LTB4 antagonist
BIIL 284
BIIL 284 is a Leukotriene B4 (LTB4) antagonist prodrug with negligible binding affinity (Ki = 230 nM) and represents an excellent tool for in vivo experiments to study LTB4 receptor antagonism. After p.o. administration the molecule is metabolized to BIIL 315, which is a highly potent LTB4 receptor antagonist (Ki = 1.9 nM). The compound should only be administered p.o. as the gut is the major side of metabolism.1 Together with BIIL 284, we also offer BIIL 315 on opnMe.com and which is provided to study the effect of LTB4 signaling in vitro.
Please note that BIIL 284 is shipped as a co-crystal of ethanol. The molecular weight of this co-crystal is 584.7 g/mol or Da.
Background information
The LTB4 receptor is a G-protein coupled receptor (GPCR) with high affinity specifically to Leukotriene B4 (LTB4), which is a dihydroxy fatty acid formed from arachidonic acid by the 5-lipoxygenase pathway2. LTB4 is one of the most powerful mediators involved in inflammatory processes. Binding of LTB4 to the receptor particularly activates neutrophilic leukocytes and triggers chemotaxis, degranulation and oxidative burst. In particular, neutrophilic leukocytes are readily attracted and activated by LTB4, producing an accumulation of neutrophils and also macrophages, T lymphocytes and eosinophils at the site of inflammation. Thus, LTB4 has been suggested to be an important participant in the pathophysiology of inflammatory processes of many human diseases with unmet medical need. The inhibition of LTB4 has caused a reduction of inflammatory processes in various diseases models in vivo1,2.
A crystal structure of the LTB4 receptor was published in 2018 by Hori et al3.
Crystal structure of LTB4 receptor with BIIL 260 (PDB code: 5X33)3.
Due to its prodrug character, BIIL 284 displays negligible affinity to the LTB4 receptor (Ki = 230 nM). BIIL 315 (Ki = 1.9 nM), which is formed from BIIL 284, however, binds with high affinity to the LTB4 receptor. BIIL 315 potently inhibits LTB4-induced intracellular Ca2+ release in human neutrophils (IC50 value of 0.75 nM) as measured with Fura-21. In the presence of 0.1% BSA, the inhibitory potency was reduced by 6-fold due to protein binding. Additionally, BIIL 315 (IC50 = 0.65 nM) potently inhibited LTB4-induced chemotaxis of human polymorphonuclear leukocytes (PMNLs)1. LTB4 receptor kinetic analysis of BIIL 315 revealed slow off-dissociation. The Ki value calculated from the kinetic is 4 pM for BIIL 315 on human neutrophil granulocyte membranes. Consequently, BIIL 315 is the dominating LTB4 antagonist in vivo4. The negative control BIIS 035 did not display any binding affinity and can be used for in vitro experiments.
| PROBE NAME | BIIL 284 | BIIL 315 | BIIS 035 |
| MW [Da, free base]a | 538.6 | 642.7 | 610.7 |
| LTB4 receptor binding (Ki) [nM]b | 230 | 1.9 | >1000 |
| Inhibition of LTB4-induced Ca2+ (IC50) [nM] | --- | 0.75 | --- |
| Inhibition of LTB4-induced chemotaxis in human PMNLs (IC50) [nM] | --- | 0.65 | --- |
a For the salt form you will get, please refer to the label on the vial and for molecular weight of salt, please refer to the FAQs
b Assay conditions are described in reference 1
BIIL 284 displays low solubility. It should only be administered p.o. as the gut is the major side of metabolism1. Metabolism is not present after IV injection of BIIL 284 and additionally causes the compound to crystalize in plasma due to low solubility.
| PROBE NAME | BIIL 284 | BIIS 035 |
| LogD @ pH2 / pH11 | 3.2 / 5.2 | 4.1 / >6 |
| Solubility @ pH 7 [µg/mL] | 0.2 | <1.0 |
| Microsomal stability (human/mouse/rat) [% QH] | 81 / n.d. / n.d. | 61 / n.a. / 61 |
| Hepatocyte stability (human/mouse/rat) [% QH] | 89 / 96 / n.d. | n.a. |
| Plasma Protein Binding (human/mouse/rat) [%] | n.d. / - / - | n.a. |
| hERG [inh. % @ 10 µM] | 12.7 | n.a. |
**BIIL 284 is a prodrug and seems to be primarily metabolized in the gut wall before absorption
in vivo studies revealed that BIIL 315 is the dominant active metabolite in rats after p.o. administration. BIIL 284 is only found in minor concentrations in plasma. Further studies indicated the gut to be the major site of metabolism. BIIL 284 is only poorly absorbed from standard aqueous suspension media. Administration with the addition of solubilizing agents was tolerated by rat and mini-pigs (to a certain degree). Due to low solubility, intravenous administration of BIIL 284 should not be performed because the compound crystallizes out in the plasma4.
