Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for UGT1A1 and Atazanavir Prescribing

UGT1A1 polymorphisms and metabolic phenotypes in indigenous peoples from the Brazilian Amazon

OBJECTIVES

To explore the distribution of clinically relevant UGT1A1 polymorphisms and inferred UGT1A1 phenotypes in two Indigenous groups (Paiter-Suruí and Yanomami) from reservation areas in the Brazilian Amazon.

METHODS

Ninety-two Yanomami and 88 Paiter-Suruí were genotyped with a validated panel of ancestry informative markers. Individuals with >90% Native ancestry were genotyped for the promoter TA repeat (rs8175347) polymorphism and UGT1A1*6 (rs4148323) by direct sequencing, and for UGT1A1*80 (rs887829) by TaqMan allele discrimination. The UGT1A1 metabolic phenotypes were inferred from UGT1A1 diplotypes.

RESULTS

All Yanomami and 85 (96.6%) Paiter-Suruí had >92% Native ancestry. UGT1A1 genotype data from these individuals revealed: (i) the absence of both alleles with five and eight TA repeats [TA(5) and TA(8)]; (ii) TA(7) allele frequency of 0.470 in Yanomami and 0.441 in Paiter-Suruí; (iii) rs4148323 was absent in Paiter-Suruí and detected in two Yanomami (frequency 0.012); (iv) a perfect linkage disequilibrium (LD) between rs887829C>T and the promoter repeat polymorphisms in both cohorts: C allele with TA(6) and T allele with TA(7). The distribution of the inferred UGT1A1 metabolizer phenotypes did not differ between cohorts (Paiter-Suruí and Yanomami): the intermediate metabolizer was the most common (50.6-55.4%), followed by the normal (30.6-24.1%) and the slow (18.8-20.5%) phenotypes.

CONCLUSION

This is the first report on the frequency distribution of clinically relevant UGT1A1 variants and inferred UGT1A1 metabolic phenotypes in two major Native populations from indigenous reservation areas in the Brazilian Amazon, namely the Paiter-Suruí and Yanomami. The TA(5) and TA(8) repeats were absent, whereas TA(7) was common (frequency >0.50) in both cohorts. The intronic rs887829 variant ( UGT1A1 * 80 ) single nucleotide variant was found in perfect LD with the promoter TA repeats. The rs4148323 SNP was absent (Paiter-Suruí) or rare (Yanomami). The frequency of high-risk UGT1A1 poor metabolizer phenotype was 1.6- to 2-fold higher in the indigenous cohorts compared to nonindigenous Brazilians.

Pharmacogenetics of plasma dolutegravir exposure during 1-month rifapentine/isoniazid treatment of latent tuberculosis

In Advancing Clinical Therapeutics Globally protocol A5372, a pharmacokinetic study of dolutegravir with 1-month of daily rifapentine/isoniazid, twice-daily dolutegravir offset the induction effects of rifapentine on plasma dolutegravir trough concentrations (C trough ). Here, we characterize the impact on dolutegravir C trough of UGT1A1 , AADAC , and NAT2 polymorphisms that affect dolutegravir, rifapentine, and isoniazid, respectively. People with HIV receiving dolutegravir-based antiretroviral therapy with an indication to treat latent tuberculosis underwent pharmacokinetic sampling during dolutegravir 50 mg once daily alone, and on day 28 of dolutegravir 50 mg twice daily with rifapentine/isoniazid. Multivariable linear regression models characterized genetic associations with dolutegravir C trough . Among 30 participants evaluable for genetic associations, median (Q1, Q3) day 0 dolutegravir C trough was 1745 (1099, 2694) ng/ml, and day 28 was 2146 (1412, 2484) ng/ml. Day 28 C trough was higher with UGT1A1 rs887829 TT [geometric mean ratio (GMR) = 1.65; 90% confidence interval (CI): 0.97-2.78] and CT (GMR = 1.38; 90% CI: 1.02-1.86) than with CC, and was higher with AADAC rs1803155 GG (GMR = 1.79; 90% CI: 1.09-2.93) and AG (GMR = 1.48; 90% CI: 1.14-1.90) than with AA. Median day 28 C trough ranged from 1205 (1063, 1897) ng/ml with 4 total UGT1A1 and AADAC risk alleles, to 3882 and 3717 ng/ml with only one risk allele. Individuals with concomitant AADAC slow metabolizer and UGT1A1 normal metabolizer genotypes may be at greater risk for clinically significant drug-drug interactions between rifapentine/isoniazid and dolutegravir.

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.

Pharmacogenetics of the Treatment of Neglected Diseases

BACKGROUND/OBJECTIVES

Pharmacogenetics (PGx) aims to identify individuals more likely to suffer from adverse reactions or therapeutic failure in drug treatments. However, despite most of the evidence in this area being from European populations, some diseases have also been neglected, such as HIV infection, malaria, and tuberculosis. With this review, we aim to emphasize which pharmacogenetic tests are ready to be implemented in treating neglected diseases that have some evidence and call attention to what is missing for these three diseases.

METHODS

A critical literature review on the PGx of HIV infection, malaria, and tuberculosis was performed.

RESULTS

There are three PGx guidelines for antiretroviral drugs used in HIV infection, one for malaria, and none for tuberculosis. Some evidence is already available, and some genes have already been identified, such as CYP2D6 for primaquine treatment and NAT2 for isoniazid. However, some barriers to the implementation are the lack of evidence due to the few studies on the diseases themselves and the admixture of the most affected populations, which must be considered, given the genetic differentiation of these populations.

CONCLUSIONS

PGx tests such as abacavir are already implemented in some places, and efavirenz/atazanavir is ready to implement if this medication is used. Other gene-drug associations were found but still do not present a clear recommendation. We call attention to the need to generate more evidence for testing treatments for other neglected diseases, such as malaria and tuberculosis, given their epidemiological importance and for the public health of less favored populations.

Drug-drug interactions in HIV-infected patients receiving chemotherapy

INTRODUCTION

Coadministration of antiretrovirals and anti-cancer medications may present many complex clinical scenarios. This is characterized by the potential for drug-drug interactions (DDIs) and the challenges that arise in patient management. In this article, we investigate the potential for DDIs between antiretrovirals, including protease inhibitors (PIs), non-nucleoside reverse transcriptase inhibitors, nucleoside reverse transcriptase inhibitors (NRTIs), integrase strand transfer inhibitors (INSTIs), and anti-cancer medications.

AREAS COVERED

PubMed, Google Scholar, and Clinicaltrials.gov were searched for relevant articles in April 2024. Our review highlights PIs and NNRTIs as particularly prone to DDIs with anticancer agents, with implications for efficacy and toxicity of concomitant cancer therapy. We explain the mechanisms for interactions, emphasizing the significance of pharmacokinetic effects and enzyme induction or inhibition. We discuss clinical challenges encountered in the management of patients receiving combined ART and cancer therapy regimens.

EXPERT OPINION

Data are lacking for potential DDIs between antiretroviral and anti-cancer agents. While some interactions are documented, others are theoretical and based on the pharmacokinetic properties of the medications. Awareness of these interactions, inter-collaborative care between healthcare providers, and standardized treatment guidelines are all crucial for achieving optimal treatment outcomes and ensuring the well-being of patients with HIV/AIDS and cancer comorbidities.

Pharmacogenetic Panel Testing: A Review of Current Practice and Potential for Clinical Implementation

Pharmacogenetics (PGx) aims to optimize drug treatment outcomes by using a patient's genetic profile for individualized drug and dose selection. Currently, reactive and pretherapeutic single-gene PGx tests are increasingly applied in clinical practice in several countries and institutions. With over 95% of the population carrying at least one actionable PGx variant, and with drugs impacted by these genetic variants being in common use, pretherapeutic or preemptive PGx panel testing appears to be an attractive option for better-informed drug prescribing. Here, we discuss the current state of PGx panel testing and explore the potential for clinical implementation. We conclude that available evidence supports the implementation of pretherapeutic PGx panel testing for drugs covered in the PGx guidelines, yet identification of specific patient populations that benefit most and cost-effectiveness data are necessary to support large-scale implementation.

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.

