Recombinant Human Enzyme Research Articles

RF34 | PMON202 The Human Metabolic Profile of Estetrol

Abstract Objectives Estetrol (E4), a native estrogen produced by the fetal human liver, has four hydroxyl-groups, making it structurally distinct from other estrogens. We determined the human metabolic profile of E4, which is recently marketed combined with drospirenone as a novel contraceptive and is currently in development for the relief of menopausal symptoms. Method: We studied the in vitro metabolism of E4 using human hepatocytes, human liver microsomes and recombinant CYP enzymes in reaction phenotyping studies to evaluate the role of human cytochrome P450 enzymes, UDP-glucuronosyltransferases (UGT) and sulfotransferases (SULT). Furthermore, we evaluated the in vivo metabolism of E4 in an open-label, non-randomised phase 1 human absorption, distribution, metabolism, and excretion study, in which six healthy postmenopausal participants received a single oral solution containing 15 mg [14C]-E4. We analysed blood (up to 240h), urine and faecal samples (up to 312h). Metabolite profiling and identification was performed using liquid chromatography with tandem mass spectrometry. Results The in vitro studies showed that E4 undergoes extensive phase 2 metabolism to form glucuronide and sulphate conjugates. UGT2B7 is the key enzyme catalysing the direct glucuronidation of E4 and SULT1E1 is the dominant sulfotransferase for sulphate conjugation in vitro. Unlike for other estrogens, oxidative phase 1 metabolism by P450 enzymes does not play a major role in the metabolism of E4. Following oral administration of E4 to humans, the major metabolites observed in human plasma were E4-16-glucuronide, E4-3-glucuronide and E4-glucuronide-sulfate (respectively 62%, 17% and 9% of radioactivity at the time of maximum plasma concentration [Tmax]). At Tmax, unchanged E4 accounts for only 7.5% of plasma radioactivity. Main metabolites quantified in urine during the first 6 hours after administration were E4-16-glucuronide and E4-3-glucuronide (respectively 77.4% and 16.5% of urine radioactivity). Approximately 69% of the total administered radioactivity was recovered in urine and 22% in faeces. Mass spectrometry showed that E4 was not present in urine but was detected in faeces and that E4 is not converted back into one of the other natural estrogens (estriol, estradiol, estrone). Conclusions Altogether, these data suggest that E4 has a unique metabolic profile. E4 is a terminal end-product of estrogen metabolism, which is not converted back, in vivo, into active metabolites like estriol, estradiol or estrone. Unlike for other estrogens, CYP450 enzymes do not play a major role in the metabolic pathway of E4. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m., Monday, June 13, 2022 12:48 p.m. - 12:53 p.m.

Non-additive mixture effects of benzo[a]pyrene and pesticides in vitro and in vivo: Role of AhR signaling

Polycyclic aromatic hydrocarbons (PAHs) and pesticides are two major groups of environmental contaminants which humans are simultaneously exposed to. However, potential mixture interactions of these groups of chemicals are not well-studied. In this study, the effects of binary mixtures of the PAH benzo[a]pyrene (B[a]P) and the commonly used pesticides chlorpyrifos, paraquat and tebuconazole on human liver HepG2 cells were investigated. The results showed that binary mixtures of B[a]P and paraquat or tebuconazole mainly caused additive effects on cell viability and cytochrome P4501a1 (CYP1A1) expression compared to single compound exposures. In contrast, the binary mixture with chlorpyrifos interacted antagonistically on cell viability and ROS production, whereas synergistic effects were observed for induction of CYP1A1 expression. B[a]P and chlorpyrifos also inhibited the activity of recombinant human CYP1A1 enzyme. To verify the synergistic in vitro results, zebrafish (Danio rerio) embryos were exposed to binary mixtures of B[a]P and chlorpyrifos. The mixtures caused synergistic induction of CYP1A expression, as well as synergistic developmental toxicity on multiple endpoints including non-inflated swim bladder, yolk-sac and pericardial edema, and spinal deformation. The effects were reduced upon morpholino-mediated knockdown of the aryl hydrocarbon receptor (AhR), indicating an AhR-dependence of the synergistic toxicity. Altogether, these data suggest that the combination of AhR activation and CYP1A1 inhibition is responsible for the underlying non-additive interaction between B[a]P and chlorpyrifos in vitro and in vivo.

Hepatic glutamine synthetase controls N5-methylglutamine in homeostasis and cancer

Glutamine synthetase (GS) activity is conserved from prokaryotes to humans, where the ATP-dependent production of glutamine from glutamate and ammonia is essential for neurotransmission and ammonia detoxification. Here, we show that mammalian GS uses glutamate and methylamine to produce a methylated glutamine analog, N5-methylglutamine. Untargeted metabolomics revealed that liver-specific GS deletion and its pharmacological inhibition in mice suppress hepatic and circulating levels of N5-methylglutamine. This alternative activity of GS was confirmed in human recombinant enzyme and cells, where a pathogenic mutation in the active site (R324C) promoted the synthesis of N5-methylglutamine over glutamine. N5-methylglutamine is detected in the circulation, and its levels are sustained by the microbiome, as demonstrated by using germ-free mice. Finally, we show that urine levels of N5-methylglutamine correlate with tumor burden and GS expression in a β-catenin-driven model of liver cancer, highlighting the translational potential of this uncharacterized metabolite.

