Effect of the Most Relevant CYP3A4 and CYP3A5 Polymorphisms on the Pharmacokinetic Parameters of 10 CYP3A Substrates

Occurrence of the two major regulated mycotoxins, ochratoxin A and fumonisin B1, in cereal and cereal-based products in Europe and toxicological effects: A review

Among cereal contaminants, mycotoxins are of concern due to their importance in terms of food and feed safety. The difficulty in establishing a diagnosis for mycotoxicosis relies on the fact that the effects are most often subclinical for chronic exposure and the most common scenario is multi-contamination by various toxins. Mycotoxin co-occurrence is a major food safety concern as additive or even synergic toxic impacts may occur, but also regarding current regulations as they mainly concern individual mycotoxin levels in specific foods and feed in the food chain. However, due to the large number of possible mycotoxin combinations, there is still limited knowledge on co-exposure toxicity data, which depends on several parameters. In this context, this systematic review aims to provide an overview of the toxic effects of two regulated mycotoxins, namely ochratoxin A and fumonisin B1. This review focused on the 2012-2022 period and analysed the occurrence in Europe of the selected mycotoxins in different food matrices (cereals and cereal-derived products), and their toxic impact, alone or in combination, on in vitro intestinal and hepatic human cells. To better understand and evaluate the associated risks, further research is needed using new approach methodologies (NAM), such as in vitro 3D models. KEY CONTRIBUTION: Cereals and their derived products are the most important food source for humans and feed for animals worldwide. This manuscript is a state of the art review of the literature over the last ten years on ochratoxin A and fumonisin B1 mycotoxins in these products in Europe as well as their toxicological effects, alone and in combination, on human cells. Future perspectives and some challenges regarding the assessment of toxicological effects of mycotoxins are also discussed.

ABCB1 attenuates brain exposure to the KRASG12C inhibitor opnurasib whereas binding to mouse carboxylesterase 1c influences its plasma exposure

Opnurasib (JDQ443) is a newly developed oral KRASG12C inhibitor, with a binding mechanism distinct from the registered KRASG12C inhibitors sotorasib and adagrasib. Phase I and II clinical trials for opnurasib in NSCLC are ongoing. We evaluated the pharmacokinetic roles of the ABCB1 (P-gp/MDR1) and ABCG2 (BCRP) efflux and OATP1 influx transporters, and of the metabolizing enzymes CYP3A and CES1 in plasma and tissue disposition of oral opnurasib, using genetically modified cell lines and mouse models. In vitro, opnurasib was potently transported by human (h)ABCB1 and slightly by mouse (m)Abcg2. In Abcb1a/b- and Abcb1a/b;Abcg2-deficient mice, a significant ∼100-fold increase in brain-to-plasma ratios was observed. Brain penetration was unchanged in Abcg2-/- mice. ABCB1 activity in the blood-brain barrier may therefore potentially limit the efficacy of opnurasib against brain metastases. The Abcb1a/b transporter activity could be almost completely reversed by co-administration of elacridar, a dual ABCB1/ABCG2 inhibitor, increasing the brain penetration without any behavioral or postural signs of acute CNS-related toxicity. No significant pharmacokinetic roles of the OATP1 transporters were observed. Transgenic human CYP3A4 did not substantially affect the plasma exposure of opnurasib, indicating that opnurasib is likely not a sensitive CYP3A4 substrate. Interestingly, Ces1-/- mice showed a 4-fold lower opnurasib plasma exposure compared to wild-type mice, whereas no strong effect was seen on the tissue distribution. Plasma Ces1c therefore likely binds opnurasib, increasing its retention in plasma. The obtained pharmacokinetic insights may be useful for further optimization of the clinical efficacy and safety of opnurasib, and might reveal potential drug-drug interaction risks.

Major Genetic Drivers of Statin Treatment Response in African Populations and Pharmacogenetics of Dyslipidemia Through a One Health Lens

A One Health lens is increasingly significant to address the intertwined challenges in planetary health concerned with the health of humans, nonhuman animals, plants, and ecosystems. A One Health approach can benefit the public health systems in Africa that are overburdened by noncommunicable, infectious, and environmental diseases. Notably, the COVID-19 pandemic revealed the previously overlooked two-fold importance of pharmacogenetics (PGx), for individually tailored treatment of noncommunicable diseases and environmental pathogens. For example, dyslipidemia, a common cardiometabolic risk factor, has been identified as an independent COVID-19 severity risk factor. Observational data suggest that patients with COVID-19 infection receiving lipid-lowering therapy may have better outcomes. However, among African patients, the response to these drugs varies from patient to patient, pointing to the possible contribution of genetic variation in important pharmacogenes. The PGx of lipid-lowering therapies may underlie differences in treatment responses observed among dyslipidemia patients as well as patients comorbid with COVID-19 and dyslipidemia. Genetic variations in APOE, ABCB1, CETP, CYP2C9, CYP3A4, CYP3A5, HMGCR, LDLR, NPC1L1, and SLCO1B1 genes affect the pharmacogenomics of statins, and they have individually been linked to differential responses to dyslipidemia and COVID-19 treatment. African populations are underrepresented in PGx research. This leads to poor accounting of additional diverse genetic variants that could be important in understanding interindividual and between-population variations in therapeutic responses to dyslipidemia and COVID-19. This expert review examines and synthesizes the salient and priority PGx variations, as seen through a One Health lens in Africa, to improve and inform personalized medicine in both dyslipidemia and COVID-19.

The influence of drug-induced metabolic enzyme activity inhibition and CYP3A4 gene polymorphism on aumolertinib metabolism

The purpose of this study is to clarify the drug interaction profile of aumolertinib, and the influence of CYP3A4 genetic polymorphism on aumolertinib metabolic characteristics. Through microsomal enzyme reactions, we screened 153 drugs and identified 15 that significantly inhibited the metabolism of aumolertinib. Among them, telmisartan and carvedilol exhibited potent inhibitory activities in rat liver microsomes (RLM) and human liver microsomes (HLM). In vivo, the pharmacokinetic parameters of aumolertinib, including AUC and Cmax, were significantly altered when co-administered with carvedilol, with a notable decrease in the clearance rate CLz/F. Interestingly, the pharmacokinetic parameters of the metabolite HAS-719 exhibited a similar trend as aumolertinib when co-administered. Mechanistically, both telmisartan and carvedilol exhibited a mixed-type inhibition on the metabolism of aumolertinib. Additionally, we used a baculovirus-insect cell expression system to prepare 24 recombinant CYP3A4 microsomes and obtained enzymatic kinetic parameters using aumolertinib as a substrate. Enzyme kinetic studies obtained the kinetic parameters of various CYP3A4 variant-mediated metabolism of aumolertinib. Based on the relative clearance rates, CYP3A4.4, 5, 7, 8, 9, 12, 13, 14, 17, 18, 19, 23, 24, 33, and 34 showed significantly lower clearance rates compared to the wild-type. Among the different CYP3A4 variants, the inhibitory potency of telmisartan and carvedilol on the metabolism of aumolertinib also varied. The IC50 values of telmisartan and carvedilol in CYP3A4.1 were 6.68 ± 1.76 μM and 0.60 ± 0.25 μM, respectively, whereas in CYP3A4.12, the IC50 exceeded 100 μM. Finally, we utilized adeno-associated virus to achieve liver-specific high expression of CYP3A4*1 and CYP3A4*12. In the group with high expression of the less active CYP3A4*12, the magnitude of the drug-drug interaction was significantly attenuated. In conclusion, CYP3A4 genetic polymorphism not only influences the pharmacokinetic characteristics of aumolertinib, but also the inhibitory potency of telmisartan and carvedilol on it.

The polymorphisms of candidate pharmacokinetic and pharmacodynamic genes and their pharmacogenetic impacts on the effectiveness of risperidone maintenance therapy among Saudi children with autism

BACKGROUND

Antipsychotics, including risperidone (RIS), are frequently indicated for various autism spectrum disorder (ASD) manifestations; however, "actionable" PGx testing in psychiatry regarding antipsychotic dosing and selection has limited applications in routine clinical practice because of the lack of standard guidelines, mostly due to the inconsistency and scarcity of genetic variant data. The current study is aimed at examining the association of RIS effectiveness, according to ABC-CV and CGI indexes, with relevant pharmacokinetics (PK) and pharmacodynamics (PD) genes.

METHODS

Eighty-nine ASD children who received a consistent RIS-based regimen for at least 8 weeks were included. The Axiom PharmacoFocus Array technique was employed to generate accurate star allele-predicted phenotypes of 3 PK genes (CYP3A4, CYP3A5, and CYP2D6). Genotype calls for 5 candidate PD receptor genes (DRD1, DRD2, DRD3, HTR2C, and HTR2A) were obtained and reported as wild type, heterozygous, or homozygous for 11 variants.

