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    Mayo experts provide insights into how genes affect medication response

The Mayo Clinic Center for Individualized Medicine team at this year's Clinical Pharmacogenomics Symposium in Florida.

Pharmacogenomics – how a person’s genes affect medication response – is touching virtually every area of medical care.  Findings from the Mayo Clinic RIGHT study (Right Drug, Right Dose, Right Time–Using Genomic Data to Individualize Treatment) showed that 99% of participants had at least one genetic variant that may affect their response to medications.   

But for many health care providers, understanding the rapidly advancing field of pharmacogenomics and how it applies to the patients they care for, can be a challenge. To help bridge this knowledge gap, Mayo Clinic Center for Individualized Medicine recently held a Clinical Pharmacogenomics Symposium on the Mayo Clinic campus in Florida. Providers and pharmacists from Mayo Clinic and other institutions gathered to learn firsthand how pharmacogenomics is already guiding clinical care.    

William Palmer, M.D.

“As part of our mission, the Center for Individualized Medicine is committed to educate health care providers about how to translate genomics discoveries into patient care. This symposium was a perfect example of that effort, and we received glowing feedback from attendees and speakers for our case-based approach. This model offers physicians practical ways to incorporate pharmacogenomics into the selection of the best, individualized therapy for patients,” says William Palmer, M.D., a gastroenterologist at Mayo Clinic’s campus in Florida.

Mayo pharmacogenomics expert, Richard Weinshilboum, M.D., kicked off the symposium followed by Mayo pharmacist Michael Schuh, Pharm.D., R.Ph., who presented Pharmacogenomics 101 to introduce the underlying concepts of using genomics to guide treatment decisions.

Michael Schuh, Pharm.D., R.Ph.

“For many medications, pharmacogenomics may help predict whether a patient will benefit from the therapy or be at risk for suffering serious, sometimes life-threatening side effects,” says Dr. Schuh.

Highlights from the event showcase the pivotal role pharmacogenomics is already playing across many medical specialties.  

Breast cancer

Approximately 75% of breast cancers are estrogen receptor positive, meaning the cancer cells grow in response to the hormone estrogen. Many of these patients benefit from anti-estrogen therapies, such as tamoxifen and aromatase inhibitors, to reduce the risk of cancer recurrence after surgery.

Lauren Cornell, M.D.

However, some patients have variations in the CYP2D6 gene that may prevent them from processing these medications normally and benefitting from the treatment.

“Pharmacogenomics testing can help identify those patients who process these drugs too slowly or too rapidly. In these cases, physicians can consider whether to adjust the medication dose or select a different therapy,” explains Mayo Clinic internist Lauren Cornell, M.D.

Neurological diseases

William Freeman, M.D.

Pharmacogenomics testing can also play a key role in identifying those patients who take anti-seizure medications who may be at risk for developing serious side effects.

“Three of four commonly used anti-seizure medications carry a risk for life-threatening skin reactions,” says William Freeman, M.D., a neurologist at Mayo Clinic’s campus in Florida. “Patients with certain variants are at increased risk for developing Stevens-Johnson syndrome, a rare skin disorder that requires emergency treatment and hospitalization. In the future, I hope technology will help us identify these patients before treatment, so an alternative therapy can be used.”  

According to Dr. Freeman, pharmacogenomics can also play a key role in the treatment of patients who suffer from a ruptured aneurysm in the brain (aneurysmal subarachnoid hemorrhage), a life-threatening condition.

“Each year, 30,000 patients will suffer from a ruptured aneurysm. While the drug nimodipine can be an effective treatment, those patients with certain genetic variants may develop low blood pressure (hypotension) with this therapy. Pharmacogenomics testing can help us identify those patients at risk, so we can individualize dosing and ensure the best outcomes,” says Dr. Freeman.


Eric Matey, Pharm.D., R.Ph.

According to Mayo Clinic pharmacist Eric Matey, Pharm.D., R.Ph., 16.2 million adults in the U.S. had at least one major depressive episode and 50% of those individuals received medication therapy in 2016.

“Studies have shown that even for those patients who take commonly used medications, known as selective serotonin reuptake inhibitors, only approximately one third of them achieve remission from their symptoms,” says Dr. Matey.

He presented two cases where pharmacogenomics testing helped identify alternative therapies that enabled patients to finally find relief from depression.

“Often times, patients experience increasing side effects as they try multiple antidepressants, all the while still suffering from their depression symptoms. Pharmacogenomics testing can play a key role in helping physicians identify the right therapy the first time,” Dr. Matey says.

Reducing the risk of addiction

Sanjay Bagaria, M.D.

As the number of opioid overdose cases rise, physicians are exploring how pharmacogenomics testing can help guide the prescribing of these potentially addictive therapies.

“While we are working to reduce the quantity and duration of opioids being prescribed after surgery, pharmacogenomics can also provide critical information to improve recovery,” says Sanjay Bagaria, M.D., Mayo Clinic surgeon, and Cecilia and Dan Carmichael Family Associate Director for the Center for Individualized Medicine in Florida

“Some patients have genetic variants that cause them to process pain medications more slowly. If we have pharmacogenomics test results prior to surgery, it helps guide the selection of the most appropriate therapy for each patient and may reduce the risk for addiction.”

Read more about Mayo Clinic’s pharmacogenomics research

The latest advances in cancer care

Learn more about pharmacogenomics at the Individualized Medicine 2019 pre-conference sessions on September 20, 2019 in Scottsdale, Arizona.

Other key conference themes include:

  • CAR-T cell therapy
  • Clonality
  • Pharmacogenomics
  • Lineage Plasticity
  • National Cancer Institute match

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