pharmacogenetic testing and individualized medicine
TRANSCRIPT
PHARMACOGENETIC TESTINGAND
INDIVIDUALIZED MEDICINE:
THE ANSWER WE’VE BEEN WAITING FOR?
BRADY BRADSHAW, MDCENTRAL FL ASSOCIATION OF MARRIAGE & FAMILY THERAPISTS
October 1, 2020
OUTLINE
• Patient Case
• Genetics in Medicine
• Testing in Medicine
• Pharmacogenetic testing in Psychiatry
• Patient cases
PATIENT CASE
CASE 1- AMY
• Amy- 40 yo female w/ established diagnosis of Bipolar I
• Current presentation- Horribly depressed, despite multiple medications
• History of psychiatric hospitalizations x 3
• Prev psychiatrist had referred for ECT
MEDICATION HISTORY- PREVIOUS
• SEROQUEL XR 200mg- helpful, but weight gain [antipsychotic, mood stab]
• SAPHRIS 10mg- cannot recall effect, took for 5 months [antipsychotic, mood stab]
• LATUDA unk dose- akathisia [antipsychotic, mood stab]
• REXULTI- unk dose- dystonic reaction within days [antipsychotic, mood stab]
• LEXAPRO- unk dose, many years ago, did not like how she felt [antidepressant]
• AMBIEN- not effective [sedative, hypnotic]
MEDICATION HX- CURRENT MEDS
• LAMICTAL 400mg- unsure when started or if helpful [mood stab]
• LITHIUM ER 600mg- since 2015, when inc dose, supratherapeutic [mood stab]
• TOPAMAX 100mg- for migraines [mood stab]
• WELLBUTRIN XL 300mg- started 2016 [antidepressant]
• CLONAZEPAM 1mg- for anxiety [anxiolytic]
SHE GETS A TEST!
BASICS OF GENETIC TESTING
GENETICS IN MEDICINE
• What is a gene?
• Human Genome Project
• Cystic Fibrosis, cancer
• https://ghr.nlm.nih.gov/primer/basics/gene
INDIVIDUALIZED MEDICINE
• Precision, personalized medicine
• Treat disease earlier and more effectively?
• Taking into account unique differences in metabolism of medications
• Less side effects?
• More effective medications?
• Getting to the “right” medicine more quickly and without negative medication trials
PHARMACOGENETICS
• How psychiatry does personalized medicine
• Selection of medication based on genetic factors associated with drug response and tolerability
• Tolerability- how a drug effects you, both positive and negative side effects
• Humans vary genetically- including in how we metabolize drugs
TESTING IN MEDICINE-LABORATORY AND IMAGING
When and Why do we do it?
LAB TESTS IN MEDICINE
• What are we measuring?
• Should accurately measure what the test says it is measuring
• Why are we measuring it?
• What are we going to do with the results?
• Does the result impact outcome?
• Does the result impact morbidity/mortality?
LAB TEST EXAMPLE
• TSH- Thyroid functioning
• Considered standard of care when evaluating depression/anxiety sx
• If abnormal, patient would get thyroid treated first, before AD treatment
• If abnormal, getting treatment for thyroid disease early prevents worsening disease, gets patient better faster
LAB TESTING GONE AWRY
• Testing without knowing what you are looking for
• May have an abnormal result, but does not change the outcome
• E.g. Cortisol in depression
• May get a result you do not know what to do with- incidental findings
• Costly for patient/health care system
• Create anxiety for incidental findings
How Does it Measure Up?
PHARMACOGENETIC TESTING (PGT)
PHARMACOGENETIC TESTING
• Many different brands- Genesight
• What does it measure?
• Pharmacokinetics (P450):
• Three metabolic enzymes: 2D6, 2C19, 1A2
• Pharmacodynamics:
• SLC6A4- serotonin transporter gene
• HTR2A- serotonin 2A receptor gene
P450 ENZYMES
• We are talking about the genes encoding these enzymes
• Present in most tissues in the body
• In the liver- break down medications
• Some medications can increase or decrease the activity of specific enzymes, affecting how a drug is metabolized
• Drug-drug interactions
• Other substances can also interact and affect the action of these enzymes- e.g grapefruit juice, Saint John’s Wort, Tobacco smoking
• Small percentages of individuals have over or under-active enzyme types
THE CLAIM
• Genesight claims that the provider can get to the right medication sooner, and that patients will feel better faster
• Based on the assumption that knowing an individual’s genetic information regarding these enzymes will equate to choosing the right medication sooner
HOW IS IT DONE?
• Cotton cheek swabs collect the DNA
• Results overnighted to Assurex
• MD receives results in 36 hours
• Reports on 38 psychotropic medications,
also ADHD medications
THEORETICALLY…Great! I’ll just choose a green medication for my
patient!
BUT WHAT DOES THE DATA SHOW?