RESULTS

Based on the ABC total score, 42 (47.2%) children were classified as responders, while 47 (52.8%) were classified as nonresponders. Multivariate logistic regression analyses, adjusted for nongenetic factors, suggested nonsignificant impacts of the star allele-predicted phenotypes of all 3 PK genes on improvement in ASD symptoms or CGI scores. However, significant positive or negative associations of certain PD variants involved in dopaminergic and serotonergic pathways were observed with specific ASD core and noncore symptom subdomains. Our significant polymorphism findings, mainly those in DRD2 (rs1800497, rs1799978, and rs2734841), HTR2C (rs3813929), and HTR2A (rs6311), were largely consistent with earlier findings (predictors of RIS effectiveness in adult schizophrenia patients), confirming their validity for identifying ASD children with a greater likelihood of core symptom improvement compared to noncarriers/wild types. Other novel findings of this study, such as significant improvements in DRD3 rs167771 carriers, particularly in ABC total and lethargy/social withdrawal scores, and DRD1 rs1875964 homozygotes and DRD2 rs1079598 wild types in stereotypic behavior, warrant further verification in biochemical and clinical studies to confirm their feasibility for inclusion in a PGx panel.

CONCLUSION

In conclusion, we provide evidence of potential genetic markers involved in clinical response variability to RIS therapy in ASD children. However, replication in prospective samples with greater ethnic diversity and sample sizes is necessary.

Developments in pharmacogenetics, pharmacogenomics, and personalized medicine

The development of Pharmacogenetics and Pharmacogenomics in Western Europe is highly relevant in the worldwide scenario. Despite the usually low institutional support, many research groups, composed of basic and clinical researchers, have been actively working for decades in this field. Their contributions made an international impact and paved the way for further studies and pharmacogenomics implementation in clinical practice. In this manuscript, that makes part of the Special Issue entitled Spanish Pharmacology, we present an analysis of the state of the art of Pharmacogenetics and Pharmacogenomics research in Europe, we compare it with the developments in Spain, and we summarize the most salient contributions since 1988 to the present, as well as recent developments in the clinical application of pharmacogenomics knowledge. Finally, we present some considerations on how we could improve translation to clinical practice in this specific scenario.

Spice-drug interactions: a case report on the use of turmeric, curry and ginger in a renal transplant patient on tacrolimus

Tacrolimus is a widely used immunosuppressant for the prevention of rejection after transplantation. In vitro studies suggest that interactions exist between spices and tacrolimus. We present the case of a renal transplant patient aged around 70 years who was treated with prednisone, mycophenolate-mofetil and tacrolimus. The patient had a pre-transplant dietary habit of consuming foods spiced with turmeric, curry and ginger. The following protocol was implemented in parallel with close monitoring of plasma tacrolimus concentrations: administration of 10 g/day of turmeric for 4 days, then 10 g/day of curry for 4 days and then 10 g/day of ginger for 4 days. No change in tacrolimus plasma concentrations during and after the implementation of the protocol was observed. The impact of turmeric, curry and ginger on plasma tacrolimus concentrations seems negligible in vivo although further studies are needed. A shared decision to test the impact of spice consumption in a patient with dietary habits involving these spices seems reasonable.

Exploring the impact of ethnicity on drug pharmacokinetics using PBPK models: A case study with lansoprazole in Japanese subjects

AIMS

The aim of this study is to demonstrate the use of PBPK modelling to explore the impact of ethnic differences on drug PK.

METHODS

A PBPK model developed for lansoprazole was used to predict the clinical PK of lansoprazole in Japanese subjects by incorporating the physiological parameters of a Japanese population into the model. Further verification of the developed Japanese population with clinical studies involving eight other CYP substrates-omeprazole, ticlopidine, alprazolam, midazolam, nifedipine, cinacalcet, paroxetine and dextromethorphan-was also carried out.

RESULTS

The PK of lansoprazole in both Caucasian and Japanese subjects was well predicted by the model as the observed data were within the 5th and 95th percentiles across all the clinical studies. In age- and sex-matched simulations in both the Caucasian and Japanese populations, the predicted PK (mean ± SD) of a single oral dose of 30-mg lansoprazole was higher in the Japanese population in all cases, with more than twofold higher AUC of 5.98 ± 6.43 mg/L.h (95% CI: 4.72, 7.24) vs. 2.46 ± 2.45 mg/L.h (95% CI: 1.98, 2.94) in one scenario. In addition, in two out of the nine clinical DDIs of lansoprazole and the additional CYP substrates simulated using the Japanese population, the predicted DDI in Japanese was more than 1.25-fold that in Caucasians, indicating an increased DDI liability.

CONCLUSIONS

By accounting for various physiological parameters that characterize a population in a PBPK model, the impact of the different identified interethnic differences on the drug's PK can be explored, which can inform the adoption of drugs from one region to another.

The Influence of Cytochrome P450 Polymorphisms on Pharmacokinetic Profiles and Treatment Outcomes Among Malaria Patients in Sub-Saharan Africa: A Systematic Review

Background

Sub-Saharan Africa (SSA) population is genetically diverse and heterogenous thus variability in drug response among individuals is predicted to be high. Cytochrome P450 (CYP450) polymorphisms is a major source of variability in drug response. This systematic review presents the influence of CYP450 single nucleotide polymorphisms (SNPs), particularly CYP3A4*1B, CYP2B6*6 and CYP3A5*3 on antimalarial drug plasma concentrations, efficacy and safety in SSA populations.

Methods

Searching for relevant studies was done through Google Scholar, Cochrane Central Register of controlled trials (CENTRAL), PubMed, Medline, LILACS, and EMBASE online data bases. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used. Two independent reviewers extracted data from the studies.

Results

Thirteen studies reporting the influence of CYP450 SNPs on plasma concentrations, efficacy and safety were included in the final data synthesis. CYP3A4*1B, CYP3A5*5, CYP2B6*6 and CYP2C8*2 did not affect antimalarial drug plasma concentration significantly. There was no difference in treatment outcomes between malaria patients with variant alleles and those with wild type alleles.

Conclusion

This review reports lack of influence of CYP3A4*1B, CYP3A5*3, CYP2C8*3 and CYP2B6*6 SNPs on PK profiles, efficacy and safety in SSA among P. falciparum malaria patients.

Bortezomib Pharmacogenetic Biomarkers for the Treatment of Multiple Myeloma: Review and Future Perspectives

Multiple myeloma (MM) is a hematological neoplasm for which different chemotherapy treatments are used with several drugs in combination. One of the most frequently used drugs for the treatment of MM is the proteasome inhibitor bortezomib. Patients treated with bortezomib are at increased risk for thrombocytopenia, neutropenia, gastrointestinal toxicities, peripheral neuropathy, infection, and fatigue. This drug is almost entirely metabolized by cytochrome CYP450 isoenzymes and transported by the efflux pump P-glycoprotein. Genes encoding both enzymes and transporters involved in the bortezomib pharmacokinetic pathway are highly polymorphic. The response to bortezomib and the incidence of adverse drug reactions (ADRs) vary among patients, which could be due to interindividual variations in these possible pharmacogenetic biomarkers. In this review, we compiled all pharmacogenetic information relevant to the treatment of MM with bortezomib. In addition, we discuss possible future perspectives and the analysis of potential pharmacogenetic markers that could influence the incidence of ADR and the toxicity of bortezomib. It would be a milestone in the field of targeted therapy for MM to relate potential biomarkers to the various effects of bortezomib on patients.

Drug-drug interactions involving CFTR modulators: a review of the evidence and clinical implications

INTRODUCTION

Cystic fibrosis (CF) is characterized by mucus accumulation impairing the lungs, gastrointestinal tract, and other organs. Cystic fibrosis transmembrane conductance regulator (CFTR) modulators (ivacaftor, tezacaftor, elexacaftor, and lumacaftor) significantly improve lung function and nutritional status; however, they are substrates, inhibitors, and/or inducers of certain CYP enzymes and transporters, raising the risk of drug-drug interactions (DDI) with common CF medications.

AREAS COVERED

A literature search was conducted for DDIs involving CFTR modulators by reviewing new drug applications, drug package inserts, clinical studies, and validated databases of substrates, inhibitors, and inducers. Clinically, CYP3A inducers and inhibitors significantly decrease and increase systemic concentrations of elexacaftor/tezacaftor/ivacaftor, respectively. Additionally, lumacaftor and ivacaftor alter concentrations of CYP3A and P-gp substrates. Potential DDIs without current clinical evidence include ivacaftor and elexacaftor's effect on CYP2C9 and OATP1B1/3 substrates, respectively, and OATP1B1/3 and P-gp inhibitors' effect on tezacaftor. A literature review was conducted using PubMed.

EXPERT OPINION

Dosing recommendations for CFTR modulators with DDIs are relatively comprehensive; however, recommendations on timing of dosing transition of CFTR modulators when CYP3A inhibitors are initiated or discontinued is incomplete. Certain drug interactions may be managed by choosing an alternative treatment to avoid/minimize DDIs. Next generation CFTR modulator therapies under development are expected to provide increased activity with reduced DDI risk.

