Frequency of the CYP2C19*17 polymorphism in a Chilean population and its effect on voriconazole plasma concentration in immunocompromised children

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.

Pharmacogenetic Aspects of Drug Metabolizing Enzymes and Transporters in Pediatric Medicine: Study Progress, Clinical Practice and Future Perspectives

As the activity of certain drug metabolizing enzymes or transporter proteins can vary with age, the effect of ontogenetic and genetic variation on the activity of these enzymes is critical for the accurate prediction of treatment outcomes and toxicity in children. This makes pharmacogenetic research in pediatrics particularly important and urgently needed, but also challenging. This review summarizes pharmacogenetic studies on the effects of genetic polymorphisms on pharmacokinetic parameters and clinical outcomes in pediatric populations for certain drugs, which are commonly prescribed by clinicians across multiple therapeutic areas in a general hospital, organized from those with the most to the least pediatric evidence among each drug category. We also further discuss the research status of the gene-guided dosing regimens and clinical implementation of pediatric pharmacogenetics. More and more drug-gene interactions are demonstrated to have clinical validity for children, and pharmacogenomics in pediatrics have shown evidence-based benefits to enhance the efficacy and precision of existing drug dosing regimens in several therapeutic areas. However, the most important limitation to the implementation is the lack of high-quality, rigorous pediatric prospective clinical studies, so adequately powered interventional clinical trials that support incorporation of pharmacogenetics into the care of children are still needed.

Nanotechnology-Based Approaches for Voriconazole Delivery Applied to Invasive Fungal Infections

Invasive fungal infections increase mortality and morbidity rates worldwide. The treatment of these infections is still limited due to the low bioavailability and toxicity, requiring therapeutic monitoring, especially in the most severe cases. Voriconazole is an azole widely used to treat invasive aspergillosis, other hyaline molds, many dematiaceous molds, Candida spp., including those resistant to fluconazole, and for infections caused by endemic mycoses, in addition to those that occur in the central nervous system. However, despite its broad activity, using voriconazole has limitations related to its non-linear pharmacokinetics, leading to supratherapeutic doses and increased toxicity according to individual polymorphisms during its metabolism. In this sense, nanotechnology-based drug delivery systems have successfully improved the physicochemical and biological aspects of different classes of drugs, including antifungals. In this review, we highlighted recent work that has applied nanotechnology to deliver voriconazole. These systems allowed increased permeation and deposition of voriconazole in target tissues from a controlled and sustained release in different routes of administration such as ocular, pulmonary, oral, topical, and parenteral. Thus, nanotechnology application aiming to delivery voriconazole becomes a more effective and safer therapeutic alternative in the treatment of fungal infections.

Therapeutic drug monitoring and CYP2C19 genotyping guide the application of voriconazole in children

BACKGROUND

This study used therapeutic drug monitoring (TDM) and CYP2C19 gene polymorphism analysis to explore the efficacy and safety of different doses of voriconazole (VCZ) for the clinical treatment of pediatric patients, with the aim of providing guidelines for individualized antifungal therapy in children.

METHODS

Our study enrolled 94 children with 253 VCZ concentrations. The genotyping of CYP2C19 was performed by polymerase chain reaction (PCR)-pyrosequencing. VCZ trough concentration (C_trough) was detected by high-performance liquid chromatography-tandem mass spectrometry. SPSS 23.0 was used to analyze the correlations between VCZ concentration, CYP2C19 phenotype, adverse effects (AEs), and drug-drug interactions.

RESULTS

A total of 94 children aged between 1 and 18 years (median age 6 years) were enrolled in the study. In total, 42.6% of patients reached the therapeutic range at initial dosing, while the remaining patients reached the therapeutic range after the adjustment of the dose or dosing interval. CYP2C19 gene polymorphism was performed in 59 patients. Among these patients, 24 (40.7%) had the normal metabolizer (NM) phenotype, 26 (44.1%) had the intermediate metabolizer (IM) phenotype, and 9 (15.3%) had the poor metabolizer (PM) phenotype. No cases of the rapid metabolizer (RM) or ultrarapid metabolizer (UM) phenotypes were found. The initial VCZ C_trough was significantly higher in patients with the PM and IM phenotypes than in those with the NM phenotype. The combination of immunosuppressive drugs (ISDs) did not affect VCZ C_trough. The incidence of AEs was 25.5%, and liver function damage (46.2%) and gastrointestinal reactions (19.2%) were the most common.

CONCLUSIONS

Our study showed significant individual differences of VCZ metabolism in children. Combining TDM with CYP2C19 gene polymorphism has important guiding significance for individualized antifungal therapy in pediatric patients.