Inhibition of OATP1B1/3 Rather Than UGT1A1 May Be the Major Cause of the Bilirubin Elevation After Atazanavir Administration

Atazanavir has been reported to increase total serum bilirubin level up to ninefold. It is widely believed that the observed total bilirubin elevation is primarily due to UGT1A1 inhibition. However, UGT enzymes are well-known as a low-affinity and high-capacity system, and the observed drug-drug interaction mediated by UGTs is usually less than twofold. There were discrepancies in the explanation of total bilirubin elevation due to UGT1A1 inhibition alone, suggesting the contribution of other mechanism(s) to the interaction. As atazanavir is a potent OATP1B1/3 inhibitor and the hepatic uptake of both unconjugated and conjugated bilirubin are mediated by OATP1B1/3, these transporters could be involved in the bilirubin-atazanavir interaction. To better understand the roles of UGT1A1 and OATP1B1/3 in this interaction, it would be useful to characterize the contribution of each individual pathway to the interaction. As multiple compounds, pathways, and potentially UGT1A1 polymorphism are involved, a thorough physiologically-based pharmacokinetic (PBPK) analysis was utilized to integrate the information from various relevant in vitro and clinical studies to quantitatively estimate the contribution of UGT1A1 and OATP1B1/3 inhibition to the interaction between bilirubin and atazanavir. The PBPK analysis indicated that UGT1A1 inhibition plays a modest role in bilirubin and atazanavir interaction contributing less than 33%. The results also suggested that unconjugated bilirubin is less sensitive than raltegravir upon UGT1A1 inhibition, therefore, unconjugated bilirubin may not be a useful endogenous biomarker for UGT1A1 inhibition. The analysis demonstrated that the metabolism of unconjugated bilirubin shares common features of other UGT enzyme-mediated reactions.

Allele frequency of genetic variations related to the UGT1A1 gene-drug pair in a group of Iranian population

Objectives

The efficacy and safety of drug treatments vary widely due to genetic variations. Pharmacogenomics investigates the impact of genetic variations on patient drug response. This research investigates the frequency of UGT1A1 genetic variations in the Iranian population, comparing them with global data to provide insights into the pharmacogenomic approach in the Iranian population.

Methods

The study was conducted using the data of the Bushehr Elderly Health (BEH) program, a population-based cohort study of the elderly population aged ≥ 60 years. Genotyping of three UGT1A1 variant alleles (UGT1A1*6, UGT1A1*27, and UGT1A1*80) was performed on a group of 2730 elderly Iranian participants with the Infinium Global Screening Array.

Results

The genotyping analysis revealed significant differences compared to major global populations that were addressed in the gnomAD database. UGT1A1*80 was found at a high frequency (32.34%), and followed by UGT1A1*6 (0.76%) and UGT1A1*27 (0.018) at a low frequency in the Iranian group.

Conclusions

The UGT1A1*80 was the more prevalent allele between investigated alleles in the present study which can be considered as an important allele for pharmacogenomic testing.

Population-scale variability of the human UDP-glycosyltransferase gene family

Human UDP-glycosyltransferases (UGTs) are responsible for the glycosylation of a wide variety of endogenous substrates and commonly prescribed drugs. Different genetic polymorphisms in UGT genes are implicated in interindividual differences in drug response and cancer risk. However, the genetic complexity beyond these variants has not been comprehensively assessed. We here leveraged whole-exome and whole-genome sequencing data from 141,456 unrelated individuals across 7 major human populations to provide a comprehensive profile of genetic variability across the human UGT gene family. Overall, 9666 exonic variants were observed, of which 98.9% were rare. To interpret the functional impact of UGT missense variants, we developed a gene family-specific variant effect predictor. This algorithm identified a total of 1208 deleterious variants, most of which were found in African and South Asian populations. Structural analysis corroborated the predicted effects for multiple variations in substrate binding sites. Combined, our analyses provide a systematic overview of UGT variability, which can yield insights into interindividual differences in phase 2 metabolism and facilitate the translation of sequencing data into personalized predictions of UGT substrate disposition.

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.

High Burden of Ileus and Pneumonia in Clozapine-Treated Individuals With Schizophrenia: A Finnish 25-Year Follow-Up Register Study

OBJECTIVE

The authors used longitudinal biobank data with up to 25 years of follow-up on over 2,600 clozapine users to derive reliable estimates of the real-world burden of clozapine adverse drug events (ADEs).

METHODS

A total of 2,659 participants in the FinnGen biobank project had a schizophrenia diagnosis and clozapine purchases with longitudinal electronic health record follow-up for up to 25 years after clozapine initiation. Diseases and health-related events enriched during clozapine use were identified, adjusting for disease severity. The incidence and recurrence of ADEs over years of clozapine use, their effect on clozapine discontinuation and deaths, and their pharmacogenetics were studied.

RESULTS

Median follow-up time after clozapine initiation was 12.7 years. Across 2,157 diseases and health-related events, 27 were enriched during clozapine use, falling into five disease categories: gastrointestinal hypomotility, seizures, pneumonia, other acute respiratory tract infections, and tachycardia, along with a heterogeneous group including neutropenia and type 2 diabetes, among others. Cumulative incidence estimates for ileus (severe gastrointestinal hypomotility) and pneumonia were 5.3% and 29.5%, respectively, 20 years after clozapine initiation. Both events were significantly associated with increased mortality among clozapine users (ileus: odds ratio=4.5; pneumonia: odds ratio=2.8). Decreased genotype-predicted CYP2C19 and CYP1A2 activities were associated with higher pneumonia risk.

CONCLUSIONS

Clozapine-induced ileus and pneumonia were notably more frequent than has previously been reported and were associated with increased mortality. Two CYP genes influenced pneumonia risk. Pneumonia and ileus call for improved utilization of available preventive measures.

Survival predictors in patients with pancreatic cancer on liposomal irinotecan plus fluorouracil/leucovorin: a multicenter observational study

Background

Approximately half of the patients with advanced pancreatic ductal adenocarcinoma (PDAC) receive subsequent lines of chemotherapy. Recently, the liposomal irinotecan (nal-IRI) plus 5-fluorouracil/leucovorin (5-FU/LV) regimen is recommended as subsequent lines of chemotherapy. However, little is known about the predictive factors for the nal-IRI + 5-FU/LV regimen, especially in patients with previous irinotecan (IRI) exposure.

Objectives

We investigated the predictive factors associated with nal-IRI + 5-FU/LV treatment in patients with PDAC.

Design

Multicenter, retrospective cohort study.

Methods

This study included patients with advanced PDAC who received the nal-IRI + 5-FU/LV regimen for palliative purposes.

Results

Overall, 268 patients were treated with nal-IRI + 5-FU/LV. The median overall survival (OS) was 7.9 months (95% confidence interval (CI): 7.0-8.8), while the median progression-free survival (PFS) was 2.6 months (95% CI: 1.9-3.2). An albumin level of<4.0 g/dL, neutrophil-to-lymphocyte ratio (NLR) of ⩾3.5, liver or peritoneal metastasis, and a history of >3 lines of palliative chemotherapy were associated with worse OS. An NLR of ⩾3.5 and liver metastasis were significant predictive factors for worse PFS. Previous exposure to IRI was not a significant predictor. Patients without prior IRI (no-IRI) treatment showed relatively longer OS and PFS compared to IRI responders and nonresponders, but these differences were not significant when compared specifically to the responders (OS: 8.8 vs 8.1 months, p = 0.388; PFS: 3.6 vs 2.6 months, p = 0.126).

Conclusion

An NLR of ⩾3.5 and liver metastasis were associated with worse PFS. Prior IRI exposure was not a significant predictive factor for OS and PFS, especially in IRI responders.