A Single-center, Open-label, Parallel Control Study Comparing the Pharmacokinetics and Safety of a Single Oral Dose of Roflumilast and Its Active Metabolite Roflumilast N-oxide in Healthy Chinese and Caucasian Volunteers

Roflumilast is a phosphodiesterase-4 inhibitor which treats chronic obstructive pulmonary disease (COPD). Roflumilast N-oxide is the major metabolite of roflumilast with a similar mechanism of action to roflumilast. Although racial differences in roflumilast drug disposition have been observed, the necessity of dose adjustment is subject to debate. This study compares the pharmacokinetics of a single 500 μg dose of roflumilast in healthy Chinese and Caucasian subjects under uniform conditions. Chinese subjects were found to have longer t_1/2 and higher AUC_0-t and C_max than Caucasian subjects. The point estimates on the geometric mean of AUC_0-t in Chinese subjects were 22% higher for roflumilast and 46% higher for roflumilast N-oxide. Point estimates on the geometric mean of C_max were 9% and 24% higher for roflumilast and roflumilast N-oxide, respectively. Total phosphodiesterase-4 (PDE4) inhibitory (tPDE4i) activity, a theoretical parameter that describes the combined contribution to PDE4 inhibitory activity of roflumilast and roflumilast N-oxide, was 44% higher in Chinese subjects than in Caucasian subjects. With about a 10-fold higher plasma AUC compared to the parent roflumilast and a much longer observed half-life, roflumilast N-oxide has been estimated to contribute about 90% of tPDE4i, with 10% attributed to the parent compound roflumilast. Following body weight normalization, these figures were lower but remained significant. Safety analysis showed signs of reduced tolerance or different pharmacodynamic response to roflumilast in Chinese recipients than in Caucasians. Our results suggest that Chinese patients should receive a dose of roflumilast lower than 500 μg daily during future clinical trials.

Developing supervised machine learning algorithms to evaluate the therapeutic effect and laboratory-related adverse events of cyclosporine and tacrolimus in renal transplants

BACKGROUND

Single nucleotide polymorphisms influence the effects of tacrolimus and cyclosporine in renal transplants.

AIM

We set out to use machine learning algorithms (MLAs) to identify variables that predict the therapeutic effects and adverse events following tacrolimus and cyclosporine administration in renal transplant patients.

METHOD

We sampled 120 adult renal transplant patients (on cyclosporine or tacrolimus). Generalized linear model (GLM), support vector machine (SVM), artificial neural network (ANN), Chi-square automatic interaction detection, classification and regression tree, and K-nearest neighbors were the chosen MLAs. The mean absolute error (MAE), relative mean square error (RMSE), and regression coefficient (β) with a 95% confidence interval (CI) were used as the model parameters.

RESULTS

For a stable dose of tacrolimus, the MAEs (RMSEs) of GLM, SVM, and ANN were 1.3 (1.5), 1.3 (1.8), and 1.7 (2.3) mg/day, respectively. GLM revealed that the POR*28 genotype and age significantly predicted the stable dose of tacrolimus as follows: POR*28 (β -1.8; 95% CI -3, -0.5; p = 0.006), and age (β -0.04; 95% CI -0.1, -0.006; p = 0.02). For a stable dose of cyclosporine, MAEs (RMSEs) of 93.2 (103.4), 79.1 (115.2), and 73.7 (91.7) mg/day were observed with GLM, SVM, and ANN, respectively. GLM revealed the following predictors of a stable dose of cyclosporine: CYP3A5*3 (β -80.8; 95% CI -130.3, -31.2; p = 0.001), and age (β -3.4; 95% CI -5.9, -0.9; p = 0.007).

CONCLUSION

We observed that various MLAs could identify significant predictors that were useful to optimize tacrolimus and cyclosporine dosing regimens; yet, the findings must be externally validated.

Genetic Variation in CYP2D6 and SLC22A1 Affects Amlodipine Pharmacokinetics and Safety

Amlodipine is an antihypertensive drug with unknown pharmacogenetic biomarkers. This research is a candidate gene study that looked for associations between amlodipine pharmacokinetics and safety and pharmacogenes. Pharmacokinetic and safety data were taken from 160 volunteers from eight bioequivalence trials. In the exploratory step, 70 volunteers were genotyped for 44 polymorphisms in different pharmacogenes. CYP2D6 poor metabolizers (PMs) showed higher half-life (t1/2) (univariate p-value (puv) = 0.039, multivariate p-value (pmv) = 0.013, β = -5.31, R2 = 0.176) compared to ultrarapid (UMs), normal (NMs) and intermediate metabolizers (IMs). SLC22A1 rs34059508 G/A genotype was associated with higher dose/weight-corrected area under the curve (AUC72/DW) (puv = 0.025; pmv = 0.026, β = 578.90, R2 = 0.060) compared to the G/G genotype. In the confirmatory step, the cohort was increased to 160 volunteers, who were genotyped for CYP2D6, SLC22A1 and CYP3A4. In addition to the previous associations, CYP2D6 UMs showed a lower AUC72/DW (puv = 0.046, pmv = 0.049, β = -68.80, R2 = 0.073) compared to NMs, IMs and PMs and the SLC22A1 rs34059508 G/A genotype was associated with thoracic pain (puv = 0.038) and dizziness (puv = 0.038, pmv = 0.014, log OR = 10.975). To our knowledge, this is the first work to report a strong relationship between amlodipine and CYP2D6 and SLC22A1. Further research is needed to gather more evidence before its application in clinical practice.

Pharmacogenomics in Asians: Differences and similarities with other human populations

INTRODUCTION

Various pharmacogenomic (PGx) variants differ widely in different ethnicities. and clinical outcomes associated with these variants may also be substantially varied. Literature was searched in different databases, i.e. PubMed, ScienceDirect, Web of Science, and PharmGKB, from inception to 30 June 2022 for this review.

AREAS COVERED

Certain PGx variants were distinctly varied in Asian populations compared to the other human populations, e.g. CYP2C19*2,*3,*17; CYP2C9*2,*3; CYP2D6*4,*5,*10,*41; UGT1A1*6,*28; HLA-B*15:02, HLA-B*15:21, HLA-B*58:01, and HLA-A*31:01. However, certain other variants do not vary greatly between Asian and other ethnicities, e.g. CYP3A5*3; ABCB1, and SLCO1B1*5. As evident in this review, the risk of major adverse cardiovascular events (MACE) was much stronger in Asian patients taking clopidogrel and who inherited the CYP2C19 loss-of-function alleles, e.g. CYP2C19*2 and*3, when compared to the western/Caucasian patients. Additionally, the risk of carbamazepine-induced severe cutaneous adverse drug reactions (SCARs) for the patients inheriting HLA-B*15:02 and HLA-B*15:21 alleles varied significantly between Asian and other ethnicities. In contrast, both Caucasian and Asian patients inheriting the SLCO1B1*5 variant possessed a similar magnitude of muscle toxicity, i.e. myopathy.

EXPERT OPINION

Asian countries should take measures toward expanding PGx research, as well as initiatives for the purposes of obtaining clinical benefits from this newly evolving and economically viable treatment model.

The pharmacogenetics of the new-generation antipsychotics - A scoping review focused on patients with severe psychiatric disorders

Exploring the possible correlations between gene variations and the clinical effects of the new-generation antipsychotics is considered essential in the framework of personalized medicine. It is expected that pharmacogenetic data will be useful for increasing the treatment efficacy, tolerability, therapeutic adherence, functional recovery, and quality of life in patients with severe psychiatric disorders (SPD). This scoping review investigated the available evidence about the pharmacokinetics, pharmacodynamics, and pharmacogenetics of five new-generation antipsychotics, i.e., cariprazine, brexpiprazole, aripiprazole, lumateperone, and pimavanserin. Based on the analysis of 25 primary and secondary sources and the review of these agents' summaries of product characteristics, aripiprazole benefits from the most relevant data about the impact of gene variability on its pharmacokinetics and pharmacodynamics, with significant consequences on this antipsychotic's efficacy and tolerability. The determination of the CYP2D6 metabolizer status is important when administering aripiprazole, either as monotherapy or associated with other pharmacological agents. Allelic variability in genes encoding dopamine D2, D3, and serotonin, 5HT2A, 5HT2C receptors, COMT, BDNF, and dopamine transporter DAT1 was also associated with different adverse events or variations in the clinical efficacy of aripiprazole. Brexpiprazole also benefits from specific recommendations regarding the CYP2D6 metabolizer status and the risks of associating this antipsychotic with strong/moderate CYP2D6 or CYP3A4 inhibitors. US Food and Drug Administration (FDA) and European Medicines Agency (EMA) recommendations about cariprazine refer to possible pharmacokinetic interactions with strong CYP3A4 inhibitors or inducers. Pharmacogenetic data about cariprazine is sparse, and relevant information regarding gene-drug interactions for lumateperone and pimavanserin is yet lacking. In conclusion, more studies are needed to detect the influence of gene variations on the pharmacokinetics and pharmacodynamics of new-generation antipsychotics. This type of research could increase the ability of clinicians to predict favorable responses to specific antipsychotics and to improve the tolerability of the treatment regimen in patients with SPD.

