Absorption, Distribution, Metabolism, and Excretion of Icenticaftor (QBW251) in Healthy Male Volunteers at Steady State and In Vitro Phenotyping of Major Metabolites.

Icenticaftor (QBW251) is a potentiator of the CFTR protein and is currently in clinical development for the treatment of chronic obstructive pulmonary disease and chronic bronchitis. An absorption, distribution, metabolism, and excretion (ADME) study was performed at steady state to determine the pharmacokinetics, mass balance, and metabolite profiles of icenticaftor in humans. In this open-label study, six healthy men were treated with unlabeled oral icenticaftor (400 mg b.i.d.) for 4 days. A single oral dose of [14C]icenticaftor was administered on Day 5, and unlabeled icenticaftor was administered b.i.d. from the evening of Day 5 to Day 12. Unchanged icenticaftor accounted for 18.5% of plasma radioactivity. Moderate to rapid absorption of icenticaftor was observed (median Tmax: 4 hours), with 93.4% of the dose absorbed. It exhibited moderate distribution (Vz/F: 335 L) and was extensively metabolized, principally through N-glucuronidation, O-glucuronidation, and/or O-demethylation. The metabolites M8 and M9, formed by N-glucuronidation and O-glucuronidation of icenticaftor, respectively, represented the main entities detected in plasma (35.3% and 14.5%, respectively) in addition to unchanged icenticaftor (18.5%). The apparent mean T1/2 of icenticaftor was 15.4 hours in blood and 20.6 hours in plasma. Icenticaftor was eliminated from the body mainly through metabolism followed by renal excretion, and excretion of radioactivity was complete after 9 days. In vitro phenotyping of icenticaftor showed that cytochrome P450 and uridine diphosphate glucuronosyltransferase were responsible for 31% and 69% of the total icenticaftor metabolism in human liver microsomes, respectively. This study provided invaluable insights into the disposition of icenticaftor. Significance Statement The ADME of a single radioactive oral dose of icenticaftor was evaluated at steady state to investigate the nonlinear pharmacokinetics observed previously with icenticaftor. [14C]Icenticaftor demonstrated good systemic availability after oral administration and was extensively metabolized and moderately distributed to peripheral tissues. The most abundant metabolites, M8 and M9, were formed by N-glucuronidation and O-glucuronidation of icenticaftor, respectively. Phenotyping demonstrated that [14C]icenticaftor was metabolized predominantly by UGT1A9 with a remarkably low Km value.

Drug-drug interactions of icenticaftor (QBW251) with a 5-probe cytochrome P450 cocktail and oral contraceptives.

A drug-drug interaction (DDI) study was conducted to evaluate the effect of icenticaftor (QBW251) on the pharmacokinetics (PK) of a 5-probe cytochrome P450 (CYP) substrate cocktail, guided by in vitro studies in human hepatocytes and liver microsomes. Another DDI study investigated the effect of icenticaftor on the PK and pharmacodynamics (PD) of a monophasic oral contraceptive (OC) containing ethinyl estradiol (EE) and levonorgestrel (LVG) in premenopausal healthy female subjects. The static-mechanistic DDI assessment indicated that icenticaftor may moderately induce the metabolic clearance of co-medications metabolized by CYP3A4 (area under the concentration-time curve [AUC] ratio: 0.47) and potentially CYP2C; icenticaftor may also weakly inhibit the metabolic clearance of co-medications metabolized by CYP1A2 and CYP3A4 (AUC ratio: 1.35 and 1.86, respectively) and moderately inhibit CYP2B6 (AUC ratio: 2.11). In the CYP substrate cocktail DDI study, icenticaftor 300 mg twice daily (b.i.d.) moderately inhibited CYP1A2 (AUC ratio: 3.35) and CYP2C19 (AUC ratio: 2.70). As expected from the results of the in vitro studies, weak induction was observed for CYP3A4 (AUC ratio: 0.51) and CYP2C8 (AUC ratio: 0.66). In the OC DDI study, co-administration of icenticaftor 450 mg b.i.d. with monophasic OC containing 30-µg EE and 150-µg LVG once daily reduced the plasma exposure of both components by approximately 50% and led to increased levels of follicle-stimulating hormone and luteinizing hormone. These results provide valuable guidance for the use of icenticaftor in patients taking concomitant medications that are substrates of CYP enzymes or patients using OCs.

Discovery of Icenticaftor (QBW251), a Cystic Fibrosis Transmembrane Conductance Regulator Potentiator with Clinical Efficacy in Cystic Fibrosis and Chronic Obstructive Pulmonary Disease.

