Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines for CYP3A5 Genotype and Tacrolimus Dosing

Predictive value of tacrolimus concentration/dose ratio in first post-transplant week for CYP3A5-polymorphism in kidney-transplant recipients

BACKGROUND

Tacrolimus (TAC) is metabolized primarily by the CYP3A-encoded enzyme family (CYP3A4, CYP3A5, and CYP3A7). Individuals expressing the CYP3A51 allele are considered fast metabolizers and generally require higher TAC doses to reach therapeutic levels.

AIM

To evaluate the predictive value of the TAC concentration-to-dose (C0/D) ratio for identifying CYP3A5 polymorphisms in renal transplant recipients.

METHODS

Eighty-six de novo kidney transplant recipients with TAC-based immunosuppression from the Department of Nephrology and Dialysis at Military Hospital 103 (Hanoi, Vietnam) were included in this retrospective study. Blood samples were collected within the first week post-transplantation to monitor TAC levels and to perform genotyping for CYP3A5 genetic polymorphisms.

RESULTS

The CYP3A53/3 genotype was identified in 37 patients (43%), CYP3A51/3 in 40 patients (46.5%), and CYP3A51/1 in 9 patients (10.5%). Patients carrying the CYP3A51/3 or CYP3A51/1 genotype, classified as fast metabolizers (CYP3A5 expressers), had significantly lower TAC C0 concentrations and C0/D ratios compared to slow metabolizers (CYP3A53/3 genotype) at multiple time points during follow-up (all P < 0.001). Notably, the TAC C0/D ratio obtained on day 1 (0.91) was shown to predict CYP3A5 polymorphism with a sensitivity of 84.6% and a specificity of 84.6%.

CONCLUSION

This study demonstrates that the TAC C0/D ratio provides a reliable predictive value for CYP3A5 polymorphisms, which can be used to individualize TAC dosing in renal transplant recipients in Vietnam and other low-income countries.

Impact of CYP3A5 1* and 3* single nucleotide variants on tacrolimus pharmacokinetics and graft rejection risk in pediatric kidney transplant patients

Tacrolimus, a calcineurin inhibitor, is widely used to prevent allograft rejection in kidney transplant recipients. Its metabolism is predominantly mediated by the cytochrome P450 3A5 (CYP3A5) enzyme, and single nucleotide variants (SNVs) within intron 3 of the CYP3A5 gene are strongly associated with interindividual variability in enzyme expression and activity. These SNVs can generate a cryptic splice site, resulting in either preserved enzymatic function classified as expressers (CYP3A5 *1/*1 and *1/*3) or loss of function, classified as non-expressers (CYP3A5 *3/*3). Differential expression of CYP3A5 contributes to variability in tacrolimus pharmacokinetics and clinical outcomes, including graft rejection and therapeutic efficacy. In this study, we evaluated three pharmacokinetic parameters: trough concentration (TAC-C0), weight-adjusted daily dose (TAC-D, mg/kg), and dose-normalized trough concentration (TAC-C0/D). One-way ANOVA was used to assess differences in these parameters between CYP3A5 expressers and non-expressers. Additionally, Poisson regression was performed to examine associations between clinical/genetic variables and the incidence rate of acute rejection events. Genotyping was conducted in 45 pediatric kidney transplant recipients. The CYP3A5 *3/*3 genotype was most prevalent (66.7%), followed by *1/*3 (26.7%) and *1/*1 (6.7%). During the 6-month post-transplant period, CYP3A5 expressers required significantly higher tacrolimus doses to achieve target trough levels. Increased drug exposure was associated with a higher incidence of rejection events, whereas CYP3A5 expression correlated with a reduced rate of rejection. These findings underscore the clinical utility of CYP3A5 genotyping for optimizing tacrolimus dosing strategies. Carriers of functional CYP3A5 alleles (*1/*3 or *1/*1) benefit from individualized dose adjustments to achieve therapeutic concentrations and reduce the risk of graft rejection.

Regulation of the immune microenvironment and immunotherapy after liver transplantation

Liver transplantation (LT) is a primary treatment option for patients with end-stage liver disease. However, post-transplantation immune regulation is critical to graft survival and long-term patient outcomes. Following liver transplantation, the recipient's immune system mounts a response against the graft, while the graft promotes anti-rejection immune reactions and the establishment of immune tolerance. In recent years, advances in the study of the immune microenvironment have provided new insights into post-transplantation immune regulation. Meanwhile, immunotherapy strategies have opened new possibilities for improving transplantation success rates and long-term survival. This review summarizes recent progress in understanding the immune microenvironment and immunotherapy following liver transplantation, focusing on key components of the transplant immune microenvironment, their regulatory networks and mechanisms, major immunosuppressive strategies, emerging immunotherapeutic approaches, and current challenges. The aim was to provide a theoretical foundation for optimizing clinical practice.

Implementing Pre-Emptive Pharmacogenetics: Impact of Early Pharmacogenetic Screening in a Pediatric Oncology Cohort of 1,151 Subjects

In pediatric oncology, pharmacogenetic guidelines are underutilized and the potential impact of pre-emptive pharmacogenetic screening remains largely unexplored despite this field's need for individualized approaches. While comprehensive pharmacogenetic guidelines are not yet available for all anticancer drugs, evidence-based recommendations exist for a subset of supportive care drugs and anticancer drugs, including thiopurines, irinotecan, capecitabine, and 5-fluorouracil. In this study, we evaluate the potential impact of pre-emptive pharmacogenetic screening by retrospectively identifying opportunities for dose or treatment adjustments within a national pediatric oncology cohort. Our analysis focused on ten genes and 28 drugs relevant to pediatric oncology, which are included in the Clinical Pharmacogenetics Implementation Consortium and the Dutch Pharmacogenetics Working Group guidelines. In a cohort of 1,151 pediatric oncology subjects, we identified that 16% of individuals could have benefited from altered drug dosing or treatment. These include dose and treatment recommendations for allopurinol, nonsteroidal anti-inflammatory drugs, phenytoin, amitriptyline, proton pump inhibitors, voriconazole, tramadol, codeine, paroxetine, tacrolimus, rasburicase, and 6-mercaptopurine. As genetic data increasingly becomes available through molecular diagnostics in pediatric oncology, there is a unique opportunity to re-utilize this data for pre-emptive pharmacogenetic screening. Leveraging genetic profiles to guide clinicians in drug selection and dose optimization can improve patient outcomes by enhancing the safety and efficacy of treatments. We therefore recommend incorporating pharmacogenetic screening into clinical workflows to advance personalized medicine in pediatric oncology.

Prevalence of Actionable Exposures to Pharmacogenetic Medications Among Solid Organ Transplant Recipients in a Population-Scale Biobank

Background/Objectives: Solid organ transplant (SOT) recipients are exposed to multiple medications, many of which have pharmacogenetic (PGx) prescribing recommendations. This study leveraged data from a population-scale biobank and an enterprise data warehouse to determine the prevalence of actionable exposures to PGx medications among kidney, heart, and lung transplant recipients during the first six months post-transplant. Methods: We conducted a retrospective analysis of adult SOT patients with genetic data available from the Colorado Center for Personalized Medicine (CCPM) biobank and clinical data from Health Data Compass (HDC). We evaluated 29 variants in 13 pharmacogenes and 42 Clinical Pharmacogenetics Implementation Consortium (CPIC) level A or B medications (i.e., sufficient evidence to recommend at least one prescribing action based on genetics). The primary outcome was actionable exposure to a PGx medication (i.e., actionable phenotype and a prescription for an affected PGx medication). Results: The study included 358 patients. All patients were prescribed at least one PGx medication, and 49.4% had at least one actionable exposure to a PGx medication during the first six months post-transplant. The frequency of actionable exposure was highest for tacrolimus (15.4%), followed by proton pump inhibitors (PPIs) (15.1%) and statins (12.8%). Statin actionable exposures significantly differed by transplant type, likely due to variations in prescribing patterns and actionable phenotypes for individual statins. Conclusions: Our findings highlight the potential clinical utility of PGx testing among SOT patients. Further studies are needed to address the impact on clinical outcomes and the optimal timing of PGx testing in the SOT population.

Alleles of CYP3A5 and their association with renal function in chronic kidney disease

Background

The cytochrome P450 family 3 subfamily A polypeptide 5 (CYP3A5) gene plays an important role in renal function through its product's involvement in metabolizing endogenous substances and drugs, including immunosuppressants used following kidney transplantation. A single-nucleotide polymorphism, CYP3A5*3 (rs776746), produces a non-functional variant that may influence progression of chronic kidney disease (CKD) by impairing renal filtration. However, the frequency of the CYP3A5*3 allele in the Thai population and its association with renal parameters remain underexplored. This study aimed to determine the prevalence of CYP3A5 polymorphisms and their association with renal function.

Methods

We investigated the distribution of CYP3A5 polymorphisms in 329 northeastern Thai participants, including 205 CKD patients and 124 healthy controls. Genotyping was performed using the TaqMan allelic discrimination assay. Renal function parameters were assessed and compared between CYP3A5*1 and CYP3A5*3 allele carriers.