Molecular Mechanisms of Tyrosine Kinase Inhibitor Resistance in Chronic Myeloid Leukemia

The hematopoietic neoplasm chronic myeloid leukemia (CML) is a rare disease caused by chromosomal reciprocal translocation t(9;22)(q34:q11) with subsequent formation of the BCR-ABL1 fusion gene. This fusion gene encodes a constitutively active tyrosine kinase, which results in malignant transformation of the cells. Since 2001, CML can be effectively treated using tyrosine kinase inhibitors (TKIs) such as imatinib, which prevent phosphorylation of downstream targets by blockade of the BCR-ABL kinase. Due to its tremendous success, this treatment became the role model of targeted therapy in precision oncology. Here, we review the mechanisms of TKI resistance focusing on BCR-ABL1-dependent and -independent mechanisms. These include the genomics of the BCR-ABL1, TKI metabolism and transport and alternative signaling pathways.

Understanding inter-individual variability in pharmacokinetics/pharmacodynamics of aripiprazole in children with tic disorders: Individualized administration based on physiological development and CYP2D6 genotypes

Objective: This study aims to develop a combined population pharmacokinetic (PPK) model for aripiprazole (ARI) and its main active metabolite dehydroaripiprazole (DARI) in pediatric patients with tic disorders (TD), to investigate the inter-individual variability caused by physiological and genetic factors in pharmacokinetics of ARI and optimize the dosing regimens for pediatric patients. Methods: A prospective PPK research was performed in Chinese children with TD. Totally 84 patients aged 4.83-17.33 years were obtained for the pharmacokinetic analysis. 27 CYP2D6 and ABCB1 gene alleles were detected. Moreover, the clinical efficacy was evaluated according to reduction rate of Yale Global Tic Severity Scale (YGTSS) score at the 12th week comparing with the baseline. Monte Carlo simulations were used to evaluate and optimize dosing regimens. Results: The PPK model was established to predict the concentrations of ARI and DARI. Body weight and CYP2D6 genotype were the significant covariates affecting the clearance of ARI. The DARI/ARI metabolic ratios (MRs) of AUC24h, Cmin and Cmax at the steady state of results were ultra-rapid metabolizers (UMs) > normal metabolizers (NMs) > intermediated metabolizers (IMs). MRs could be used to distinguish UMs or IMs from other patients. The best predictor of clinical efficacy for TD was the trough concentration of ARI and the cut-off point was 101.636 ng/ml. Conclusion: The pharmacokinetics of ARI and DARI in pediatric TD were significantly influenced by body weight and CYP2D6 genotype. Individualized dosing regimens were recommended for pediatric patients with TD to ensure clinical efficacy.

Drug-drug interactions involving combinations of antipsychotic agents with antidiabetic, lipid-lowering, and weight loss drugs

INTRODUCTION

Patients with severe mental illness (SMI) have a high risk for diabetes, dyslipidemia, and other components of metabolic syndrome. Patients with these metabolic comorbidities and cardiac risk factors should receive not only antipsychotics but also medications aiming to reduce cardiovascular risk. Therefore, many patients may be exposed to clinically relevant drug-drug interactions.

AREAS COVERED

This narrative review summarizes data regarding the known or potential drug-drug interactions between antipsychotics and medications treating metabolic syndrome components, except for hypertension, which has been summarized elsewhere. A literature search in PubMed and Scopus up to 7/31/2021 was performed regarding interactions between antipsychotics and drugs used to treat metabolic syndrome components, aiming to inform clinicians' choice of medication for patients with SMI and cardiometabolic risk factors in need of pharmacologic interventions.

EXPERT OPINION

The cytochrome P450 system and, to a lesser extent, the P-glycoprotein transporter is involved in the pharmacokinetic interactions between antipsychotics and some statins or saxagliptin. Regarding pharmacodynamic interactions, the available information is based mostly on small studies, and for newer classes, like PCSK9 inhibitors or SGLT2 inhibitors, data are still lacking. However, there is sufficient information to guide clinicians in the process of selecting safer antipsychotic-cardiometabolic risk reduction drug combinations.

The Prognostic Role of CYP Enzyme in Kidney Transplantation: A Single Centre Experience

BACKGROUND

The main goal of immunosuppressive agents is to reach a balance of preserving allograft function while minimizing adverse effects. The purpose of our research is to corroborate the role of CYP3A enzyme in developing individual medication therapy via measuring medicine levels in patients' blood samples.

METHODS

This retrospective analysis studies 15 kidney transplant recipients. We carried out genotyping (CYP3A5, CYP3A4) after isolating DNA and RNA in patient and donor blood samples; we also determined CYP3A4 messenger RNA expression in case of recipients. Tacrolimus blood levels, dosage, and tacrolimus concentration normalized by dose and the body weight (C₀/D ratio) were evaluated.

RESULTS

In this research, recipients were divided into 2 groups based on their CYP3A5 genotype. Those who carry CYP3A5*1 allele (*1/*1 or *1/*3) are CYP3A5 expressors, whereas those who are homozygous for the nonfunctional CYP3A5*3 allele are CYP3A5 nonexpressors. There were 3 patients with functioning CYP3A5 enzyme (patients with CYP3A5*1/*3 genotype) where increased tacrolimus metabolism was expected. Our data show that C₀/D ratio of CYP3A5 nonexpressors was around 3 times higher than of CYP3A5 expressors. Looking at CYP3A4 enzyme, we found 1 patient carried CYP3A4*22/*22 genotype where we expected decreased CYP3A4 expression. It is clear that this patient had adequate therapy medication levels (9.50 μg/L) despite having received very low dosage of tacrolimus (0.03 mg/weight/d).

CONCLUSIONS

Our results confirmed the importance of determining CYP status of recipients after a transplant because individual differences were observed in tacrolimus treatment that were partly influenced by CYP status of recipients.

Association Between Race and Opioid-Induced Respiratory Depression: An International Post Hoc Analysis of the Prediction of Opioid-induced Respiratory Depression In Patients Monitored by Capnography Trial

BACKGROUND

Opioid-induced respiratory depression (OIRD) is common on the medical and surgical wards and is associated with increased morbidity and health care costs. While previous studies have investigated risk factors for OIRD, the role of race remains unclear. We aim to investigate the association between race and OIRD occurrence on the medical/surgical ward.

METHODS

This is a post hoc analysis of the PRediction of Opioid-induced respiratory Depression In patients monitored by capnoGraphY (PRODIGY) trial; a prospective multinational observational blinded study of 1335 general ward patients who received parenteral opioids and underwent blinded capnography and oximetry monitoring to identify OIRD episodes. For this study, demographic and perioperative data, including race and comorbidities, were analyzed and assessed for potential associations with OIRD. Univariable χ 2 and Mann-Whitney U tests were used. Stepwise selection of all baseline and demographic characteristics was used in the multivariable logistic regression analysis.

RESULTS

A total of 1253 patients had sufficient racial data (317 Asian, 158 Black, 736 White, and 42 other races) for inclusion. The incidence of OIRD was 60% in Asians (N = 190/317), 25% in Blacks (N = 40/158), 43% in Whites (N = 316/736), and 45% (N = 19/42) in other races. Baseline characteristics varied significantly: Asians were older, more opioid naïve, and had higher opioid requirements, while Blacks had higher incidences of heart failure, obesity, and smoking. Stepwise multivariable logistic regression revealed that Asians had increased risk of OIRD compared to Blacks (odds ratio [OR], 2.49; 95% confidence interval [CI], 1.54-4.04; P = .0002) and Whites (OR, 1.38; 95% CI, 1.01-1.87; P = .0432). Whites had a higher risk of OIRD compared to Blacks (OR, 1.81; 95% CI, 1.18-2.78; P = .0067). The model's area under the curve was 0.760 (95% CI, 0.733-0.787), with a Hosmer-Lemeshow goodness-of-fit test P value of .23.

CONCLUSIONS

This post hoc analysis of PRODIGY found a novel association between Asian race and increased OIRD incidence. Further study is required to elucidate its underlying mechanisms and develop targeted care pathways to reduce OIRD in susceptible populations.

LaGAT: link-aware graph attention network for drug-drug interaction prediction

MOTIVATION

Drug-drug interaction (DDI) prediction is a challenging problem in pharmacology and clinical applications. With the increasing availability of large biomedical databases, large-scale biological knowledge graphs containing drug information have been widely used for DDI prediction. However, large knowledge graphs inevitably suffer from data noise problems, which limit the performance and interpretability of models based on the knowledge graph. Recent studies attempt to improve models by introducing inductive bias through an attention mechanism. However, they all only depend on the topology of entity nodes independently to generate fixed attention pathways, without considering the semantic diversity of entity nodes in different drug pair links. This makes it difficult for models to select more meaningful nodes to overcome data quality limitations and make more interpretable predictions.

RESULTS

To address this issue, we propose a Link-aware Graph Attention method for DDI prediction, called LaGAT, which is able to generate different attention pathways for drug entities based on different drug pair links. For a drug pair link, the LaGAT uses the embedding representation of one of the drugs as a query vector to calculate the attention weights, thereby selecting the appropriate topological neighbor nodes to obtain the semantic information of the other drug. We separately conduct experiments on binary and multi-class classification and visualize the attention pathways generated by the model. The results prove that LaGAT can better capture semantic relationships and achieves remarkably superior performance over both the classical and state-of-the-art models on DDI prediction.