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel are established as the primary causative factor in the devastating lung disease cystic fibrosis (CF). More recently, cigarette smoke exposure has been shown to be associated with dysfunctional airway epithelial ion transport, suggesting a role for CFTR in the pathogenesis of chronic obstructive pulmonary disease (COPD). Here, the identification and characterization of a high throughput screening hit 6 as a potentiator of mutant human F508del and wild-type CFTR channels is reported. The design, synthesis, and biological evaluation of compounds 7-33 to establish structure-activity relationships of the scaffold are described, leading to the identification of clinical development compound icenticaftor (QBW251) 33, which has subsequently progressed to deliver two positive clinical proofs of concept in patients with CF and COPD and is now being further developed as a novel therapeutic approach for COPD patients.

Absorption, Distribution, Metabolism, and Excretion of Capmatinib (INC280) in Healthy Male Volunteers and In Vitro Aldehyde Oxidase Phenotyping of the Major Metabolite.

Capmatinib (INC280), a highly selective and potent inhibitor of the MET receptor tyrosine kinase, has demonstrated clinically meaningful efficacy and a manageable safety profile in patients with advanced non-small-cell lung cancer harboring MET exon 14-skipping mutations. We investigated the absorption, distribution, metabolism, and excretion of capmatinib in six healthy male volunteers after a single peroral dose of 600 mg 14C-labeled capmatinib. The mass balance, blood and plasma radioactivity, and plasma capmatinib concentrations were determined along with metabolite profiles in plasma, urine, and feces. The metabolite structures were elucidated using mass spectrometry and comparing with reference compounds. The parent compound accounted for most of the radioactivity in plasma (42.9% ± 2.9%). The extent of oral absorption was estimated to be 49.6%; the Cmax of capmatinib in plasma was reached at 2 hours (median time to reach Cmax). The apparent mean elimination half-life of capmatinib in plasma was 7.84 hours. Apparent distribution volume of capmatinib during the terminal phase was moderate-to-high (geometric mean 473 l). Metabolic reactions involved lactam formation, hydroxylation, N-dealkylation, formation of a carboxylic acid, hydrogenation, N-oxygenation, glucuronidation, and combinations thereof. M16, the most abundant metabolite in plasma, urine, and feces was formed by lactam formation. Absorbed capmatinib was eliminated mainly by metabolism and subsequent biliary/fecal and renal excretion. Excretion of radioactivity was complete after 7 days. CYP phenotyping demonstrated that CYP3A was the major cytochrome P450 enzyme subfamily involved in hepatic microsomal metabolism, and in vitro studies in hepatic cytosol indicated that M16 formation was mainly catalyzed by aldehyde oxidase. SIGNIFICANCE STATEMENT: The absorption, distribution, metabolism, and excretion of capmatinib revealed that capmatinib had substantial systemic availability after oral administration. It was also extensively metabolized and largely distributed to the peripheral tissue. Mean elimination half-life was 7.84 hours. The most abundant metabolite, M16, was formed by imidazo-triazinone formation catalyzed by cytosolic aldehyde oxidase. Correlation analysis, specific inhibition, and recombinant enzymes phenotyping demonstrated that CYP3A is the major enzyme subfamily involved in the hepatic microsomal metabolism of [14C]capmatinib.

An integrated assessment of the ADME properties of the CDK4/6 Inhibitor ribociclib utilizing preclinical in vitro, in vivo, and human ADME data.

Ribociclib (LEE011, Kisqali ®) is a highly selective small molecule inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6), which has been approved for the treatment of advanced or metastatic breast cancer. A human ADME study was conducted in healthy male volunteers following a single oral dose of 600 mg [14 C]-ribociclib. Mass balance, blood and plasma radioactivity, and plasma ribociclib concentrations were measured. Metabolite profiling and identification was conducted in plasma, urine, and feces. An assessment integrating the human ADME results with relevant in vitro and in vivo non-clinical data was conducted to provide an estimate of the relative contributions of various clearance pathways of the compound. Ribociclib is moderately to highly absorbed across species (approx. 59% in human), and is extensively metabolized in vivo, predominantly by oxidative pathways mediated by CYP3A4 (ultimately forming N-demethylated metabolite M4) and, to a lesser extent, by FMO3 (N-hydroxylated metabolite M13). It is extensively distributed in rats, based on QWBA data, and is eliminated rapidly from most tissues with the exception of melanin-containing structures. Ribociclib passed the placental barrier in rats and rabbits and into milk of lactating rats. In human, 69.1% and 22.6% of the radiolabeled dose were excreted in feces and urine, respectively, with 17.3% and 6.75% of the 14 C dose attributable to ribociclib, respectively. The remainder was attributed to numerous metabolites. Taking into account all available data, ribociclib is estimated to be eliminated by hepatic metabolism (approx. 84% of total), renal excretion (7%), intestinal excretion (8%), and biliary elimination (1%).

