Jeffrey J. Hale

The novel NK1 receptor antagonist MK-0869 (L-754,030) and its water soluble phosphoryl prodrug, L-758,298, inhibit acute and delayed cisplatin-induced emesis in ferrets

The anti-emetic profile of the novel brain penetrant tachykinin NK1 receptor antagonist MK-0869 (L-754,030) 2-(R)-(1-(R)-(3,5-bis(trifluoromethyl)phenylethoxy)-3-(S)-(4-fluor o)phenyl-4-(3-oxo-1,2,4-triazol-5-yl)methylmorpholine and its water soluble prodrug, L-758,298, has been examined against emesis induced by cisplatin in ferrets. In a 4 h observation period, MK-0869 and L-758,298 (3 mg/kg i.v. or p.o.) inhibited the emetic response to cisplatin (10 mg/kg i.v.). The anti-emetic protection afforded by MK-0869 (0.1 mg/kg i.v.) was enhanced by combined treatment with either dexamethasone (20 mg/kg i.v.) or the 5-HT3 receptor antagonist ondansetron (0.1 mg/kg i.v.). In a model of acute and delayed emesis, ferrets were dosed with cisplatin (5 mg/kg i.p.) and the retching and vomiting response recorded for 72 h. Pretreatment with MK-0869 (4-16 mg/kg p.o.) dose-dependently inhibited the emetic response to cisplatin. Once daily treatment with MK-0869 (2 and 4 mg/kg p.o.) completely prevented retching and vomiting in all ferrets tested. Further when daily dosing began at 24 h after cisplatin injection, when the acute phase of emesis had already become established, MK-0869 (4 mg/kg p.o. at 24 and 48 h after cisplatin) prevented retching and vomiting in three out of four ferrets. These data show that MK-0869 and its prodrug, L-758,298, have good activity against cisplatin-induced emesis in ferrets and provided a basis for the clinical testing of these agents for the treatment of emesis associated with cancer chemotherapy.

In vitro and in vivo predictors of the anti-emetic activity of tachykinin NK1 receptor antagonists

The ability of tachykinin NK1 receptor antagonists to inhibit GR73632 (D-Ala-[L-Pro9,Me-Leu8]substance P-(7-11))-induced foot tapping in gerbils was employed as an indirect measure of brain penetration and this was compared with their ability to prevent acute emesis induced by cisplatin in ferrets. (+)-GR203040 ((2S,3S and 2R,3R)-2-methoxy-5-tetrazol-1-yl-benzyl-(2-phenyl-piperidin- 3-yl)-amine), CP-99,994 ((2S,3S)-cis-3-(2-methoxybenzylamino)-2-phenyl piperidine) dihydrochloride), and L-742,694 (2-(S)-(3,5-bis(trifluoromethyl)benzyloxy)-3-(S)-phenyl-4-(5-(3-oxo-1,2, 4-triazolo)methylmorpholine) potently inhibited GR73632-induced foot tapping (ID50 < or = 0.85 mg/kg), and acute retching induced by cisplatin (ID50 < or = 0.18 mg/kg). RPR100893 ((3aS,4S,7aS)-7,7-diphenyl-4-(2-methoxyphenyl)-2-[(S)-2-(2-m ethoxyphenyl)proprionyl] perhydroisoindol-4-ol) was not a potent antagonist of retching (ID50 4.1 mg/kg) or foot tapping (ID50 > 10 mg/kg). High doses (3-10 mg/kg) of CGP49823 ((2R,4S)-2-benzyl-1-(3,5-dimethylbenzoyl)-N-[(4-quinolinyl)methyl] -4-piperineamine) dihydrochloride), FK888 (N2-[(4R)-4-hydroxy-1-(1-methyl-1H-indol-3-yl)carbonyl-L-propyl]-N-methy l-N-phenylmethyl-L-3-(2-naphthyl)-alaninamide), and LY303870 ((R)-1-[N-(2-methoxybenzyl)acetylamino]-3-(1H-indol-3-yl)-2-[N-(2-(4-(pi peridinyl)piperidin-1-yl)acetyl)amino]propane) were required to inhibit foot tapping; these agents were not anti-emetic in this dose range. SR140333 ((S)-1-[2-[3-(3,4-dichlorphenyl)-1 (3-isopropoxyphenylacetyl)piperidin-3-yl] ethyl]-4-phenyl-1 azaniabicyclo [2.2.2]octane; 3-10 mg/kg) failed to inhibit foot tapping or emesis. Affinities for the human and ferret tachykinin NK1 receptor were highly correlated (r = 0.93, P = 0.0008). Inhibition of foot tapping in gerbils, but not NK1 receptor binding affinity, predicted anti-emetic activity in ferrets (r = 0.75, P < 0.01). These findings confirm that the anti-emetic activity of tachykinin NK1 receptor antagonists is dependent on brain penetration.