AVAILABILITYAND IMPLEMENTATION

The source code and data are available at https://github.com/Azra3lzz/LaGAT.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

CYP3A5*3 and SLCO1B1 c.521T>C Polymorphisms Influence the Pharmacokinetics of Atorvastatin and 2-Hydroxy Atorvastatin

There is a large variability in individual responses to atorvastatin administration. This study assessed the pharmacogenetic effects of solute carrier organic anion transporter family member 1B1 (SLCO1B1, c.388A>G and c.521T>C) and cytochrome P450 3A5 (CYP3A5, CYP3A5*3) genetic polymorphisms on the pharmacokinetics of atorvastatin and its active metabolite, 2-hydroxy (2-OH) atorvastatin, in 46 individuals who were administered a clinically used single oral dosage of 80 mg. The Cmax and AUC of atorvastatin in CYP3A5*3/*3 carriers were 2.6- and 2.8-fold higher, respectively, than those in CYP3A5*1/*1 carriers, and similar results were observed for 2-OH atorvastatin pharmacokinetics. SLCO1B1 c.521T>C also increased the AUC of atorvastatin and 2-OH atorvastatin. The AUC ratio of atorvastatin and 2-OH atorvastatin were not affected by SLCO1B1 c.388A>G or c.521T>C, whereas CYP3A5*3 reduced the AUC ratio. In an analysis evaluating the simultaneous effect of the SLCO1B1 c.521T>C and CYP3A5*3 polymorphisms, SLCO1B1 c.521TT/CYP3A5*1/*1 carriers showed lower Cmax and AUC values for atorvastatin and 2-OH atorvastatin than in individuals with the SLCO1B1 c.521T>C and/or CYP3A5*3 genotypes. Among the participants with the SLCO1B1 c.521TT genotype, the CYP3A5*3 carriers had a higher systemic exposure to atorvastatin and 2-OH atorvastatin than the CYP3A5*1/*1 carriers. Thus, SLCO1B1 c.521T>C and CYP3A5*3 polymorphisms affect the pharmacokinetics of atorvastatin and 2-OH atorvastatin.

Predicting drug response and toxicity in metastatic colorectal cancer: the role of germline markers

INTRODUCTION

Despite the introduction of targeted agents leading to therapeutic advances, clinical management of patients with metastatic colorectal cancer (mCRC) is still challenged by significant interindividual variability in treatment outcomes, both in terms of toxicity and therapy efficacy. The study of germline genetic variants could help to personalize and optimize therapeutic approaches in mCRC.

AREAS COVERED

A systematic review of pharmacogenetic studies in mCRC patients published on PubMed between 2011 and 2021, evaluating the role of germline variants as predictive markers of toxicity and efficacy of drugs currently approved for treatment of mCRC, was perfomed.

EXPERT OPINION

Despite the large amount of pharmacogenetic data published to date, only a few genetic markers (i.e., DPYD and UGT1A1 variants) reached the clinical practice, mainly to prevent the toxic effects of chemotherapy. The large heterogeneity of available studies represents the major limitation in comparing results and identifying potential markers for clinical use, the role of which remains exploratory in most cases. However, the available published findings are an important starting point for future investigations. They highlighted new promising pharmacogenetic markers within the network of inflammatory and immune response signaling. In addition, the emerging role of previously overlooked rare variants has been pointed out.

Interplay of Vitamin D and CYP3A4 Polymorphisms in Endocrine Disorders and Cancer

Vitamin D has received considerable optimistic attention as a potentially important factor in many pathological states over the past few decades. However, the proportion of the active form of vitamin D metabolites responsible for biological activity is highly questionable in disease states due to flexible alterations in the enzymes responsible for their metabolism. For instance, CYP3A4 plays a crucial role in the biotransformation of vitamin D and other drug substances. Food-drug and/or drug-drug interactions, the disease state, genetic polymorphism, age, sex, diet, and environmental factors all influence CYP3A4 activity. Genetic polymorphisms in CYP450-encoding genes have received considerable attention in the past few decades due to their extensive impact on the pharmacokinetic and dynamic properties of drugs and endogenous substances. In this review, we focused on CYP3A4 polymorphisms and their interplay with vitamin D metabolism and summarized the role of vitamin D in calcium homeostasis, bone diseases, diabetes, cancer, other diseases, and drug substances. We also reviewed clinical observations pertaining to CYP3A4 polymorphisms among the aforementioned disease conditions. In addition, we highlighted the future perspectives of studying the pharmacogenetics of CYP3A4, which may have potential clinical significance for developing novel diagnostic genetic markers that will ascertain disease risk and progression.

Drug-drug interactions involving antipsychotics and antihypertensives

INTRODUCTION

Antipsychotics represent the mainstay in the treatment of patients diagnosed with major psychiatric disorders. Hypertension, among other components of metabolic syndrome, is a common finding in these patients. For their psychiatric and physical morbidity, many patients receive polypharmacy, exposing them to the risk of clinically relevant drug-drug interactions.

AREAS COVERED

This review summarizes the knowledge regarding the known or potential drug-drug interactions between antipsychotics and the main drug classes used in the treatment of hypertension. We aimed to provide the clinician an insight into the pharmacokinetic and pharmacodynamic interactions between these drugs for a better choice of combinations of drugs to treat both the mental illness and cardiovascular risk factors. For this, we performed a literature search in PubMed and Scopus databases, up to 31 July 2021.

EXPERT OPINION

The main pharmacokinetic interactions between antipsychotics and antihypertensive drugs involve mainly the cytochrome P450 system. The pharmacodynamic interactions are produced by multiple mechanisms, leading to concurrent binding to the same receptors. The data available regarding drug-drug interactions is mostly based on case reports and small studies and therefore should be interpreted with caution. The current knowledge is sufficiently strong to guide clinicians in selecting safer drug combinations as summarized here.

Role of Pharmacogenetics in the Treatment of Acute Myeloid Leukemia: Systematic Review and Future Perspectives

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by remarkable toxicity and great variability in response to treatment. Plenteous pharmacogenetic studies have already been published for classical therapies, such as cytarabine or anthracyclines, but such studies remain scarce for newer drugs. There is evidence of the relevance of polymorphisms in response to treatment, although most studies have limitations in terms of cohort size or standardization of results. The different responses associated with genetic variability include both increased drug efficacy and toxicity and decreased response or resistance to treatment. A broad pharmacogenetic understanding may be useful in the design of dosing strategies and treatment guidelines. The aim of this study is to perform a review of the available publications and evidence related to the pharmacogenetics of AML, compiling those studies that may be useful in optimizing drug administration.

The Potential Application of Extracellular Vesicles from Liquid Biopsies for Determination of Pharmacogene Expression

Pharmacogenomics (PGx) entails the study of heritability of drug response. This may include both variability in genes related to pharmacokinetics (drug absorption, distribution, metabolism and excretion) and pharmacodynamics (e.g., drug receptors or signaling pathways). Individualizing drug therapy taking into account the genetic profile of the patient has the potential to make drug therapy safer and more effective. Currently, this approach relies on the determination of genetic variants in pharmacogenes by genotyping. However, it is widely acknowledged that large variability in gene expression is attributed to non-structural genetic variants. Therefore, at least from a theoretical viewpoint individualizing drug therapy based upon expression of pharmacogenes rather than on genotype may be advantageous but has been difficult to implement in the clinical setting. Extracellular vesicles (EVs) are lipid encapsulated structures that contain cargo such as lipids, nucleic acids and proteins. Since their cargo is tissue- and cell-specific they can be used to determine the expression of pharmacogenes in the liver. In this review, we describe methods of EV isolation and the potential of EVs isolated from liquid biopsies as a tool to determine the expression of pharmacogenes for use in personalized medicine.

Evaluation of hepatic CYP3A enzyme activity using endogenous markers in lung cancer patients treated with cisplatin, dexamethasone, and aprepitant

PURPOSE

Aprepitant is used with dexamethasone and 5-HT₃ receptor antagonists as an antiemetic treatment for chemotherapy, including cisplatin. Aprepitant is a substrate of cytochrome P450 (CYP) 3A4 and is known to cause its inhibition and induction. In addition, dexamethasone is a CYP3A4 substrate that induces CYP3A4 and CYP3A5 expression. In this study, we aimed to quantitatively evaluate the profile of CYP3A activity using its endogenous markers in non-small cell lung cancer patients receiving a standard cisplatin regimen with antiemetics, including aprepitant.

METHODS

Urinary 11β-hydroxytestosterone (11β-OHT)/testosterone concentration ratio and plasma 4β-hydroxycholesterol (4β-OHC) concentrations were measured before and after cisplatin treatment (days 1, 4, and 8). CYP3A5 was genotyped, and plasma aprepitant concentrations were measured on day 4 to examine its influence on CYP3A endogenous markers.