Metabolism and Disposition of Siponimod, a Novel Selective S1P1/S1P5 Agonist, in Healthy Volunteers and In Vitro Identification of Human Cytochrome P450 Enzymes Involved in Its Oxidative Metabolism.

Siponimod, a next-generation selective sphingosine-1-phosphate receptor modulator, is currently being investigated for the treatment of secondary progressive multiple sclerosis. We investigated the absorption, distribution, metabolism, and excretion (ADME) of a single 10-mg oral dose of [14C]siponimod in four healthy men. Mass balance, blood and plasma radioactivity, and plasma siponimod concentrations were measured. Metabolite profiles were determined in plasma, urine, and feces. Metabolite structures were elucidated using mass spectrometry and comparison with reference compounds. Unchanged siponimod accounted for 57% of the total plasma radioactivity (area under the concentration-time curve), indicating substantial exposure to metabolites. Siponimod showed medium to slow absorption (median Tmax: 4 hours) and moderate distribution (Vz/F: 291 l). Siponimod was mainly cleared through biotransformation, predominantly by oxidative metabolism. The mean apparent elimination half-life of siponimod in plasma was 56.6 hours. Siponimod was excreted mostly in feces in the form of oxidative metabolites. The excretion of radioactivity was close to complete after 13 days. Based on the metabolite patterns, a phase II metabolite (M3) formed by glucuronidation of hydroxylated siponimod was the main circulating metabolite in plasma. However, in subsequent mouse ADME and clinical pharmacokinetic studies, a long-lived nonpolar metabolite (M17, cholesterol ester of siponimod) was identified as the most prominent systemic metabolite. We further conducted in vitro experiments to investigate the enzymes responsible for the oxidative metabolism of siponimod. The selective inhibitor and recombinant enzyme results identified cytochrome P450 2C9 (CYP2C9) as the predominant contributor to the human liver microsomal biotransformation of siponimod, with minor contributions from CYP3A4 and other cytochrome P450 enzymes.

Absorption, Distribution, Metabolism, and Excretion of the Oral Prostaglandin D2 Receptor 2 Antagonist Fevipiprant (QAW039) in Healthy Volunteers and In Vitro.

Fevipiprant is a novel oral prostaglandin D2 receptor 2 (DP2; also known as CRTh2) antagonist, which is currently in development for the treatment of severe asthma and atopic dermatitis. We investigated the absorption, distribution, metabolism, and excretion properties of fevipiprant in healthy subjects after a single 200-mg oral dose of [14C]-radiolabeled fevipiprant. Fevipiprant and metabolites were analyzed by liquid chromatography coupled to tandem mass spectrometry and radioactivity measurements, and mechanistic in vitro studies were performed to investigate clearance pathways and covalent plasma protein binding. Biotransformation of fevipiprant involved predominantly an inactive acyl glucuronide (AG) metabolite, which was detected in plasma and excreta, representing 28% of excreted drug-related material. The AG metabolite was found to covalently bind to human plasma proteins, likely albumin; however, in vitro covalent binding to liver protein was negligible. Excretion was predominantly as unchanged fevipiprant in urine and feces, indicating clearance by renal and possibly biliary excretion. Fevipiprant was found to be a substrate of transporters organic anion transporter 3 (OAT3; renal uptake), multidrug resistance gene 1 (MDR1; possible biliary excretion), and organic anion-transporting polypeptide 1B3 (OATP1B3; hepatic uptake). Elimination of fevipiprant occurs via glucuronidation by several uridine 5'-diphospho glucuronosyltransferase (UGT) enzymes as well as direct excretion. These parallel elimination pathways result in a low risk of major drug-drug interactions or pharmacogenetic/ethnic variability for this compound.

Absorption, distribution, metabolism, and excretion of [(14)C]BYL719 (alpelisib) in healthy male volunteers.