An Investigational Study on the Role of CYP2D6, CYP3A4 and UGTs Genetic Variation on Fesoterodine Pharmacokinetics in Young Healthy Volunteers

Introduction: Fesoterodine is one of the most widely used antimuscarinic drugs to treat an overactive bladder. Fesoterodine is extensively hydrolyzed by esterases to 5-hydroxymethyl tolterodine (5-HMT), the major active metabolite. CYP2D6 and CYP3A4 mainly metabolize 5-HMT and are, therefore, the primary pharmacogenetic candidate biomarkers. Materials and Methods: This is a candidate gene study designed to investigate the effects of 120 polymorphisms in 33 genes (including the CYP, COMT, UGT, NAT2, and CES enzymes, ABC and SLC transporters, and 5-HT receptors) on fesoterodine pharmacokinetics and their safety in 39 healthy volunteers from three bioequivalence trials. Results: An association between 5-HMT exposure (dose/weight corrected area under the curve (AUC/DW) and dose/weight corrected maximum plasma concentration (Cmax/DW)), elimination (terminal half-life (T1/2) and the total drug clearance adjusted for bioavailability (Cl/F)), and CYP2D6 activity was observed. Poor/intermediate metabolizers (PMs/IMs) had higher 5-HMT AUC/DW (1.5-fold) and Cmax/DW (1.4-fold) values than the normal metabolizers (NMs); in addition, the normal metabolizers (NMs) had higher 5-HMT AUC/DW (1.7-fold) and Cmax/DW (1.3-fold) values than the ultrarapid metabolizers (UMs). Lower 5-HMT exposure and higher T1/2 were observed for the CYP3A4 IMs compared to the NMs, contrary to our expectations. Conclusions: CYP2D6 might have a more important role than CYP3A4 in fesoterodine pharmacokinetics, and its phenotype might be a better predictor of variation in its pharmacokinetics. An association was observed between different genetic variants of different genes of the UGT family and AUC, Cmax, and CL/F of 5-HMT, which should be confirmed in other studies.

Patterns of pharmacogenetic variation in nine biogeographic groups

Frequencies of pharmacogenetic (PGx) variants are known to differ substantially across populations but much of the available PGx literature focuses on one or a few population groups, often defined in nonstandardized ways, or on a specific gene or variant. Guidelines produced by the Clinical Pharmacogenetic Implementation Consortium (CPIC) provide consistent methods of literature extraction, curation, and reporting, including comprehensive curation of allele frequency data across nine defined "biogeographic groups" from the PGx literature. We extracted data from 23 CPIC guidelines encompassing 19 genes to compare the sizes of the populations from each group and allele frequencies of altered function alleles across groups. The European group was the largest in the curated literature for 16 of the 19 genes, while the American and Oceanian groups were the smallest. Nearly 200 alleles were detected in nonreference groups that were not reported in the largest (reference) group. The genes CYP2B6 and CYP2C9 were more likely to have higher frequencies of altered function alleles in nonreference groups compared to the reference group, while the genes CYP4F2, DPYD, SLCO1B1, and UGT1A1 were less likely to have higher frequencies in nonreference groups. PGx allele frequencies and function differ substantially across nine biogeographic groups, all but two of which are underrepresented in available PGx data. Awareness of these differences and increased efforts to characterize the breadth of global PGx variation are needed to ensure that implementation of PGx-guided drug selection does not further widen existing health disparities among populations currently underrepresented in PGx data.

Insights into pharmacogenetics, drug-gene interactions, and drug-drug-gene interactions

This review explores genetic contributors to drug interactions, known as drug-gene and drug-drug-gene interactions (DGI and DDGI, respectively). This article is part of a mini-review issue led by the International Society for the Study of Xenobiotics (ISSX) New Investigators Group. Pharmacogenetics (PGx) is the study of the impact of genetic variation on pharmacokinetics (PK), pharmacodynamics (PD), and adverse drug reactions. Genetic variation in pharmacogenes, including drug metabolizing enzymes and drug transporters, is common and can increase the risk of adverse drug events or contribute to reduced efficacy. In this review, we summarize clinically actionable genetic variants, and touch on methodologies such as genotyping patient DNA to identify genetic variation in targeted genes, and deep mutational scanning as a high-throughput in vitro approach to study the impact of genetic variation on protein function and/or expression in vitro. We highlight the utility of physiologically based pharmacokinetic (PBPK) models to integrate genetic and chemical inhibitor and inducer data for more accurate human PK simulations. Additionally, we analyze the limitations of historical ethnic descriptors in pharmacogenomics research. Altogether, the work herein underscores the importance of identifying and understanding complex DGI and DDGIs with the intention to provide better treatment outcomes for patients. We also highlight current barriers to wide-scale implementation of PGx-guided dosing as standard or care in clinical settings.

Genetic Variation in CYP2D6, UGT1A4, SLC6A2 and SLCO1B1 Alters the Pharmacokinetics and Safety of Mirabegron

Mirabegron is a drug used in overactive bladder (OAB) treatment. Genetic variation in pharmacogenes might alter its pharmacokinetics, affecting its efficacy and safety. This research aimed to analyze the impact of genetic variation on mirabegron pharmacokinetics and safety. Volunteers from three bioequivalence trials (n = 79), treated with a single or a multiple dose of mirabegron 50 mg under fed or fasting conditions, were genotyped for 115 variants in pharmacogenes and their phenotypes were inferred. A statistical analysis was performed, searching for associations between genetics, pharmacokinetics and safety. CYP2D6 intermediate metabolizers showed a higher elimination half-life (t1/2) (univariate p-value (puv) = 0.018) and incidence of adverse reactions (ADRs) (puv = 0.008, multivariate p (pmv) = 0.010) than normal plus ultrarapid metabolizers. The UGT1A4 rs2011425 T/G genotype showed a higher t1/2 than the T/T genotype (puv = 0.002, pmv = 0.003). A lower dose/weight corrected area under the curve (AUC/DW) and higher clearance (CL/F) were observed in the SLC6A2 rs12708954 C/C genotype compared to the C/A genotype (puv = 0.015 and 0.016) and ADR incidence was higher when the SLCO1B1 function was decreased (puv = 0.007, pmv = 0.010). The lower elimination and higher ADR incidence when CYP2D6 activity is reduced suggest it might be a useful biomarker in mirabegron treatment. UGT1A4, SLC6A2 and SLCO1B1 might also be involved in mirabegron pharmacokinetics.

Frequency of pharmacogenomic variation and medication exposures among All of Us Participants

Pharmacogenomics promises improved outcomes through individualized prescribing. However, the lack of diversity in studies impedes clinical translation and equitable application of precision medicine. We evaluated the frequencies of PGx variants, predicted phenotypes, and medication exposures using whole genome sequencing and EHR data from nearly 100k diverse All of Us Research Program participants. We report 100% of participants carried at least one pharmacogenomics variant and nearly all (99.13%) had a predicted phenotype with prescribing recommendations. Clinical impact was high with over 20% having both an actionable phenotype and a prior exposure to an impacted medication with pharmacogenomic prescribing guidance. Importantly, we also report hundreds of alleles and predicted phenotypes that deviate from known frequencies and/or were previously unreported, including within admixed American and African ancestry groups.

Genetic determinants of serum bilirubin using inferred native American gene variants in Chilean adolescents

Gene variants in the UGT1A1 gene are strongly associated with circulating bilirubin levels in several populations, as well as other variants of modest effect across the genome. However, the effects of such variants are unknown regarding the Native American ancestry of the admixed Latino population. Our objective was to assess the Native American genetic determinants of serum bilirubin in Chilean admixed adolescents using the local ancestry deconvolution approach. We measured total serum bilirubin levels in 707 adolescents of the Chilean Growth and Obesity Cohort Study (GOCS) and performed high-density genotyping using the Illumina-MEGA array (>1.7 million genotypes). We constructed a local ancestry reference panel with participants from the 1000 Genomes Project, the Human Genome Diversity Project, and our GOCS cohort. Then, we inferred and isolated haplotype tracts of Native American, European, or African origin to perform genome-wide association studies. In the whole cohort, the rs887829 variant and others near UGT1A1 were the unique signals achieving genome-wide statistical significance (b = 0.30; p = 3.34 × 10-57). After applying deconvolution methods, we found that significance is also maintained in Native American (b = 0.35; p = 3.29 × 10-17) and European (b = 0.28; p = 1.14 × 10-23) ancestry components. The rs887829 variant explained a higher percentage of the variance of bilirubin in the Native American (37.6%) compared to European ancestry (28.4%). In Native American ancestry, carriers of the TT genotype of this variant averaged 4-fold higher bilirubinemia compared to the CC genotype (p = 2.82 × 10-12). We showed for the first time that UGT1A1 variants are the primary determinant of bilirubin levels in Native American ancestry, confirming its pan-ethnic relevance. Our study illustrates the general value of the local ancestry deconvolution approach to assessing isolated ancestry effects in admixed populations.