Results

In the entire cohort, the allele frequency of CYP3A5*3 was 63.2%, with genotype frequencies of CYP3A5*1/*1 (16.7%), CYP3A5*1/*3 (40.1%), and CYP3A5*3/*3 (43.2%). There was no significant difference in the CYP3A5 allele frequencies between CKD and control groups. CYP3A5*3 carriers exhibited significantly lower eGFR, urine creatinine and serum creatinine clearance and higher UACR compared to CYP3A5*1 carriers. After adjusting for confounders, CYP3A5*3 remained significantly associated with reduced urine creatinine.

Conclusion

This study highlights a high prevalence of CYP3A5 polymorphisms in the northeastern Thai population. The association of the CYP3A5*3 allele with renal function parameters underscores the need for further research into the mechanisms by which CYP3A5 affects kidney function, which could inform personalized CKD management strategies.

Development and Validation of a Nomogram for Predicting Subtherapeutic Tacrolimus Blood Levels in Renal Transplant Recipients: A Multivariate Logistic Regression Analysis

This study constructs a nomogram risk prediction model to identify factors affecting subtherapeutic tacrolimus (FK506) blood concentrations in postrenal transplant patients, enhancing clinical management. Data from renal transplant patients treated with tacrolimus from January to December 2023 were analyzed using multivariate logistic regression to identify risk factors. A nomogram model was constructed and validated through cross-validation and bootstrapping. Predictive performance was assessed via receiver operating characteristic curve and Hosmer- Lemeshow test. Among 340 patients, 224 achieved target FK506 concentrations (5-15 ng/mL). Independent risk factors for subtherapeutic levels included white blood cell count ≤4 × 10^9/L, total bilirubin >20 μmol/L, creatinine >73 μmol/L, and blood urea nitrogen ≤7.1 mmol/L. The model's receiver operating characteristic area under the curve was 0.84, with a Hosmer- Lemeshow test P-value of .386, indicating high predictive accuracy and good calibration. The nomogram effectively predicts subtherapeutic FK506 levels, providing a valuable tool for personalized patient management. Future research should refine and externally validate the model.

Cytochrome P450 phenotyping using the Geneva cocktail improves metabolic capacity prediction in a hospitalized patient population

AIMS

Liver cytochromes (CYPs) play an important role in drug metabolism but display a large interindividual variability resulting both from genetic and environmental factors. Most drug dose adjustment guidelines are based on genetics performed in healthy volunteers. However, hospitalized patients are not only more likely to be the target of new prescriptions and drug treatment modifications than healthy volunteers, but will also be more subject to polypharmacy, drug-drug interactions, or to suffer from disease or inflammation affecting CYP activities.

METHODS

We compared predicted phenotype based on genetic data and measured phenotype using the Geneva cocktail to determine the extent of drug metabolizing enzyme variability in a large population of hospitalized patients (>500) and healthy young volunteers (>300). We aimed to assess the correlation between predicted and measured phenotype in the two populations.

RESULTS

We found that, even in cases where the genetically predicted metabolizer group correlates well with measured CYP activity at group level, this prediction lacks accuracy for the determination of individual metabolizer capacities. Drugs can have a profound impact on CYP activity, but even after combining genetic and drug treatment information, the activity of a significant proportion of extreme metabolizers could not be explained.

CONCLUSIONS

Our results support the use of measured metabolic ratios in addition to genotyping for accurate determination of individual metabolic capacities to guide personalized drug prescription.

Frequency and Implications of High-Risk Pharmacogenomic Phenotypes Identified in a Diverse Australian Pediatric Oncology Cohort

Pharmacogenomics remains underutilized in pediatric oncology, despite the existence of evidence-based guidelines. Implementation of pharmacogenomics-informed prescribing could improve medication safety and efficacy in pediatric oncology patients, who are at high risk of adverse drug reactions. This study examines the prevalence of high-risk pharmacogenomic phenotypes and the prescription of relevant medications in a diverse Australian pediatric oncology cohort, highlighting the potential impact of pharmacogenomic testing in this unique population. Whole genome sequencing data from 180 patients were analyzed to assess 14 genes with evidence-based pharmacogenomic guidelines relevant to pediatric oncology. Over 90% of patients had at least one high-risk phenotype, with 20% presenting four or more. Ondansetron, mercaptopurine, omeprazole, pantoprazole, and voriconazole were commonly prescribed medications that have pharmacogenomic prescribing recommendations, with the latter three showing the highest actionability rates. High-risk phenotypes were most frequently observed for CYP2C19 and CYP2D6, with 30% of patients having a high-risk phenotype for both genes. This study underscores the potential utility of pharmacogenomics in pediatric oncology patients across a range of pharmacogenes and commonly prescribed medications. The findings support advocacy for implementing broad, pre-emptive pharmacogenomic testing in oncology patients to improve treatment safety and efficacy.

Decoding the selective chemical modulation of CYP3A4

Drug-drug interactions associate with concurrent uses of multiple medications. Cytochrome P450 (CYP) 3A4 metabolizes a large portion of marketed drugs. To maintain the efficacy of drugs metabolized by CYP3A4, pan-CYP3A inhibitors such as ritonavir are often co-administered. Although selective CYP3A4 inhibitors have greater therapeutic benefits as they avoid inhibiting unintended CYPs and undesirable clinical consequences, the high homology between CYP3A4 and CYP3A5 has hampered the development of such selective inhibitors. Here, we report a series of selective CYP3A4 inhibitors with scaffolds identified by high-throughput screening. Structural, functional, and computational analyses reveal that the differential C-terminal loop conformations and two distinct ligand binding surfaces disfavor the binding of selective CYP3A4 inhibitors to CYP3A5. Structure-guided design of compounds validates the model and yields analogs that are selective for CYP3A4 versus other major CYPs. These findings demonstrate the feasibility to selectively inhibit CYP3A4 and provide guidance for designing better CYP3A4 selective inhibitors.

CYP3A Genotype Is Associated With Variability in the Exposure and Clearance of the Novel Oncogenic Transcription Inhibitor Lurbinectedin

Lurbinectedin is an oncogenic transcription inhibitor indicated for the treatment of small cell lung cancer (SCLC), which has also shown activity against other malignancies. In this work, two independent cohorts of 180 (discovery cohort) and 719 (validation cohort) cancer patients receiving lurbinectedin in Phases I, II, or III clinical trials were enrolled. Using a population pharmacokinetic (popPK) model of the discovery cohort, patients with extremely high (n = 10, cohort 1) and low (n = 10, cohort 2) etaCL values (i.e., a variable used as a surrogate of unexplained CL interindividual variability) were identified. They were sequenced for 42 candidate genes involved in lurbinectedin pharmacokinetics. A total of 34 variants located in 20 genes were significantly associated with lurbinectedin etaCL; the best nine hits (located in CYP3A5, CYP3A4, ABCB1, ARNT, NR5A2, NR1H4, and FOXA3) were subsequently genotyped in the validation cohort. A strong additive association between CYP3A4 and CYP3A5 genotypes (informed as a CYP3A activity score [AS] variable) and lurbinectedin clearance (CL) and exposure was confirmed, for example, patients with an AS of 3, 2, or 1 showed a 2.3-, 1.6-, and 1.5-fold higher total lurbinectedin CL compared to those with an AS of 0 and 2.3-, 1.8-, and 1.6-fold higher unbound lurbinectedin CL. In conclusion, preemptive CYP3A genotyping may offer a valuable approach for personalizing treatment with lurbinectedin in cancer patients.

Optimizing tacrolimus dosage in post-renal transplantation using DoseOptimal framework: profiling CYP3A5 genetic variants for interpretability

BACKGROUND

Achieving optimal tacrolimus dosing is vital for effectively balancing therapeutic efficacy and safety, as CYP3A5 genetic variants and inter-patient variability emphasize the need for precision strategies.

AIM

This study aimed to optimize tacrolimus dosage prediction for renal transplant recipients by incorporating genetic polymorphisms, specifically profiling CYP3A5 genetic variants, within the DoseOptimal framework to enhance interpretability and accuracy of dosing decisions.

METHOD

The dataset comprised clinical, demographic, and CYP3A5 genetic variants information from 1045 stable tacrolimus-treated patients. The DoseOptimal framework was developed by integrating the strengths of the most effective algorithms from fifteen machine learning models. SHapley Additive exPlanations (SHAP) and decision tree insights were incorporated to enhance the framework's interpretability. The framework's performance was assessed using mean absolute error (MAE) and the coefficient of determination (R2 score). The F-statistic and p value were calculated to validate the framework's statistical significance.

RESULTS

The DoseOptimal framework demonstrated robust performance with an R2 score of 0.884 in the training set and 0.830 in the testing set. The MAE was 0.40 mg/day (95% CI 0.38-0.43) in the training set and 0.41 mg/day (95% CI 0.38-0.45) in the testing set. The framework predicted the ideal tacrolimus dosage in 87.6% (n = 275) of the test cohort, with 3.2% (n = 10) underestimation and 9.2% (n = 29) overestimation. The framework's statistical significance was confirmed with an F-statistic of 266.095 and a p value < 0.001.

CONCLUSION

The framework provides precision medicine-based dosing solutions tailored to individual genetic profiles, minimizing dosing errors and enhancing patient outcomes.

