was prepared and the activity of Neutrophile Elastase (NE) and of the related proteases Cathepsin G (CatG) and Proteinase 3 (PR3) in the lavage neutrophils was measured.
The production of active Neutrophil Elastase in peripheral neutrophils was completely attenuated by BI-9740 in a dose dependent manner with an ED50 of 0.05 mg/kg. The levels of active CatG and PR3 were similarly reduced.
ENZYME | DOSE | % REDUCTION VS LPS CONTROL |
| NE | 0.5 mg/kg | 91 |
| PR3 | 0.5 mg/kg | 97 |
| CatG | 0.5 mg/kg | 100 |
Data were normalized by setting the mean of the non-LPS (vehicle only) control to 0% and the mean of the LPS control to 100%. A non-linear regression fit to calculate the half-maximal effective dose (ED50) was applied suing GraphPad Prism. Data are shown as mean and SEM.
BI-1821 is provided as a negative control for BI-9740.
Structure of BI-1821, a negative control for CatC
BI-9740 shows a > 1,000x selectivity versus the related proteases Cathepsin B, F, H, K, L and S and displays no activity against 34 unrelated proteases from different classes up to a concentration of 10 µM.
The testing of BI-9740 against 80 different receptors and transporters identified the following activities:
1) BI-9740 shows agonistic activity on the kappa opioid receptor (KOR) with an EC50 of 1.2 µM (protein-free assay).
2) BI-9740 shows inhibitory activity on the 5HT-transporter with an IC50 of 0.71 µM (protein-free assay).
The negative control BI-1821 showed more than 50% inhibition @ 10 µM in 3 out of 44 targets (KAPPA(KOP), M2/H, M1/H).
SELECTIVITY DATA AVAILABLE | BI-9740 | BI-1821 |
SafetyScreen44™ with kind support of  | Yes | Yes |
| Invitrogen® | No | No |
| DiscoverX® | No | No |
| Dundee | No | No |
Download selectivity data:
BI-9740_selectivityData_0.xlsx
BI-1821_selectivityData.xlsx
The X-ray crystal structure of Cathepsin C in complex with BI-9740 is available via the “Contact us” form.
BI-9740, 3-D conformation co-crystalized in the CatC protein
Daniel Guay, Christian Beaulieu and David M. Percival Therapeutic Utility and Medicinal Chemistry of Cathepsin C Inhibitors Current Topics in Medicinal Chemistry 2010, 10, 2010, 708-716 DOI: 10.2174/156802610791113469, PubMed
BI-9740 is a very potent, highly selective and orally bioavailable CatC inhibitor. BI-9740 shows no species selectivity and displays low nM IC50 in human, mouse and rat CatC assays. BI-9740 has high solubility at pH 2.2, 4.5 and 7. BI-9740 has very good in vitro and in vivo PK properties in several animal species (mouse, rat, minipig).
When you plan a publication, please use the following acknowledgement:
BI-9740 was kindly provided by Boehringer Ingelheim via its open innovation platform opnMe, available at https://www.opnme.com.