Identification of Optimal Urinary Biomarkers of Synthetic Cannabinoids BZO-HEXOXIZID, BZO-POXIZID, 5F-BZO-POXIZID, and BZO-CHMOXIZID for Illicit Abuse Monitoring.

The continuous introduction of new synthetic cannabinoid (SC) subtypes and analogues remains a major problem worldwide. Recently, a new "OXIZID" generation of SCs surfaced in seized materials across various countries. Hence, there is an impetus to identify urinary biomarkers of the OXIZIDs to detect their abuse. We adapted our previously reported two-pronged approach to investigate the metabolite profiles and disposition kinetics of 4 OXIZID analogues, namely, BZO-HEXOXIZID (MDA-19), BZO-POXIZID (5C-MDA-19), 5F-BZO-POXIZID (5F-MDA-19), and BZO-CHMOXIZID (CHM-MDA-19). First, bottom-up in vitro incubation experiments comprising metabolite identification, metabolic stability, and reaction phenotyping were performed using human liver microsomes and recombinant human cytochrome P450 enzymes. Second, top-down analysis of authentic urine samples from drug abusers was performed to corroborate the in vitro findings and establish a panel of urinary biomarkers. A total of 42 to 51 metabolites were detected for each OXIZID, and their major metabolic pathways included N-alkyl and phenyl hydroxylation, oxidative defluorination (for 5F-BZO-POXIZID), oxidation to ketone and carboxylate, amide hydrolysis, and N-dealkylation. The OXIZIDs were metabolically unstable, mainly metabolized by cytochromes P3A4, P3A5, and P2C9, and demonstrated mechanism-based inactivation of cytochrome P3A4. Integrating with the results of 4 authentic urine samples, the parent drug and both N-alkyl and phenyl mono-hydroxylated metabolites of each OXIZID were determined as suitable urinary biomarkers. Drug enforcement agencies worldwide may apply these biomarkers in routine monitoring procedures to identify abusers and counter the escalation of OXIZID abuse.

Cytochromes P450 2C8 and 3A Catalyze the Metabolic Activation of the Tyrosine Kinase Inhibitor Masitinib.

Masitinib is a small molecule tyrosine kinase inhibitor under investigation for the treatment of amyotrophic lateral sclerosis, mastocytosis, and COVID-19. Hepatotoxicity has been reported in some patients while taking masitinib. The liver injury is thought to involve hepatic metabolism of masitinib by cytochrome P450 (P450) enzymes to form chemically reactive, potentially toxic metabolites. The goal of the current investigation was to determine the P450 enzymes involved in the metabolic activation of masitinib in vitro. In initial studies, masitinib (30 μM) was incubated with pooled human liver microsomes in the presence of NADPH and potassium cyanide to trap reactive iminium ion metabolites as cyano adducts. Masitinib metabolites and cyano adducts were analyzed using reversed-phase liquid chromatography-tandem mass spectrometry. The primary active metabolite, N-desmethyl masitinib (M485), and several oxygenated metabolites were detected along with four reactive metabolite cyano adducts (MCN510, MCN524, MCN526, and MCN538). To determine which P450 enzymes were involved in metabolite formation, reaction phenotyping experiments were conducted by incubation of masitinib (2 μM) with a panel of recombinant human P450 enzymes and by incubation of masitinib with human liver microsomes in the presence of P450-selective chemical inhibitors. In addition, enzyme kinetic assays were conducted to determine the relative kinetic parameters (apparent Km and Vmax) of masitinib metabolism and cyano adduct formation. Integrated analysis of the results from these experiments indicates that masitinib metabolic activation is catalyzed primarily by P450 3A4 and 2C8, with minor contributions from P450 3A5 and 2D6. These findings provide further insight into the pathways involved in the generation of reactive, potentially toxic metabolites of masitinib. Future studies are needed to evaluate the impact of masitinib metabolism on the toxicity of the drug in vivo.

Evaluation of Novel Inhibitors of Tryptophan Dioxygenases for Enzyme and Species Selectivity Using Engineered Tumour Cell Lines Expressing Either Murine or Human IDO1 or TDO2.