Impact of CYP3A4 and ABCB1 genetic variants on tacrolimus dosing in Greek kidney transplant recipients

Background

Tacrolimus, an approved first-line calcineurin inhibitor, is widely prescribed in organ transplantation to prevent allograft rejection. Its narrow therapeutic index requires precise management to achieve optimal dosing and to minimize adverse drug events (ADEs) while ensuring its therapeutic efficacy. Among several factors, genetic differences contribute significantly to the inter-individual and inter-ethnic variability in pharmacokinetics (PK) of tacrolimus in kidney transplant recipients. As a result, investigating the role of genetic variation in Greek transplant recipients becomes crucial to optimizing therapeutic strategies and enhancing the efficacy of immunosuppressive treatment.

Hypothesis

Genetic variants which are known to influence the activity of enzymes or drug-transporters critical to tacrolimus pharmacokinetics, may significantly affect the required kidney post-transplant tacrolimus daily dose.

Aim

To assess the correlation of ABCB1 genetic variants (rs1128503, rs2229109) and CYP3A4 (rs2242480, rs4986910) with tacrolimus dose-adjusted trough concentration (C0/D), in Greek kidney transplant recipients.

Methods

Ninety-four unrelated Greek kidney transplant recipients were included in this study from the Department of Nephrology and Kidney Transplantation of the University General Hospital of Patras. Patients' dose-adjusted trough levels were measured at five distinct time points after transplantation and analyzed in relation to the possible influence of CYP3A4 and correlated with the abovementioned ABCB1 genetic variants using standard genotyping analysis and Sanger sequencing.

Results

The genetic variants rs1128503, rs2229109, rs2242480, rs4986910 did not show any significant association with the daily dosing requirements of tacrolimus for at least 1 year, in Greek patients who have undergone kidney transplant.

Conclusion

It remains uncertain whether these genetic variants influence the assessment of the appropriate tacrolimus dosing 1 year after transplantation in Greek kidney transplant recipients.

Characterizing the Use of Prolonged-Release Once-Daily Tacrolimus (LCPT) across Canada

Background

Tacrolimus is the most common calcineurin inhibitor given to kidney and liver transplant recipients. Prolonged-release once-daily tacrolimus (LCPT) is the newest formulation of this drug, but prescribing practices for tacrolimus across Canada are unknown.

Objectives

To investigate the use of tacrolimus across Canada, by determining coverage for the drug, exploring prescribing practices and factors related to decision-making, and identifying management methods for patients with rapid metabolism of tacrolimus.

Methods

A mixed-methods, descriptive study using survey-based data collection and qualitative interviews was undertaken. The medical director and a pharmacist from each adult kidney and liver transplant centre in Canada were invited to complete an electronic questionnaire consisting of 8 open-ended questions concerning their respective transplant programs' coverage for and use of tacrolimus. Interested participants completed a one-on-one virtual follow-up interview to explore experiences.

Results

A total of 28 health care providers participated in the survey, of whom 18 completed an interview, achieving representation from 15 (79%) of 19 kidney transplant programs and 3 (38%) of 8 liver transplant programs. Prescribing habits varied, with immediate-release tacrolimus (IR-Tac) being the most commonly preferred formulation (due to provider experience), followed by extended-release tacrolimus (ER-Tac) and LCPT. Most survey respondents (26/28) indicated that their centres used LCPT for maintenance but not de novo immunosuppression. The most common reason for conversion to LCPT was to reduce tremors or to address suspected rapid metabolism; barriers to uptake of LCPT included perceived disadvantages related to cost and coverage.

Conclusions

Prescribing practices for tacrolimus varied across Canada. IR-Tac was the most commonly used formulation, followed by ER-Tac. LCPT was used primarily in the maintenance phase for people with neurotoxicity or rapid metabolism, but there was a lack of consistency in how rapid metabolism was defined.

Allele and genotype frequencies of variants in P450 cytochromes, transports, and DNA repair enzymes in the Dominican Republic population

Introduction

Single-nucleotide variants (SNVs) give rise to important inter-individual and inter-ethnic variabilities in the metabolism and disposition of several therapeutic agents and may cause differences in the treatment response to clinically important drugs like antiarrhythmics, antidepressants, antihistamines, and antipsychotics, among others. Information about the prevalence of variants in the Dominican Republic population is still limited. The aim of this study was to describe the frequency distribution of 32 SNVs from 14 genes with pharmacogenetic interest within a sample of 150 unrelated healthy individuals.

Methods

Genotype and allele frequencies were determined, and pairwise Wright's FST statistic was evaluated.

Results

Hardy-Weinberg equilibrium deviations were found in seven loci from CYP2D6 (rs16947, rs3892097, rs1058164, rs1135840, and rs28371725) and CYP2C19 (rs12769205 and rs4244285) genes. The minor allele frequencies ranged from 0.01 to 0.50 values in the xenobiotic biotransformation enzymes and transporter genes. The average admixture estimates were 51.6%, 39.5%, and 8.9% for European, African, and Amerindian ancestries, respectively. Pairwise FST analysis revealed that Dominicans displayed genetic similarity to Latin American populations, especially those with Afro-Caribbean ancestry, given the selected variants. Higher differences were identified from East and South Asians, Europeans, and Africans, in which several values above the FST threshold for moderate differentiation were identified within variants in CYP2C, CYP3A, CYP1A1, ABCB1, SLC45A2, XRCC1, and XRCC3 genes.

Conclusions

These results should allow establishing the clinical relevance of pharmacogenetic testing in variant alleles related to drug transport and metabolism genes in this population.

Whole-Exome Sequencing Followed by dPCR-Based Personalized Genetic Approach in Solid Organ Transplantation: A Study Protocol and Preliminary Results

Genetic profiling and molecular biology methods have made it possible to study the etiology of the end-stage organ disease that led to transplantation, the genetic factors of compatibility and tolerance of the transplant, and the pharmacogenetics of immunosuppressive drugs and allowed for the development of monitoring methods for the early assessment of allograft rejection. This study aims to report the design and baseline characteristics of an integrated personalized genetic approach in solid organ transplantation, including whole-exome sequencing (WES) and the monitoring of dd-cfDNA by dPCR. Preliminary results reported female recipients with male donors undergoing two pediatric and five adult kidney and three heart transplantations. WES revealed a pathogenic mutation in RBM20 and VUS in TTN and PKP2 in heart recipients, while kidney donors presented mutations in UMOD and APOL1 associated with autosomal-dominant kidney diseases, highlighting the risks requiring the long-term monitoring of recipients, donors, and their family members. %dd-cfDNA levels were generally stable but elevated in cadaveric kidney recipient and one pediatric patient with infectious complications and genetic variants in the ABCB1 and ABCC2 genes. These findings highlight the potential of combining genetic and molecular biomarker-based approaches to improve donor-recipient matching, predict complications, and personalize post-transplant care, paving the way for precision medicine in transplantation.

Effects of Opioids in Cancer Pain: An Interplay Among Genetic Factors, Immune Response, and Clinical Outcomes-A Scoping Review

Background/Objectives: Managing cancer-related pain presents complex challenges involving the interplay between analgesic efficacy, immune system responses, and patient outcomes. Methods: Following the Scale for the Assessment of Narrative Review Articles (SANRA) criteria, we conducted a comprehensive literature search in Medline, Scopus, and Web of Science databases. The review synthesized evidence regarding opioid pain management modalities, genetic variations affecting pain perception, and associated drug metabolism. Results: The literature reveals significant associations between opioid administration and immune function, with potential implications for cancer progression and survival. Genetic polymorphisms in key genes influence individual responses to pain opioid metabolism and, finally, pain management strategies. The immunosuppressive effects of opioids emerge as a critical consideration in cancer pain management, potentially influencing disease progression and treatment outcomes. Conclusions: Genetic variants influence analgesic efficacy, while the interaction between opioid-induced immunosuppression and genetic factors impacts both pain control and survival outcomes. This emphasizes the need for personalized treatment approaches considering individual genetic profiles and immune function.

Implementation of Integrated Clinical Pharmacogenomics Testing at an Academic Medical Center

BACKGROUND

Pharmacogenomics has demonstrated benefits for clinical care, including a reduction in adverse events and cost savings. However, barriers in expanded implementation of pharmacogenomics testing include prolonged turnaround times and integration of results into the electronic health record with clinical decision support. A clinical workflow was developed and implemented to facilitate in-house result generation and incorporation into the electronic health record at a large academic medical center.

METHODS

An 11-gene actionable pharmacogenomics panel was developed and validated using a QuantStudio 12K Flex platform. Allelic results were exported to a custom driver and rules engine, and result messages, which included a diplotype and predicted metabolic phenotype, were sent to the electronic health record; an electronic consultation (eConsult) service was integrated into the workflow. Postimplementation monitoring was performed to evaluate the frequency of actionable results and turnaround times.

RESULTS

The actionable pharmacogenomics panel covered 39 alleles across 11 genes. Metabolic phenotypes were resulted alongside gene diplotypes, and clinician-facing phenotype summaries (Genomic Indicators) were presented in the electronic health record. Postimplementation, 8 clinical areas have utilized pharmacogenomics testing, with 56% of orders occurring in the outpatient setting; 22.1% of requests included at least one actionable pharmacogene, and 67% of orders were associated with a pre- or postresult electronic consultation. Mean turnaround time from sample collection to result was 4.6 days.