Genetic variation in UGT1A1 is not associated with altered liver biochemical parameters in healthy volunteers participating in bioequivalence trials

Introduction: Bioequivalence clinical trials are conducted in healthy volunteers whose blood tests should be within normal limits; individuals with Gilbert syndrome (GS) are excluded from these studies on suspicion of any liver disease, even if the change is clinically insignificant. GS is a benign genetic disorder characterized by elevated bilirubin levels, the primary cause of which is the presence of polymorphisms in UGT1A1 gene. In this work, subjects with UGT1A1 intermediate (IM) or poor (PM) metabolizer genotype-informed phenotypes were investigated to determine whether they have a higher incidence of liver disease or other biochemical parameters. Methods: The study population comprised 773 healthy volunteers who underwent biochemical analysis at baseline and at the end of the study which were genotyped for UGT1A1*80 (rs887829), as an indicator of UGT1A1*80+*28 (rs887829 and rs3064744), and UGT1A1*6 (rs4148323). Results: Bilirubin levels were higher in subjects IMs and PMs compared to normal metabolizers (NMs). Decreased uric acid levels was observed in PMs compared to NMs. No associations were observed in liver enzyme levels according to UGT1A1 phenotype. Discussion: Considering that there is no hepatic toxicity in subjects with UGT1A1 IM or PM phenotype, who are more likely to develop GS, this study suggests that they could be included in bioequivalence clinical trials as their biochemical parameters are not affected outside normal ranges.

Identification of ADME genes polymorphic variants linked to trastuzumab-induced cardiotoxicity in breast cancer patients: Case series of mono-institutional experience

BACKGROUND

Long-term survival induced by anticancer treatments discloses emerging frailty among breast cancer (BC) survivors. Trastuzumab-induced cardiotoxicity (TIC) is reported in at least 5% of HER2+BC patients. However, TIC mechanism remains unclear and predictive genetic biomarkers are still lacking. Interaction between systemic inflammation, cytokine release and ADME genes in cancer patients might contribute to explain mechanisms underlying individual susceptibility to TIC and drug response variability. We present a single institution case series to investigate the potential role of genetic variants in ADME genes in HER2+BC patients TIC experienced.

METHODS

We selected data related to 40 HER2+ BC patients undergone to DMET genotyping of ADME constitutive variant profiling, with the aim to prospectively explore their potential role in developing TIC. Only 3 patients ("case series"), who experienced TIC, were compared to 37 "control group" matched patients cardiotoxicity-sparing. All patients underwent to left ventricular ejection fraction (LVEF) evaluation at diagnosis and during anti-HER2 therapy. Each single probe was clustered to detect SNPs related to cardiotoxicity.

RESULTS

In this retrospective analysis, our 3 cases were homogeneous in terms of clinical-pathological characteristics, trastuzumab-based treatment and LVEF decline. We identified 9 polymorphic variants in 8 ADME genes (UGT1A1, UGT1A6, UGT1A7, UGT2B15, SLC22A1, CYP3A5, ABCC4, CYP2D6) potentially associated with TIC.

CONCLUSION

Real-world TIC incidence is higher compared to randomized clinical trials and biomarkers with potential predictive value aren't available. Our preliminary data, as proof of concept, could suggest a predictive role of pharmacogenomic approach in the identification of cardiotoxicity risk biomarkers for anti-HER2 treatment.

Genetic evaluation in indeterminate acute liver failure: A post hoc analysis

BACKGROUND AND STUDY AIMS

There are limited data regarding indeterminate acute liver failure (ALF). The study aims to perform a post hoc analysis using genetic methods for the ALF cases with indeterminate etiology.

PATIENTS AND METHODS

Stored blood samples from these patients with indeterminate ALF were collected. Whole-exome sequencing (WES) was used to evaluate the pathogenesis of indeterminate ALF.

RESULTS

A total of 16 samples from 11 adult patients and 5 pediatric patients with indeterminate ALF were available. Among the adult patients, one female patient was identified with two heterozygous variants (c.2333G > T (p.Arg778Leu) and c.2310C > G (p.Leu770 = )) in the adenosine triphosphatase copper-transporting beta (ATP7B) gene, and two male patients were found to harbor heterozygous and homozygous variants (c.686C > A (p.Pro229Gln) plus homozygousvariantA(TA)6TAAinsTA (-), andc.1456 T > G (p.Tyr486Asp) plus c.211G > A (p.Gly71Arg)) in the uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene. For the pediatric patients, single heterozygous variant (c.2890C > T (p.Arg964Cys)) in the polymerase gamma (POLG) gene was found in 1 male child, and two heterozygous variants (c.1909A > G (p.Lys637Glu) and c.3646G > A (p.Val1216Ile)) in the tetratricopeptide repeat domain 37 (TTC37) gene were found in 1 female child. No variants clinically associated with known liver diseases were revealed in the remaining patients.

CONCLUSION

These results expand the knowledge of ALF with indeterminate etiology. WES is helpful to reveal possible candidate genes for indeterminate ALF, but incomplete consistency between the genotype and phenotype in some cases still challenge the accurate diagnosis.

Pharmacokinetics and pharmacodynamics of antibody-drug conjugates for the treatment of patients with breast cancer

INTRODUCTION

Currently three antibody-drug-conjugates (ADC) are approved by the European Medicines Agency (EMA) for treatment of breast cancer (BC) patient: trastuzumab-emtansine, trastuzumab-deruxtecan and sacituzumab-govitecan. ADC are composed of a monoclonal antibody (mAb) targeting a specific antigen, a cytotoxic payload and a linker. Pharmacokinetics (PK) and pharmacodynamics (PD) distinguish ADC from conventional chemotherapy and must be understood by clinicians.

AREAS COVERED

Our review delineates the PK/PD profiles of ADC approved for the treatment of BC with insight for future development. This is an expert opinion literature review based on the EMA's Assessment Reports, enriched by a comprehensive literature search performed on Medline in August 2023.

EXPERT OPINION

All three ADC distributions are described by a two-compartment structure: tissue and serum. Payload concentration peak is immediate but remains at low concentration. The distribution varied for all ADC only with body weight. mAb will be metabolised firstly by the saturable complex formation of ADC/Tumour-Receptor and secondly by binding of FcgRs in immune cells. They are all excreted in the bile and faeces with minimal urine elimination. Dose adjustments, apart from weight, are not recommended. Novel ADC are composed of cleavable linkers with various targets/payloads with the same PK/PD properties, but novel structures of ADC are in development.

Pharmacogenomics and adverse effects of anti-infective drugs in children

Children, as a special group, have their own peculiarities in terms of individualized medication use compared to adults. Adverse drug reactions have been an important issue that needs to be addressed in the hope of safe medication use in children, and the occurrence of adverse drug reactions is partly due to genetic factors. Anti-infective drugs are widely used in children, and they have always been an important cause of the occurrence of adverse reactions in children. Pharmacogenomic technologies are becoming increasingly sophisticated, and there are now many guidelines describing the pharmacogenomics of anti-infective drugs. However, data from paediatric-based studies are scarce. This review provides a systematic review of the pharmacogenomics of anti-infective drugs recommended for gene-guided use in CPIC guidelines by exploring the relationship between pharmacogenetic frequencies and the incidence of adverse reactions, which will help inform future studies of individualized medication use in children.

Dolutegravir pharmacokinetics in Ugandan patients with TB and HIV receiving standard- versus high-dose rifampicin

Higher rifampicin doses may improve tuberculosis treatment outcomes. This could however exacerbate the existing drug interaction with dolutegravir. Moreover, the metabolism of dolutegravir may also be affected by polymorphism of UGT1A1, a gene that codes for uridine diphosphate glucuronosyltransferase. We used population pharmacokinetic modeling to compare the pharmacokinetics of dolutegravir when coadministered with standard- versus high-dose rifampicin in adults with tuberculosis and HIV, and investigated the effect of genetic polymorphisms. Data from the SAEFRIF trial, where participants were randomized to receive first-line tuberculosis treatment with either standard- 10 mg/kg or high-dose 35 mg/kg rifampicin alongside antiretroviral therapy, were used. The dolutegravir model was developed with 211 plasma concentrations from 44 participants. The median (interquartile range) rifampicin area under the curve (AUC) in the standard- and high-dose arms were 32.3 (28.7-36.7) and 153 (138-175) mg·h/L, respectively. A one-compartment model with first-order elimination and absorption through transit compartments best described dolutegravir pharmacokinetics. For a typical 56 kg participant, we estimated a clearance, absorption rate constant, and volume of distribution of 1.87 L/h, 1.42 h-1, and 12.4 L, respectively. Each 10 mg·h/L increase in the AUC of coadministered rifampicin from 32.3 mg·h/L led to a 2.3 (3.1-1.4) % decrease in dolutegravir bioavailability. Genetic polymorphism of UGT1A1 did not significantly affect dolutegravir pharmacokinetics. Simulations of trough dolutegravir concentrations show that the 50 mg twice-daily regimen attains both the primary and secondary therapeutic targets of 0.064 and 0.3 mg/L, respectively, regardless of the dose of coadministered rifampicin, unlike the once-daily regimen.

