Browsing by Subject "Pharmacogenetic"

Now showing 1 - 4 of 4
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    CYP2D6 Genotype is Not Associated with Survival in Breast Cancer Patients Treated with Tamoxifen: Results from a Population-based Study
    (SpringerLink, 2017-11) Hertz, D.L.; Kidwell, K.M.; Hilsenbeck, S.G.; Oesterreich, S.; Philips, S.; Chenault, C.; Hartmaier, R.J.; Skaar, Todd C.; Sikora, M.J.; Rae, J.M.; Medicine, School of Medicine
    Purpose: A number of studies have tested the hypothesis that breast cancer patients with low-activity CYP2D6 genotypes achieve inferior benefit from tamoxifen treatment, putatively due to lack of metabolic activation to endoxifen. Studies have provided conflicting data, and meta-analyses suggest a small but significant increase in cancer recurrence, necessitating additional studies to allow for accurate effect assessment. We conducted a retrospective pharmacogenomic analysis of a prospectively collected community-based cohort of patients with estrogen receptor-positive breast cancer to test for associations between low-activity CYP2D6 genotype and disease outcome in 500 patients treated with adjuvant tamoxifen monotherapy and 500 who did not receive any systemic adjuvant therapy. Methods: Tumor-derived DNA was genotyped for common, functionally consequential CYP2D6 polymorphisms (*2, *3, *4, *6, *10, *41, and copy number variants) and assigned a CYP2D6 activity score (AS) ranging from none (0) to full (2). Patients with poor metabolizer (AS = 0) phenotype were compared to patients with AS > 0 and in secondary analyses AS was analyzed quantitatively. Clinical outcome of interest was recurrence free survival (RFS) and analyses using long-rank test were adjusted for relevant clinical covariates (nodal status, tumor size, etc.). Results: CYP2D6 AS was not associated with RFS in tamoxifen treated patients in univariate analyses (p > 0.2). In adjusted analyses, increasing AS was associated with inferior RFS (Hazard ratio 1.43, 95% confidence interval 1.00-2.04, p = 0.05). In patients that did not receive tamoxifen treatment, increasing CYP2D6 AS, and AS > 0, were associated with superior RFS (each p = 0.0015). Conclusions: This population-based study does not support the hypothesis that patients with diminished CYP2D6 activity achieve inferior tamoxifen benefit. These contradictory findings suggest that the association between CYP2D6 genotype and tamoxifen treatment efficacy is null or near null, and unlikely to be useful in clinical practice.
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    Implementation of Clinical Cytochrome P450 3A Genotyping for Tacrolimus Dosing in a Large Kidney Transplant Program
    (Wiley, 2023) Tillman, Emma; Nikirk, Miley G.; Chen, Jeanne; Skaar, Todd C.; Shugg, Tyler; Maddatu, Judith P.; Sharfuddin, Asif A.; Eadon, Michael T.; Medicine, School of Medicine
    Tacrolimus is a calcineurin inhibitor with a narrow therapeutic range and is metabolized by cytochrome P450 (CYP) isoenzymes CYP3A4 and CYP3A5. The Clinical Pharmacogenetic Implementation Consortium published evidence-based guidelines for CYP3A5 normal/intermediate metabolizers prescribed tacrolimus, yet few transplant centers have implemented routine testing. The objective of this study was to implement preemptive CYP3A genotyping into clinical practice in a large kidney transplant program and to evaluate workflow feasibility, potential clinical benefit, and reimbursement to identify barriers and determine sustainability. Preemptive pharmacogenetic testing for CYP3A5 and CYP3A4 was implemented in all patients listed for a kidney transplant as part of standard clinical care. Genotyping was performed at the listing appointment, results were reported as discrete data in the electronic medical record, and education and clinical decision support alerts were developed to provide pharmacogenetic-recommended tacrolimus dosing. During this initial phase, all patients were administered standard tacrolimus dosing, and clinical and reimbursement outcomes were collected. Greater than 99.5% of genotyping claims were reimbursed by third-party payers. CYP3A5 normal/intermediate metabolizers had significantly fewer tacrolimus trough concentrations within the target range and a significantly longer time to their first therapeutic trough compared to poor metabolizers. The challenge of tacrolimus dosing is magnified in the African American population. The US Food and Drug Administration drug label recommends increased starting doses in African ancestry, yet only ≈66% of African Americans in our cohort were normal/intermediate metabolizers who required higher doses. Routine CYP3A5 genotyping may overcome this issue by using genotype over race as a more accurate predictor of drug response.