RESULTS

The urinary 11β-OHT/testosterone concentration ratio in the 35 patients included in this study increased by 2.65-fold and 1.21-fold on days 4 and 8 compared with day 1, respectively. Their plasma 4β-OHC concentration increased by 1.46-fold and 1.66-fold, respectively. The mean plasma aprepitant concentration on day 4 was 1,451 ng/mL, which is far lower than its inhibitory constant. The allele frequencies of CYP3A5*1 and CYP3A5*3 were 0.229 and 0.771, respectively. In patients with the CYP3A5*1 allele, the plasma 4β-OHC concentration was significantly lower at baseline but more potently increased with chemotherapy.

CONCLUSION

CYP3A activity was significantly induced from day 4 to day 8 in patients receiving cisplatin and three antiemetic drugs.

Evaluation of genetic polymorphism of CYP3A5 in normal healthy participants from western India - A cross-sectional study

BACKGROUND

CYP3A5 enzymes belong to the phase I Group of drug-metabolizing enzymes, which are involved in the metabolism of 50% of the drugs. Participants with CYP3A5 genotype: CYP3A5 *1/*1 are fast metabolizers of drugs and hence will require higher dosing. Whereas those with CYP3A5 * 3/*3 are poor metabolizers of drugs and will require a lower dose to achieve target drug concentration in the blood and those with CYP3A5 * 1/*3 have intermediate drug metabolizing activity. Pharmacogenetic evaluation may improve disease outcomes by maximizing the efficacy and minimizing the toxicity of drugs in patients.

MATERIALS AND METHODS

This is a single-center cross-sectional study conducted in the year 2018-2019 to study the population prevalence of genetic polymorphisms of CYP3A5 in healthy participants from western India. Eligible participants willing to give written, informed consent were enrolled in the study. Subsequently, 2 ml venous blood was collected the deoxyribonucleic acid was extracted and then stored at ‒20°C. Genotyping was done by a polymerase chain reaction and restriction fragment length polymorphism.

RESULTS

A total of 400 participants with a median age of 22 years (range: 18-58 years) were included. Among them, the genotype prevalence for CYP3A5 * 1/*1 was 17% (n = 67/400); CYP3A5 * 1/*3 was 37% (n = 149/400) and that of CYP3A5 * 3/*3 was 46% (184/400). Out of the total 400 healthy participants analyzed, the allele frequency for CYP3A5 * 1 was 35% (142/400) and that of CYP3A5*3 was 65% (259/400).

CONCLUSION

The genotype prevalence for CYP3A5 * 3*3 (46%) and the allele frequency for CYP3A5 * 3 (65%) respectively were the highest among the western Indian population.

Drug-Drug Interactions in Vestibular Diseases, Clinical Problems, and Medico-Legal Implications

Peripheral vestibular disease can be treated with several approaches (e.g., maneuvers, surgery, or medical approach). Comorbidity is common in elderly patients, so polytherapy is used, but it can generate the development of drug-drug interactions (DDIs) that play a role in both adverse drug reactions and reduced adherence. For this reason, they need a complex kind of approach, considering all their individual characteristics. Physicians must be able to prescribe and deprescribe drugs based on a solid knowledge of pharmacokinetics, pharmacodynamics, and clinical indications. Moreover, full information is required to reach a real therapeutic alliance, to improve the safety of care and reduce possible malpractice claims related to drug-drug interactions. In this review, using PubMed, Embase, and Cochrane library, we searched articles published until 30 August 2021, and described both pharmacokinetic and pharmacodynamic DDIs in patients with vestibular disorders, focusing the interest on their clinical implications and on risk management strategies.

Effect of CYP3A5 and CYP3A4 Genetic Variants on Fentanyl Pharmacokinetics in a Pediatric Population

Fentanyl is an anesthetic/analgesic commonly used in surgical and recovery settings. CYP3A4 and CYP3A5 encode enzymes, which metabolize fentanyl; genetic variants in these genes impact fentanyl pharmacokinetics in adults. Pharmacokinetic (PK) studies are difficult to replicate in children due to the burden of additional blood taken solely for research purposes. The aim of this study is to test the effect of CYP3A5 and CYP3A4 genetic variants on fentanyl PKs in children using opportunistically collected samples. Fentanyl concentrations were measured from remnant blood specimens and dosing data were extracted from electronic health records. Variant data defining CYP3A4*1G and CYP3A5*3 and *6 alleles were available from prior genotyping; alleles with no variant were defined as *1. The study cohort included 434 individuals (median age 9 months, 52% male subjects) and 1,937 fentanyl concentrations were available. A two-compartment model was selected as the base model, and the final covariate model included age, weight, and surgical severity score. Clearance was significantly associated with either CYP3A5*3 or CYP3A5*6 alleles, but not the CYP3A4*1G allele. A genotype of CYP3A5*1/*3 or CYP3A5*1/*6 (i.e., intermediate metabolizer status) was associated with a 0.84-fold (95% confidence interval (CI): 0.71-1.00) reduction in clearance vs. CYP3A5*1/*1 (i.e., normal metabolizer status). CYP3A5*3/*3, CYP3A5*3/*6, or CYP3A5*6/*6 (i.e., poor metabolizer status) was associated with a 0.76-fold (95% CI: 0.58-0.99) reduction in clearance. In the final model, expected clearance was 8.9 and 6.8 L/hour for a normal and poor metabolizer, respectively, with median population covariates (9 months old, 7.7 kg, low surgical severity).

Pharmacogenomics insights into precision pediatric oncology

PURPOSE OF REVIEW

Pharmacogenomic insights provide an opportunity to optimize medication dosing regimens and patient outcomes. However, the potential for interindividual genomic variability to guide medication dosing and toxicity monitoring is not yet standard of care. In this review, we present advances for the thiopurines, anthracyclines and vincristine and provide perspectives on the actionability of pharmacogenomic guidance in the future.

RECENT FINDINGS

The current guideline on thiopurines recommends that those with normal predicted thiopurine methyltransferase and NUDT15 expression receive standard-of-care dosing, while 'poor metabolizer' haplotypes receive a decreased 6-mercaptopurine starting dose to avoid bone marrow toxicity. Emerging evidence established significant polygenic contributions that predispose to anthracycline-induced cardiotoxicity and suggest this knowledge be used to identify those at higher risk of complications. In the case of vincristine, children who express CYP3A5 have a significantly reduced risk of peripheral neuropathy compared with those expressing an inactive form or the CYP3A4 isoform.

SUMMARY

The need for adequately powered pediatric clinical trials, coupled with the study of epigenetic mechanisms and their influence on phenotypic variation and the integration of precision survivorship into precision approaches are featured as important areas for focused investments in the future.

CYP3A-status is associated with blood concentration and dose-requirement of tacrolimus in heart transplant recipients

High inter-individual variability in tacrolimus clearance is attributed to genetic polymorphisms of CYP3A enzymes. However, due to CYP3A phenoconversion induced by non-genetic factors, continuous changes in tacrolimus-metabolizing capacity entail frequent dose-refinement for optimal immunosuppression. In heart transplant recipients, the contribution of patients' CYP3A-status (CYP3A5 genotype and CYP3A4 expression) to tacrolimus blood concentration and dose-requirement was evaluated in the early and late post-operative period. In low CYP3A4 expressers carrying CYP3A5*3/*3, the dose-corrected tacrolimus level was significantly higher than in normal CYP3A4 expressers or in those with CYP3A5*1. Modification of the initial tacrolimus dose was required for all patients: dose reduction by 20% for low CYP3A4 expressers, a 40% increase for normal expressers and a 2.4-fold increase for CYP3A5*1 carriers. The perioperative high-dose corticosteroid therapy was assumed to ameliorate the low initial tacrolimus-metabolizing capacity during the first month. The fluctuation of CYP3A4 expression and tacrolimus blood concentration (C₀/D) was found to be associated with tapering and cessation of corticosteroid in CYP3A5 non-expressers, but not in those carrying CYP3A5*1. Although monitoring of tacrolimus blood concentration cannot be omitted, assaying recipients' CYP3A-status can guide optimization of the initial tacrolimus dose, and can facilitate personalized tacrolimus therapy during steroid withdrawal in the late post-operative period.

Influence of CYP2D6 and CYP3A5 Polymorphisms on the Pharmacokinetics and Pharmacodynamics of Bisoprolol in Hypertensive Chinese Patients

Purpose: This study was performed to investigate the effects of common polymorphisms in CYP2D6 and CYP3A5 on the plasma concentrations and antihypertensive effects of bisoprolol in hypertensive Chinese patients. Methods: One hundred patients with essential hypertension were treated with open-label bisoprolol 2.5 mg daily for 6 weeks. Clinic blood pressure (BP) and ambulatory BP (ABP) were measured after the placebo run-in and after 6 weeks treatment. Peak plasma concentrations of bisoprolol were measured at 3 h after the first dose and 3 h after the dose after 6 weeks treatment. Trough levels were measured before the dose after 6 weeks treatment. Bisoprolol plasma concentrations were measured with a validated liquid chromatography tandem mass spectrometry method. Six common polymorphisms in CYP2D6 and the CYP3A5 ^* 3 polymorphism were genotyped by TaqMan® assay. Results: After 6 weeks of treatment, clinic BP and heart rate were significantly reduced by 14.3 ± 10.9/8.4 ± 6.2 mmHg (P < 0.01) and 6.3 ± 7.6 BPM (P < 0.01), respectively. Similar reductions were seen in ABP values. Bisoprolol plasma concentration at 3 h after the first dose and 3 h post-dose after 6 weeks of treatment were significantly associated with baseline body weight (P < 0.001) but there was no significant effect of the CYP2D6 and CYP3A5 polymorphisms on these or the trough plasma concentrations. There was no significant association of the CYP2D6 and CYP3A5 polymorphisms or plasma bisoprolol concentrations with the clinic BP or ABP responses to bisoprolol. Conclusion: Bisoprolol 2.5 mg daily effectively reduced BP and HR. The common polymorphisms in CYP2D6 that were examined and the CYP3A5 ^* 3 polymorphism appear to have no benefit in predicting the hemodynamic response to bisoprolol in these patients.