Food Administration and Not Genetic Variants Causes Pharmacokinetic Variability of Tadalafil and Finasteride

Tadalafil and finasteride are used in combination for the management of benign prostatic hyperplasia (BPH). Genetic variations in genes involved in the metabolism and transport of tadalafil or finasteride (i.e., pharmacogenes) could affect their pharmacokinetic processes altering their drug exposure, efficacy, and toxicity. The main objective of this study was to investigate the effects of variants in pharmacogenes on the pharmacokinetics of tadalafil and finasteride. An exploratory candidate gene study involving 120 variants in 33 genes was performed with 66 male healthy volunteers from two bioequivalence clinical trials after administration of tadalafil/finasteride 5 mg/5 mg under fed or fasting conditions. Afterwards, a confirmatory study was conducted with 189 male and female volunteers receiving tadalafil 20 mg formulations in seven additional bioequivalence clinical trials. Regarding tadalafil, fed volunteers showed higher area in the time-concentration curve (AUC∞), maximum plasma concentration (Cmax), and time to reach Cmax (tmax) compared to fasting volunteers; male volunteers also showed higher AUC∞ and Cmax compared to female volunteers. Furthermore, fed volunteers presented higher finasteride AUC∞, Cmax and tmax compared to fasting individuals. Variants in ABCC3, CYP1A2, CES1, NUDT15, SLC22A1/A2 and UGT2B10 were nominally associated with pharmacokinetic variation in tadalafil and/or finasteride but did not remain significant after correction for multiple comparisons. Genetic variation did not demonstrate to clinically impact on the pharmacokinetics of finasteride and tadalafil; however, additional studies with larger sample sizes are needed to assess the effect of rare variants, such as CYP3A4*20 or *22, on tadalafil and finasteride pharmacokinetics.

Impact of Sex and Genetic Variation in Relevant Pharmacogenes on the Pharmacokinetics and Safety of Valsartan, Olmesartan and Hydrochlorothiazide

Drug combination therapy is the most common pharmacological strategy for hypertension management. No pharmacogenetic biomarkers for guiding hypertension pharmacotherapy are available to date. The study population were 64 volunteers from seven bioequivalence trials investigating formulations with valsartan, olmesartan and/or hydrochlorothiazide. Every volunteer was genotyped for 10 genetic variants in different transporters' genes. Additionally, valsartan-treated volunteers were genotyped for 29 genetic variants in genes encoding for different metabolizing enzymes. Variability in pharmacokinetic parameters such as maximum concentration (Cmax) and time to reach it (tmax), the incidence of adverse drug reactions (ADRs) and blood pressure measurements were analyzed as a function of pharmacogenetic and demographic parameters. Individuals with the ABCB1 rs1045642 T/T genotype were associated with a higher valsartan tmax compared to those with T/G and G/G genotypes (p < 0.001, β = 0.821, R2 = 0.459) and with a tendency toward a higher postural dizziness incidence (11.8% vs. 0%, p = 0.070). A higher hydrochlorothiazide dose/weight (DW)-corrected area under the curve (AUC∞/DW) was observed in SLC22A1 rs34059508 G/A volunteers compared to G/G volunteers (p = 0.050, β = 1047.35, R2 = 0.051), and a tendency toward a higher postural dizziness incidence (50% vs. 1.6%, p = 0.063). Sex impacted valsartan and hydrochlorothiazide pharmacokinetics, showing a lower exposure in women, whereas no significant differences were found for olmesartan pharmacokinetics.

Design, Implementation, and Assessment Approaches Within an Advanced Human Immunodeficiency Virus (HIV) Elective Course

Introduction: An estimated 38 million people are living with human immunodeficiency virus (HIV) worldwide. Pharmacists are well positioned to provide care to patients with HIV, but gaps in HIV education among pharmacists exist. Recognizing the need to educate and prepare future pharmacists, a 2-credit advanced HIV elective course was created for Doctor of Pharmacy students at Washington State University College of Pharmacy and Pharmaceutical Sciences in the United States, and Masters of Clinical Pharmacy students from University of Western Cape School of Pharmacy in South Africa. Methods: Course topics included diagnosis and treatment of HIV in children and adults, management of common comorbidities, pre-exposure prophylaxis, pharmacogenetic applications, and antiretroviral drug-drug interactions. Course effectiveness was evaluated using student examination results. Student perceptions were evaluated using pre- and post-course self-assessments involving abilities, confidence, and attitudes toward caring for people living with HIV. Results: Student pharmacists demonstrated competency in HIV knowledge, demonstrated skills in application to clinical-based scenarios, and reported significantly improved confidence and abilities as well as positive changes in attitudes toward people with HIV. Conclusion: This course contributed to student learning across different student cohorts in an institutional program in the United States including successful execution of distance learning and clinical application for students at a program in South Africa.

Implementation of Pharmacogenetics in First-Line Care: Evaluation of Its Use by General Practitioners

Pharmacogenetics (PGx) can explain/predict drug therapy outcomes. There is, however, unclarity about the use and usefulness of PGx in primary care. In this study, we investigated PGx tests ordered by general practitioners (GPs) in 2021 at Dept. Clinical Chemistry, Erasmus MC, and analyzed the gene tests ordered, drugs/drug groups, reasons for testing and single-gene versus panel testing. Additionally, a survey was sent to 90 GPs asking about their experiences and barriers to implementing PGx. In total, 1206 patients and 6300 PGx tests were requested by GPs. CYP2C19 was requested most frequently (17%), and clopidogrel was the most commonly indicated drug (23%). Regarding drug groups, antidepressants (51%) were the main driver for requesting PGx, followed by antihypertensives (26%). Side effects (79%) and non-response (27%) were the main indicators. Panel testing was preferred over single-gene testing. The survey revealed knowledge on when and how to use PGx as one of the main barriers. In conclusion, PGx is currently used by GPs in clinical practice in the Netherlands. Side effects are the main reason for testing, which mostly involves antidepressants. Lack of knowledge is indicated as a major barrier, indicating the need for more education on PGx for GPs.

NAT2 phenotype alters pharmacokinetics of rivaroxaban in healthy volunteers

Rivaroxaban is a direct inhibitor of factor Xa, a member of direct oral anticoagulant group of drugs (DOACs). Despite being a widely extended alternative to vitamin K antagonists (i.e., acenocoumarol, warfarin) the interindividual variability of DOACs is significant, and may be related to adverse drug reaction occurrence or drug inefficacy, namely hemorrhagic or thromboembolic events. Since there is not a consistent analytic practice to monitor the anticoagulant activity of DOACs, previously reported polymorphisms in genes coding for proteins responsible for the activation, transport, or metabolism of DOACs were studied. The study population comprised 60 healthy volunteers, who completed two randomized, crossover bioequivalence clinical trials between two different rivaroxaban formulations. The effect of food, sex, biogeographical origin and 55 variants (8 phenotypes and 47 single nucleotide polymorphisms) in drug metabolizing enzyme genes (such as CYP2D6, CYP2C9, NAT2) and transporters (namely, ABCB1, ABCG2) on rivaroxaban pharmacokinetics was tested. Individuals dosed under fasting conditions presented lower tmax (2.21 h vs 2.88 h, β = 1.19, R2 =0.342, p = 0.012) compared to fed volunteers. NAT2 slow acetylators presented higher AUC∞ corrected by dose/weight (AUC∞/DW; 8243.90 vs 7698.20 and 7161.25 h*ng*mg /ml*kg, β = 0.154, R2 =0.250, p = 0.044), higher Cmax/DW (1070.99 vs 834.81 and 803.36 ng*mg /ml*kg, β = 0.245, R2 =0.320, p = 0.002), and lower tmax (2.63 vs 3.19 and 4.15 h, β = -0.346, R2 =0.282, p = 0.047) than NAT2 rapid and intermediate acetylators. No other association was statistically significant. Thus, slow NAT2 appear to have altered rivaroxaban pharmacokinetics, increasing AUC∞ and Cmax. Nonetheless, further research should be conducted to verify NAT2 involvement on rivaroxaban pharmacokinetics and to determine its clinical significance.