Pharmacogenetic Analysis of Voriconazole Treatment in Children

Voriconazole is among the first-line antifungal drugs to treat invasive fungal infections in children and known for its pronounced inter- and intraindividual pharmacokinetic variability. Polymorphisms in genes involved in the metabolism and transport of voriconazole are thought to influence serum concentrations and eventually the therapeutic outcome. To investigate the impact of these genetic variants and other covariates on voriconazole trough concentrations, we performed a retrospective data analysis, where we used medication data from 36 children suffering from invasive fungal infections treated with voriconazole. Data were extracted from clinical information systems with the new infrastructure SwissPK^cdw, and linear mixed effects modelling was performed using R. Samples from 23 children were available for DNA extraction, from which 12 selected polymorphism were genotyped by real-time PCR. 192 (49.1%) of 391 trough serum concentrations measured were outside the recommended range. Voriconazole trough concentrations were influenced by polymorphisms within the metabolizing enzymes CYP2C19 and CYP3A4, and within the drug transporters ABCC2 and ABCG2, as well as by the co-medications ciprofloxacin, levetiracetam, and propranolol. In order to prescribe an optimal drug dosage, pre-emptive pharmacogenetic testing and careful consideration of co-medications in addition to therapeutic drug monitoring might improve voriconazole treatment outcome of children with invasive fungal infections.

Effects of CYP2C19, CYP2C9 and CYP3A4 gene polymorphisms on plasma voriconazole levels in Chinese pediatric patients

OBJECTIVES

Voriconazole is the most commonly used antifungal agent in clinical application. Previous studies suggested that voriconazole was extensively metabolized by CYP450 enzyme system, including CYP2C19, CYP2C9 and CYP3A4, which contributed to the individual variability of the pharmacokinetic process of voriconazole. This study aimed to investigate the effects of CYP2C19, CYP2C9 and CYP3A4 gene polymorphisms on plasma voriconazole concentrations in Chinese pediatric patients.

METHODS

This study prospectively evaluated pediatric patients administrating voriconazole for the treatment or prophylaxis of invasive fungal infections from October 2018 to July 2020. Seven single-nucleotide polymorphisms in CYP2C19 (CYP2C19*2, CYP2C19*3, and CYP2C19*17), CYP2C9 (CYP2C9*3, CYP2C9*13) and CYP3A4 (CYP3A4*22, rs4646437) were detected by real-time fluorescent PCR with TaqMan probes. The voriconazole trough plasma concentration was determined by UPLC-MS/MS.

RESULTS

A total of 68 pediatric patients were enrolled in this study. Our results showed that voriconazole plasma concentrations of patients with CYP2C19*2 or CYP2C19*3 allele were significantly higher than that with wild-type carriers (P < 0.0001, P = 0.004, respectively). However, CYP2C9*3 and CYP3A4 rs4646437 were not significantly associated with voriconazole plasma levels. The CYP2C19*17, CYP2C9*13 and CYP3A4*22 alleles were not observed in our study. Additionally, multiple linear regression analysis indicated that CYP2C19*2 and CYP2C19*3 alleles remained predictors of voriconazole plasma concentration (r2 = 0.428; P < 0.0001). For CYP2C19 metabolizer phenotype, trough concentration of voriconazole was significantly lower in NM group compared with IM (P < 0.0001) and PM (P = 0.004) groups.

CONCLUSION

Voriconazole plasma levels in pediatric patients are mainly affected by CYP2C19 gene polymorphisms.

Combined Effect of CYP2C19 Genetic Polymorphisms and C-Reactive Protein on Voriconazole Exposure and Dosing in Immunocompromised Children

BACKGROUND

Pediatric patients have significant interindividual variability in voriconazole exposure. The aim of the study was to identify factors associated with voriconazole concentrations and dose requirements to achieve therapeutic concentrations in pediatric patients.

METHODS

Medical records of pediatric patients were retrospectively reviewed. Covariates associated with voriconazole plasma concentrations and dose requirements were adjusted by using generalized linear mixed-effect models.