THE DATA FROM GENESIGHT
• Positive studies were poorly designed
• Well-designed studies were negative
• Genesight’s newest study- 1167 subjects, randomized but not blind. Found that there were no significant differences between the two groups- Depression severity and time to remission
PHARMACODYNAMICS DATA
Data do not support this theory
The serotonin transporter gene-In theory, short version of this
gene predicts lower response and more side effects w/ SSRI’s
THE FDA
• November 2018- Recommended against pharmacogenetic testing
• Test’s claims have not been reviewed by FDA
• Not supported by FDA-approved drug label
• “Inappropriately selecting or changing drug treatment based on the results from insufficiently substantiated genetic tests, could lead to potentially serious health consequences for patients.”
• “The relationship between DNA variations and the effectiveness of AD medications has never been established.”
• “…Could potentially lead to patient harm.”
• https://www.fda.gov/medical-devices/safety-communications/fda-warns-against-use-many-genetic-tests-unapproved-claims-predict-patient-response-specific
DATA WE DO HAVE
• Clinical Pharmacogenetics Implementation Corsortium (CPIC) and the FDA
• List of drug-gene interactions that are valid and reliable
• These are considered “informative” but not “actionable.”
• Meaning, it is not suggested to check these routinely
CLINICAL VIGNETTES
OUTCOMES- AMY
• Green Medications- She is taking and not effective
• Red medications- Saphris, Rexulti, Sertraline
• Red warning- Will need higher doses
• Patient had severe negative side effect to very low doses
• Was this helpful?
ANOTHER APPROACH
• Taking a good history
• Does a patient tend to be sensitive to side effects?
• Does a patient tend to respond to higher/lower doses?
• Are we treating the correct diagnosis (if non-response)?
CASE 2- ROSE
• Rose is a 40 yo female w/ hx of Generalized anxiety d/o and ADHD
• Current presentation- easily overwhelmed, anxious, disorganized
• During the history, patient reports a history of sensitivity to medication
• Sleep also sensitive to sugar, exercise
MEDICATION HISTORY- PREVIOUS
• ADDERALL 5mg- insomnia [amphetamine stimulant]
• VYVANSE- insomnia [amphetamine stimulant]
• RITALIN 10mg- insomnia [methylphenidate stimulant]
• WELLBUTRIN unk dose- insomnia [antidepressant]
• LEXAPRO- unk dose- felt numb, sleepy [antidepressant]
WHAT DO WE KNOW ABOUT ROSE?
• She is very sensitive to medications
• She needs medication that is short-acting
• She needs better coverage for her anxiety- PRN not sufficient
• She needs to be started at very low doses of medication
• She will be sensitive to fine changes in medication- increase gradually
CURRENT MEDS- STABLE
• SERTRALINE 75MG- started at 12.5mg [antidepressant]
• RITALIN 5MG- takes ¼ of a pill, PRN [methylphenidate stimulant]
• XANAX 0.25mg- takes ¼ of a pill PRN [benzodiazepine]
CONCLUSIONS
TAKE HOME POINTS
• The field of genetics and bioinformatics is exciting and has major potential
• For psychiatry specifically, data do not support routine use of pharmacogenetic testing
• Testing does not change outcomes
• FDA recommends against testing
• May have negative impact on patient care
• Careful history may be more effective
• Patient preference- once given education
REFERENCES
• Aiken, Chris, MD. (2019). A Second Look at Genetic Testing. The Carlat Report, March 2019.
• Bradley, P, Shiekh, M, Mehra, V, et al. (2018) Improved Efficacy with targeted pharmacogenetic-guided treatment of patients with depression and anxiety: A randomized clinical trial demonstrating clinical utility. Journal of Psychiatric Research. 96. 10.1016
• Carlat, Daniel, MD. (2015) The GeneSight Genetic Test: A Review of the Evidence, May 2015. https://www.thecarlatreport.com/newsletter-issue/tcprv13n5/
• FDA warning: https://www.fda.gov/medical-devices/safety-communications/fda-warns-against-use-many-genetic-tests-unapproved-claims-predict-patient-response-specific
• Hamilton, Steven, PhD, MD. (2019) The Uses of Pharmacogenetic Testing. The Carlat Report
• Howland, Robert H. MD. (2014) Pharmacogenetic Testing in Clinical Psychiatry. The Carlat Report, October 2014. https://www.thecarlatreport.com/the-carlat-psychiatry-report/pharmacogenetic-testing-clinical-psychiatry/
• Moran, Mark. “Psychiatric News” What Pharmacogenetic Testing Can, Can’t Tell You About Your Patient, Psychiatry Online, 16 Feb 2019, https://psychnews.psychiatryonline.org/doi/10.1176/appi.pn.2018.pp2b2
• Perez, V., Salavert, A, Espadaler, J et al. (2017) Efficacy of prospective pharmacogenetic testing in the treatment of major depressive disorder: results of a randomized, double-blind clinical trial. BMC Psychiatry. 17:250. 10.1186/s 12888-017-1412-1