Population Pharmacogenomics in Croatia: Evaluating the PGx Allele Frequency and the Impact of Treatment Efficiency

BACKGROUND

Adverse drug reactions (ADRs) are a significant cause of mortality, and pharmacogenomics (PGx) offers the potential to optimize therapeutic efficacy while minimizing ADRs. However, there is a lack of data on the Croatian population, highlighting the need for investigating the most common alleles, genotypes, and phenotypes to establish national guidelines for drug use.

METHODS

A single-center retrospective cross-sectional study was performed to examine the allele, genotype, and phenotype frequencies of drug-metabolizing enzymes, receptors, and other proteins in a random sample of 522 patients from Croatia using a 28-gene PGx panel.

RESULTS

Allele frequencies, genotypes, and phenotypes for the investigated genes were determined. No statistically significant differences were found between the Croatian and European populations for most analyzed genes. The most common genotypes observed in the patients resulted in normal metabolism rates. However, some genes showed higher frequencies of altered metabolism rates.

CONCLUSIONS

This study provides insights into the allele, genotype, and phenotype frequencies of drug-metabolizing enzymes, receptors, and other associated proteins in the Croatian population. The findings contribute to optimizing drug use guidelines, potentially reducing ADRs, and improving therapeutic efficacy. Further research is needed to tailor population-specific interventions based on these findings and their long-term benefits.

SNP rs11185644 in RXRA gene and SNP rs2235544 in DIO1 gene predict dosage requirements in a cross-sectional sample of hypothyroid patients

BACKGROUND AND PURPOSE

Primary hypothyroidism due to abnormality in the thyroid gland is the most common endocrine disease The recommended starting dose of levothyroxine replacement therapy is 1.6 µg/kg. This dose however is not optimal for every patient and dose adjustments are frequently done. Genetic polymorphisms in the absorption and metabolism pathway of levothyroxine are likely to influence its dose requirements. This study aimed to study the influence of genetic polymorphisms on levothyroxine replacement requirements.

METHODS

This was a cross-sectional study. Participants were recruited through a private nutrition clinic and through announcements distributed in the University of Petra in Amman, Jordan between September 2020 and February 2021. Hypothyroid patients had already been on stable doses of levothyroxine for the previous 3 months. A questionnaire was distributed to collect demographic and clinical information and a blood sample was taken for DNA extraction and clinical biochemistry analysis. rs11249460, rs2235544, rs225014, rs225015, rs3806596, rs11185644, rs4588, rs602662 were analyzed using Applied Biosystems TaqMan™ SNP Genotyping Assays on Rotor-Gene® Q and rs3064744 by direct sequencing. SPSS and Excel were used to perform analysis.

RESULTS

76 patients were studied. The equation we calculated to find predicted daily dose of levothyroxine (mcg/kg) is 3.22+ (0.348 for CT genotype of rs11185644, 0 for other genotypes) + 0.027*disease duration (years) - 0.014*age (years) - 0.434*T3 (pmol/L) levels+ (0.296 for CC genotype of rs2235544, 0 for other genotypes).

CONCLUSION

SNP rs11185644 in RXRA gene and SNP rs2235544 in DIO1 affect dose requirement in hypothyroid patients and if confirmed in larger trials they can be used to individualize thyroxine starting doses.

Pharmacogenomic panel testing provides insight and enhances medication management in people with HIV

OBJECTIVE

Our study aimed to assess the impact of pharmacogenomic panel testing in people with HIV (PWH).

DESIGN

Prospective, observational intervention assessment.

METHODS

One hundred PWH were provided a comprehensive pharmacogenomic panel during routine care visits within the HIV specialty clinic of a large academic medical center. The panel determined the presence of specific genetic variants that could predict response or toxicity to commonly prescribed antiretroviral therapy (ART) and non-ART medications. An HIV specialty pharmacist reviewed the results with participants and the care team. The pharmacist (1) recommended clinically actionable interventions based on the participants' current drug therapy, (2) assessed for genetic explanations for prior medication failures, adverse effects, or intolerances, and (3) advised on potential future clinically actionable care interventions based on individual genetic phenotypes.

RESULTS

Ninety-six participants (median age 53 years, 74% white, 84% men, 89% viral load <50 copies/ml) completed panel testing, yielding 682 clinically relevant pharmacogenomic results (133 major, 549 mild-moderate). Ninety participants (89 on ART) completed follow-up visits with 65 (72%) receiving clinical recommendations based on current medication profiles. Of the 105 clinical recommendations, 70% advised additional monitoring for efficacy or toxicity, and 10% advised alteration of drug therapy. Panel results offered explanation for prior ART inefficacy in one participant and ART intolerance in 29%. Genetic explanation for non-ART toxicity was seen in 21% of participants, with genetic contributors to inefficacy of non-ART therapy identified in 39% of participants.

CONCLUSION

Preliminary data in a small cohort of PWH demonstrates benefit of routine pharmacogenomic panel testing.

Interethnic differences in drug response: projected impact of genetic variations in the Saudi population

Ethnicity is known to have an impact on drug responses. This is particularly important for drugs that have a narrow therapeutic window, nonlinearity in pharmacokinetics and are metabolized by enzymes that demonstrate genetic polymorphisms. However, most clinical trials are conducted among Caucasians, which might limit the usefulness of the findings of such studies for other ethnicities. The representation of participants from Saudi Arabia in global clinical trials is low. Therefore, there is a paucity of evidence to assess the impact of ethnic variability in the Saudi population on drug response. In this article, the authors assess the projected impact of genetic polymorphisms in drug-metabolizing enzymes and drug targets on drug response in the Saudi population.

Towards Evidence-Based Implementation of Pharmacogenomics in Southern Africa: Comorbidities and Polypharmacy Profiles across Diseases

Pharmacogenomics may improve patient care by guiding drug selection and dosing; however, this requires prior knowledge of the pharmacogenomics of drugs commonly used in a specific setting. The aim of this study was to identify a preliminary set of pharmacogenetic variants important in Southern Africa. We describe comorbidities in 3997 patients from Malawi, South Africa, and Zimbabwe. These patient cohorts were included in pharmacogenomic studies of anticoagulation, dyslipidemia, hypertension, HIV and breast cancer. The 20 topmost prescribed drugs in this population were identified. Using the literature, a list of pharmacogenes vital in the response to the top 20 drugs was constructed leading to drug-gene pairs potentially informative in translation of pharmacogenomics. The most reported morbidity was hypertension (58.4%), making antihypertensives the most prescribed drugs, particularly amlodipine. Dyslipidemia occurred in 31.5% of the participants, and statins were the most frequently prescribed as cholesterol-lowering drugs. HIV was reported in 20.3% of the study participants, with lamivudine/stavudine/efavirenz being the most prescribed antiretroviral combination. Based on these data, pharmacogenes of immediate interest in Southern African populations include ABCB1, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP3A4, CYP3A5, SLC22A1, SLCO1B1 and UGT1A1. Variants in these genes are a good starting point for pharmacogenomic translation programs in Southern Africa.

Computational pharmacogenotype extraction from clinical next-generation sequencing

Background

Next-generation sequencing (NGS), including whole genome sequencing (WGS) and whole exome sequencing (WES), is increasingly being used for clinic care. While NGS data have the potential to be repurposed to support clinical pharmacogenomics (PGx), current computational approaches have not been widely validated using clinical data. In this study, we assessed the accuracy of the Aldy computational method to extract PGx genotypes from WGS and WES data for 14 and 13 major pharmacogenes, respectively.

Methods

Germline DNA was isolated from whole blood samples collected for 264 patients seen at our institutional molecular solid tumor board. DNA was used for panel-based genotyping within our institutional Clinical Laboratory Improvement Amendments- (CLIA-) certified PGx laboratory. DNA was also sent to other CLIA-certified commercial laboratories for clinical WGS or WES. Aldy v3.3 and v4.4 were used to extract PGx genotypes from these NGS data, and results were compared to the panel-based genotyping reference standard that contained 45 star allele-defining variants within CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A4, CYP3A5, CYP4F2, DPYD, G6PD, NUDT15, SLCO1B1, TPMT, and VKORC1.