RESULTS

A total of 682 voriconazole steady-state trough concentrations from 91 Chinese pediatric patients were included. Voriconazole exposure was lower in the CYP2C19 normal metabolizer (NM) group compared with the intermediate metabolizer (IM) group and the poor metabolizer (PM) group (p = 0.0016, p < 0.0001). The median daily dose of voriconazole required to achieve therapeutic range demonstrated a significant phenotypic dose effect: 20.8 mg/kg (range, 16.2-26.8 mg/kg) for the CYP2C19 NM group, 18.2 mg/kg (range, 13.3-21.8 mg/kg) for the CYP2C19 IM group, and 15.2 mg/kg (range, 10.7-19.1 mg/kg) for the CYP2C19 PM group, respectively. The extent of impact of C-reactive protein (CRP) levels on voriconazole trough concentrations and dose requirements varied between CYP2C19 phenotypes. Increases of 20, 120, 245, and 395 mg/L from 5 mg/L in CRP levels were associated with increases in voriconazole trough concentration by 22.22, 50, 64.81, and 75% respectively, in the NM group; by 39.26, 94.48, 123.93, and 146.63%, respectively, in the IM group; and by 17.17, 37.34, 46.78, and 53.65%, respectively, in the PM group. Meanwhile, increases of 20, 120, 245, and 395 mg/L from 5 mg/L in CRP levels were associated with increases in voriconazole dose requirements by 7.15, 14.23, 17.35, and 19.43%, respectively, in the PM group; with decreases in voriconazole dose requirements by 3.71, 7.38, 8.97, and 10.03%, respectively, in the NM group; and with decreases by 4, 9.10, 11.05, and 12.35%, respectively, in the IM group. In addition, age and presence of immunosuppressants had significant effects on voriconazole exposure.

CONCLUSIONS

Our study suggests that CYP2C19 phenotypes, CRP concentrations, age, and the presence of immunosuppressants were factors associated with the pharmacokinetic changes in voriconazole. There was heterogeneity in the effect of CRP on voriconazole plasma concentrations across different CYP2C19 genotypes. Combining relevant factors with dose adaptation strategies in therapeutic drug monitoring may help to reduce the incidence of subtherapeutic and supratherapeutic concentrations in clinical practice.

Genetic Susceptibility to Fungal Infections and Links to Human Ancestry

Over the ages, fungi have associated with different parts of the human body and established symbiotic associations with their host. They are mostly commensal unless there are certain not so well-defined factors that trigger the conversion to a pathogenic state. Some of the factors that induce such transition can be dependent on the fungal species, environment, immunological status of the individual, and most importantly host genetics. In this review, we discuss the different aspects of how host genetics play a role in fungal infection since mutations in several genes make hosts susceptible to such infections. We evaluate how mutations modulate the key recognition between the pathogen associated molecular patterns (PAMP) and the host pattern recognition receptor (PRR) molecules. We discuss the polymorphisms in the genes of the immune system, the way it contributes toward some common fungal infections, and highlight how the immunological status of the host determines fungal recognition and cross-reactivity of some fungal antigens against human proteins that mimic them. We highlight the importance of single nucleotide polymorphisms (SNPs) that are associated with several of the receptor coding genes and discuss how it affects the signaling cascade post-infection, immune evasion, and autoimmune disorders. As part of personalized medicine, we need the application of next-generation techniques as a feasible option to incorporate an individual’s susceptibility toward invasive fungal infections based on predisposing factors. Finally, we discuss the importance of studying genomic ancestry and reveal how genetic differences between the human race are linked to variation in fungal disease susceptibility.

Retrospective analysis of the association of the expression and single nucleotide polymorphisms (SNPs) of the TLR4, PTX3 and Dectin-1 (CLEC/A) genes with development of invasive aspergillosis among haematopoietic stem cell transplant recipients with oncohaematological disorders

OBJECTIVES

Several studies described single nucleotide polymorphisms (SNPs) on pattern recognition receptor (PRR) such as toll-like receptors (TLRs), dendritic cell-associated C-type lectin-1 (Dectin-1/CLEC7A) genes of patients with invasive fungal infections (IFIs) caused by Candida and Aspergillus. We screened TLR4, Dectin-1 and PTX3 polymorphisms in a Turkish population with invasive aspergillosis (IA) underlying haematological malignancies.

METHODS

In this case-control study, a cohort of 59 patients with haematological malignancies were included. There were 26 IA patients assigned by the EORTC-MSG criteria and 33 patients with no evidence of fungal disease. DNA and RNA were isolated from frozen bone marrow and serum samples. RNA levels and polymorphisms of TLR4 (rs4986790, rs4986791), Dectin-1 (rs16910526, rs7309123) and PTX3 (rs2305619, rs3816527) were determined. The odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated by unconditional logistic regression analysis.

RESULTS AND CONCLUSIONS

TLR4, PTX3 and Dectin-1 genes were downregulated in aspergillosis cohort under similar haematological conditions. TLR4 expression was 0.0626 ± 0.032 in controls when compared to IA patients as 0.0077 ± 0.014, and the difference was significant (P = .026). There was a difference in also the PTX3 gene among IA (0.0043 ± 0.004) and control (0.5265 ± 0.0043) groups (P = .035). The Dectin-1 (CLEC/A) expression was downregulated in IA group (0.1887 ± 0.072 & 0.0655 ± 0.010) but not statistically significant (P > .05). Conditional logistic regression analyses indicated that the GT genotype of rs16910526 polymorphism in Dectin-1 gene was associated with lower risk of IA (odds ratio = 3.635, 95% confidence interval = 0.690-3.138, P = .04).