CONCLUSIONS

A pharmacogenomics pipeline was successfully operationalized at a quaternary academic medical center, with direct integration of results into the electronic health record, clinical decision support, and eConsult services.

Pre-emptive pharmacogenetic testing in the acute hospital setting: a cross-sectional study

BACKGROUND

Pharmacogenetic-guided prescribing can be used to improve the safety and effectiveness of medicines. There are several approaches by which this intervention might be implemented in clinical practice, which will vary depending on the health system and clinical context.

AIM

To understand the clinical utility of panel-based pharmacogenetic testing in patients admitted acutely to hospital and to establish variables that predict if an individual might benefit from the intervention.

DESIGN

A cross-sectional study recruiting patients admitted acutely to hospital.

METHODS

Participants underwent panel-based pharmacogenetic testing, and their genetic results were analysed in their context of the medicines they had been exposed to as an inpatient. The primary outcome was the proportion of patients with clinically actionable gene-drug interactions. Individual variables that predict the clinical utility of pharmacogenetic testing were established via logistic regression.

RESULTS

Genetic and prescribing data were available for 482 inpatients (55% male; median age 61.2 years; range: 18-96), 97.9% of whom carried a pharmacogenetic result of interest. During their admission, 79.5% of patients were exposed to a medicine for which there is pharmacogenetic prescribing guidance available. Just under one in seven individuals (13.7%) had a clinically actionable gene-drug interaction. Increasing age (>50 years) was positively correlated with the likelihood (2.7-fold increased risk) of having a clinically actionable interaction.

CONCLUSIONS

These findings demonstrate the potential scale, and potential clinical utility, of pharmacogenetic testing as an intervention, highlighting the need to develop infrastructure to support healthcare professionals make use of this emerging tool.

Clinical Pharmacogenetic Testing and Application: 2024 Updated Guidelines by the Korean Society for Laboratory Medicine

In the era of precision medicine, pharmacogenetics has substantial potential for addressing inter-individual variability in drug responses. Although pharmacogenetics has been a research focus for many years, resulting in the establishment of several formal guidelines, its clinical implementation remains limited to several gene-drug combinations in most countries, including Korea. The main causes of delayed implementation are technical challenges in genotyping and knowledge gaps among healthcare providers; therefore, clinical laboratories play a critical role in the timely implementation of pharmacogenetics. This paper presents an update of the Clinical Pharmacogenetic Testing and Application guidelines issued by the Korean Society for Laboratory Medicine and aims to provide the necessary information for clinical laboratories planning to implement or expand their pharmacogenetic testing. Current knowledge regarding nomenclature, gene-drug relationships, genotyping technologies, testing strategies, methods for clinically relevant information delivery, QC, and reimbursements has been curated and described in this guideline.

Impact of Pharmacogenomic Testing in Pediatric Heart and Kidney Transplant

BACKGROUND

Pediatric solid organ transplantation is a complex process including a tightly orchestrated medication regimen, essential for prevention of infection, rejection, graft failure, and mortality. Pharmacogenomic (PGx) testing tailors medication therapy to the individual patient, focusing on safety, efficacy, and avoidance of adverse effects. Implementation of PGx panel results into clinical practice for pediatric transplant patients has not been evaluated.

METHODS

Pediatric patients evaluated for heart, kidney, or combined heart-kidney transplant at a tertiary children's hospital from October 2021 to October 2023 received PGx panel testing.

PRIMARY OUTCOME MEASURE

Report the prevalence of actionable PGx variants for key genes impacting pharmacotherapy in pre- and post-heart and kidney transplant populations.

RESULTS

A total of 73 patients were included, predominately white (84.9%) and male (64.4%), with a mean age of 8.8 ± 6.4 years. Indications for PGx testing included evaluation for heart transplant (38.4%), kidney transplant (38.4%), combined heart-kidney transplant (4.1%), or to inform posttransplant care (19.2%). All patients had at least one actionable phenotype identified. 37 of 73 patients (50.7%) had at least one actionable phenotype for the transplant-specific genes captured including CYP3A5, SLCO1B1, G6PD, TPMT, prothrombin (Factor 2), and Factor V Leiden. 16 of 73 patients (21.9%) had actionable CYP3A5 phenotypes. 15 of 73 (20.5%) had actionable SLCO1B1 phenotypes. 9 of 73 patients (12.3%) had actionable TPMT phenotypes. 5 of 73 (6.8%) had Prothrombin or Factor V Leiden variants.

CONCLUSIONS

Routine pretransplant PGx testing provided information that was actionable and could be utilized to optimize posttransplant medications for all patients.

Effect of CYP 3A4*1B and CYP3A5*3 Gene Polymorphisms in Antirejection of Tacrolimus in Liver Transplant Patients

BACKGROUND

Tacrolimus is a substrate of CYP 3A5; to reduce the rate of liver injury and rejection in liver transplant (LT) recipients, it is feasible to optimize the administration of tacrolimus by adding CYP gene polymorphism.

METHODS

We divided 151 LT recipients randomly into an optimization group and a control group. All were tested routinely for clinical indicators such as FK506 trough concentration and biochemistry, and their complications and survival were observed. The optimization group additionally detected single nucleotide polymorphisms in the CYP 3A4*1B and CYP 3A5*3 genes.

RESULTS

There were no significant differences in tacrolimus dosage, FK506 trough concentrations, and concentration/dose value between the 2 groups. In the optimization group, all patients tested CYP 3A4*1B as wild type. CYP 3A5*3 detection classification included 35 with the G/G mutation (45.5%) and 36 A/G wild-type individuals (46.8%). The concentration/dose values of G/G mutant patients were significantly higher than those of A/G wild-type and A/A mutant patients (G/G vs. A/G; P < .05), and no significant difference in FK506.

CONCLUSION

The CYP 3A4*1B genotype has less influence on tacrolimus metabolism. The genetic polymorphism of CYP 3A5*3 is obvious and largely affects tacrolimus metabolism, and the variant patients need lower doses of tacrolimus to reach the target concentration.

Physiologically-based pharmacokinetic modeling to predict the exposure and provide dosage regimens of tacrolimus in pregnant women with infection disease

Tacrolimus is extensively used for the prevention of graft rejection following solid organ transplantation in pregnant women. However, knowledge gaps in the dosage of tacrolimus for pregnant patients with different CYP3A5 genotypes and infection conditions have been identified. This study aimed to develop a pregnant physiologically based pharmacokinetic (PBPK) model to characterize the maternal and fetal pharmacokinetics of tacrolimus during pregnancy and explore and provide dosage adjustments. We developed PBPK models for nonpregnant patients and validated them via data from previous clinical studies using PK-Sim and Mobi software. To extrapolate to pregnancy, we considered anatomical, physiological, and metabolic alterations and simulated tacrolimus by adding six groups of IL-6 concentrations (0, 5, 25, 50, 500, and 5000 pg/mL). Models were verified by assessing goodness-of-fit plots and ratios of predicted-to-observed pharmacokinetic parameters. The developed PBPK models adequately describe the available clinical data; the fold errors of the predicted and observed values of the area under the curve and peak plasma concentration were between 0.59 and 1.64, and the average folding error and the absolute average folding error values for all concentration-time data points were 1.15 and 1.36, respectively. The simulation results indicated that the area under the steady-state concentration‒time curve and trough concentrations decreased from the first to the third trimester of pregnancy. The trough concentrations were not within the therapeutic range (4-11 ng/mL) in pregnant patients with the CYP3A5 genotype for most of the infection conditions and exceeded its effective concentration in all the CYP3A5 nonexpressers. Based on the model-derived dosing regimen, the tacrolimus trough concentration in pregnant patients with different CYP3A5 genotypes could fall into the therapeutic window, which provided a clinical practice reference for dosage adjustments during pregnancy.

Retrospective Analysis of Tacrolimus Levels: The First 56 Days Following Allogeneic Hematopoietic Stem Cell Transplant and Patient Outcomes

BACKGROUND

Despite prophylaxis, acute graft-versus-host disease (aGVHD) occurs in up to 40% to 60% of patients undergoing an allogeneic hematopoietic stem cell transplantation (alloHSCT). Tacrolimus remains a common GVHD prophylactic medication used in combination with mycophenolate or methotrexate.

OBJECTIVE

The purpose of this study was to compare tacrolimus levels up to day +56 to clinical outcomes in patients who underwent alloHSCT.

METHODS

This was a retrospective cohort study of adult patients who underwent alloHSCT between January 2009 and April 2019 at Oregon Health and Science University (OHSU) Hospital. A logistic regression analysis was performed using SAS software to evaluate the association between tacrolimus concentration range and the GVHD grade outcome.

RESULTS

There were 295 patients included in the study. The median patient age was 53 years (range 18-72), the majority were males (55%), with a median comorbidity index of 2 (range 0-9). Most patients received peripheral blood stem cell transplant (95%). The median tacrolimus levels were divided into 4 groups: (1) between 3.8 and 4.9 ng/mL, (2) 5.0 and 7.9 ng/mL, (3) 8.0 and 9.9 ng/mL, and (4) 10.0 and 10.7 ng/mL in 8 (2.7%), 206 (69.8%), 71 (24.1%), and 10 (3.4%) of patients, respectively. The odds ratio of 0.193 (95% confidence interval [CI]: 0.045-0.836) suggested that patients in the tacrolimus 8 to 12 ng/mL range were approximately 80.5% less likely to have grade 3 to 4 aGVHD compared to those in the 5 to 8 ng/mL range.