Results

Mean WGS read depth was >30x for all variant regions except for G6PD (average read depth was 29 reads), and mean WES read depth was >30x for all variant regions. For 94 patients with WGS, Aldy v3.3 diplotype calls were concordant with those from the genotyping reference standard in 99.5% of cases when excluding diplotypes with additional major star alleles not tested by targeted genotyping, ambiguous phasing, and CYP2D6 hybrid alleles. Aldy v3.3 identified 15 additional clinically actionable star alleles not covered by genotyping within CYP2B6, CYP2C19, DPYD, SLCO1B1, and NUDT15. Within the WGS cohort, Aldy v4.4 diplotype calls were concordant with those from genotyping in 99.7% of cases. When excluding patients with CYP2D6 copy number variation, all Aldy v4.4 diplotype calls except for one CYP3A4 diplotype call were concordant with genotyping for 161 patients in the WES cohort.

Conclusion

Aldy v3.3 and v4.4 called diplotypes for major pharmacogenes from clinical WES and WGS data with >99% accuracy. These findings support the use of Aldy to repurpose clinical NGS data to inform clinical PGx.

Drug-drug interactions that alter the exposure of glucuronidated drugs: Scope, UDP-glucuronosyltransferase (UGT) enzyme selectivity, mechanisms (inhibition and induction), and clinical significance

Drug-drug interactions (DDIs) arising from the perturbation of drug metabolising enzyme activities represent both a clinical problem and a potential economic loss for the pharmaceutical industry. DDIs involving glucuronidated drugs have historically attracted little attention and there is a perception that interactions are of minor clinical relevance. This review critically examines the scope and aetiology of DDIs that result in altered exposure of glucuronidated drugs. Interaction mechanisms, namely inhibition and induction of UDP-glucuronosyltransferase (UGT) enzymes and the potential interplay with drug transporters, are reviewed in detail, as is the clinical significance of known DDIs. Altered victim drug exposure arising from modulation of UGT enzyme activities is relatively common and, notably, the incidence and importance of UGT induction as a DDI mechanism is greater than generally believed. Numerous DDIs are clinically relevant, resulting in either loss of efficacy or an increased risk of adverse effects, necessitating dose individualisation. Several generalisations relating to the likelihood of DDIs can be drawn from the known substrate and inhibitor selectivities of UGT enzymes, highlighting the importance of comprehensive reaction phenotyping studies at an early stage of drug development. Further, rigorous assessment of the DDI liability of new chemical entities that undergo glucuronidation to a significant extent has been recommended recently by regulatory guidance. Although evidence-based approaches exist for the in vitro characterisation of UGT enzyme inhibition and induction, the availability of drugs considered appropriate for use as 'probe' substrates in clinical DDI studies is limited and this should be research priority.

The pharmacogenomic landscape of an Indigenous Australian population

Background: Population genomic studies of individuals of Indigenous ancestry have been extremely limited comprising <0.5% of participants in international genetic databases and genome-wide association studies, contributing to a "genomic gap" that limits their access to personalised medicine. While Indigenous Australians face a high burden of chronic disease and associated medication exposure, corresponding genomic and drug safety datasets are sorely lacking. Methods: To address this, we conducted a pharmacogenomic study of almost 500 individuals from a founder Indigenous Tiwi population. Whole genome sequencing was performed using short-read Illumina Novaseq6000 technology. We characterised the pharmacogenomics (PGx) landscape of this population by analysing sequencing results and associated pharmacological treatment data. Results: We observed that every individual in the cohort carry at least one actionable genotype and 77% of them carry at least three clinically actionable genotypes across 19 pharmacogenes. Overall, 41% of the Tiwi cohort were predicted to exhibit impaired CYP2D6 metabolism, with this frequency being much higher than that for other global populations. Over half of the population predicted an impaired CYP2C9, CYP2C19, and CYP2B6 metabolism with implications for the processing of commonly used analgesics, statins, anticoagulants, antiretrovirals, antidepressants, and antipsychotics. Moreover, we identified 31 potentially actionable novel variants within Very Important Pharmacogenes (VIPs), five of which were common among the Tiwi. We further detected important clinical implications for the drugs involved with cancer pharmacogenomics such as thiopurines and tamoxifen, immunosuppressants like tacrolimus and certain antivirals used in the hepatitis C treatment due to potential differences in their metabolic processing. Conclusion: The pharmacogenomic profiles generated in our study demonstrate the utility of pre-emptive PGx testing and have the potential to help guide the development and application of precision therapeutic strategies tailored to Tiwi Indigenous patients. Our research provides valuable insights on pre-emptive PGx testing and the feasibility of its use in ancestrally diverse populations, emphasizing the need for increased diversity and inclusivity in PGx investigations.

Genetic polymorphisms influencing deferasirox pharmacokinetics, efficacy, and adverse drug reactions: a systematic review and meta-analysis

Objective: Deferasirox is an iron-chelating agent prescribed to patients with iron overload. Due to the interindividual variability of deferasirox responses reported in various populations, this study aims to determine the genetic polymorphisms that influence drug responses. Methods: A systematic search was performed from inception to March 2022 on electronic databases. All studies investigating genetic associations of deferasirox in humans were included, and the outcomes of interest included pharmacokinetics, efficacy, and adverse drug reactions. Fixed- and random-effects model meta-analyses using the ratio of means (ROM) were performed. Results: Seven studies involving 367 participants were included in a meta-analysis. The results showed that subjects carrying the A allele (AG/AA) of ABCC2 rs2273697 had a 1.23-fold increase in deferasirox C_max (ROM = 1.23; 95% confidence interval [CI]:1.06-1.43; p = 0.007) and a lower Vd (ROM = 0.48; 95% CI: 0.36-0.63; p < 0.00001), compared to those with GG. A significant attenuated area under the curve of deferasirox was observed in the subjects with UGT1A3 rs3806596 AG/GG by 1.28-fold (ROM = 0.78; 95% CI: 0.60-0.99; p = 0.04). In addition, two SNPs of CYP24A1 were also associated with the decreased C_trough: rs2248359 CC (ROM = 0.50; 95% CI: 0.29-0.87; p = 0.01) and rs2585428 GG (ROM = 0.47; 95% CI: 0.35-0.63; p < 0.00001). Only rs2248359 CC was associated with decreased C_min (ROM = 0.26; 95% CI: 0.08-0.93; p = 0.04), while rs2585428 GG was associated with a shorter half-life (ROM = 0.44; 95% CI: 0.23-0.83; p = 0.01). Conclusion: This research summarizes the current evidence supporting the influence of variations in genes involved with drug transporters, drug-metabolizing enzymes, and vitamin D metabolism on deferasirox responses.

Review of genetic and pharmacogenetic differences in cytotoxic and targeted therapies for pancreatic cancer in African Americans

Pancreatic ductal adenocarcinoma (PDAC) is currently the third leading cause of cancer mortality and the incidence is projected to increase by 2030. Despite recent advances in its treatment, African Americans have a 50-60% higher incidence and 30% higher mortality rate when compared to European Americans possibly resulting from differences in socioeconomic status, access to healthcare, and genetics. Genetics plays a role in cancer predisposition, response to cancer therapeutics (pharmacogenetics), and in tumor behavior, making some genes targets for oncologic therapeutics. We hypothesize that the germline genetic differences in predisposition, drug response, and targeted therapies also impact PDAC disparities. To demonstrate the impact of genetics and pharmacogenetics on PDAC disparities, a review of the literature was performed using PubMed with variations of the following keywords: pharmacogenetics, pancreatic cancer, race, ethnicity, African, Black, toxicity, and the FDA-approved drug names: Fluoropyrimidines, Topoisomerase inhibitors, Gemcitabine, Nab-Paclitaxel, Platinum agents, Pembrolizumab, PARP-inhibitors, and NTRK fusion inhibitors. Our findings suggest that the genetic profiles of African Americans may contribute to disparities related to FDA approved chemotherapeutic response for patients with PDAC. We recommend a strong focus on improving genetic testing and participation in biobank sample donations for African Americans. In this way, we can improve our current understanding of genes that influence drug response for patients with PDAC.

