Evaluation of Icotinib as a Potent and Selective Inhibitor of Aldehyde Oxidase for Reaction Phenotyping in Human Hepatocytes

Aldehyde oxidase (AO) is a molybdenum cofactor-containing cytosolic enzyme that has gained prominence due to its involvement in the developmental failure of several drug candidates in first-in-human trials. Unlike cytochrome P450s (P450) and glucuronosyltransferase, AO substrates have been plagued by poor in vitro to in vivo extrapolation, leading to low systemic exposures and underprediction of human dose. However, apart from measuring a drug's AO clearance rates, it is also important to determine the relative contribution to metabolism by this enzyme (fm,AO). Although hydralazine is the most well-studied time-dependent inhibitor (TDI) of AO and is frequently employed for AO reaction phenotyping in human hepatocytes to derive fm,AO, multiple studies have expressed concerns pertaining to its utility in providing accurate estimates of fm,AO values due to its propensity to significantly inhibit P450s at the concentrations typically used for reaction phenotyping. In this study, we characterized icotinib, a cyclized analog of erlotinib, as a potent TDI of AO-inactivating human liver cytosolic zoniporide 2-oxidation equipotently with erlotinib with a maximal inactivate rate/inactivator concentration at half maximal inactivation rate (K I) ratio of 463 and 501 minute-1mM-1 , respectively. Moreover, icotinib also exhibits selectivity against P450 and elicits significantly weaker inhibition against human liver microsomal UGT1A1/3 as compared with erlotinib. Finally, we evaluated icotinib as an inhibitor of AO for reaction phenotyping in cryopreserved human hepatocytes and demonstrated that it can yield more accurate prediction of fm,AO compared with hydralazine and induce sustained suppression of AO activity at higher cell densities, which will be important for reaction phenotyping endeavors of low clearance drugs SIGNIFICANCE STATEMENT: In this study, we characterized icotinib as a potent time-dependent inhibitor of AO with ample selectivity margins against the P450s and UGT1A1/3 and demonstrated its utility for reaction phenotyping in human hepatocytes to obtain accurate estimates of fm,AO for victim DDI risk predictions. We envisage the adoption of icotinib in place of hydralazine in AO reaction phenotyping.

Challenges and Opportunities for In Vitro-In Vivo Extrapolation of Aldehyde Oxidase-Mediated Clearance: Toward a Roadmap for Quantitative Translation

Underestimation of aldehyde oxidase (AO)-mediated clearance by current in vitro assays leads to uncertainty in human dose projections, thereby reducing the likelihood of success in drug development. In the present study we first evaluated the current drug development practices for AO substrates. Next, the overall predictive performance of in vitro-in vivo extrapolation of unbound hepatic intrinsic clearance (CLint,u) and unbound hepatic intrinsic clearance by AO (CLint,u,AO) was assessed using a comprehensive literature database of in vitro (human cytosol/S9/hepatocytes) and in vivo (intravenous/oral) data collated for 22 AO substrates (total of 100 datapoints from multiple studies). Correction for unbound fraction in the incubation was done by experimental data or in silico predictions. The fraction metabolized by AO (fmAO) determined via in vitro/in vivo approaches was found to be highly variable. The geometric mean fold errors (gmfe) for scaled CLint,u (mL/min/kg) were 10.4 for human hepatocytes, 5.6 for human liver cytosols, and 5.0 for human liver S9, respectively. Application of these gmfe's as empirical scaling factors improved predictions (45%-57% within twofold of observed) compared with no correction (11%-27% within twofold), with the scaling factors qualified by leave-one-out cross-validation. A road map for quantitative translation was then proposed following a critical evaluation on the in vitro and clinical methodology to estimate in vivo fmAO In conclusion, the study provides the most robust system-specific empirical scaling factors to date as a pragmatic approach for the prediction of in vivo CLint,u,AO in the early stages of drug development. SIGNIFICANCE STATEMENT: Confidence remains low when predicting in vivo clearance of AO substrates using in vitro systems, leading to de-prioritization of AO substrates from the drug development pipeline to mitigate risk of unexpected and costly in vivo impact. The current study establishes a set of empirical scaling factors as a pragmatic tool to improve predictability of in vivo AO clearance. Developing clinical pharmacology strategies for AO substrates by utilizing mass balance/clinical drug-drug interaction data will help build confidence in fmAO.