Indoleamine 2, 3-dioxygenase 1 (IDO1) is commonly expressed by cancers as a mechanism for evading the immune system. Preclinical and clinical studies have indicated the potential of combining IDO1 inhibitors with immune therapies for the treatment of cancer, strengthening an interest in the discovery of novel dioxygenase inhibitors for reversing tumour-mediated immune suppression. To facilitate the discovery, development and investigation of novel small molecule inhibitors of IDO1 and its hepatic isozyme tryptophan dioxygenase (TDO2), murine tumour cells were engineered to selectively express either murine or human IDO1 and TDO2 for use as tools to dissect both the species specificity and isoenzyme selectivity of newly discovered inhibitors. Lewis lung carcinoma (LLTC) lines were engineered to express either murine or human IDO1 for use to test species selectivity of the novel inhibitors; in addition, GL261 glioma lines were engineered to express either human IDO1 or human TDO2 and used to test the isoenzyme selectivity of individual inhibitors in cell-based assays. The 20 most potent inhibitors against recombinant human IDO1 enzyme, discovered from a commissioned screening of 40,000 compounds in the Australian WEHI compound library, returned comparable IC50 values against murine or human IDO1 in cell-based assays using the LLTC-mIDO1 and LLTC-hIDO1 line, respectively. To test the in vivo activity of the hits, transfected lines were inoculated into syngeneic C57Bl/6 mice. Individual LLTC-hIDO1 tumours showed variable expression of human IDO1 in contrast to GL261-hIDO1 tumours which were homogenous in their IDO1 expression and were subsequently used for in vivo studies. W-0019482, the most potent IDO1 inhibitor identified from cell-based assays, reduced plasma and intratumoural ratios of kynurenine to tryptophan (K:T) and delayed the growth of subcutaneous GL261-hIDO1 tumours in mice. Synthetic modification of W-0019482 generated analogues with dual IDO1/TDO2 inhibitory activity, as well as inhibitors that were selective for either TDO2 or IDO1. These results demonstrate the versatility of W-0019482 as a lead in generating all three subclasses of tryptophan dioxygenase inhibitors which can be applied for investigating the individual roles and interactions between IDO1 and TDO2 in driving cancer-mediated immune suppression.

Distal kinetic deuterium isotope effect: Phenyl ring deuteration attenuates N-demethylation of Lu AF35700

The N-demethylation of zicronapine (7) and three of its deuterated analogs 8 – 10 has been studied in human in vitro metabolism systems. While the N-deuterio-methyl analog 8 did not behave differently from the parent in human liver microsomes, a significantly reduced rate of N-demethylation was observed as a consequence of benzene ring deuteration (compound 7vs.9). Additional deuteration of the N-methyl group, which as mentioned had shown no effect in isolation, further decreased the rate of the N-demethylation reaction (compound 10vs.9). This paper presents and discusses this unprecedented ‘distal kinetic isotope effect’ that was observed when incubating the test compounds with human liver microsomes or recombinant human CYP450 liver enzymes.

Molecular dynamics simulation and in vitro evaluation of herb-drug interactions involving dietary polyphenols and CDK inhibitors in breast cancer chemotherapy.

Dietary polyphenols such as quercetin and curcumin have been extensively administered to patients with cancer in the form of herbal supplements. They may have a synergistic anticancer effect; however, a risk of pharmacokinetic interactions with selective CDK-4/6 inhibitors that are metabolized by the CYP3A4 enzyme exists. Considering these pharmacokinetic aspects, the current study examined the effects of curcumin and quercetin on human CYP3A4 to ascertain CYP3A4-mediated herb-drug interactions with CDK inhibitors. In this study, using in silico methods and CYP3A4 inhibition kinetics in human liver microsomes and recombinant CYP3A4 enzymes, the effects of concentration-dependent inhibition of CYP3A4 by quercetin and curcumin on CDK inhibitors metabolism were examined. Based on our in-silico docking findings, curcumin and quercetin were considerably bound to CYP3A4 protein and displace CDK inhibitors from the CYP3A4 substrate binding domain. The IC50 values of curcumin and quercetin were 16.10 and 0.05 μM, respectively, for CYP3A4-mediated 1'-hydroxylation of midazolam. The dietary polyphenols prolonged the in vitro half-life of palbociclib and ribociclib by 6.4-fold and decreased their intrinsic microsomal clearance by approximately 4.6 times. Our findings indicate that curcumin and quercetin effectively cause herb-drug interactions and should be cautiously used to avoid therapeutic failure.

