Transcriptional Regulation of Azole Antifungal Resistance and Tolerance in Candida Glabrata

Azole antifungal resistance has emerged as a significant problem in the management of infections caused by fungi including Candida species. In recent years, Candida glabrata has become the second most common cause of mucosal and invasive fungal infections in humans second to Candida albicans. Not only are systemic C. glabrata infections characterized by high mortality rates, treatment failures to the azole class of antifungals, the most widely used antifungal for treatment of Candida infections, have been reported. Contributing to this problem, C. glabrata exhibits intrinsic reduced susceptibility to the azole antifungals, and the development of high-level azole resistance during therapy has been reported in oral as well as bloodstream C. glabrata isolates in immunocompromised patients. The azole antifungals are fungistatic against Candida species, thus C. glabrata also exhibits tolerance to the azoles which may contribute to both therapeutic failures and ultimately the development of high-level azole resistance. In C. glabrata clinical isolates, the predominant mechanism behind azole resistance is upregulated expression of multidrug transporter genes CgCDR1 and CgPDH1. It was previously reported that azole-resistant mutants (MIC ≥ 64 μg/ml) of strain 66032 (MIC = 16 μg/ml) similarly show coordinate CDR1-PDH1 upregulation, and in one of these (F15) a putative gain-of-function mutation was identified in the single molecule homologue of Saccharomyces cerevisiae transcription factors Pdr1p–Pdr3p. Here we show that disruption of C. glabrata PDR1 conferred equivalent fluconazole hypersensitivity (MIC = 2 μg/ml) to both F15 and 66032 and eliminated both constitutive and fluconazole-induced CDR1-PDH1 expression. Reintroduction of wild-type or F15 PDR1 alleles fully reversed these effects; together these results demonstrate a role for this gene in both acquired and intrinsic azole resistance. CDR1 disruption had a partial effect, reducing fluconazole trailing in both strains while restoring wild-type susceptibility (MIC = 16 μg/ml) to F15. In an azole-resistant clinical isolate, PDR1 disruption reduced azole MICs eight- to 64-fold with no effect on sensitivity to other antifungals. To extend this analysis, C. glabrata gene expression microarrays were generated and used to analyze genome-wide expression in F15 relative to its parent. Homologues of 10 S. cerevisiae genes previously shown to be Pdr1p–Pdr3p targets were upregulated (YOR1, RTA1, RSB1, RPN4, YLR346c and YMR102c along with CDR1, PDH1 and PDR1 itself) or downregulated (PDR12); roles for these genes include small molecule transport and transcriptional regulation. However, expression of 99 additional genes was specifically altered in C. glabrata F15; their roles include transport (e.g. QDR2, YBT1), lipid metabolism (ATF2, ARE1), cell stress (HSP12, CTA1), DNA repair (YIM1, MEC3) and cell wall function (MKC7, MNT3). These azole resistance-associated changes could affect C. glabrata tissue-specific virulence; in support of this, we detected differences in F15 oxidant, alcohol and weak acid sensitivities. C. glabrata provides a promising model for studying the genetic basis of multidrug resistance and its impact on virulence. We next examined the genome-wide gene expression profiles in four matched azole-susceptible and –resistant clinical isolate sets of C. glabrata in which CgCDR1 gene expression was upregulated in the resistant isolate. Of all the genes identified in the gene expression profiles for these four matched pairs, there were nine genes that were commonly upregulated with CgCDR1 in all four isolate sets (YOR1, LCB5, RTA1, YIM1, YIL077c, POG1, HFD1, GLK1, and FMS1). We then sequenced CgPDR1 from each susceptible and resistant isolate and found two alleles with novel gain-of-function mutations. A third isolate, and its susceptible parent, harbored a CgPDR1 allele with a frameshift mutation which presumably results in a truncated CgPdr1p. The final resistant isolate had noPDR1 mutation. CgPDR1 alleles with putative gain-of-function mutations were expressed in a common background strain in which CgPDR1 had been disrupted, and genome-wide gene expression profiles were examined to determine if different mutations inCgPDR1 result in different target gene activation and fluconazole MICs. Microarray analysis comparing these re-engineered strains to their respective parent strains identified a core set of commonly differentially-expressed genes as well as genes uniquely regulated by specific mutations

Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines for CYP2C9 and HLA-B Genotype and Phenytoin Dosing

Phenytoin is a widely used antiepileptic drug with a narrow therapeutic index and large inter-patient variability partly due to genetic variations in CYP2C9. Furthermore, the variant allele HLA-B*15:02 is associated with an increased risk of Stevens-Johnson syndrome and toxic epidermal necrolysis in response to phenytoin treatment. We summarize evidence from the published literature supporting these associations and provide recommendations for the use of phenytoin based on CYP2C9 and/or HLA-B genotype (also available on PharmGKB: www.pharmgkb.org)