Predicting routes of phase I and II metabolism based on quantum mechanics and machine learning

1. Unexpected metabolism could lead to the failure of many late-stage drug candidates or even the withdrawal of approved drugs. Thus, it is critical to predict and study the dominant routes of metabolism in the early stages of research. In this study, we describe the development and validation of a 'WhichEnzyme' model that accurately predicts the enzyme families most likely to be responsible for a drug-like molecule's metabolism. Furthermore, we combine this model with our previously published regioselectivity models for Cytochromes P450, Aldehyde Oxidases, Flavin-containing Monooxygenases, UDP-glucuronosyltransferases and Sulfotransferases - the most important Phase I and Phase II drug metabolising enzymes - and a 'WhichP450' model that predicts the Cytochrome P450 isoform(s) responsible for a compound's metabolism. The regioselectivity models are based on a mechanistic understanding of these enzymes' actions, and use quantum mechanical simulations with machine learning methods to accurately predict sites of metabolism and the resulting metabolites. We train heuristic based on the outputs of the 'WhichEnzyme', 'WhichP450', and regioselectivity models to determine the most likely routes of metabolism and metabolites to be observed experimentally. Finally, we demonstrate that this combination delivers high sensitivity in identifying experimentally reported metabolites and higher precision than other methods for predicting in vivo metabolite profiles.

Validation of an LC-MS/MS method for quantitation of fostemsavir in plasma

BACKGROUND

A novel, sensitive and specific LC-MS/MS technique was developed and validated for the quantification of fostemsavir in human plasma and its pharmacokinetic application in rabbits.

METHODS

Chromatographic separation of the fostemsavir and fosamprenavir (internal standard) were achieved on Zorbax C18 (50 mm × 2 mm × 5 μm) column with 0.80 mL/min flow rate and coupled with API6000 triple quadrupole MS in multi reaction monitoring mode by applying mass transitions m/z 584.16/105.03 for fostemsavir and m/z 586.19/57.07 for the internal standard.

RESULTS

The calibration curve exhibited linearity in concentration range of 58.5-2340.0 ng/mL for fostemsavir. The LLOQ was 58.5 ng/mL. The validated LC-MS/MS process was effectively applied for the analysis of plasma in healthy rabbits for determinations of Fostemsavir. From the pharmacokinetic data, the mean of C_max and T_max were 198.19 ± 5.85 ng/mL and 2.42 ± 0.13, respectively. Plasma concentration reduced with t_1/2 of 7.02 ± 0.14. AUC_0→Last value obtained was 2374.87 ± 29.75 ng. h/ml, respectively.

CONCLUSION

In summary, the developed method has been successfully validated and pharmacokinetic parameters were demonstrated after oral administration of Fostemsavir to healthy rabbits.

Evaluation of the Pharmacokinetic Drug Interaction of Capmatinib With Itraconazole and Rifampicin and Potential Impact on Renal Transporters in Healthy Subjects