P-148 Denudation employing human recombinant hyaluronidase enzyme does not affect fertilization and blastocyst formation rates in sibling oocytes from patients undergoing ART: A prospective randomized study

Abstract Study question Does human recombinant hyaluronidase (Cumulase®) improve fertilization and blastocyst formation rates in sibling human oocytes compared to bovine-derived hyaluronidase? Summary answer The use of Cumulase® for oocyte denudation does not appear to affect fertilization or usable blastocyst formation rate in patients undergoing intracytoplasmic sperm injection (ICSI). What is known already Bovine-derived hyaluronidase has been widely employed to denude the cumulus-oocyte complexes (COCs) prior to ICSI or oocyte vitrification. Nonetheless, the recent concern for its safety, due to its animal origin, has led to the development of alternatives ascertaining the enzyme’s purity. It has been reported that human recombinant hyaluronidase is not equally effective as its bovine-derived analogue, leading to a longer time required for complete denudation coupled by the subsequent toxicity risk for oocytes. This may result to lower fertilization and blastocyst formation rates. Although there are some studies on IVF outcomes with recombinant hyaluronidase, its use remains rather limited. Study design, size, duration This randomized double-blinded clinical trial was conducted at Citmer Reproductive Medicine, in Puebla and Monterrey, Mexico from February to December 2021. The impact of denudation on sibling oocytes from 103 patients employing bovine-derived hyaluronidase (InVitroCare®) or human recombinant hyaluronidase (ICSI Cumulase® (rHuPH20), CooperSurgical®) was evaluated. A total of 1237 oocytes were assigned as follows: The Hyaluronidase Group included 626 oocytes, while the Cumulase® Group included 611 oocytes. Preimplantation Genetic Testing was performed in 18 cycles. Participants/materials, setting, methods After retrieval, COCs were incubated for 2-4 h and placed in microdropets with 10 IU/mL bovine-derived hyaluronidase or Cumulase® in culture media GlobalTotal® (LifeGlobal®) for granulosa cells removal. COCs were gently pipetted up and down employing 20 μL and 150 μm tips. Metaphase II oocytes were injected and incubated for 17-20 hours in 8% CO2, 20% O2, 37°C. Normally fertilized zygotes were cultured to blastocyst stage and embryo development was evaluated. Seventy-nine blastocysts were biopsied. Main results and the role of chance The mean age of the patients was 32.12±1.11 years old. A total of 506 and 493 metaphase II oocytes from Groups 1 and 2 respectively were subjected to ICSI. Normal fertilization rates for oocytes treated with Hyaluronidase and Cumulase® were 71.34% (n = 361) and 72.41% (n = 357) respectively, with no statistically significant differences between the two groups (p = 0.35). Usable blastocysts rate (selected for embryo transfer or blastocyst cryopreservation) did not differ with any statistical difference between the bovine-derived hyaluronidase (n = 170, 47.09%) and the Cumulase® treated oocytes (n = 158, 44.25%), (p = 0.44). Preimplantation genetic testing for aneuploidies (PGT-A) was performed in 18 cycles. Seventy-nine blastocysts were biopsied and tested. Fourty-seven embryos from the bovine-derived hyaluronidase group were biopsied, presenting with a euploidy rate of 51.06% (n = 24), compared to 32 embryos from the recombinant hyaluronidase group with a euploidy rate of 50% (n = 16). Results indicated no statistically significant difference (p = 0.92). These data support that human recombinant hyaluronidase presents with similar efficacy to bovine-derived hyaluronidase. in terms of normal fertilization, embryo development as well as euploidy rates. Limitations, reasons for caution The small sample size regarding the euploidy outcome stands as a limitation of the study. Further studies should focus on the effect of recombinant hyaluronidase on genetic anomalies on blastocysts. Wider implications of the findings Fertilization, usable blastocyst and euploidy rates did not differ when employing bovine-derived or human recombinant hyaluronidase, rendering the latter a safe and efficient alternative. However, it is important to assess long-term effects, as only a limited number of studies report on perinatal and neonatal outcomes Trial registration number 25-12-21MTYPUECIT

Characterization and identification of the metabolites of dihydromethysticin by ultra-high-performance liquid chromatography orbitrap high-resolution mass spectrometry.

Dihydromethysticin, a natural component from Piper methysticum Forst, has been reported to display pharmacological effects in mental disorders and some malignant tumors. However, the metabolism of this component remained unknown. The goal of this work was conducted to discover the metabolic profiles of dihydromethysticin. The in vitro incubation was performed by incubating dihydromethysticin with rat, monkey, and human liver microsomes and hepatocytes. An analytical assay of ultra-high performance liquid chromatography combined with Orbitrap high-resolution mass spectrometry was utilized to detect and identify the metabolites. With high resolution mass spectrometric determination, the accurate mass, elemental composition, and product ions of the metabolites were determined, which enabled structural characterization to become easy. Under the present conditions, four phase-I metabolites, as well as six phase-II metabolites, were detected and their tentative structures were characterized by mass spectra. M4 was found as the most abundant metabolite both in liver microsomes and hepatocytes. Cytochrome P450 1A2, 2C9, and 3A4 contributed to the formation of this metabolite by using human recombinant P450 enzymes. M4 can be oxidized into reactive ortho-quinone intermediate followed by conjugating with glutathione. M4 was also subject to glucuronidation (M1 and M2) and methylation (M5). Demethylenation, oxidation, hydroxylation, glucuronidation, glutathionylation, and methylation were the primary metabolic pathways of dihydromethysticin. This study provides in vitro metabolism data of dihydromethysticin, which is indispensable for understanding the disposition of this compound.