CONCLUSION AND RELEVANCE

Overall, we found that higher levels of tacrolimus (range 8-12 ng/mL) in the first 8 weeks post-transplant were associated with improved outcomes without increased rate of relapse.

CYP3A5 and POR gene polymorphisms as predictors of infection and graft rejection in post-liver transplant patients treated with tacrolimus - a cohort study

Liver transplantation is the only curative option for patients with advanced stages of liver disease, with tacrolimus used as the immunosuppressive drug of choice. Genetic variability can interfere with drug response, potentially leading to overexposure or underexposure. This study aims to investigate the association of CYP3A4 (rs2740574, rs2242480, rs35599367), CYP3A5 (rs776746, rs10264272), POR (rs1057868) and ABCB1 (rs1128503, rs2229109, rs9282564) gene polymorphisms with infection, acute rejection, and renal failure. The logistic regression model found an influence of CYP3A5 (rs776746) and POR28 (rs1057868) on the development of acute rejection after liver transplantation (p = 0.028). It also found an association between carriers of the variant allele of the POR*28 gene and infection.

Inhibition of Tacrolimus Metabolism by Cannabidiol and Its Metabolites In Vitro

Drug interactions are major causes of interindividual variability in tacrolimus exposure and effect. Tacrolimus, a widely used drug in transplant patients, is metabolized by CYP3A4 and CYP3A5. Cannabidiol (CBD) use after transplant is common. Clinical cases suggest CBD may alter tacrolimus exposure, but the mechanism of this interaction is unknown. We hypothesize that cannabidiol will inhibit tacrolimus metabolism in vitro mainly through CYP3A5 inhibition. In pooled human liver microsomes (HLMs) and recombinant (r) CYP3A4 and CYP3A5 enzymes, tacrolimus (1 μM) metabolism was determined using substrate depletion method in the absence (control) and the presence of 10 μM CBD, 7-hydroxyCBD, and 7-carboxyCBD. Ketoconazole (1 μM) served as a positive control for the inhibition of CYP3A. Linear regression analyses were performed to obtain kinetic parameters of the depletion. Tacrolimus depletion half-life was 2.54, 0.922, and 0.351 min with pooled HLMs, rCYP3A4, and rCYP3A5, respectively. In pooled HLMs, CBD and 7-hydroxyCBD increased tacrolimus half-life by 0.8- and 2.3-fold (both p < 0.0001), respectively. In rCYP3A4, CBD, 7-hydroxyCBD, and ketoconazole prolonged tacrolimus half-life by 5.8-, 14-, and 7.7-fold, respectively. In rCYP3A5, CBD, 7-hydroxyCBD, and ketoconazole prolonged half-life by 29.3-, 19.7-, and 0.1-fold, respectively. In all experiments, 7-carboxyCBD had minimal effect on tacrolimus depletion. CBD and 7-hydroxyCBD inhibited tacrolimus metabolism in vitro. CBD showed stronger inhibition in rCYP3A5 than rCYP3A4. The demonstrated CYP3A5 selectivity of cannabidiol may contribute to the in vitro identification of CYP3A5 substrates in new drug development. Our results support the potential of a clinical drug-drug interaction between CBD and tacrolimus.

CYP3A5 pharmacogenetic testing for tacrolimus in pediatric heart transplant patients: a budget impact analysis

BACKGROUND

Pharmacogenomic testing can optimize drug efficacy and minimize adverse effects. CYP3A5 polymorphisms affect the metabolism of tacrolimus. We sought to estimate the budget impact of preemptive pharmacogenomic testing for CYP3A5 in pediatric heart transplantation patients from an institutional perspective.

METHODS

A decision tree was constructed to estimate the budget impact of pediatric heart transplant patients (age ≤18 years) initiated on tacrolimus with and without CYP3A5 pharmacogenomic testing. The budget impact of preemptive pharmacogenomic testing versus no pharmacogenomic testing was calculated. One-way sensitivity analysis and alternative analyses were conducted to assess the robustness of results to changes in model parameters.

RESULTS

CYP3A5 genotype-guided dosing provided savings of up to $17 225 per patient compared to standard dosing. These savings decreased to $11 759 when using another institution's data for the standard-dosing group. The time to achieve therapeutic concentration in the poor metabolizer genotype-guided dosing group had the largest impact on cost savings while the cost of the pharmacogenetic test had the smallest impact on cost savings.

CONCLUSION

Implementing CYP3A5 testing could save $17 225 per pediatric heart transplant patient receiving tacrolimus. As pharmacogenomic testing becomes more widespread, institutions should track resource requirements and outcomes to determine the best implementation policies going forward.

French-Speaking Network of Pharmacogenetics (RNPGx) Recommendations for Clinical Use of Mavacamten

Mavacamten, the first drug in the class of β-cardiac myosin modulator, is used for the treatment of patients with hypertrophic cardiomyopathy. This orally administered drug demonstrates wide interpatient variability in pharmacokinetics parameters, due in part to variant CYP2C19 alleles. Individuals who are CYP2C19 poor metabolizers have increased exposure and are at increased risk of reduced cardiac hypercontractility. To ensure the safety of all patients, European Medicines Agency recommends CYP2C19 preemptive genotyping, and consecutively, to adapt maintenance and initial mavacamten doses, and to manage drug-drug interactions, according to CYP2C19 phenotype. In this article, we summarize evidence from the literature supporting the association between CYP2C19 phenotype and pharmacological features of mavacamten and provide, beyond biologic guidelines, therapeutic recommendations for the use of mavacamten based on CYP2C19 and CYP3A4/CYP3A5 genotype.

Customizing Tacrolimus Dosing in Kidney Transplantation: Focus on Pharmacogenetics

ABSTRACT

Different polymorphisms in genes encoding metabolizing enzymes and drug transporters have been associated with tacrolimus pharmacokinetics. In particular, studies on CYP3A4 and CYP3A5, and their combined cluster have demonstrated their significance in adjusting tacrolimus dosing to minimize under- and overexposure thereby increasing the proportion of patients who achieve tacrolimus therapeutic target. Many factors influence the pharmacokinetics of tacrolimus, contributing to inter-patient variability affecting individual dosing requirements. On the other hand, the growing use of population pharmacokinetic models in solid organ transplantation, including different tacrolimus formulations, has facilitated the integration of pharmacogenetic data and other variables into algorithms to easier implement the personalized dose adjustment in transplant centers. The future of personalized medicine in transplantation lies in implementing these models in clinical practice, with pharmacogenetics as a key factor to account for the high inter-patient variability in tacrolimus exposure. To date, three clinical trials have validated the clinical application of these approaches. The aim of this review is to provide an overview of the current studies regarding the different population pharmacokinetic including pharmacogenetics and those translated to the clinical practice for individualizing tacrolimus dose adjustment in kidney transplantation.

Survey of the utilization of genotype-guided tacrolimus management in United States solid organ transplant centers

INTRODUCTION

Genotype-guided tacrolimus management is not routine in clinical practice despite the availability of Clinical Pharmacogenetics Implementation Consortium dosing guidelines. Prior surveys have evaluated patient and provider perspectives of pharmacogenetics (PGx) in transplant, but limited recent data exists on tacrolimus PGx implementation across United States transplant centers.

METHODS

An electronic survey was distributed to transplant pharmacists regarding utilization of tacrolimus PGx, methods of implementing PGx, and barriers to clinical implementation. A survey response was requested for each organ program within the transplant center.

RESULTS

A total of 90 programs from 69 transplant centers (28.1% of active U.S. transplant centers) responded to the survey. Tacrolimus PGx was utilized for patient care in 14 programs (15.6%). There was substantial variability in the implementation methods and application of tacrolimus PGx results among transplant programs. In programs that had not implemented tacrolimus PGx, common barriers for implementation included PGx testing cost and availability and lack of evidence for clinical utility.

CONCLUSION

Implementation of PGx guided tacrolimus in solid organ transplant centers remains limited with heterogeneity in the implementation approach. Additional research is needed to establish the clinical utility of PGx guided tacrolimus and education on reimbursement and testing resources may help to increase uptake.

Impact of Genetic Variants on Pregabalin Pharmacokinetics and Safety

Background/Objectives: Pregabalin is a useful therapeutic option for patients with anxiety or neuropathic pain. Genetic variants in certain genes encoding for transporters related to absorption and distribution could have an impact on the efficacy and safety of the drug. Furthermore, extreme phenotypes in metabolic enzymes could alter pregabalin-limited metabolism. Methods: In this study, we included 24 healthy volunteers participating in a bioequivalence clinical trial and administered pregabalin 300 mg orally; 23 subjects were genotyped for 114 variants in 31 candidate genes, and we explored their impact on pregabalin pharmacokinetics and safety. Results: The uncorrected mean (±SD) of AUC∞ and Cmax were 61,097 ± 14,762 ng*h/mL and 7802 ± 1659 ng/mL, respectively, which were significantly higher in females than in males (p = 0.002 and p = 0.001, respectively), with no differences in dose/weight (DW)- corrected exposure metrics. NAT2 slow acetylators (SAs) showed a 16-18% increase in exposure compared to intermediate (IAs) and normal (NAs) acetylators; NAT2 SAs exhibited a 25% higher t1/2 as compared with NAT2 IAs and 58% higher compared to NAT2 NAs. In contrast, neither the NAT2 phenotype nor other genetic variants were related to pregabalin adverse drug reaction (ADR) occurrence. On the contrary, sex and sex-related exposure differences (i.e., females and their higher exposure compared to males) were the main predictors of ADR occurrence. Conclusions: Our findings suggest that NAT2 could be partially responsible for the minor proportion of pregabalin metabolism, but the effect of NAT2 phenotype does not seem clinically relevant. Therefore, pharmacogenetic biomarkers appear to play a restrained role in pregabalin pharmacotherapy.