Reviewing pharmacogenetics to advance precision medicine for opioids

BACKGROUND

Adequate opioid prescribing is critical for therapeutic success of pain management. Despite the widespread use of opioids, optimized opioid therapy remains unresolved with risk of accidental lethal overdosing. With the emergence of accumulating evidence linking genetic variation to opioid response, pharmacogenetic based treatment recommendations have been proposed.

OBJECTIVE

The aim of this review is to evaluate pharmacogenetic evidence and provide an overview on genes involved in the pharmacokinetics and pharmacodynamics of opioids.

METHODS

For this review, a systematic literature search of published articles was used in PubMed®, with no language restriction and between the time period of January 2000 to December 2020. We reviewed randomized clinical studies, study cohorts and case reports that investigated the influence of genetic variants on selected opioid pharmacokinetics and pharmacodynamics. In addition, we reviewed current CPIC clinical recommendations for pharmacogenetic testing.

RESULTS

Results of this review indicate consistent evidence supporting the association between selected genetic variants of CYP2D6 for opioid metabolism. CPIC guidelines include recommendations that indicate the avoidance of tramadol use, in addition to codeine, in CYP2D6 poor metabolizers and ultrarapid metabolizers, and to monitor intermediate metabolizers for less-than-optimal response. While there is consistent evidence for OPRM1 suggesting increased postoperative morphine dosing requirements in A118G G-allele carriers, the clinical relevance remains limited.

CONCLUSION

There is emerging evidence of clinical relevance of CYP2D6 and, to a lesser extent, OPRM1 polymorphism in personalized opioid drug dosing. As a result, first clinics have started to implement pharmacogenetic guidelines for CYP2D6 and codeine.

In vitro effects of 95% khat ethanol extract (KEE) on human recombinant cytochrome P450 (CYP)1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2 and CYP3A5

OBJECTIVES

Khat, a natural amphetamine-like psychostimulant plant, are widely consumed globally. Concurrent intake of khat and xenobiotics may lead to herb-drug interactions and adverse drug reactions (ADRs). This study is a continuation of our previous study, targeted to evaluate the in vitro inhibitory effects of khat ethanol extract (KEE) on human cytochrome (CYP) 1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2, and CYP3A5, major human drug metabolizing enzymes.

METHODS

In vitro fluorescence enzyme assays were employed to assess CYPs inhibition with the presence and absence of various KEE concentrations.

RESULTS

KEE reversibly inhibited CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2 and CYP3A5 but not CYP1A2 with IC₅₀ values of 25.5, 99, 4.5, 21, 27, 17, and 10 μg/mL respectively. No irreversible inhibition of KEE on all the eight CYPs were identified. The K_i values of CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2 and CYP3A5 were 20.9, 85, 4.8, 18.3, 59.3, 3, and 21.7 μg/mL, respectively. KEE inhibited CYP2B6 via competitive or mixed inhibition; CYP2E1 via un-competitive or mixed inhibition; while CYP2A6, CYP2C8, CYP2C19, CYP2J2 and CYP3A5 via non-competitive or mixed inhibition.

CONCLUSIONS

Caution should be taken by khat users who are on medications metabolized by CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2, and CYP3A5.

Single Nucleotide Polymorphism Induces Divergent Dynamic Patterns in CYP3A5: A Microsecond Scale Biomolecular Simulation of Variants Identified in Sub-Saharan African Populations

Pharmacogenomics aims to reveal variants associated with drug response phenotypes. Genes whose roles involve the absorption, distribution, metabolism, and excretion of drugs, are highly polymorphic between populations. High coverage whole genome sequencing showed that a large proportion of the variants for these genes are rare in African populations. This study investigated the impact of such variants on protein structure to assess their functional importance. We used genetic data of CYP3A5 from 458 individuals from sub-Saharan Africa to conduct a structural bioinformatics analysis. Five missense variants were modeled and microsecond scale molecular dynamics simulations were conducted for each, as well as for the CYP3A5 wildtype and the Y53C variant, which has a known deleterious impact on enzyme activity. The binding of ritonavir and artemether to CYP3A5 variant structures was also evaluated. Our results showed different conformational characteristics between all the variants. No significant structural changes were noticed. However, the genetic variability seemed to act on the plasticity of the protein. The impact on drug binding might be drug dependant. We concluded that rare variants hold relevance in determining the pharmacogenomics properties of populations. This could have a significant impact on precision medicine applications in sub-Saharan Africa.

CYP3A4∗22 Genotyping in Clinical Practice: Ready for Implementation?

Cytochrome P450 3A4 (CYP3A4) is the most important drug metabolizing enzyme in the liver, responsible for the oxidative metabolism of ∼50% of clinically prescribed drugs. Therefore, genetic variation in CYP3A4 could potentially affect the pharmacokinetics, toxicity and clinical outcome of drug treatment. Thus far, pharmacogenetics for CYP3A4 has not received much attention. However, the recent discovery of the intron 6 single-nucleotide polymorphism (SNP) rs35599367C > T, encoding the CYP3A4^∗22 allele, led to several studies into the pharmacogenetic effect of CYP3A4^∗22 on different drugs. This allele has a relatively minor allele frequency of 3-5% and an effect on CYP3A4 enzymatic activity. Thus far, no review summarizing the data published on several drugs is available yet. This article therefore addresses the current knowledge on CYP3A4^∗22. This information may help in deciding if, and for which drugs, CYP3A4^∗22 genotype-based dosing could be helpful in improving drug therapy. CYP3A4^∗22 was shown to significantly influence the pharmacokinetics of several drugs, with currently being most thoroughly investigated tacrolimus, cyclosporine, and statins. Additional studies, focusing on toxicity and clinical outcome, are warranted to demonstrate clinical utility of CYP3A4^∗22 genotype-based dosing.

Pharmacogenomics of Impaired Tyrosine Kinase Inhibitor Response: Lessons Learned From Chronic Myelogenous Leukemia

The use of small molecules became one key cornerstone of targeted anti-cancer therapy. Among them, tyrosine kinase inhibitors (TKIs) are especially important, as they were the first molecules to proof the concept of targeted anti-cancer treatment. Since 2001, TKIs can be successfully used to treat chronic myelogenous leukemia (CML). CML is a hematologic neoplasm, predominantly caused by reciprocal translocation t(9;22)(q34;q11) leading to formation of the so-called BCR-ABL1 fusion gene. By binding to the BCR-ABL1 kinase and inhibition of downstream target phosphorylation, TKIs, such as imatinib or nilotinib, can be used as single agents to treat CML patients resulting in 80 % 10-year survival rates. However, treatment failure can be observed in 20-25 % of CML patients occurring either dependent or independent from the BCR-ABL1 kinase. Here, we review approved TKIs that are indicated for the treatment of CML, their side effects and limitations. We point out mechanisms of TKI resistance focusing either on BCR-ABL1-dependent mechanisms by summarizing the clinically observed BCR-ABL1-mutations and their implications on TKI binding, as well as on BCR-ABL1-independent mechanisms of resistances. For the latter, we discuss potential mechanisms, among them cytochrome P450 implications, drug efflux transporter variants and expression, microRNA deregulation, as well as the role of alternative signaling pathways. Further, we give insights on how TKI resistance could be analyzed and what could be learned from studying TKI resistance in CML in vitro.

Synthesis and Characterization of Some New Quinoxalin-2(1H)one and 2-Methyl-3H-quinazolin-4-one Derivatives Targeting the Onset and Progression of CRC with SRA, Molecular Docking, and ADMET Analyses

The pathogenesis of colorectal cancer is a multifactorial process. Dysbiosis and the overexpression of COX-2 and LDHA are important effectors in the initiation and development of the disease through chromosomal instability, PGE2 biosynthesis, and induction of the Warburg effect, respectively. Herein, we report the in vitro testing of some new quinoxalinone and quinazolinone Schiff’s bases as: antibacterial, COX-2 and LDHA inhibitors, and anticolorectal agents on HCT-116 and LoVo cells. Moreover, molecular docking and SAR analyses were performed to identify the structural features contributing to the biological activities. Among the synthesized molecules, the most active cytotoxic agent, (6d) was also a COX-2 inhibitor. In silico ADMET studies predicted that (6d) would have high Caco-2 permeability, and %HIA (99.58%), with low BBB permeability, zero hepatotoxicity, and zero risk of sudden cardiac arrest, or mutagenicity. Further, (6d) is not a potential P-gp substrate, instead, it is a possible P-gpI and II inhibitor, therefore, it can prevent or reverse the multidrug resistance of the anticancer drugs. Collectively, (6d) can be considered as a promising lead suitable for further optimization to develop anti-CRC agents or glycoproteins inhibitors.

