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Mark W Linder, Ph.D., DABCC, FACB Medical Director, EVP Operations Kristen K. Reynolds Ph.D. Associate Medical Director, VP Laboratory Operations Mark P. Borgman, Ph.D. Assistant Medical Director, Director of Laboratories Copyright 2010-12 PGXL Laboratories LLC, Louisville KY All materials herein are the exclusive property of PGXL laboratories
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Enabling Personalized Medicine Intuitive Medicine Precision Medicine Indicators Suggest: Diagnostic services will trump therapeutics ( Clayton M Christenson in: The Innovator’s Prescription, MaCGraw Hill, 2009)
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~60% of meds in top 20 list causing ADRs are linked to a genetic variation 122 drugs have FDA box warnings related to genetics
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4 Clinical Applications of Pharmacogenetic Information Anti-coagulation – Warfarin – Plavix (clopidogrel ) Psychiatry – Anti-depressants Oncology – Thiopurines – Tamoxifen – EGFRi’s Pain management – Codeine – Methadone Epilepsy – Phenytoin – Carbamazepine Diabetes – Glipizide
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Application of Pharmacogenomics to Anti-platelet therapy
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6 Clopidogrel (Plavix) activation. PharmGKB.org
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7 Antiplatelet Response ~ 30% of patients have deficiency in CYP2C19 – CYP2C19 *1/*2 (28%) – CYP2C19 *2/*2 (2%) Decreased activation of clopidogrel – Decreased amount of active metabolite – High on-treatment platelet reactivity
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Influence of CYP2C19 on Clopidogrel Response
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TreatmentCV EventsBleed EventsICER Genotype guided813340 Clopidogrel1210380$ 6,790 Prasugrel990500$ 11,710 Cost-effectiveness comparisons Reese, E.S. et. al., Pharmacotherapy 2012;32(4):323–332
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Application of Pharmacogenomics to warfarin therapy
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11 The Problem Reynolds et al. Pers Med 2007;4(1):11-31.
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12 40% of population have deficient CYP2C9 > 70% of population have decreased VKOR and are more sensitive to warfarin Genetics of Warfarin metabolism and response
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Accumulation Steady-State Linder et al. J Thrombosis & Thrombolysis 2002;14:227-232 13 CYP2C9 status increases magnitude of accumulation/unit dose as well as time to achieve steady-state CONFIDENTIAL
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VKORC1 -1639 G>A genotype dictates S-warfarin therapeutic concentration Dose 2.7 ± 1.2 mg Dose 4.2 ± 2.2 mg Dose 6.7 ± 3.3 mg All within INR 2-3 Zhu Y et al. Clin Chem 2007;53(7):1199-1205. 14 CONFIDENTIAL
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Calculation of estimated maintenance dose Modeling of individualized response to dose changes Guidance for: Monitoring strategy Dosing modifications Transition: induction to maintenance therapy 16 PerMIT:Warfarin © Powered by PG XL Laboratories CONFIDENTIAL
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All; 66 y/o, female, 130 lbs
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18 Concentration/Response Time Profile Genotype: CYP2C9*1*2 // VKOR C1 GG Estimated Maintenance dose: 6.3 mg/d (5.7 – 7.0) Time to Steady-State; 11 to 15 days Target therapeutic concentration: 0.8 mg/L...... 6 mg/d.......10, 10, 8, 6 mg/d Linder MW et al. 2011 (unpublished results) CONFIDENTIAL
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State-of-the-art estimation of optimal warfarin doses, from induction to transitional, maintenance, and INR- adjustment dosing Dynamic and interactive tools that respond physician decisions Ongoing application of PGx results Minimized risk of out-of-range INRs
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Randomized Control Pilot Trial In collaboration with the University of Utah Standard of care vs PerMIT:warfarin Target enrollment of 15 subjects per arm Outcomes Time to first therapeutic INR Time to stable therapy Overall time in range Incidence of above range INR’s
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Outcomes
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Fundamental Principles Genetic variability in drug metabolism significantly increases risk of ADRs and non-response Genetic variation can be managed : Poor Metabolizers Decreased maintenance dosing (20 – 70% ) Increased pro-drug dosing Allow longer time to reach Steady-State Allow longer time between medication changes Increased observation Choose alternative medication Rapid metabolizers Increased dosages (50 – 200%) Decreased pro-drug dosages
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Clinical Implementation – Identify conflicts – Assess impact on care – Manage conflicts Avoid pro-drugs in PM’s Increase or decrease dosing Alert/inform patient of potential side-effects
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Thank You
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