Innovation in cancer pharmacotherapy through integrative consideration of germline and tumor genomes

Precision cancer medicine is widely established, and numerous molecularly targeted drugs for various tumor entities are approved or are in development. Personalized pharmacotherapy in oncology has so far been based primarily on tumor characteristics, for example, somatic mutations. However, the response to drug treatment also depends on pharmacological processes summarized under the term ADME (absorption, distribution, metabolism, and excretion). Variations in ADME genes have been the subject of intensive research for >5 decades, considering individual patients' genetic makeup, referred to as pharmacogenomics (PGx). The combined impact of a patient's tumor and germline genome is only partially understood and often not adequately considered in cancer therapy. This may be attributed, in part, to the lack of methods for combined analysis of both data layers. Optimized personalized cancer therapies should, therefore, aim to integrate molecular information, which derives from both the tumor and the germline genome, and taking into account existing PGx guidelines for drug therapy. Moreover, such strategies should provide the opportunity to consider genetic variants of previously unknown functional significance. Bioinformatic analysis methods and corresponding algorithms for data interpretation need to be developed to integrate PGx data in cancer therapy with a special meaning for interdisciplinary molecular tumor boards, in which cancer patients are discussed to provide evidence-based recommendations for clinical management based on individual tumor profiles. SIGNIFICANCE STATEMENT: The era of personalized oncology has seen the emergence of drugs tailored to genetic variants associated with cancer biology. However, the full potential of targeted therapy remains untapped owing to the predominant focus on acquired tumor-specific alterations. Optimized cancer care must integrate tumor and patient genomes, guided by pharmacogenomic principles. An essential prerequisite for realizing truly personalized drug treatment of cancer patients is the development of bioinformatic tools for comprehensive analysis of all data layers generated in modern precision oncology programs.

Value of Pharmacogenetic Testing Assessed with Real-World Drug Utilization and Genotype Data

Implementation of pharmacogenetic testing in clinical care has been slow and with few exceptions is hindered by the lack of real-world evidence on how to best target testing. In this retrospective register-based study, we analyzed a nationwide cohort of 1,425,000 patients discharged from internal medicine or surgical wards and a cohort of 2,178 university hospital patients for purchases and prescriptions of pharmacogenetically actionable drugs. Pharmacogenetic variants were obtained from whole genome genotype data for a subset (n = 930) of the university hospital patients. We investigated factors associated with receiving pharmacogenetically actionable drugs and developed a literature-based cost-benefit model for pre-emptive pharmacogenetic panel testing. In a 2-year follow-up, 60.4% of the patients in the nationwide cohort purchased at least one pharmacogenetically actionable drug, most commonly ibuprofen (25.0%) and codeine (19.4%). Of the genotyped subset, 98.8% carried at least one actionable pharmacogenetic genotype and 23.3% had at least one actionable gene-drug pair. Patients suffering from musculoskeletal or cardiovascular diseases were more prone to receive pharmacogenetically actionable drugs during inpatient episode. The cost-benefit model included frequently dispensed drugs in the university hospital cohort, comprising ondansetron (19.4%), simvastatin (7.4%), clopidogrel (5.0%), warfarin (5.1%), (es)citalopram (5.3%), and azathioprine (0.5%). For untargeted pre-emptive pharmacogenetic testing of all university hospital patients, the model indicated saving €17.49 in direct healthcare system costs per patient in 2 years without accounting for the cost of the test itself. Therefore, it might be reasonable to target pre-emptive pharmacogenetic testing to patient groups most likely to receive pharmacogenetically actionable drugs.

The tradeoff between the efficacy of calcineurin inhibitors: prevention of allograft rejection vs. post-transplant renal and cardiovascular complications

Solid organ transplantation has emerged as a crucial intervention in the field of medicine. During transplantation, our human body perceives the organ as an exogenous entity or graft, initiating an immune reaction to eliminate it. This immune response ultimately culminates in the rejection of the graft. So, to mitigate the possibility of graft rejection, implementing immune suppression is imperative. In this context, the utilization of calcineurin inhibitors (CNIs) assumes a pivotal role. Calcineurin inhibitors significantly preserve immunosuppression following solid organ transplantation. Calcineurin inhibitors have considerably improved short-term results in renal transplantation by reducing acute rejection rates. Concerning the limited therapeutic window of these medications, careful monitoring of pharmacological treatment and individual doses is required. However, a significant number of patients do experience CNI toxicity. Side effects of CNIs include renal failure, hypertension, respiratory disorders, gastrointestinal damage, gingivitis, and so on. Higher trough level of the drug causes acute nephrotoxicity, which is of three types: functional toxicity, tubular toxicity, and vascular toxicity. Acute nephrotoxicity, if untreated, leads to irreversible, progressive deterioration of allograft function, leading to chronic nephrotoxicity. Cardiovascular toxicity of CNIs includes atrial hypertension caused by vasoconstriction of the afferent arteriole, vascular remodeling, hypertrophy, dyslipidemia, and also the onset of diabetes. Such clinical complications further affect the patient's survivability and subjective well-being, possibly leading to graft loss. This review focuses on the most severe side effects of CNIs: renal and cardiovascular toxicity.

Effect of Genetic Variants on Rosuvastatin Pharmacokinetics in Healthy Volunteers: Involvement of ABCG2, SLCO1B1 and NAT2

Statins are the primary drugs used to prevent cardiovascular disease by inhibiting the HMG-CoA reductase, an enzyme crucial for the synthesis of LDL cholesterol in the liver. A significant number of patients experience adverse drug reactions (ADRs), particularly musculoskeletal problems, which can affect adherence to treatment. Recent clinical guidelines, such as those from the Clinical Pharmacogenetics Implementation Consortium (CPIC) in 2022, recommend adjusting rosuvastatin doses based on genetic variations in the ABCG2 and SLCO1B1 genes to minimize ADRs and improve treatment efficacy. Despite these adjustments, some patients still experience ADRs. So, we performed a candidate gene study to better understand the pharmacogenetics of rosuvastatin. This study included 119 healthy volunteers who participated in three bioequivalence trials of rosuvastatin alone or in combination with ezetimibe at the Clinical Trials Unit of the Hospital Universitario de La Princesa (UECHUP). Participants were genotyped using a custom OpenArray from ThermoFisher that assessed 124 variants in 38 genes associated with drug metabolism and transport. No significant differences were observed according to sex or biogeographic origin. A significant increase in t1/2 (pmultivariate(pmv) = 0.013) was observed in the rosuvastatin plus ezetimibe trial compared with the rosuvastatin alone trials. Genetic analysis showed that decreased (DF) and poor function (PF) volunteers for the ABCG2 transporter had higher AUC∞/DW (adjusted dose/weight), AUC72h/DW and Cmax/DW compared to normal function (NF) volunteers (pmv< 0.001). DF and PF volunteers for SLCO1B1 showed an increase in AUC72h/DW (pmv = 0.020) compared to increased (IF) and NF individuals. Results for ABCG2 and SLCO1B1 were consistent with the existing literature. In addition, AUC∞/DW, AUC72h/DW and Cmax/DW were increased in intermediate (IA) and poor (PA) NAT2 acetylators (pmv = 0.001, pmv< 0.001, pmv< 0.001, respectively) compared to rapid acetylators (RA), which could be associated through a secondary pathway that was previously unknown.

Pharmacogenomic landscape of the Thai population from genome sequencing of 949 individuals

Inter-individual variability in drug responses is significantly influenced by genetic factors, underscoring the importance of population-specific pharmacogenomic studies to optimize clinical outcomes. In this study, we analyzed whole genome sequencing data from 949 unrelated Thai individuals and conducted an in-depth analysis of 3239 genes involved in drug pharmacokinetics, pharmacodynamics, or immune-mediated adverse drug reactions. We identified 43 single nucleotide polymorphisms (SNPs), 134 diplotypes, and 15 human leukocyte antigen (HLA) alleles, all with moderate to high clinical significance. On average, each Thai individual carried 14 SNPs, one to two HLA alleles, and six diplotypes with actionable phenotypic associations. Clinically important diplotypes were present in over 20% of individuals for seven genes (CYP2A6, CYP2B6, CYP2C19, CYP3A5, NAT2, SLCO1B1, and VKORC1). In addition, clinically significant SNPs with allele frequencies exceeding 20% were identified among 15 genes, including VKORC1, CYP4F2, and ABCG2. We also identified 21,211 potentially deleterious variants among 3239 genes. Of these variants, 3746 were novel. The comprehensive dataset from this study serves as a valuable resource of pharmacogenomic variants in the Thai population, which will facilitate the development of personalized drug therapies and enhance patient care in Thailand.