PURPOSE: To determine the pharmacokinetics of the p110α-selective inhibitor alpelisib (BYL719) in humans, to identify metabolites in plasma and excreta, and to characterize pathways of biotransformation. METHODS: Four healthy male volunteers received a single oral dose of [(14)C]-labeled alpelisib (400 mg, 2.78 MBq). Blood, urine, and feces samples were collected throughout the study. Total radioactivity was measured by liquid scintillation counting, and metabolites were quantified and identified by radiometry and mass spectrometry. Complementary in vitro experiments characterized the hydrolytic, oxidative, and conjugative enzymes involved in metabolite formation. RESULTS: Over 50 % of [(14)C] alpelisib was absorbed, with a T(max) of 2 h and an elimination half-life from plasma of 13.7 h. Over the first 12 h, exposure to alpelisib and the primary metabolite M4 was 67.9 and 26.7 % of total drug-related material in circulation, respectively. Mass balance was achieved, with 94.5 % of administered radioactivity recovered in excreta. In total, 38.2 % of alpelisib was excreted unchanged, while 39.5 % was excreted as M4. Based on the excreta pools analyzed, excretion occurred mainly via feces (79.8 % of administered dose); 13.1 % was excreted via urine. In vitro experiments showed that spontaneous and enzymatic hydrolysis contributed to M4 formation, while CYP3A4-mediated oxidation and UGT1A9-mediated glucuronidation formed minor metabolites. Alpelisib was well tolerated, and no new safety concerns were raised during this study. CONCLUSIONS: Alpelisib was rapidly absorbed and cleared by multiple metabolic pathways; the primary metabolite M4 is pharmacologically inactive. Alpelisib has limited potential for drug-drug interactions and is therefore a promising candidate for combination therapy.

Metabolism and disposition of the oral absorption enhancer 14C-radiolabeled 8-(N-2-hydroxy-5-chlorobenzoyl)-amino-caprylic acid (5-CNAC) in healthy postmenopausal women and supplementary investigations in vitro.

8-(N-2-hydroxy-5-chlorobenzoyl)-amino-caprylic acid (5-CNAC), a compound lacking pharmacological activity enhances the absorption of salmon calcitonin, when co-administered. Disposition and biotransformation of 5-CNAC was studied in six healthy postmenopausal women following a single oral dose of 200mg (14)C-radiolabeled 5-CNAC (as disodium monohydrate salt). Blood, plasma, urine and feces collected over 7 days were analyzed for radioactivity. Metabolite profiles were determined in plasma and excreta and metabolite structures were elucidated by LC-MS/MS, LC-(1)H NMR, enzymatic methods and by comparison with reference compounds. Oral 5-CNAC was safe and well tolerated in this study population. 5-CNAC absorption was rapid (t(max)=0.5h; C(max)=9.00 ± 2.74 µM (mean ± SD, n=6) and almost complete. The elimination half-life (t(½)) was 1.5 ± 1.1h. The radioactive dose was excreted mainly in urine (≥ 90%) in form of metabolites and 0.071% as intact 5-CNAC. Excretion of radioactivity in feces was minor and mostly as metabolites (<3%). Radioactivity in plasma reached C(max) (35.4 ± 7.9 µM) at 0.75 h and declined with a half-life of 13.9 ± 4.3h. 5-CNAC accounted for 5.8% of the plasma radioactivity AUC(0-24h). 5-CNAC was rapidly cleared from the systemic circulation, primarily by metabolism. Biotransformation of 5-CNAC involved: (a) stepwise degradation of the octanoic acid side chain and (b) conjugation of 5-CNAC and metabolites with glucuronic acid at the 2-phenolic hydroxyl group. The metabolism of 5-CNAC in vivo could be reproduced in vitro in human hepatocytes. No metabolism of 5-CNAC was observed in human liver microsomes.

Pharmacokinetics, metabolism, and disposition of deferasirox in beta-thalassemic patients with transfusion-dependent iron overload who are at pharmacokinetic steady state.