A retrospective analysis of preemptive pharmacogenomic testing in 22,918 individuals from China

BACKGROUND

Pharmacogenomics (PGx) examines the influence of genetic variation on drug responses. With more and more Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines published, PGx is gradually shifting from the reactive testing of single gene toward the preemptive testing of multiple genes. But the profile of PGx genes, especially for the intra-country diversity, is not well understood in China.

METHODS

We retrospectively collected preemptive PGx testing data of 22,918 participants from 20 provinces of China, analyzed frequencies of alleles, genotypes and phenotypes of pharmacogenes, predicted drug responses for each participant, and performed comparisons between different provinces.

RESULTS AND CONCLUSION

After analyzing 15 pharmacogenes from CPIC guidelines of 31 drugs, we found that 99.97% of individuals may have an atypical response to at least one drug; the participants carry actionable genotypes leading to atypical dosage recommendation for a median of eight drugs. Over 99% of the participants were recommended a decreased warfarin dose based on genetic factors. There were 20 drugs with high-risk ratios from 0.18% to 58.25%, in which clopidogrel showed the highest high-risk ratio. In addition, the high-risk ratio of rasburicase in GUANGDONG (risk ratio (RR) = 13.17, 95%CI:4.06-33.22, p < 0.001) and GUANGXI (RR = 23.44, 95%CI:8.83-52.85, p < 0.001) were significantly higher than that in all provinces. Furthermore, the diversity we observed among 20 provinces suggests that preemptive PGx testing in different geographical regions in China may need to pay more attention to specific genes. These results emphasize the importance of preemptive PGx testing and provide essential evidence for promoting clinical implementation in China.

Impact of polymorphisms in CYP and UGT enzymes and ABC and SLCO1B1 transporters on the pharmacokinetics and safety of desvenlafaxine

Venlafaxine pharmacokinetic variability and pharmacotherapy outcomes are well known to be related to CYP2D6 pharmacogenetic phenotype. In contrast, scarce pharmacogenetic information is available nowadays concerning desvenlafaxine, its active metabolite first marketed in 2012. The aim of this study was to evaluate the impact of 29 alleles in 12 candidate genes (e.g., CYP enzymes like CYP2D6, CYP3A4, or CYP2C19; ABC transporters like ABCB1; SLCO1B1; and UGT enzymes like UGT1A1) on desvenlafaxine pharmacokinetic variability and tolerability. Pharmacokinetic parameters and adverse drug reaction (ADR) incidence obtained from six bioequivalence clinical trials (n = 98) evaluating desvenlafaxine formulations (five with single dose administration and one with multiple-dose administration) were analyzed. No genetic polymorphism was related to pharmacokinetic variability or ADR incidence. Volunteers enrolled in the multiple-dose clinical trial also showed a higher incidence of ADRs, e.g., xerostomia or appetite disorders. Volunteers experiencing any ADR showed a significantly higher area under the time-concentration curve (AUC) than those not experiencing any ADR (5115.35 vs. 4279.04 ng*h/mL, respectively, p = 0.034). In conclusion, the strong dose-dependent relationship with the occurrence of ADRs confirms that the mechanism of action of desvenlafaxine is essentially dose-dependent.

PAnno: A pharmacogenomics annotation tool for clinical genomic testing

Introduction: Next-generation sequencing (NGS) technologies have been widely used in clinical genomic testing for drug response phenotypes. However, the inherent limitations of short reads make accurate inference of diplotypes still challenging, which may reduce the effectiveness of genotype-guided drug therapy. Methods: An automated Pharmacogenomics Annotation tool (PAnno) was implemented, which reports prescribing recommendations and phenotypes by parsing the germline variant call format (VCF) file from NGS and the population to which the individual belongs. Results: A ranking model dedicated to inferring diplotypes, developed based on the allele (haplotype) definition and population allele frequency, was introduced in PAnno. The predictive performance was validated in comparison with four similar tools using the consensus diplotype data of the Genetic Testing Reference Materials Coordination Program (GeT-RM) as ground truth. An annotation method was proposed to summarize prescribing recommendations and classify drugs into avoid use, use with caution, and routine use, following the recommendations of the Clinical Pharmacogenetics Implementation Consortium (CPIC), etc. It further predicts phenotypes of specific drugs in terms of toxicity, dosage, efficacy, and metabolism by integrating the high-confidence clinical annotations in the Pharmacogenomics Knowledgebase (PharmGKB). PAnno is available at https://github.com/PreMedKB/PAnno. Discussion: PAnno provides an end-to-end clinical pharmacogenomics decision support solution by resolving, annotating, and reporting germline variants.

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.

The Uridine diphosphate (UDP)-glycosyltransferases (UGTs) superfamily: the role in tumor cell metabolism

UDP-glycosyltransferases (UGTs), important enzymes in biotransformation, control the levels and distribution of numerous endogenous signaling molecules and the metabolism of a wide range of endogenous and exogenous chemicals. The UGT superfamily in mammals consists of the UGT1, UGT2, UGT3, and UGT8 families. UGTs are rate-limiting enzymes in the glucuronate pathway, and in tumors, they are either overexpressed or underexpressed. Alterations in their metabolism can affect gluconeogenesis and lipid metabolism pathways, leading to alterations in tumor cell metabolism, which affect cancer development and prognosis. Glucuronidation is the most common mammalian conjugation pathway. Most of its reactions are mainly catalyzed by UGT1A, UGT2A and UGT2B. The body excretes UGT-bound small lipophilic molecules through the bile, urine, or feces. UGTs conjugate a variety of tiny lipophilic molecules to sugars, such as galactose, xylose, acetylglucosamine, glucuronic acid, and glucose, thereby inactivating and making water-soluble substrates, such as carcinogens, medicines, steroids, lipids, fatty acids, and bile acids. This review summarizes the roles of members of the four UGT enzyme families in tumor function, metabolism, and multiple regulatory mechanisms, and its Inhibitors and inducers. The function of UGTs in lipid metabolism, drug metabolism, and hormone metabolism in tumor cells are among the most important topics covered.

Influence of UGT1A1 and SLC22A6 polymorphisms on the population pharmacokinetics and pharmacodynamics of raltegravir in HIV-infected adults: a NEAT001/ANRS143 sub-study

Using concentration-time data from the NEAT001/ARNS143 study (single sample at week 4 and 24), we determined raltegravir pharmacokinetic parameters using nonlinear mixed effects modelling (NONMEM v.7.3; 602 samples from 349 patients) and investigated the influence of demographics and SNPs (SLC22A6 and UGT1A1) on raltegravir pharmacokinetics and pharmacodynamics. Demographics and SNPs did not influence raltegravir pharmacokinetics and no significant pharmacokinetic/pharmacodynamic relationships were observed. At week 96, UGT1A1*28/*28 was associated with lower virological failure (p = 0.012), even after adjusting for baseline CD4 count (p = 0.048), but not when adjusted for baseline HIV-1 viral load (p = 0.082) or both (p = 0.089). This is the first study to our knowledge to assess the influence of SNPs on raltegravir pharmacodynamics. The lack of a pharmacokinetic/pharmacodynamic relationship is potentially an artefact of raltegravir's characteristic high inter and intra-patient variability and also suggesting single time point sampling schedules are inadequate to thoroughly assess the influence of SNPs on raltegravir pharmacokinetics.

A Combination of Novel HIV-1 Protease Inhibitor and Cytochrome P450 (CYP) Enzyme Inhibitor to Explore the Future Prospective of Antiviral Agents: Evotaz

Viruses belong to the class of micro-organisms that are well known for causing infections in the human body. Antiviral medications are given out to prevent the spread of disease-causing viruses. When the viruses are actively reproducing, these agents have their greatest impact. It is particularly challenging to develop virus-specific medications since viruses share the majority of the metabolic functions of the host cell. In the continuous search for better antiviral agents, the United States Food and Drug Administration (USFDA) approved a new drug named Evotaz on January 29, 2015 for the treatment of human immunodeficiency virus (HIV). Evotaz is a combined once-daily fixed drug, containing Atazanavir, an HIV protease inhibitor, and cobicistat, an inhibitor of the human liver cytochrome P450 (CYP) enzyme. The medication is created such that it can kill viruses by concurrently inhibiting protease and CYP enzymes. The medicine is still being studied for a number of criteria, but its usefulness in children under the age of 12 is currently unknown. The preclinical and clinical characteristics of Evotaz, as well as its safety and efficacy profiles and a comparison of the novel drug with antiviral medications presently available in the market, are the main topics of this review paper.