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    Polymorphisms in drug-metabolizing enzymes and steady-state exemestane concentration in postmenopausal patients with breast cancer
    (Springer Nature, 2017-12) Hertz, Daniel L.; Kidwell, Kelley M.; Seewald, Nicholas J.; Gersch, Christina L.; Desta, Zeruesenay; Flockhart, David A.; Storniolo, Ana-Maria; Stearns, Vered; Skaar, Todd C.; Hayes, Daniel F.; Henry, N. Lynn; Rae, James M.; Medicine, School of Medicine
    Discovery of clinical and genetic predictors of exemestane pharmacokinetics was attempted in 246 post-menopausal patients with breast cancer enrolled on a prospective clinical study. A sample was collected two hours after exemestane dosing at a 1 or 3 month study visit to measure drug concentration. The primary hypothesis was that patients carrying the low-activity CYP3A4*22 (rs35599367) SNP would have greater exemestane concentration. Additional SNPs in genes relevant to exemestane metabolism (CYP1A1/2, CYP1B1, CYP3A4, CYP4A11, AKR1C3/4, AKR7A2) were screened in secondary analyses and adjusted for clinical covariates. CYP3A4*22 was associated with a 54% increase in exemestane concentration (p<0.01). Concentration was greater in patients who reported White race, had elevated aminotransferases, renal insufficiency, lower body mass index, and had not received chemotherapy (all p<0.05), and CYP3A4*22 maintained significance after adjustment for covariates (p<0.01). These genetic and clinical predictors of exemestane concentration may be useful for treatment individualization in patients with breast cancer.
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    Precision medicine to identify, prevent, and treat pediatric obesity
    (Wiley, 2024) Tillman, Emma M.; Mertami, Selsbiel; Medicine, School of Medicine
    Pediatric obesity is a growing health concern that has many secondary adverse health implications. Personalized medicine is a tool that can be used to optimize diagnosis and treatments of many diseases. In this review, we will focus on three areas related to the genetics of pediatric obesity: (i) genetic causes predisposing to pediatric obesity, (ii) pharmacogenomics that may predict weight gain associated with pharmacotherapy, and (iii) pharmacogenomics of anti-obesity pharmacotherapy. This narrative review evaluates genetic cause of pediatric obesity and how genetic findings can be used to optimize pharmacotherapy to minimize weight gain and optimize obesity treatment in pediatric patients. Pediatric obesity has many genetic causes including genomic obesity syndromes and monogenic obesity disorders. Several genetic etiologies of obesity have current or emerging targeted genetic therapies. Pharmacogenomic (PGx) targets associated with pharmacotherapy-induced weight gain have been identified for antipsychotic, antiepileptic, antidepressant therapies, and steroids, yet to date no clinical guidelines exist for application use of PGx to tailor pharmacotherapy to avoid weight gain. As legislation evolves for genetic testing coverage and technology advances, this will decrease cost and expand access to genetic testing. This will result in identification of potential genetic causes of obesity and genes that predispose to pharmacotherapy-induced weight gain. Advances in precision medicine can ultimately lead to development of clinical practice guidelines on how to apply genetic findings to optimize pharmacotherapy to treat genetic targets of obesity and avoid weight gain as an adverse event associated with pharmacotherapy.