Subcutaneous nivolumab versus intravenous nivolumab in patients with previously treated, advanced, or metastatic clear cell renal cell carcinoma.

TPS4621 Background: Nivolumab (NIVO), a programmed death-1 immune checkpoint inhibitor, has demonstrated clinical efficacy across patients with different tumor types, including clear cell renal cell carcinoma (ccRCC), when administered via IV infusion. As an alternative to IV infusion, subcutaneous (SC) administration alleviates the need for IV ports, thereby lowering the risk of associated complications such as infections and phlebitis. SC formulation also reduces the time for dose preparation and administration, which may decrease overall treatment burden and reduce patient time in the clinic, benefiting patients and healthcare providers and improving overall healthcare resource utilization. SC-administered NIVO consists of NIVO co-formulated with the recombinant human hyaluronidase PH20 enzyme (NIVO + rHuPH20), which aims to increase the dispersion and absorption of NIVO within the SC space. SC NIVO + rHuPH20 was shown to be safe and well tolerated in a phase 1/2 study, warranting further investigation (Lonardi S et al. J Clin Oncol 2021;39(suppl 15):2575). Methods: CheckMate 67T is a multicenter, randomized, open-label, phase 3 study that will evaluate the noninferiority of SC NIVO + rHuPH20 versus IV NIVO in patients with advanced or metastatic ccRCC who have progressed after receiving ≤ 2 prior systemic treatment regimens. Key inclusion criteria are age ≥ 18 years, histologically confirmed advanced or metastatic ccRCC, measurable disease by RECIST v1.1 within 28 days prior to randomization, and a Karnofsky performance status ≥ 70. Key exclusion criteria are untreated symptomatic metastases to the central nervous system, other malignancy, autoimmune diseases, HIV-positive status with AIDS-defining infection within past year or current CD4 count < 350 cells/μL, other serious or uncontrolled disorders including severe, acute SARS-CoV-2 infection, and prior treatment with immune checkpoint inhibitors, other T-cell–targeting antibody drugs, or live attenuated vaccines within 30 days of first study treatment. At least 454 eligible patients will be randomized to receive SC NIVO + rHuPH20 or IV NIVO. The primary objectives are to demonstrate pharmacokinetic (PK) noninferiority of SC NIVO versus IV NIVO, as measured by time-averaged serum concentration over the first 28 days (Cavgd28) and trough serum concentration at steady state (Cminss) (co-primary endpoints). Secondary endpoints include objective response rate by blinded independent central review, additional PK parameters, safety, efficacy, and immunogenicity of SC NIVO and IV NIVO. This study is currently enrolling patients globally. Clinical trial information: NCT04810078.

High‐resolution accurate mass approach to characterization of SCO‐267 metabolites using liquid chromatography hybrid quadrupole Orbitrap mass spectrometry

RationaleSCO‐267 is a potent full agonist of G‐protein‐coupled receptor 40. As a promising therapeutic agent for type 2 diabetes mellitus, it is necessary to elucidate its metabolite profiles during the stage of drug development for safety considerations.MethodsThe in vitro metabolism was investigated by incubating SCO‐267 (5 μM) with liver microsomes and hepatocytes (rat and human). For in vivo metabolism, SCO‐267 (10 mg/kg) was orally administered to rats and plasma samples were collected. The metabolites were identified via measurements of accurate mass, elemental composition and product ions using liquid chromatography coupled to hybrid quadrupole Orbitrap high‐resolution mass spectrometry (LC‐Orbitrap‐MS).ResultsA total of 19 metabolites were structurally identified. M2 (hydroxyl‐SCO‐267), M15 (SCO‐267‐acyl‐glucuronide), M16 (desmethyl‐SCO‐267) and M17 (desneopentyl‐SCO‐267) were verified with reference standards. M2, M11, M16 and M17 were the major metabolites originating from hydroxylation, O‐demethylation and N‐dealkylation, respectively. Phenotyping study with recombinant human P450 enzymes demonstrated that hydroxylation (M2 and M11) was mainly catalyzed by CYP2C8 and 3A4; demethylation (M16) was mainly catalyzed by CYP2D6, and less catalyzed by CYP2C8 and 3A4; and N‐dealkylation (M17) was exclusively triggered by CYP3A4.ConclusionsHydroxylation, O‐demethylation, N‐dealkylation and acyl glucuronidation were the major metabolic pathways of SCO‐267. This study is the first to discover the metabolic fates of SCO‐267, which provides a basis for safety assessment of this drug candidate.

Long-term Safety and Efficacy of Avalglucosidase Alfa in Patients With Late-Onset Pompe Disease.