Deferasirox (ICL670) is a novel once-daily, orally administered iron chelator to treat chronic iron overload in patients with transfusion-dependent anemias. Absorption, distribution, metabolism, and excretion of [14C]deferasirox at pharmacokinetic steady state was investigated in five adult beta-thalassemic patients. Deferasirox (1000 mg) was given orally once daily for 6 days to achieve steady state. On day 7, patients received a single oral 1000-mg dose (approximately 20 mg/kg) of [14C]deferasirox (2.5 MBq). Blood, plasma, feces, and urine samples collected over 7 days were analyzed for radioactivity, deferasirox, its iron complex Fe-[deferasirox]2, and metabolites. Deferasirox was well absorbed. Deferasirox and its iron complex accounted for 87 and 10%, respectively, of the radioactivity in plasma (area under the curve at steady state). Excretion occurred largely in the feces (84% of dose), and 60% of the radioactivity in the feces was identified as deferasirox. Apparently unchanged deferasirox in feces was partly attributable to incomplete intestinal absorption and partly to hepatobiliary elimination of deferasirox (including first-pass elimination) and of its glucuronide. Renal excretion was only 8% of the dose and included mainly the glucuronide M6. Oxidative metabolism by cytochrome 450 enzymes to M1 [5-hydroxy (OH) deferasirox, presumably by CYP1A] and M4 (5'-OH deferasirox, by CYP2D6) was minor (6 and 2% of the dose, respectively). Direct and indirect evidence indicates that the main pathway of deferasirox metabolism is via glucuronidation to metabolites M3 (acyl glucuronide) and M6 (2-O-glucuronide).

Absorption, distribution, metabolism, and elimination of the direct renin inhibitor aliskiren in healthy volunteers.

Aliskiren (2(S),4(S),5(S),7(S)-N-(2-carbamoyl-2-methylpropyl)-5-amino-4-hydroxy-2,7-diisopropyl-8-[4-methoxy-3-(3-methoxypropoxy)phenyl]-octanamid hemifumarate) is the first in a new class of orally active, nonpeptide direct renin inhibitors developed for the treatment of hypertension. The absorption, distribution, metabolism, and excretion of [(14)C]aliskiren were investigated in four healthy male subjects after administration of a single 300-mg oral dose in an aqueous solution. Plasma radioactivity and aliskiren concentration measurements and complete urine and feces collections were made for 168 h postdose. Peak plasma levels of aliskiren (C(max)) were achieved between 2 and 5 h postdose. Unchanged aliskiren represented the principal circulating species in plasma, accounting for 81% of total plasma radioactivity (AUC(0-infinity)), and indicating very low exposure to metabolites. Terminal half-lives for radioactivity and aliskiren in plasma were 49 h and 44 h, respectively. Dose recovery over 168 h was nearly complete (91.5% of dose); excretion occurred almost completely via the fecal route (90.9%), with only 0.6% recovered in the urine. Unabsorbed drug accounted for a large dose proportion recovered in feces in unchanged form. Based on results from this and from previous studies, the absorbed fraction of aliskiren can be estimated to approximately 5% of dose. The absorbed dose was partly eliminated unchanged via the hepatobiliary route. Oxidized metabolites in excreta accounted for at least 1.3% of the radioactive dose. The major metabolic pathways for aliskiren were O-demethylation at the phenyl-propoxy side chain or 3-methoxy-propoxy group, with further oxidation to the carboxylic acid derivative.

Pimecrolimus: absorption, distribution, metabolism, and excretion in healthy volunteers after a single oral dose and supplementary investigations in vitro.

The absorption and disposition of pimecrolimus, a calcineurin inhibitor developed for the treatment of inflammatory skin diseases, was investigated in four healthy volunteers after a single oral dose of 15 mg of [(3)H]pimecrolimus. Supplementary information was obtained from in vitro experiments. Pimecrolimus was rapidly absorbed. After t(max) (1-3 h), its blood concentrations fell quickly to 3% of C(max) at 24 h, followed by a slow terminal elimination phase (average t(1/2) 62 h). Radioactivity in blood decreased more slowly (8% of C(max) at 24 h). The tissue and blood cell distribution of pimecrolimus was high. The metabolism of pimecrolimus in vivo, which could be well reproduced in vitro (human liver microsomes), was highly complex and involved multiple oxidative O-demethylations and hydroxylations. In blood, pimecrolimus was the major radiolabeled component up to 24 h (49% of radioactivity area under the concentration-time curve(0-24) h), accompanied by a large number of minor metabolites. The average fecal excretion of radioactivity between 0 and 240 h amounted to 78% of dose and represented predominantly a complex mixture of metabolites. In urine, 0 to 240 h, only about 2.5% of the dose and no parent drug was excreted. Hence, pimecrolimus was eliminated almost exclusively by oxidative metabolism. The biotransformation of pimecrolimus was largely catalyzed by CYP3A4/5. Metabolite pools generated in vitro showed low activity in a calcineurin-dependent T-cell activation assay. Hence, metabolites do not seem to contribute significantly to the pharmacological activity of pimecrolimus.