Capmatinib is a highly specific, potent, and selective mesenchymal-epithelial transition factor inhibitor predominantly eliminated by cytochrome P450 (CYP) 3A4 and aldehyde oxidase. Here, we investigated the effects of a strong CYP3A inhibitor (itraconazole) and a strong CYP3A inducer (rifampicin) on single-dose pharmacokinetics of capmatinib. In addition, serum creatinine and cystatin C were monitored to assess the potential inhibition of renal transporters by capmatinib. This was an open-label, 2-cohort (inhibition and induction), 2-period (capmatinib alone and inhibition/induction periods) study in healthy subjects. In the inhibition cohort, capmatinib (400 mg/day) was given alone, then with itraconazole (200 mg/day for 10 days, 5-day lead-in before coadministration). In the induction cohort, capmatinib (400 mg/day) was given alone, then with rifampicin (600 mg/day for 9 days, 5-day lead-in before coadministration). Fifty-three subjects (inhibition cohort, n = 27; induction cohort, n = 26) were enrolled. Coadministration of itraconazole resulted in an increase of capmatinib area under the plasma concentration-time curve from time 0 to infinity by 42% (geometric mean ratio [GMR], 1.42; 90%CI, 1.33-1.52) with no change in maximum plasma concentration (GMR, 1.03; 90%CI, 0.866-1.22). Coadministration of rifampicin resulted in a reduction of capmatinib area under the plasma concentration-time curve from time 0 to infinity by 66.5% (GMR, 0.335; 90%CI, 0.300-0.374) and a decrease in maximum plasma concentration by 55.9% (GMR, 0.441; 90%CI, 0.387-0.502). After a single dose of capmatinib, a transient increase in serum creatinine was observed with no change in serum cystatin C concentration during the 3-day monitoring period. In conclusion, coadministration of itraconazole or rifampicin resulted in clinically relevant changes in systemic exposure to capmatinib. The transient increase in serum creatinine without any increase in cystatin C suggests inhibition of renal transport by capmatinib.

Mechanism of capmatinib degradation in stress conditions including degradation product characterization using ultra-high-performance liquid chromatography-quadrupole-time of flight mass spectrometry and stability-indicating analytical method development

RATIONALE

Capmatinib (CMT) has been recently approved for the treatment of non-small cell lung cancer by the United States Food and Drug Administration (USFDA). Till date, the degradation mechanism of CMT in different stress conditions is not known. Moreover, degradation products (DPs) of the drug are yet to be identified. Characterization study on degradation products of CMT has not been reported before. Furthermore, no previously reported literature is available on the stability-indicating method of CMT.

METHODS

Owing to the lack of such scientific reports, we developed a sensitive, stability-indicating method for CMT which can resolve it from all its degradation products. The method was validated as per the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH Q2 [R1]) guideline. We studied and established the degradation mechanism of CMT in different stress conditions. One degradation product (DP2) was isolated and characterized using ¹ H NMR.

RESULTS

The degradation products (DP1, DP2 and DP3) of the drug have been identified and characterized for the first time by using high-resolution mass spectrometry and ¹ H NMR spectroscopy. CMT was found to become degraded under acidic, basic and photolytic stress conditions in the solution phase to yield three major DPs. The drug was found to be stable in neutral hydrolysis, oxidation and thermal stress conditions.

CONCLUSIONS

DP1 was formed under acidic and basic hydrolytic conditions, whereas DP2 and DP3 were formed under photolytic conditions. Characterization of all the DPs has been carried out to establish their structures and understand the molecular mechanism behind the degradation of the drug. Few studies reported quantitative analysis of CMT and its metabolites in biological fluids. However, this is the first study to identify the unknown DPs of CMT and the mechanism of its degradation. Moreover, this article reports a stability-indicating analytical method for CMT which has not yet been reported in any literature.

HPLC with Fluorescence and Photodiode Array Detection for Quantifying Capmatinib in Biological Samples: Application to In Vivo and In Vitro Studies

Capmatinib, a recently approved tyrosine kinase inhibitor, is used for the treatment of non-small cell lung cancer. We describe two new HPLC methods for capmatinib quantification in vivo and in vitro. HPLC with a fluorescence detection method was used to quantify capmatinib in plasma for the first time. The method was successfully applied in a pharmacokinetic study following a 10 mg/kg oral dose of capmatinib given to rats. The chromatographic separation was performed using a Eurospher II 100-3 C18H (50 × 4 mm, 3 µm) column and a mobile phase containing 10 mM of ammonium acetate buffer (pH 5.5): acetonitrile (70:30, v/v), at a flow rate of 2.0 mL min^-1. The study also describes the use of HPLC-PDA for the first time for the determination of capmatinib in human liver microsomes and describes its application to study its metabolic stability in vitro. Our results were in agreement with those reported using LC-MS/MS, demonstrating the reliability of the method. The study utilized a Gemini-NX C18 column and a mobile phase containing methanol: 20 mM ammonium formate buffer pH 3.5 (53:47, v/v), delivered at a flow rate of 1.1 mL min^-1. These methods are suitable for supporting pharmacokinetic studies, particularly in bioanalytical labs lacking LC-MS/MS capabilities.