External evaluation of tacrolimus population pharmacokinetic models in adult lung transplant patients: How to enhance the predictive ability of the model?

PURPOSE

Tacrolimus is the cornerstone of current immunosuppressive strategies after lung transplantation. However, its narrow therapeutic range and considerable pharmacokinetic variability pose challenges for individualized treatment. Several tacrolimus population pharmacokinetic (popPK) models have been developed for precision dosing in adult lung transplant patients. However, their applicability across different clinical settings remains uncertain. The aim of this study was to evaluate the external predictability of these models and identify influential factors.

METHODS

Published models were systematically retrieved and assessed based on an external dataset of 39 patients (1240 tacrolimus trough concentrations) using three approaches: (1) prediction-based diagnosis using dosing records and patient characteristics; (2) simulation-based diagnosis, with prediction- and variability-corrected visual predictive checks (pvcVPC) and normalized prediction distribution error tests (NPDE); and (3) Bayesian forecasting using one to four observations for posterior predictions. We also investigated the impact of model structure and covariates on predictability.

RESULTS

The predictive performance of six published models was externally evaluated, but none demonstrated satisfactory accuracy in prediction- and simulation-based diagnosis. Bayesian forecasting yielded satisfactory results with only one prior observation and optimal predictive performance with 2-3 priors for all included models. The structural model parameterized on plasma tacrolimus concentration outperformed others. Significant correlations were observed between prediction-error and daily tacrolimus dose, postoperative day, and voriconazole co-administration.

CONCLUSIONS

The overall predictive performance of all published models was unsatisfactory, making direct extrapolation inappropriate. However, Bayesian forecasting significantly improves predictive performance. Utilizing plasma tacrolimus concentration for parameter estimation can improve the predictive ability of tacrolimus popPK models.

CYP3A4 and CYP3A5: the crucial roles in clinical drug metabolism and the significant implications of genetic polymorphisms

CYP3A, a key member of the cytochrome P450 (CYP450) superfamily, is integral to drug metabolism, processing a substantial portion of medications. Their role in drug metabolism is particularly prominent, as CYP3A4 and CYP3A5 metabolize approximately 30-50% of known drugs. The genetic polymorphism of CYP3A4/5 is significant inter-individual variability in enzymatic activity, which can result in different pharmacokinetic profiles in response to the same drug among individuals. These polymorphisms can lead to either increased drug toxicity or reduced therapeutic effects, requiring dosage adjustments based on genetic profiles. Consequently, the study of the enzymatic activity of CYP3A4/5 gene variants is of great importance for the formulation of personalized treatment regimens. This article first reviews the role of CYP3A4/5 in drug metabolism in the human body, including inhibitors and inducers of CYP3A4/5 and drug-drug interactions. In terms of genetic polymorphism, it discusses the detection methods, enzymatic kinetic characteristics, and clinical guidelines for CYP3A5. Finally, the article summarizes the importance of CYP3A4/5 in clinical applications, including personalized therapy, management of drug-drug interactions, and adjustment of drug doses. This review contributes to the understanding of the functions and genetic characteristics of CYP3A4/5, allowing for more effective clinical outcomes through optimized drug therapy.

Model-informed precision dosing: State of the art and future perspectives

Model-informed precision dosing (MIPD) stands as a significant development in personalized medicine to tailor drug dosing to individual patient characteristics. MIPD moves beyond traditional therapeutic drug monitoring (TDM) by integrating mathematical predictions of dosing and considering patient-specific factors (patient characteristics, drug measurements) as well as different sources of variability. For this purpose, rigorous model qualification is required for the application of MIPD in patients. This review delves into new methods in model selection and validation, also highlighting the role of machine learning in improving MIPD, the utilization of biosensors for real-time monitoring, as well as the potential of models integrating biomarkers for efficacy or toxicity for precision dosing. The clinical evidence of TDM and MIPD is discussed for various medical fields including infection medicine, oncology, transplant medicine, and inflammatory bowel diseases, thereby underscoring the role of pharmacokinetics/pharmacodynamics and specific biomarkers. Further research, particularly randomized clinical trials, is warranted to corroborate the value of MIPD in enhancing patient outcomes and advancing personalized medicine.

Synergistic Effect of Cytochrome P450 Family 3 Subfamily A Member 5 (CYP3A5) Genetic Variants in Tacrolimus Dose Determination in Indian Renal Transplant Patients

Tacrolimus (TAC) has a narrow therapeutic index and shows interindividual variabilities in its blood concentration. Although guidelines recommend a genetic variant (rs776746) to determine the optimized TAC dose, discrepancies in accuracy have been noted. Therefore, studying other variants of CYP3A5 may improve the accuracy of the TAC dose. Clinical exome sequencing (CES) was performed in 219 renal transplant patients. The SNPs of CYP3A5 covered by CES were recorded. The TAC blood trough concentration/dose (C 0/D) was calculated on day 7 and months 1, 3, 6, and 12 of post-transplantation, and association with CYP3A5 genotypes was studied. Further, biopsy-proven rejection and pathological events were analyzed for their association with CYP3A5 genotypes. Out of 35 variants of CYP3A5 covered in CES, rs776746, rs15524, rs4646449, and rs464645 were significantly associated with the TAC C 0/D on day 7 and months 1, 3, and 6. Further analysis showed that the slow-metabolizing genotypes of all four SNPs synergistically associated with the TAC C 0/D on day 7 and months 1, 3, 6, and 12. The "CC" genotype of rs776746 showed a significant association (RR = 1.613; p = 0.035) with allograft rejection. In addition, cox regression analysis showed that the presence of the "CA" genotype of rs4646453 increased (HR = 7.258; 95% CI = 1.354-38.904) the risk of development of pathological events, respectively. Four variants of CYP3A5 were synergistically associated with the TAC dose determination. In addition, rs776746 and rs4646453 may be associated with allograft rejection and pathological events, respectively.

Evaluating the evidence for genotype-informed Bayesian dosing of tacrolimus in children undergoing solid organ transplantation: A systematic literature review

Tacrolimus, a calcineurin inhibitor, is a highly effective immunosuppressant used in solid organ transplantation (SOT). However, it is characterized by a narrow therapeutic range and high inter-patient variability in pharmacokinetics. Standard weight-based dosing followed by empiric dose titration is suboptimal in controlling drug concentrations, increasing risk of rejection or toxicity, particularly in the initial months post transplantation. This review explores the potential of combined pre-transplant genotyping and pharmacokinetic (PK) modelling to improve tacrolimus dosing in paediatric SOT recipients. A systematic search of Medline, Embase and Cochrane databases identified studies published between March 2013 and March 2023 that investigated genotype- and PK model-informed tacrolimus dosing in children post-SOT. The Newcastle-Ottawa Scale assessed study quality. Seven studies encompassing paediatric kidney, heart, liver and lung transplants reported using genotype and model-informed dosing. A combination of clinical and genetic factors significantly impacts tacrolimus clearance and thus initial dose recommendation. Body size, transplant organ and co-medications were consistently important, while either time post-transplant or haematocrit emerged in some studies. Several models were identified, however, with limitations evident in some and with absence of evidence for their effectiveness in optimizing initial and subsequent dosing. This review highlights the development of PK models in paediatric SOT that integrate genotype and clinical covariates to personalize early tacrolimus dosing. While promising, prospective studies are needed to validate and confirm their effectiveness in improving time to therapeutic concentrations and reducing under- or overexposure. This approach has the potential to optimize tacrolimus therapy in paediatric SOT, thereby improving outcomes.

Steroid-tacrolimus drug-drug interaction and the effect of CYP3A genotypes

AIMS

Tacrolimus, metabolized by CYP3A4 and CYP3A5 enzymes, is susceptible to drug-drug interactions (DDI). Steroids induce CYP3A genes to increase tacrolimus clearance, but the effect is variable. We hypothesized that the extent of the steroid-tacrolimus DDI differs by CYP3A4/5 genotypes.

METHODS

Kidney transplant recipients (n = 2462) were classified by the number of loss of function alleles (LOF) (CYP3A5*3, *6 and *7 and CYP3A4*22) and steroid use at each tacrolimus trough in the first 6 months post-transplant. A population pharmacokinetic analysis was performed by nonlinear mixed-effect modelling (NONMEM) and stepwise covariate modelling to define significant covariates affecting tacrolimus clearance. A stochastic simulation was performed and translated into a Shiny application with the mrgsolve and Shiny packages in R.

RESULTS

Steroids were associated with modestly higher (3%-11.8%) tacrolimus clearance. Patients with 0-LOF alleles receiving steroids showed the greatest increase (11.8%) in clearance compared to no steroids, whereas those with 2-LOFs had a negligible increase (2.6%) in the presence of steroids. Steroid use increased tacrolimus clearance by 5% and 10.3% in patients with 1-LOF and 3/4-LOFs, respectively.

CONCLUSIONS

Steroids increase the clearance of tacrolimus but vary slightly by CYP3A genotype. This is important in individuals of African ancestry who are more likely to carry no LOF alleles, may more commonly receive steroid treatment, and will need higher tacrolimus doses.

