Invasive Aspergillus infection requiring lobectomy in a CYP2C19 rapid metabolizer with subtherapeutic voriconazole concentrations

Fungal brain infection-no longer a death sentence

The aim of this case series was to provide a modern cohort of patients with cerebral aspergillosis and show the effectiveness of modern treatment concepts. In a 10-year period from January 2009 to January 2019, we identified 10 patients (6 male, 4 female) who received surgery or frameless stereotactic drainage of a cerebral aspergilloma at our center. Patients’ and disease characteristics were recorded. The median age was 65 (range 45 to 83). We conducted 133 cranial surgeries in 100 patients due to cerebral brain abscess (BA) during that time, which leads to a percentage of 10% of aspergilloma within BAs in our patient sample. We performed 3.1 surgeries per patient followed by antifungal treatment for 6 months (= median) according to the microbiological findings. Regarding comorbidities, the mean Charlson comorbidity index (CCI) at the time of admission was 5, representing an estimated 10-year survival of 21%. Six (60%) of 10 patients showed conditions of immunosuppression, one suffered endocarditis after replacement of aortic valves. Four patients showed associated frontobasal bone destruction, mycotic aneurysms, or thromboses. The mean duration of hospital stay was 37 days. Mortality was much lower than in literature. Sixty percent of the patients died during the follow-up period. The outcome of the two immunocompetent patients was more favorable. Cerebral aspergillosis is a rare, but still life-threatening, condition, which predominantly occurs in immunosuppressive conditions. Due to radical surgical and antifungal therapy for several months, mortality can be reduced dramatically.

Applying Pharmacogenomics to Antifungal Selection and Dosing: Are We There Yet?

Purpose of Review

This review summarizes recent literature for applying pharmacogenomics to antifungal selection and dosing, providing an approach to implementing antifungal pharmacogenomics in clinical practice.

Recent Findings

The Clinical Pharmacogenetics Implementation Consortium published guidelines on CYP2C19 and voriconazole, with recommendations to use alternative antifungals or adjust voriconazole dose with close therapeutic drug monitoring (TDM). Recent studies demonstrate an association between CYP2C19 phenotype and voriconazole levels, clinical outcomes, and adverse events. Additionally, CYP2C19-guided preemptive dose adjustment demonstrated benefit in two prospective studies for prophylaxis. Pharmacokinetic-pharmacodynamic modeling studies have generated proposed voriconazole treatment doses based on CYP2C19 phenotypes, with further validation studies needed.

Summary

Sufficient evidence is available for implementing CYP2C19-guided voriconazole selection and dosing among select patients at risk for invasive fungal infections. The institution needs appropriate infrastructure for pharmacogenomic testing, integration of results in the clinical decision process, with TDM confirmation of goal trough achievement, to integrate antifungal pharmacogenomics into routine clinical care.

Gene-Based Dose Optimization in Children

Pharmacogenetics is a key component of precision medicine. Genetic variation in drug metabolism enzymes can lead to variable exposure to drugs and metabolites, potentially leading to inefficacy and drug toxicity. Although the evidence for pharmacogenetic associations in children is not as extensive as for adults, there are several drugs across diverse therapeutic areas with robust pediatric data indicating important, and relatively common, drug-gene interactions. Guidelines to assist gene-based dose optimization are available for codeine, thiopurine drugs, selective serotonin reuptake inhibitors, atomoxetine, tacrolimus, and voriconazole. For each of these drugs, there is an opportunity to clinically implement precision medicine approaches with children for whom genetic test results are known or are obtained at the time of prescribing. For many more drugs that are commonly used in pediatric patients, additional investigation is needed to determine the genetic factors influencing appropriate dose.

High-Resolution Melting Assay for Genotyping Variants of the CYP2C19 Enzyme and Predicting Voriconazole Effectiveness

Voriconazole is a triazole antifungal agent recommended as primary treatment for invasive aspergillosis, as well as some other mold infections. However, it presents some pharmacokinetic singularities that lead to a great variability intra- and interindividually, nonlinear pharmacokinetics, and a narrow therapeutic range. Most experts have recommended tracing the levels of voriconazole in patients when receiving treatment. This azole is metabolized through the hepatic enzyme complex cytochrome P450 (CYPP450), with the isoenzyme CYP2C19 being principally involved. Allelic variations (polymorphisms) of the gene that encodes this enzyme are known to contribute to variability in voriconazole exposure. Three different allelic variants, CYP2C19*17, CYP2C19*2, and CYP2C19*3, could explain most of the phenotypes related to the voriconazole metabolism and some of its pharmacokinetic singularities. We designed a rapid molecular method based on high-resolution melting to characterize these polymorphisms in a total of 142 samples, avoiding sequencing. Three PCRs were designed with similar cycling conditions to run simultaneously. The results showed that our method represents a fast, accurate, and inexpensive means to study these variants related to voriconazole metabolism. In clinical practice, this could offer a useful tool to individually optimize therapy and reduce expenses in patients with fungal infections.

Distinguishing the dominant species of pathogen in ethmoidal sinusitis by sequencing DNA dataset analysis

Identifying the predominant microbial species in patients with ethmoidal sinusitis is conducive to its successful treatment. The aim of the present study was to determine the microbial composition and the predominant fungal and bacterial species in patients with ethmoidal sinusitis. A sample was obtained from 3 patients with ethmoidal sinusitis and from the ethmoid sinus of 2 healthy volunteers. Those samples were sequenced using an Illumina/Solexa sequencing platform for mapping to human, fungal, and bacterial genomes. Fungal and bacterial expressions in those samples were analyzed through bioinformatics and statistical methods. The sequencing data revealed that the dominant fungal strains in the ethmoidal sinusitis samples compared with the healthy controls (8_S33 and 10_S9) were Aspergillus oryzae and Aspergillus flavus, and the dominant bacterial strains were Haemophilus influenzae and Haemophilus parainfluenzae. Together, these findings indicate that the development of ethmoidal sinusitis is associated with the presence of fungi and bacteria, which may benefit the successful diagnosis and treatment for patients with ethmoidal sinusitis.