Single low-dose INC280-loaded theranostic nanoparticles achieve multirooted delivery for MET-targeted primary and liver metastatic NSCLC

BACKGROUND

Non-small cell lung cancer (NSCLC) patients with primary tumors and liver metastases have substantially reduced survival. Since mesenchymal-epithelial transition factor (MET) plays a significant role in the molecular mechanisms of advanced NSCLC, small molecule MET inhibitor capmatinib (INC280) hold promise for clinically NSCLC treatment. However, the major obstacles of MET-targeted therapy are poor drug solubility and off-tumor effects, even oral high-dosing regimens cannot significantly increase the therapeutic drug concentration in primary and metastatic NSCLC.

METHODS

We developed a multirooted delivery system INC280-PFCE nanoparticles (NPs) by loading INC280 into perfluoro-15-crown-5-ether for improving MET-targeted therapy. Biodistribution and anti-MET/antimetastatic effects of NPs were validated in orthotopic NSCLC and NSCLC liver metastasis models in a single low-dose. The efficacy of INC280-PFCE NPs was also explored in human NSCLC specimens.

RESULTS

INC280-PFCE NPs exhibited excellent antitumor ability in vitro. In orthotopic NSCLC models, sustained release and prolonged retention behaviors of INC280-PFCE NPs within tumors could be visualized in real-time by ¹⁹F magnetic resonance imaging (¹⁹F-MRI), and single pulmonary administration of NPs showed more significant tumor growth inhibition than oral administration of free INC280 at a tenfold higher dose. Furthermore, a single low-dose INC280-PFCE NPs administered intravenously suppressed widespread dissemination of liver metastasis without systemic toxicity. Finally, we verified the clinical translation potential of INC280-PFCE NPs in human NSCLC specimens.

CONCLUSIONS

These results demonstrated high anti-MET/antimetastatic efficacies, real-time MRI visualization and high biocompatibility of NPs after a single low-dose.

Management of Peripheral Edema in Patients with MET Exon 14-Mutated Non-small Cell Lung Cancer Treated with Small Molecule MET Inhibitors

Small molecule mesenchymal-epithelial transition (MET) inhibitors, such as crizotinib, capmatinib, and tepotinib, are treatment options for metastatic non-small cell lung cancer (NSCLC) in adult patients whose tumors have a mutation that leads to MET exon 14 skipping. In clinical trials, these MET inhibitors were associated with a high incidence of peripheral edema, although this was generally mild-to-moderate in severity. There is limited information about the mechanism involved in MET inhibitor-induced peripheral edema. Perturbation of hepatocyte growth factor (HGF)/MET signaling may disrupt the permeability balance in the vascular endothelium and thus promote edema development. Another potential mechanism is through effects on renal function, although this is unlikely to be the primary mechanism. Because edema is common in cancer patients and may not necessarily be caused by the cancer treatment, or other conditions that have similar symptoms to peripheral edema, a thorough assessment is required to ascertain the underlying cause. Before starting MET-inhibitor therapy, patients should be educated about the possibility of developing peripheral edema. Patient limb volume should be measured before initiating treatment, to aid assessment if symptoms develop. Since the exact mechanism of MET inhibitor-induced edema is unknown, management is empiric, with common approaches including compression stockings, specific exercises, massage, limb elevation, and/or diuretic treatment. Although not usually required, discontinuation of MET inhibitor treatment generally resolves peripheral edema. Early diagnosis and management, as well as patient information and education, are vital to decrease the clinical burden associated with edema, and to reinforce capmatinib treatment adherence.

Drug clearance by aldehyde oxidase: can we avoid clinical failure?