Development and validation of a population pharmacokinetic model to guide perioperative tacrolimus dosing after lung transplantation

Background

Tacrolimus therapy is standard of care for immunosuppression after lung transplantation. However, tacrolimus exposure variability during the early postoperative period may contribute to poor outcomes in this population. Few studies have examined tacrolimus pharmacokinetics (PK) during this high-risk period.

Methods

We conducted a retrospective pharmacokinetic study in lung transplant recipients at the University of Pennsylvania who were enrolled in the Lung Transplant Outcomes Group cohort. We used nonlinear mixed-effects regression to derive a population PK model in 270 patients and examined validity in a separate cohort of 114 patients. Covariates were examined with univariate analysis and a multivariable model was developed using forward and backward stepwise selection. The performance of the final model in the validation cohort was examined with calculation of prediction error (PE).

Results

We developed a 1-compartment base model with a fixed rate absorption constant. Covariates improving model fit were postoperative day, hematocrit, transplant type, CYP3A5 genotype, weight, and exposure to cytochrome p450 enzyme (CYP) inhibitor drugs. The strongest predictor of tacrolimus clearance was postoperative day, with median predicted clearance increasing more than 3-fold over the 14-day study period. In the validation cohort, the final model showed a mean PE of 36.4% (95% confidence interval 30.8%-41.9%) and a median PE of 7.2% (interquartile range -29.3% to 70.53%).

Conclusions

Tacrolimus clearance is highly dynamic during the early postlung transplant period. Population PK models that include lung-transplant-specific covariates may enable precision dosing algorithms that account for this highly dynamic clearance. Future multicenters studies including a broader set of covariates are warranted.

Impact of Paxlovid on Tacrolimus Concentration in Kidney Transplant Patients: A Retrospective Observational Study

Kidney transplant recipients, reliant on lifelong immunosuppressive therapy, face potential drug interactions with emerging treatments such as paxlovid. This study aims to provide guidance for safe administration by examining the impact of paxlovid on tacrolimus levels in kidney transplant recipients. Seven kidney transplant patients who received paxlovid between December 2022 and August 2023 were included for retrospective analysis. Tacrolimus concentration changes were investigated both during and after the administration of paxlovid. Genetic testing for CYP3A5 polymorphisms assessed individual responses. The patient's treatment process was divided into four phases according to the paxlovid administration and the Tacrolimus trough level. The variation of tacrolimus valley concentration, concentration-to-dose ratios (C/D), and creatinine values in different periods were subsequently described and analyzed. The results indicate that tacrolimus levels increased significantly after receiving paxlovid, peaking on day two with a median trough level of 21.8 ng/mL. Prior to the administration of paxlovid, the median C/D value was 6.8 times higher (903.1 to 132.5). Once the paxlovid was stopped, the C/D value and trough level progressively returned to their preadministration levels. Importantly, no graft rejections, adverse events, or neurotoxicity were noted. The levels of creatinine remained stable. During paxlovid treatment, patients adhered to a modified tacrolimus regimen and progressively resumed baseline dosage. In summary, this is the first study to indicate a significant influence of paxlovid on tacrolimus levels in Chinese patients undergoing kidney transplantation. During paxlovid treatment, careful observation and tailored tacrolimus management are crucial to guarantee safe administration and circumvent negative consequences.

A Comparison of Molecular Techniques for Improving the Methodology in the Laboratory of Pharmacogenetics

One of the most critical goals in healthcare is safe and effective drug therapy, which is directly related to an individual's response to treatment. Precision medicine can improve drug safety in many scenarios, including polypharmacy, and it requires the development of new genetic characterization methods. In this report, we use real-time PCR, microarray techniques, and mass spectrometry (MALDI-TOF), which allows us to compare them and identify the potential benefits of technological improvements, leading to better quality medical care. These comparative studies, as part of our pharmacogenetic Five-Step Precision Medicine (5SPM) approach, reveal the superiority of mass spectrometry over the other methods analyzed and highlight the importance of updating the laboratory's pharmacogenetic methodology to identify new variants with clinical impact.

CYP3A4*1B but Not CYP3A5*3 as Determinant of Long-Term Tacrolimus Dose Requirements in Spanish Solid Organ Transplant Patients

Tacrolimus (TAC) is a commonly used immunosuppressive drug in solid organ transplantation. Pharmacogenetics has been demonstrated before to be decisive in TAC pharmacotherapy. The CYP3A5*3 variant has been reported to be the main determinant of TAC dose requirements; however, other polymorphisms have also proven to be influential, especially in CYP3A5 non-expressor patients. The aim of this study is to evaluate the influence of genetic polymorphisms in TAC therapy in a cohort of Spanish transplant recipients. Genetic analysis including ten polymorphic variants was performed, and demographic and clinical data and pharmacotherapy of 26 patients were analyzed. No significant differences were found in weight-adjusted dose between CYP3A5 expressors and non-expressors (0.047 mg/kg vs. 0.044 mg/kg), while they were found for carriers of the CYP3A4*1B allele (0.101 mg/kg; p < 0.05). The results showed that patients with at least one CYP3A4*1B allele had a higher TAC dose and lower blood concentration. Dose-adjusted TAC blood levels were also lower in CYP3A4*1B carriers compared to non-carriers (0.72 ng/mL/mg vs. 2.88 ng/mL/mg). These results support the independence of CYP3A5*3 and CYP3A4*1B variants as determinants of dose requirements despite the linkage disequilibrium present between the two. The variability in genotype frequency between ethnicities may be responsible for the discrepancy found between studies.

Evaluation of the role of metabolizing enzymes and transporter variants in ezetimibe pharmacokinetics

Introduction

Ezetimibe inhibits cholesterol uptake by modulation of intestinal sterol absorption. Currently, although some studies have shown alterations in ezetimibe levels caused by alterations in the ABCG5, ABCG8, NPC1L1 or UGT1A1 genes, there are no pharmacogenetic guidelines to confirm these biomarkers. The aim of this work was to evaluate the effect of 49 variants in 22 pharmacogenes related to metabolism and transport.

Methods

A total of 96 healthy volunteers from four bioequivalence clinical trials of ezetimibe as monotherapy or in combination with simvastatin were studied. Blood samples were extracted for unconjugated ezetimibe plasma quantification and genotyping.

Results and Discussion

No association of metabolizing enzyme variants with ezetimibe pharmacokinetic parameters was found. The results show some trends in the univariate analysis for ABCB1 rs2032582 or ABCC2 rs2273697 and Cmax (p univariate (p uv ) = 0.056 and 0.087, respectively), which finally reach significance in the multivariate analysis (p multivariate (p mv ) = 0.049 and 0.048, respectively). Nevertheless, these results need to be validated in future studies.

Quantitative Proteomics for Translational Pharmacology and Precision Medicine: State of The Art and Future Outlook

Over the past 20 years, quantitative proteomics has contributed a wealth of protein expression data, which are currently used for a variety of systems pharmacology applications, as a complement or a surrogate for activity of the corresponding proteins. A symposium at the 25th North American International Society for the Study of Xenobiotics meeting, in Boston, in September 2023, was held to explore current and emerging applications of quantitative proteomics in translational pharmacology and strategies for improved integration into model-informed drug development based on practical experience of each of the presenters. A summary of the talks and discussions is presented in this perspective alongside future outlook that was outlined for future meetings. SIGNIFICANCE STATEMENT: This perspective explores current and emerging applications of quantitative proteomics in translational pharmacology and precision medicine and outlines the outlook for improved integration into model-informed drug development.

[Pharmaceutical Indication Service in a case of palmar-plantar erythema after amoxicillin and ibuprofen treatment]

Case description

Patient (29 years old) with palmo-plantar erythema, goes to the community pharmacy (FC) requesting a cream to treat atopy.

Evaluation

The patient accessed the Pharmaceutical Indication Service (SPIF), showing that the manifestations appeared 24 hours after the start of dental treatment with amoxicillin 1g/12h and ibuprofen 600 mg/8h without any concomitant medication.

Intervention

After explaining the possible relationship of the symptoms with their medication, patient was derived to the doctor with the referral report completed by SEFAC-eXPERT.

Results

The patient went to the emergency where she was treated with intravenous corticosteroid and a prescription for cetirizine 10 mg. The dentist changed the beta-lactam to a macrolide (azithromycin) and the ibuprofen to paracetamol. From the FC, the evolution of the symptoms was monitored, which took 72 hours to disappear. Allergy tests suggested avoiding beta-lactams, cephalosporins, and arylpropionics without being conclusive. Months later, the patient suffered similar symptoms after inhaling a disinfectant spray and the allergy diagnosis was confirmed.

Conclusions

The FC identified and immediately referred using SPIF a case of hypersensitivity in a patient susceptible to RNM and the SPIF helps to record the intervention and follow-up, increasing patient safety.

[Selection of pharmacogenomic variants and methodology for their use in community pharmacy]

Regulatory agencies such as the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) recognize pharmacogenetics as a key tool in their pharmacological guidelines for pharmaceutical counseling. In this context, community pharmacies play a crucial role in addressing this healthcare need, which could lead to a significant improvement in patients' quality of life by preventing ineffective or contraindicated treatments.In this work, we conducted a systematic review of the available scientific evidence regarding druggene interactions relevant to community pharmacy. We identified the main genes and polymorphisms associated with treatment response and adverse effects in primary care. Finally, we propose a model for implementing pharmacogenetic services in community pharmacies.