Immunization and Drug Metabolizing Enzymes: Focus on Hepatic Cytochrome P450 3A

OBJECTIVE

Infectious disease emergencies like the 2013-2016 Ebola epidemic and the 2009 influenza and current SARS-CoV-2 pandemics illustrate that vaccines are now given to diverse populations with preexisting pathologies requiring pharmacological management. Many natural biomolecules (steroid hormones, fatty acids, vitamins) and ~60% of prescribed medications are processed by hepatic cytochrome P450 (CYP) 3A4. The objective of this work was to determine the impact of infection and vaccines on drug metabolism.

METHODS

The impact of an adenovirus-based vaccine expressing Ebola glycoprotein (AdEBO) and H1N1 and H3N2 influenza viruses on hepatic CYP 3A4 and associated nuclear receptors was evaluated in human hepatocytes (HC-04 cells) and in mice.

RESULTS

CYP3A activity was suppressed by 55% in mice 24 h after administration of mouse-adapted H1N1, while ˂10% activity remained in HC-04 cells after infection with H1N1 and H3N2 due to global suppression of cellular translation capacity, indicated by reduction (70%, H1N1, 56%, H3N2) of phosphorylated eukaryotic translation initiation factor 4e (eIF4E). AdEBO suppressed CYP3A activity in vivo (44%) and in vitro (26%) 24 hours after infection.

CONCLUSION

As the clinical evaluation of vaccines for SARS-CoV-2 and other global pathogens rise, studies to evaluate the impact of new vaccines and emerging pathogens on CYP3A4 and other metabolic enzymes are warranted to avoid therapeutic failures that could further compromise the public health during infectious disease emergencies.

Pharmacogenetics of Carbamazepine and Valproate: Focus on Polymorphisms of Drug Metabolizing Enzymes and Transporters

Pharmacogenomics can identify polymorphisms in genes involved in drug pharmacokinetics and pharmacodynamics determining differences in efficacy and safety and causing inter-individual variability in drug response. Therefore, pharmacogenomics can help clinicians in optimizing therapy based on patient's genotype, also in psychiatric and neurological settings. However, pharmacogenetic screenings for psychotropic drugs are not routinely employed in diagnosis and monitoring of patients treated with mood stabilizers, such as carbamazepine and valproate, because their benefit in clinical practice is still controversial. In this review, we summarize the current knowledge on pharmacogenetic biomarkers of these anticonvulsant drugs.

A Critical Perspective on 3D Liver Models for Drug Metabolism and Toxicology Studies

The poor predictability of human liver toxicity is still causing high attrition rates of drug candidates in the pharmaceutical industry at the non-clinical, clinical, and post-marketing authorization stages. This is in part caused by animal models that fail to predict various human adverse drug reactions (ADRs), resulting in undetected hepatotoxicity at the non-clinical phase of drug development. In an effort to increase the prediction of human hepatotoxicity, different approaches to enhance the physiological relevance of hepatic in vitro systems are being pursued. Three-dimensional (3D) or microfluidic technologies allow to better recapitulate hepatocyte organization and cell-matrix contacts, to include additional cell types, to incorporate fluid flow and to create gradients of oxygen and nutrients, which have led to improved differentiated cell phenotype and functionality. This comprehensive review addresses the drug-induced hepatotoxicity mechanisms and the currently available 3D liver in vitro models, their characteristics, as well as their advantages and limitations for human hepatotoxicity assessment. In addition, since toxic responses are greatly dependent on the culture model, a comparative analysis of the toxicity studies performed using two-dimensional (2D) and 3D in vitro strategies with recognized hepatotoxic compounds, such as paracetamol, diclofenac, and troglitazone is performed, further highlighting the need for harmonization of the respective characterization methods. Finally, taking a step forward, we propose a roadmap for the assessment of drugs hepatotoxicity based on fully characterized fit-for-purpose in vitro models, taking advantage of the best of each model, which will ultimately contribute to more informed decision-making in the drug development and risk assessment fields.

Association of CYP3A5 Gene Polymorphisms and Amlodipine-Induced Peripheral Edema in Chinese Han Patients with Essential Hypertension

Background

Amlodipine is one of the most used members of calcium channel blockers (CCB), available to treat hypertension. It is mainly metabolized by the Cytochrome P450 3A4/5 (CYP3A4/5) in the liver. Peripheral edema emerges as the major adverse drug reaction to amlodipine and is the primary reason for discontinuation of amlodipine therapy. However, genetic changes in CYP3A5 may lead to changes in the tolerability of amlodipine.

Purpose

In this study, we were interested whether variants in CYP3A5 have a role to play in amlodipine-induced peripheral edema.

Methods

A total number of 240 Chinese Han patients that have experienced hypertension were included in the study. Sixty-four patients had experienced amlodipine-induced peripheral edema, while the remaining 176 patients with no history of edema formed the control group. Twenty-four single-nucleotide polymorphisms (SNPs) of CYP3A5 gene were sequenced by targeted region sequencing method. The relationship of these genetic variants with amlodipine-induced peripheral edema risk was assessed using logistic regression.

Results

The allele frequencies of CYP3A5*1D (rs15524), CYP3A5*1E (rs4646453) and CYP3A5*3 (rs776746) were significantly different between cases and controls (P<0.05). The CYP3A5 *3/*3 (CC) or CYP3A5 *1D/*1D (AA) carriers showed an increased risk of amlodipine-induced peripheral edema in dominant model. Meanwhile, patients carrying CYP3A5 *1E (AC/AA) showed a reduced risk of peripheral edema. Furthermore, we found a strong linkage disequilibrium among rs15524, rs4646453 and rs776746.

Conclusion

Our study reveals for the first time that CYP3A5 *1D, *1E and *3 were associated with amlodipine-induced peripheral edema in Chinese Han patients with hypertension. However, further studies comprising larger number of samples, more related genes and other factors are wanted.

Pharmacogenetic Testing of Cytochrome P450 Drug Metabolizing Enzymes in a Case Series of Patients with Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is associated with co-morbid psychiatric symptoms (disruptive behavior, anxiety, mood disorders, and psychosis) often requiring psychotropic medications. In this clinical case series of 35 patients with PWS, pharmacogenetic testing was obtained to determine allele frequencies predicting variations in activity of cytochrome (CYP) P450 drug metabolizing enzymes 2D6, 2B6, 2C19, 2C9, 3A4, and 1A2. Results were deidentified, collated, and analyzed by PWS genetic subtype: 14 deletion (DEL), 16 maternal uniparental disomy (UPD) and 5 DNA-methylation positive unspecified molecular subtype (PWS Unspec). Literature review informed comparative population frequencies of CYP polymorphisms, phenotypes, and substrate specificity. Among the total PWS cohort, extensive metabolizer (EM) activity prevailed across all cytochromes except CYP1A2, which showed greater ultra-rapid metabolizer (UM) status (p < 0.05), especially among UPD. Among PWS genetic subtypes, there were statistically significant differences in metabolizing status for cytochromes 2D6, 2C19, 2C9, 3A4 and 1A2 acting on substrates such as fluoxetine, risperidone, sertraline, modafinil, aripiprazole, citalopram, and escitalopram. Gonadal steroid therapy may further impact metabolism of 2C19, 2C9, 3A4 and 1A2 substrates. The status of growth hormone treatment may affect CYP3A4 activity with gender specificity. Pharmacogenetic testing together with PWS genetic subtyping may inform psychotropic medication dosing parameters and risk for adverse events.

Impact of polymorphisms in transporter and metabolizing enzyme genes on olanzapine pharmacokinetics and safety in healthy volunteers

Olanzapine is an atypical antipsychotic widely used for the treatment of schizophrenia, which often causes serious adverse drug reactions. Currently, there are no clinical guidelines implementing pharmacogenetic information on olanzapine. Moreover, the Dutch Pharmacogenomics Working Group (DPWG) states that CYP2D6 phenotype is not related to olanzapine response or side effects. Thus, the objective of this candidate-gene study was to investigate the effect of 72 polymorphisms in 21 genes on olanzapine pharmacokinetics and safety, including transporters (e.g. ABCB1, ABCC2, SLC22A1), receptors (e.g. DRD2, HTR2C), and enzymes (e.g. UGT, CYP and COMT), in a cohort of healthy volunteers. Polymorphisms in CYP2C9, SLC22A1, ABCB1, ABCC2, and APOC3 were related to olanzapine pharmacokinetic variability. The incidence of adverse reactions was related to several genes: palpitations to ABCB1 and SLC22A1, asthenia to ABCB1, somnolence to DRD2 and ABCB1, and dizziness to CYP2C9. However, further studies in patients are warranted to confirm the influence of these genetic polymorphisms on olanzapine pharmacokinetics and tolerability.