Despite increased awareness of aldehyde oxidase (AO) as a major drug-metabolising enzyme, predicting the pharmacokinetics of its substrates remains challenging. Several drug candidates have been terminated due to high clearance, which were subsequently discovered to be AO substrates. Even retrospective extrapolation of human clearance, from models more sensitive to AO activity, often resulted in underprediction.The questions of the current work thus were: Is there an acceptable degree of in vitro AO metabolism that does not result in high in vivo human clearance? And, if so, how can this be predicted?We built an in vitro/in vivo correlation using known AO substrates, combining multiple in vitro parameters to calculate the blood metabolic clearance mediated by AO (CLb_AO). This value was compared with observed blood clearance (CLb_-obs), establishing cut-off CLb_AO values, to discriminate between low and high CLb_-obs. The model was validated using additional literature compounds, and CLb_-obs was predicted in the correct category.This simple, categorical, semi-quantitative yet multi-factorial model is readily applicable in drug discovery. Further, it is valuable for high-clearance compounds, as it predicts the CLb group, rather than an exact CLb value, for the substrates of this poorly-characterised enzyme.

ANALYSIS OF THE SPECTRAL-LUMINESCENT PROPERTIES OF IMIDAZO[1,2-b]PYRIDO[4,3-e][1,2,4]TRIAZIN-6(7Н)-ONES

The article presents a method for the construction of a new tricyclic system of imidazo[1,2-b]pyrido[4,3-e][1,2,4]triazin-6(7Н)-ones based on subsequent reactions of the obtained 1,2-diamino-4-phenylimidazole ethyl ether of 3-methyl-6-phenylimidazo[1,2-b][1,2,4]triazin-2-carboxylic acid with dimethylformamide dimethylacetal and primary amines. The structures of the obtained compounds were confirmed using the data obtained by ¹ Н and ¹³ С NMR, HRMS, and XRD. We analysed the dependence of the absorption and photoluminescence spectra on the structure of the compounds obtained using methods of quantum chemistry. The theoretical results were compared to the data of a real experiment. The article suggests a range of practical applications for imidazo[1,2-b]pyrido[4,3-e][1,2,4]triazin-6(7Н)-ones.

Biotransformation Novel Advances - 2021 year in review

Biotransformation field is constantly evolving with new molecular structures and discoveries of metabolic pathways that impact efficacy and safety. Recent review by Kramlinger et al (2022) nicely captures the future (and the past) of highly impactful science of biotransformation (see the first article). Based on the selected articles, this review was categorized into three sections: (1) new modalities biotransformation, (2) drug discovery biotransformation, and (3) drug development biotransformation (Table 1).

Roles of selected non-P450 human oxidoreductase enzymes in protective and toxic effects of chemicals: review and compilation of reactions

This is an overview of the metabolic reactions of drugs, natural products, physiological compounds, and other (general) chemicals catalyzed by flavin monooxygenase (FMO), monoamine oxidase (MAO), NAD(P)H quinone oxidoreductase (NQO), and molybdenum hydroxylase enzymes (aldehyde oxidase (AOX) and xanthine oxidoreductase (XOR)), including roles as substrates, inducers, and inhibitors of the enzymes. The metabolism and bioactivation of selected examples of each group (i.e., drugs, “general chemicals,” natural products, and physiological compounds) are discussed. We identified a higher fraction of bioactivation reactions for FMO enzymes compared to other enzymes, predominately involving drugs and general chemicals. With MAO enzymes, physiological compounds predominate as substrates, and some products lead to unwanted side effects or illness. AOX and XOR enzymes are molybdenum hydroxylases that catalyze the oxidation of various heteroaromatic rings and aldehydes and the reduction of a number of different functional groups. While neither of these two enzymes contributes substantially to the metabolism of currently marketed drugs, AOX has become a frequently encountered route of metabolism among drug discovery programs in the past 10–15 years. XOR has even less of a role in the metabolism of clinical drugs and preclinical drug candidates than AOX, likely due to narrower substrate specificity.

Pharmacokinetics and safety of capmatinib with food in patients with MET-dysregulated advanced solid tumors

PURPOSE

In the Phase II GEOMETRY mono-1 study, the potent and selective mesenchymal-epithelial transition (MET) inhibitor capmatinib exhibited considerable efficacy in MET exon 14 skipping (METex14)-mutated metastatic non-small cell lung cancer at a dose of 400 mg BID. The current recommended dose is 400 mg BID in tablet formulation, with or without food. This article reports the pharmacokinetic (PK) profile, safety, and tolerability of capmatinib 300 and 400 mg BID given with food in MET-dysregulated advanced solid tumors.