Background and ObjectivesPompe disease is a rare, progressive neuromuscular disorder caused by deficiency of lysosomal acid α-glucosidase (GAA) and subsequent glycogen accumulation. Avalglucosidase alfa, a recombinant human GAA enzyme replacement therapy designed for increased cellular uptake and glycogen clearance, has been studied for long-term efficacy and safety in patients with late-onset Pompe disease (LOPD). Here, we report up to 6.5 years' experience with avalglucosidase alfa during the NEO1 and NEO-EXT studies.MethodsNEO1 participants with LOPD, either treatment naive (Naive Group) or receiving alglucosidase alfa for ≥9 months (Switch Group), received avalglucosidase alfa (5, 10, or 20 mg/kg every other week [qow]) for 6 months before entering NEO-EXT and continued their NEO1 dose until all proceeded with 20 mg/kg qow. Safety and efficacy, a prespecified exploratory secondary outcome, were assessed; slopes of change for efficacy outcomes were calculated from a repeated mixed-measures model.ResultsTwenty-four participants enrolled in NEO1 (Naive Group, n = 10; Switch Group, n = 14); 21 completed and 19 entered NEO-EXT; in February 2020, 17 participants remained in NEO-EXT, with data up to 6.5 years. Avalglucosidase alfa was generally well tolerated during NEO-EXT, with a safety profile consistent with that in NEO1. No deaths or treatment-related life-threatening serious adverse events occurred. Eighteen participants developed antidrug antibodies without apparent effect on clinical outcomes. No participants who were tested developed immunoglobulin E antibodies. Upright forced vital capacity %predicted remained stable in most participants, with slope estimates (95% CIs) of −0.473 per year (−1.188 to 0.242) and −0.648 per year (−1.061 to −0.236) in the Naive and Switch Groups, respectively. Six-minute walk test (6MWT) %predicted was also stable for most participants, with slope estimates of −0.701 per year (−1.571 to 0.169) and −0.846 per year (−1.567 to −0.125) for the Naive and Switch Groups, respectively. Improvements in 6MWT distance were observed in most participants aged <45 years at NEO1 enrollment in both the Naive and Switch Groups.DiscussionAvalglucosidase alfa was generally well tolerated for up to 6.5 years in adult participants with LOPD either naive to alglucosidase alfa or who had previously received alglucosidase alfa for ≥9 months.Classification of EvidenceThis study provides Class IV evidence of long-term tolerability and sustained efficacy of avalglucosidase alfa in patients with LOPD after up to 6.5 years.Trial Registration InformationNCT01898364 (NEO1 first posted: July 12, 2013; clinicaltrials.gov/ct2/show/NCT01898364); NCT02032524 (NEO-EXT first posted: January 10, 2014; clinicaltrials.gov/ct2/show/NCT02032524). First participant enrollment: NEO1—August 19, 2013; NEO-EXT—February 27, 2014.

In vitro–in silico-based prediction of inter-individual and inter-ethnic variations in the dose-dependent cardiotoxicity of R- and S-methadone in humans

New approach methodologies predicting human cardiotoxicity are of interest to support or even replace in vivo-based drug safety testing. The present study presents an in vitro–in silico approach to predict the effect of inter-individual and inter-ethnic kinetic variations in the cardiotoxicity of R- and S-methadone in the Caucasian and the Chinese population. In vitro cardiotoxicity data, and metabolic data obtained from two approaches, using either individual human liver microsomes or recombinant cytochrome P450 enzymes (rCYPs), were integrated with physiologically based kinetic (PBK) models and Monte Carlo simulations to predict inter-individual and inter-ethnic variations in methadone-induced cardiotoxicity. Chemical specific adjustment factors were defined and used to derive dose–response curves for the sensitive individuals. Our simulations indicated that Chinese are more sensitive towards methadone-induced cardiotoxicity with Margin of Safety values being generally two-fold lower than those for Caucasians for both methadone enantiomers. Individual PBK models using microsomes and PBK models using rCYPs combined with Monte Carlo simulations predicted similar inter-individual and inter-ethnic variations in methadone-induced cardiotoxicity. The present study illustrates how inter-individual and inter-ethnic variations in cardiotoxicity can be predicted by combining in vitro toxicity and metabolic data, PBK modelling and Monte Carlo simulations. The novel methodology can be used to enhance cardiac safety evaluations and risk assessment of chemicals.