| BIIL 284 | |
| Clearance [mL/min/kg]a | 41 |
| Mean residence time after i.v. dose [h]a | 0.80 |
| tmax [h]b | 1.0 |
| Cmax [nM] | 24 |
| F [%] | 0.25 |
| Vss [l/kg] | 1.9 |
| AUC0-∞ [ng*h/ml] | 69 |
| t½ | 1.0 |
a i.v. dose rat: 0.92 mg/kg
b p.o. dose rat: 70 mg/kg as a solution in Labrasol.
The efficacy of BIIL 284 was demonstrated in various in vivo LTB4 models such as
- Inhibition of LTB4-induced mouse ear inflammation (ED50 = 0.0082 mg/kg p.o.)
- Inhibition of LTB4-induced transdermal chemotaxis in guinea pigs (ED50 = 0.028 mg/kg p.o.)
For more details please see reference 11.
In addition, BIIL 284 has been investigated in disease models for asthma, rheumatoid arthritis and skin inflammation. BIIL 284 demonstrated significant efficacy in a collagen induced arthritis mouse model and reduced the antigen-induced eosinophilic bronchial influx in guinea pigs (asthma model). In the skin inflammation model a psoriasis like dermatitis LTB4-induced skin effects can be antagonized with BIIL 284. Furthermore, BIIL 284 counteracts with arachidonic acid induced skin inflammation in mice, however dermatitis is not blocked completely4.
BIIS 035 displays no affinity to the LTB4 receptor and therefore can be used as negative control for in vitro experiments.
BIIL 284 is a selective LTB4 antagonist prodrug with no relevant off-target effects in the Eurofins Safety Panel 44™.
| SELECTIVITY DATA AVILABLE | BIIL 284 | BIIS 035 |
SafetyScreen44™ with kind support of  | Yes | Yes |
| Invitrogen® | No | No |
| DiscoverX® | No | No |
| Dundee | No | No |
Download selectivity data:
BIIL-284_selectivityData.xlsx
BIIS035_selectivityData_0.xlsx
A crystal structure of leukotriene B4 receptor in complex with BIIL 260 was published by Hori et al. (PDB code: 5X33)3.
BIIL 315 was identified as the major component in plasma after p.o. administration and appears to be the dominating LTB4 antagonist of BIIL 284 in vivo. The major site of metabolism seems to be localized primarily in the gut wall. Thereby, ubiquitous esterases will convert BIIL 284 to BIIL 260, which will be further glucoronidated by UDP-glucuronyl-tranferases. Consequently, p.o. administration of BIIL 284 will lead to BIIL 315 by fast metabolism. Intravenous administration of BIIL 284 and BIIL 260 will lead only to minor formation of the more potent BIIL 315 metabolite. Furthermore, BIIL 284 displays very low solubility causing crystallization of the compound in plasma. Combining these two aspects, BIIL 284 should only be used as in vivo tool using p.o. administration4.
Prodrug BIIL 284 represents an excellent oral in vivo tool compound to study the effect of LTB4 receptor antagonism in vivo. After p.o. administration, it is converted to the highly potent LTB4 receptor antagonist BIIL 315 which was highly efficacious in various disease models1. Please note that BIIL 284 is shipped as a co-crystal of ethanol. The molecular weight of this co-crystal is 584.7 g/mol or Da.
In vitro and in vivo pharmacological characterization of BIIL 284, a novel and potent leukotriene B(4) receptor antagonist
Birke FW., Meade CJ., Anderskewitz R., Speck GA., Jennewein HM.
J Pharmacol Exp Ther. 2001, 297(1), 458-66.
Leukotriene B4 receptor antagonist LY293111 inhibits proliferation and induces apoptosis in human pancreatic cancer cells.
Tong WG., Ding XZ., Hennig R., Witt RC., Standop J., Pour PM., Adrian TE.
Clin Cancer Res. 2002, 8(10), 3232-42.
Inhibition of leukotriene B4-induced CD11B/CD18 (Mac-1) expression by BIIL 284, a new long acting LTB4 receptor antagonist, in patients with rheumatoid arthritis.
Alten R., Gromnica-Ihle E., Pohl C., Emmerich J., Steffgen J., Roscher R., Sigmund R., Schmolke B., Steinmann G.
Ann Rheum Dis. 2004, 63(2), 170-6.
When you plan a publication, please use the following acknowledgement:
BIIL 284 was kindly provided by Boehringer Ingelheim via its open innovation platform opnMe, available at https://www.opnme.com.