Prolyl hydroxylase domain-containing protein inhibitors as stabilizers of hypoxia-inducible factor: small molecule-based therapeutics for anemia.

Importance of the field: Anemia caused by chronic kidney disease and other chronic diseases or conditions can be managed by the treatment of biologic-based erythropoiesis stimulating agents (ESAs). Although these ESAs are successful in treating these anemic conditions, a small molecule-based anti-anemia medicine can potentially revolutionize the treatment of anemia by bringing convenience to patients and being cost effective. Prolyl hydroxylase domain-containing protein (PHD) inhibitors may provide an opportunity for the development of small molecule anti-anemia medicines. Areas covered in this review: This review covers efforts to target PHD enzymes for stabilization of hypoxia-inducible factor (HIF)-α subunits under normal oxygen levels as an attractive strategy to upregulate the expression of erythropoietin and genes involved in iron metabolism for the treatment of anemia. What the reader will gain: The reader will gain a brief summary of recent advances in HIF and PHD biology and a review of patents/patent applications on the subject of PHD inhibitors as HIF stabilizers for the treatment of anemia. Take home message: Several classes of PHD enzyme inhibitors have been disclosed and several are currently in clinical trials for the development of small molecule-based therapeutics for the treatment of anemia.

NK2 receptors mediate plasma extravasation in guinea-pig lower airways

1 Neurokinin (NK) receptor‐mediated extravasation has been examined in guinea‐pig airways by use of a recently described marker for microvascular protein leakage, 125I‐labelled human fibrinogen. 2 Neurokinin A (NKA) caused a dose‐dependent increase in plasma [125I]‐fibrinogen extravasation in trachea, main bronchi, secondary bronchi and intraparenchymal airways. In contrast, the NK2 selective agonist [β‐Ala8]NKA(4–10) only caused extravasation in the secondary and intraparenchymal airways. 3 The NK2 selective antagonist, SR 48968, caused a dose‐dependent inhibition of NKA and [β‐Ala8]NKA(4–10)‐induced extravasation of fibrinogen in guinea‐pig secondary bronchi and intraparenchymal airways. SR 48968 was without effect on the NKA‐induced extravasation in trachea and main bronchi. 4 NKA‐ or [β‐Ala8]NKA(4–10)‐induced plasma extravasation was not modified by pretreatment with histamine H1‐ or H2‐receptor antagonists. 5 It is concluded that NK2 receptors mediate plasma [125I]‐fibrinogen extravasation in guinea‐pig secondary bronchi and intraparenchymal airways. This effect is direct and does not depend upon histamine released from mast cells.

1,3,4-Trisubstituted pyrrolidine CCR5 receptor antagonists. Part 2: lead optimization affording selective, orally bioavailable compounds with potent anti-HIV activity.

Investigations of the structure-activity relationships of 1,3,4-trisubstituted pyrrolidine human CCR5 receptor antagonists afforded orally bioavailable compounds with the ability to inhibit HIV replication in vitro.

1,3,4-Trisubstituted pyrrolidine CCR5 receptor antagonists. Part 1: discovery of the pyrrolidine scaffold and determination of its stereochemical requirements.

A series of 1,3,4-trisubstituted pyrrolidines was discovered to have the ability to displace [(125)I]-MIP-1alpha from the CCR5 receptor expressed on Chinese hamster ovary (CHO) cell membranes. CCR5 activity was found to be dependent on the regiochemistry and the absolute stereochemistry of the pyrrolidine.

Pharmacological evaluation of LH-21, a newly discovered molecule that binds to cannabinoid CB1 receptor.