In vitro characterization of the furin inhibitor MI-1851: Albumin binding, interaction with cytochrome P450 enzymes and cytotoxicity

The substrate-analog furin inhibitor MI-1851 can suppress the cleavage of SARS-CoV-2 spike protein and consequently produces significant antiviral effect on infected human airway epithelial cells. In this study, the interaction of inhibitor MI-1851 was examined with human serum albumin using fluorescence spectroscopy and ultrafiltration techniques. Furthermore, the impacts of MI-1851 on human microsomal hepatic cytochrome P450 (CYP) 1A2, 2C9, 2C19, 2D6 and 3A4 activities were assessed based on fluorometric assays. The inhibitory action was also examined on human recombinant CYP3A4 enzyme and on hepatocytes. In addition, microsomal stability (60 min) and cytotoxicity were tested as well. MI-1851 showed no relevant interaction with human serum albumin and was significantly depleted by human microsomes. Furthermore, it did not inhibit CYP1A2, 2C9, 2C19 and 2D6 enzymes. In human hepatocytes, CYP3A4 was significantly suppressed by MI-1851 and weak inhibition was noticed in regard to human microsomes and human recombinant CYP3A4. Finally, MI-1851 did not impair the viability and the oxidative status of primary human hepatocytes (up to 100 μM concentration). Based on these observations, furin inhibitor MI-1851 appears to be potential drug candidates in the treatment of COVID-19, due to the involvement of furin in S protein priming and thus activation of the pandemic SARS-CoV-2.

Bulleyaconitine A is a sensitive substrate and competitive inhibitor of CYP3A4: One of the possible explanations for clinical adverse reactions

Bulleyaconitine A (BLA), a toxic Aconitum alkaloid, is a potent analgesic that is clinically applied to treat rheumatoid arthritis, osteoarthritis and lumbosacral pain. BLA-related adverse reactions occur frequently, but whether the underlying mechanism is related to its metabolic interplay with drug-metabolizing enzymes remains unclear. This study aimed to elucidate the metabolic characteristics of BLA and its affinity action and mechanism to drug-metabolizing enzymes to reveal whether BLA-related adverse reactions are modulated by enzymes. After incubation with human liver microsomes and recombinant human cytochrome P450 enzymes, we found that BLA was predominantly metabolized by CYP3A, in which CYP3A4 had an almost absolute advantage. In vitro, the CYP3A4 inhibitor ketoconazole noticeably suppressed the metabolism of BLA. In vivo, the AUC0-∞ values, cardiotoxicity and neurotoxicity of BLA in Cyp3a-inhibited mice were all obviously enhanced (P < 0.05) compared to those in normal mice. In the enzyme kinetics study, BLA was found to be a sensitive substrate of CYP3A4, and its characteristics were consistent with substrate inhibition (Km = 39.36 ± 10.47 μmol/L, Ks = 83.42 ± 19.65 μmol/L). BLA was further identified to be a competitive inhibitor of CYP3A4 with Ki = 53.64 μmol/L, since the intrinsic clearance (CLint) of midazolam, a selective CYP3A4 substrate, decreased significantly (P < 0.05) when incubated with BLA together in mouse liver microsomes. Overall, BLA is a sensitive substrate and competitive inhibitor of CYP3A4, and clinical adverse reactions of BLA may mechanistically related to the CYP3A4-mediated drug-drug interactions.

A privileged dual action Alzheimer's disease therapeutic platform targeting immunopathic and proteopathic mechanisms: (E)-3-styrylindoles as inhibitors of indoleamine 2,3-dioxygenase-mediated tryptophan metabolism and β-amyloid aggregation

The design of potent indoleamine 2,3-dioxygenase 1 (IDO1) enzyme inhibitors targeting immunopathic neuroinflammation has emerged as an area of interest for the treatment of Alzheimer's disease (AD); additionally, recent findings on the clinical benefits of antibodies preventing β-amyloid (Aβ) aggregation have renewed efforts to discover small molecule anti-aggregants targeting proteopathic protein misfolding. Exploiting an endogenous tryptophan-like scaffold, we describe the design and synthesis of small-molecule inhibitors of both immunopathic and proteopathic processes, thus presenting the possibility of single therapeutics acting simultaneously on multiple AD pathogeneses. Specifically, investigations on compounds that inhibit both IDO1 (in human recombinant enzyme, transfected HEK293 cells, and interferon-γ stimulated human microglia assays) and Aβ aggregation (in thioflavin-T and biotinylated-Aβ oligomeric assays) are presented. Five compounds have been identified with high potency against both targets, identifying ( E)-3-styryl indoles as useful tool compounds for developing Alzheimer's therapeutics. Brain penetration of these compounds via passive diffusion or active transport was predicted using Blood-Brain Barrier Score and Brain Exposure Efficiency Score calculations, respectively; the effects of efflux (pgp, BCRP), and influx (OCT1, OCT2) transporters were similarly predicted. Structure–activity relationships were rationalised with molecular docking and molecular dynamics simulations, which also provide insights for future lead compound optimisation.

Reevaluate In Vitro CYP3A Index Reactions of Benzodiazepines and Steroids between Humans and Dogs.