METHODS

This multicenter, open-label, Phase I study enrolled adult patients with MET-dysregulated advanced solid tumors. In the dose escalation phase, capmatinib tablets were orally administered at a dose of 300 mg BID with food; if tolerated, the dose escalation cohort of 400 mg BID was to be opened to enrollment. In the expansion phase, patients were to be enrolled at the higher of the tolerated doses. Tablets were taken within 30 minutes of an unrestricted meal type, except on cycle 1 day 1 (C1D1) and cycle 1 day 7 (C1D7), when they were given with a high-fat meal. The primary objectives were to determine the higher of the tolerated study doses and assess PK variables, with a secondary objective of safety.

FINDINGS

Overall, 35 patients (300 mg BID, n = 8; 400 mg BID, n = 27) with MET-dysregulated advanced solid tumors were enrolled; all patients had received prior antineoplastic therapy, and the most common primary site was lung (45.7%). Among PK-evaluable patients, the median T_max for capmatinib after administration with a high-fat meal (on C1D1/C1D7) was 4.0 to 5.6 hours across doses. At steady state (C1D7), capmatinib accumulation was low across dose levels (geometric mean of accumulation ratios, 1.29-1.69), with an increase in exposure (AUC_tau and C_max) from 300 to 400 mg BID. There were no occurrences of dose-limiting toxicity. All patients experienced at least 1 adverse event, and treatment-related adverse events occurred in 28 patients (80%; 300 mg BID, n = 6; 400 mg BID, n = 22), the most frequent of which were fatigue (37.1%) and nausea (34.3%).

IMPLICATIONS

Capmatinib tablet formulation at a dose of up to 400 mg BID with food is well tolerated in patients with MET-dysregulated advanced solid tumors, with safety observations consistent with the existing profile under fasted conditions. These findings support the capmatinib dosing recommendation of 400 mg BID with or without food. ClinicalTrials.gov identifier: NCT02925104.

Pharmacokinetics of capmatinib in participants with hepatic impairment: A phase 1, open-label, single-dose, parallel-group study

Aims

Capmatinib, a mesenchymal–epithelial transition factor tyrosine kinase inhibitor, is metabolized by cytochrome P450 (CYP) 3A4 and aldehyde oxidase. In individuals with hepatic impairment, alterations in hepatobiliary excretion and metabolism could lead to higher capmatinib exposure. We compared the pharmacokinetics of a single oral dose of capmatinib 200 mg administered to participants with varying degrees of hepatic impairment vs. matched controls with normal hepatic function.

Methods

This phase 1, multicentre, open‐label, parallel‐group study enrolled adult participants with normal hepatic function and mild, moderate and severe hepatic impairments. Eligible participants received a single oral dose of 200 mg capmatinib. The pharmacokinetic parameters of capmatinib were analysed and compared across participants with impaired and normal hepatic function.

Results

Of 31 enrolled participants, 29 had an evaluable pharmacokinetic profile: normal (n = 9); mild (n = 6); moderate (n = 8); severe (n = 6). Compared with the normal group, geometric mean (GM) maximum (peak) observed plasma drug concentration after single‐dose administration decreased by 27.6% in the mild group (GM ratio [GMR] = 0.724; 90% confidence interval [CI]: 0.476–1.10), by 17.2% in the moderate group (GMR = 0.828; 90% CI: 0.563–1.22) and remained unchanged in the severe group (GMR = 1.02; 90% CI: 0.669–1.55). Compared with the normal group, GM area under the plasma concentration–time curve from time zero to infinity decreased by 23.3% in the mild group (GMR = 0.767; 90% CI: 0.532–1.11), by 8.6% in the moderate group (GMR = 0.914; 90% CI: 0.652–1.28) and increased by 24% in the severe group (GMR = 1.24; 90% CI: 0.858–1.78).

Conclusion

Mild, moderate and severe hepatic impairment did not have a clinically relevant impact on capmatinib pharmacokinetics. No new safety findings are reported in this study.