LH-21 (5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-3-hexyl-1H-1,2,4-triazole) was previously reported as a neutral antagonist at the cannabinoid CB1 receptor which, despite its reported poor ability to penetrate into the brain, suppressed food intake and body weight in rats by intraperitoneal administration. In the present study, we studied the mechanism of action of LH-21 by characterizing its in vitro pharmacological properties and in vivo efficacy. LH-21 inhibited the binding of [3H]CP55940 to cloned human and rat CB1 receptors with IC50 values of 631+/-98 nM, and 690+/-41 nM, respectively, and acted as an inverse agonist in a cAMP functional assay using cultured cells expressing human, rat or mouse CB1 receptor. The compound was shown to be brain-penetrant in rats by intravenous administration. Importantly, a single dose of LH-21 (60 mg/kg, i.p.) caused a similar suppression of overnight food intake and body weight gain in wild-type and CB1 receptor knockout mice. Our results suggest that LH-21 is a low affinity inverse agonist for the CB1 receptor and does not act on the CB1 receptor to inhibit food intake in mice.

1,3,4-Trisubstituted pyrrolidine CCR5 receptor antagonists. Part 4: Synthesis of N-1 acidic functionality affording analogues with enhanced antiviral activity against HIV

A series of alpha-(pyrrolidin-1-yl)acetic acids is presented as selective and potent antivirals against HIV. Several of the pyrrolidine zwitterions demonstrated reasonable in vitro properties, enhanced antiviral activities and improved pharmacokinetic profiles over pyrrolidine 1.

1,3,8-Triazaspiro[4.5]decane-2,4-diones as efficacious pan-inhibitors of hypoxia-inducible factor prolyl hydroxylase 1-3 (HIF PHD1-3) for the treatment of anemia.

The discovery of 1,3,8-triazaspiro[4.5]decane-2,4-diones (spirohydantoins) as a structural class of pan-inhibitors of the prolyl hydroxylase (PHD) family of enzymes for the treatment of anemia is described. The initial hit class, spirooxindoles, was identified through affinity selection mass spectrometry (AS-MS) and optimized for PHD2 inhibition and optimal PK/PD profile (short-acting PHDi inhibitors). 1,3,8-Triazaspiro[4.5]decane-2,4-diones (spirohydantoins) were optimized as an advanced lead class derived from the original spiroindole hit. A new set of general conditions for C-N coupling, developed using a high-throughput experimentation (HTE) technique, enabled a full SAR analysis of the spirohydantoins. This rapid and directed SAR exploration has resulted in the first reported examples of hydantoin derivatives with good PK in preclinical species. Potassium channel off-target activity (hERG) was successfully eliminated through the systematic introduction of acidic functionality to the molecular structure. Undesired upregulation of alanine aminotransferese (ALT) liver enzymes was mitigated and a robust on-/off-target margin was achieved. Spirohydantoins represent a class of highly efficacious, short-acting PHD1-3 inhibitors causing a robust erythropoietin (EPO) upregulation in vivo in multiple preclinical species. This profile deems spirohydantoins as attractive short-acting PHDi inhibitors with the potential for treatment of anemia.

Identification of Leu276 of the S1P1 Receptor and Phe263 of the S1P3 Receptor in Interaction with Receptor Specific Agonists by Molecular Modeling, Site-Directed Mutagenesis, and Affinity Studies

Sphingosine-1-phosphate (S1P) receptor agonists are novel immunosuppressive agents. The selectivity of S1P1 against S1P3 is strongly correlated with lymphocyte sequestration and minimum acute toxicity and bradycardia. This study describes molecular modeling, site-directed mutagenesis, and affinity studies exploring the molecular basis for selectivity between S1P1 and S1P3 receptors. Computational models of human S1P1 and S1P3 receptors bound with two nonselective agonists or two S1P1-selective agonists were developed based on the X-ray crystal structure of bovine rhodopsin. The models predict that S1P1 Leu276 and S1P3 Phe263 contribute to the S1P1/S1P3 selectivity of the two S1P1-selective agonists. These residues were subjected to site-directed mutagenesis. The wild-type and mutant S1P receptors were expressed in Chinese hamster ovary cells and examined for their abilities to bind to and be activated by agonists in vitro. The results indicate that the mutations have minimal effects on the activities of the two nonselective agonists, although they have dramatic effects on the S1P1-selective agonists. These studies provide a fundamental understanding of how these two receptor-selective agonists bind to the S1P1 and S1P3 receptors, which should aid development of more selective S1P1 receptor agonists with immunosuppressive properties and improved safety profiles.