Standardizing CYP2D6 Genotype to Phenotype Translation: Consensus Recommendations from the Clinical Pharmacogenetics Implementation Consortium and Dutch Pharmacogenetics Working Group

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153095/1/cts12692_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153095/2/cts12692-sup-0001-Supinfo.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153095/3/cts12692.pd

Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines for Human Leukocyte Antigen B (HLA-B) Genotype and Allopurinol Dosing: 2015 update

The Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines for HLA-B*58:01 Genotype and Allopurinol Dosing was originally published in February 2013. We reviewed the recent literature and concluded that none of the evidence would change the therapeutic recommendations in the original guideline; therefore, the original publication remains clinically current. However, we have updated the Supplemental Material and included additional resources for applying CPIC guidelines into the electronic health record. Up-to-date information can be found at PharmGKB (http://www.pharmgkb.org)

Clinical pharmacogenetics implementation consortium guideline (CPIC) for CYP2D6 and CYP2C19 genotypes and dosing of tricyclic antidepressants: 2016 update

CYP2D6 and CYP2C19 polymorphisms affect the exposure, efficacy and safety of tricyclic antidepressants (TCAs), with some drugs being affected by CYP2D6 only (e.g., nortriptyline and desipramine) and others by both polymorphic enzymes (e.g., amitriptyline, clomipramine, doxepin, imipramine, and trimipramine). Evidence is presented for CYP2D6 and CYP2C19 genotype-directed dosing of TCAs. This document is an update to the 2012 Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for CYP2D6 and CYP2C19 Genotypes and Dosing of Tricyclic Antidepressants

Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for CYP2D6 and CYP2C19 Genotypes and Dosing of Selective Serotonin Reuptake Inhibitors

Selective serotonin reuptake inhibitors (SSRIs) are primary treatment options for major depressive and anxiety disorders. CYP2D6 and CYP2C19 polymorphisms can influence the metabolism of SSRIs, thereby affecting drug efficacy and safety. We summarize evidence from the published literature supporting these associations and provide dosing recommendations for fluvoxamine, paroxetine, citalopram, escitalopram, and sertraline based on CYP2D6 and/or CYP2C19 genotype (updates at www.pharmgkb.org)

Clinical Pharmacogenetics Implementation Consortium Guideline (CPIC) for <i>CYP2D6, ADRB1, ADRB2, ADRA2C, GRK4</i>, and <i>GRK5 </i>Genotypes and Beta-Blocker Therapy

Beta-blockers are widely used medications for a variety of indications, including heart failure, myocardial infarction, cardiac arrhythmias, and hypertension. Genetic variability in pharmacokinetic (e.g., CYP2D6) and pharmacodynamic (e.g., ADRB1, ADRB2, ADRA2C, GRK4, GRK5) genes have been studied in relation to beta-blocker exposure and response. We searched and summarized the strength of the evidence linking beta-blocker exposure and response with the six genes listed above. The level of evidence was high for associations between CYP2D6 genetic variation and both metoprolol exposure and heart rate response. Evidence indicates that CYP2D6 poor metabolizers experience clinically significant greater exposure and lower heart rate in response to metoprolol compared with those who are not poor metabolizers. Therefore, we provide therapeutic recommendations regarding genetically predicted CYP2D6 metabolizer status and metoprolol therapy. However, there was insufficient evidence to make therapeutic recommendations for CYP2D6 and other beta-blockers or for any beta-blocker and the other five genes evaluated (updates at www.cpicpgx.org).</p

Expanded Clinical Pharmacogenetics Implementation Consortium Guideline for Medication Use in the Context of G6PD Genotype

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is associated with development of acute hemolytic anemia in the setting of oxidative stress, which can be caused by medication exposure. Regulatory agencies worldwide warn against the use of certain medications in persons with G6PD deficiency, but in many cases, this information is conflicting, and the clinical evidence is sparse. This guideline provides information on using G6PD genotype as part of the diagnosis of G6PD deficiency and classifies medications that have been previously implicated as unsafe in individuals with G6PD deficiency by one or more sources. We classify these medications as high, medium, or low to no risk based on a systematic review of the published evidence of the gene-drug associations and regulatory warnings. In patients with G6PD deficiency, high-risk medications should be avoided, medium-risk medications should be used with caution, and low-to-no risk medications can be used with standard precautions, without regard to G6PD phenotype. This new document replaces the prior Clinical Pharmacogenetics Implementation Consortium guideline for rasburicase therapy in the context of G6PD genotype (updates at: www.cpicpgx.org)