ABSTRACT
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.
Subject(s)
Anemia/drug therapy , Aza Compounds/chemical synthesis , Hydantoins/chemical synthesis , Hypoxia-Inducible Factor 1/metabolism , Procollagen-Proline Dioxygenase/antagonists & inhibitors , Spiro Compounds/chemical synthesis , Animals , Aza Compounds/pharmacokinetics , Aza Compounds/pharmacology , Dogs , ERG1 Potassium Channel , Erythropoietin/biosynthesis , Ether-A-Go-Go Potassium Channels/metabolism , High-Throughput Screening Assays , Humans , Hydantoins/pharmacokinetics , Hydantoins/pharmacology , Hypoxia-Inducible Factor-Proline Dioxygenases , Indoles/chemical synthesis , Indoles/pharmacokinetics , Indoles/pharmacology , Liver/drug effects , Liver/enzymology , Macaca mulatta , Mass Spectrometry , Mice , Mice, Inbred C57BL , Protein Binding , Rats , Spiro Compounds/pharmacokinetics , Spiro Compounds/pharmacology , Structure-Activity Relationship , Up-RegulationABSTRACT
Extremely potent very late antigen-4 (VLA-4) antagonists with picomolar, whole blood activity and slow dissociation rates were discovered by incorporating an amino substituent on the proline fragment of the initial lead structure. This level of potency against the unactivated form of VLA-4 was shown to be sufficient to overcome the poor pharmacokinetic profiles typical of this class of VLA-4 antagonists, and sustained activity as measured by receptor occupancy was achieved in preclinical species after oral dosing.
Subject(s)
Integrin alpha4beta1/antagonists & inhibitors , Niacinamide/analogs & derivatives , Phenylalanine/analogs & derivatives , Administration, Oral , Animals , Cytochrome P-450 CYP3A , Cytochrome P-450 CYP3A Inhibitors , Dogs , Humans , Inhibitory Concentration 50 , Niacinamide/chemical synthesis , Niacinamide/pharmacokinetics , Niacinamide/pharmacology , Phenylalanine/administration & dosage , Phenylalanine/chemical synthesis , Phenylalanine/pharmacokinetics , Phenylalanine/pharmacology , RatsABSTRACT
Replacement of the triazolopiperazine ring of sitagliptin (DPP-4 IC(50)=18nM) with 3-(2,2,2-trifluoroethyl)-1,4-diazepan-2-one gave dipeptidyl peptidase IV (DPP-4) inhibitor 1 which is potent (DPP-4 IC(50)=2.6nM), selective, and efficacious in an oral glucose tolerance test in mice. It was selected for extensive preclinical development as a potential back-up candidate to sitagliptin.
Subject(s)
Azepines/chemistry , Diabetes Mellitus, Type 2/drug therapy , Dipeptidyl-Peptidase IV Inhibitors , Hypoglycemic Agents/chemistry , Protease Inhibitors/chemistry , Animals , Azepines/therapeutic use , Crystallography, X-Ray , Dipeptidyl Peptidase 4/chemistry , Hypoglycemic Agents/therapeutic use , Protease Inhibitors/therapeutic use , Protein Conformation , Pyrazines/chemistry , Pyrazines/therapeutic use , Rats , Rats, Inbred Strains , Sitagliptin Phosphate , Triazoles/chemistry , Triazoles/therapeutic useABSTRACT
PURPOSE: To develop and characterize a radiolabelled Substance-P antagonist useful for quantitation of neurokinin-1 receptors in the brain via PET imaging. PROCEDURE: [18F]SPA-RQ (Substance-P antagonist - receptor quantifier) was synthesized in good yield and high specific activity by alkylation of a BOC protected phenolate anion using [18F]bromofluoromethane. Removal of the BOC protecting group with trifluoroacetic acid gave [18F]SPA-RQ. RESULTS: SPA-RQ has high affinity for human, rhesus monkey and guinea pig NK1 receptors (h-IC50=67 pM) and has a log P value of 1.8. Biodistribution studies in guinea pig showed that this tracer penetrates the blood-brain barrier and selectively labels NK1 receptors in the striatum and cortex. CONCLUSION: [18F]SPA-RQ is a potent, high affinity Substance-P antagonist that can be conveniently labeled with high specific activity using [18F]fluoromethylbromide. This tracer is a useful tool for noninvasive imaging of central NK1 receptors.