Cytochrome P450 3A (CYP3A), the most important class of drug-metabolizing enzymes, participates in the metabolism of half of clinically used drugs. The CYP3A index reactions of dogs, one of the most widely used preclinical nonrodent species, are still poorly understood. This work evaluated the activity and selectivity of 10 CYP3A index reactions, including midazolam (MDZ) 1'- and 4-hydroxylation, alprazolam (APZ) and triazolam (TRZ) α- and 4-hydroxylation, testosterone (T) 6β-hydroxylation, lithocholate (LCA) 6α-hydroxylation, deoxycholate (DCA) 1β- and 5β-hydroxylation, with quantitative reaction phenotyping and kinetic analysis in human and canine recombinant CYP enzymes (rCYPs). In human studies, all reactions are reconfirmed as mixed index reactions of CYP3A with minor contributions from non-CYP3A isoforms. In canine studies, all reactions are also primarily catalyzed by CYP3A12 with lower contributions from CYP3A26. However, the canine CYP2B11 appreciably contributes to the hydroxylation of benzodiazepines except for APZ 4-hydroxylation. The canine CYP3A isoforms have lower activity than human isoforms toward T 6β-hydroxylation and LCA 6α-hydroxylation and both substrates undergo non-CYP3A catalyzed side reactions. DCA 1β- and 5β-hydroxylation are validated as the CYP3A index reactions in both humans and dogs with limited non-CYP3A contributions and side reactions. In conclusion, this work provides a comprehensive overview for the selectivity and activity of in vitro CYP3A index reactions in humans and dogs. The validated CYP3A index reactions between humans and dogs may benefit future practices in drug metabolism and drug interaction studies. SIGNIFICANCE STATEMENT: Dogs are one of the most important nonrodent animals with limited studies of cytochrome P450 enzymes than humans. This work provides the most comprehensive quantitative data to date for the selectivity and activity of CYP3A index reactions in humans and dogs. The canine CYP2B11 was found to appreciably contribute to hydroxylation of midazolam, alprazolam and triazolam, the well-known probes for human CYP3A. Deoxycholate 1β- and 5β-hydroxylation are validated as the CYP3A index reactions in both humans and dogs.

Regulation of Nrf2 and NF-κB activities may contribute to the anti-inflammatory mechanism of xylopic acid.

Xylopic acid (XA) is a kaurene diterpene which naturally exists in African plants such as Xylopia aethiopica. It has been established to exhibit acute and chronic anti-inflammatory activities from our earlier studies. This current work sets out to shed light on the potential molecular target(s) of xylopic acid. Selection of investigated targets (NF-κB, Nrf2 and PTP1B) was based on an unbiased approach, using the SPiDER in silico prediction tool, and a candidate approach, examining well-known anti-inflammatory targets. Reporter gene assays were used to test for altered NF-κB and Nrf2 activities in transfected HEK or CHO cells, respectively, and immunoblot and flow cytometric analyses examined protein expression of the Nrf2/NF-kB target genes HO-1 and VCAM-1 in HUVEC. An effect of XA on PTP1B activity assay was studied using an in vitro enzyme assay with recombinant human enzyme and pNPP as substrate as well as by looking at insulin receptor phosphorylation in HepG2 cells. XA at 30µM significantly (p < 0.001) inhibited the NF-κB-dependent reporter gene expression and enhanced activation of Nrf2 in a concentration-dependent manner when compared to the control. XA also marginally increased HO-1 protein expression levels while expression of VCAM-1 was reduced to 70% in XA-treated endothelial cells. However, XA did not show any sign of inhibition of PTP1B or a related phosphatase. Our findings suggest that the anti-inflammatory mechanism of XA entails the inhibitory effect on NF-κB and an increased activity of Nrf2, accompanied by increased expression of HO-1 and reduced expression of VCAM-1.

From tryptophan-based amides to tertiary amines: Optimization of a butyrylcholinesterase inhibitor series

Lead optimization of a series of tryptophan-based nanomolar butyrylcholinesterase (BChE) inhibitors led to tertiary amines as highly potent, achiral, sp3-rich analogues with better synthetic accessibility and high selectivity over acetylcholinesterase (one to ten thousandfold). Taking it one step further, the introduction of a carbamate warhead on the well-explored reversible scaffold allowed conversion to pseudoirreversible inhibitors that bound covalently to BChE and prolonged the duration of inhibition (half-life of 14.8 h for compound 45a-carbamoylated enzyme). Additionally, N-hydroxyindole was discovered as a novel leaving group chemotype. The covalent mechanism of action was confirmed by time-dependency experiments, progress curve analysis, and indirectly by co-crystallization with the human recombinant enzyme. Two crystal structures of BChE-inhibitor complexes were solved and coupled with the supporting molecular dynamics simulations increased our understanding of the structure-activity relationship, while also providing the necessary structural information for future optimization of this series. Overall, this research demonstates the high versatility and potential of this series of BChE inhibitors.