It’s time to dive into pharmacogenomics

Pharmacogenomics (PGx) is a rapidly growing area of precision medicine that is moving us away from a one-fits-all approach to prescribing towards one that considers inter-individual variations to drug response. Its potential to improve patient outcomes and to reduce not only healthcare costs but also costs to society is vast. And pharmacists are uniquely positioned to be at the forefront of pharmacogenomic implementation and to lead the way for other healthcare professionals.Lindsay Dixon, a pharmacist in Victoria, B.C., knows personally the importance of pharmacogenomic testing. About 10 years ago, she saw firsthand the effects of Stevens-Johnson syndrome when her younger brother was prescribed carbamazepine for a mild form of epilepsy. Stevens-Johnson syndrome is rare, but it can be life-threatening. It is a severe adverse drug reaction that can occur with certain medications, causing painful blistering of the skin and mucous membranes and can lead to serious eye problems.“It was crazy! I sat there with him, and he was all swollen up and his skin was peeling off,” she says. The syndrome progressed to where her brother lost all of his skin; it was devastating for her family.Dixon’s brother was in his early 20s and spent a few days in hospital. It took him at least two months to recover.Dixon later did a pharmacogenetic self-test, which is done by a simple cheek swab. Her profile showed in red that she should not be prescribed carbamazepine. Dixon realized that if her brother had done a pharmacogenetic test before being prescribed carbamazepine, he would have been prescribed another medication and never had to go through what he did. Her profile also showed that she is a very poor metabolizer of opioids, which explained why she didn’t experience pain relief from the analgesics she was given after her C-sections. Now, she’s having her whole family tested.Pharmacogenomic testing is not only important in preventing severe adverse drug reactions (ADRs), but it is also important in pinpointing which drugs will be effective and tolerable for patients.Jaclyn Katelnikoff, a pharmacist at Saskatoon Family Pharmacy in Saskatoon, SK, had a patient come to her who had been struggling for two years with side effects from medication she took for her mental health, despite trying several different options.Katelnikoff recommended that the patient do a pharmacogenomic test, which the patient agreed to. After interpreting the results, Katelnikoff made a recommendation for a medication change, which eliminated all the side effects. “The doctor was quite impressed that we fixed things so quickly,” Katelnikoff says.However, even if a person metabolizes the medication correctly, a patient may still have side effects, which is hard for people to understand, Katelnikoff says. She tells patients: “I have always learned something from [pharmacogenomic tests], never nothing—for either future you or current you—but this might not tell us why you’re having side effects. You could just be having side effects.”Conceptually, pharmacogenomics has been around for decades, but clinical implementation of pharmacogenomics is fairly recent, says Chad Bousman, associate professor in the department of genetics at the University of Calgary. (The Human Genome Project, which mapped and sequenced the human genome, was completed in 2003.) In Canada, we are in the early adopter phase, like many countries in the world. The U.S. is further ahead in the adoption of pharmacogenomics, largely due to benefit management programs that cover the cost of testing.In Canada, pharmacogenomic testing is still generally an out-of-pocket expense, with costs ranging from $200-$300 to over $1,000, depending on the range of the testing. However, more private health insurance companies are offering partial or full coverage of PGx testing, says Stacey D’Angelo, pharmacist and founder of Your Simple Health in Toronto.Because pharmacogenetic testing is not paid for by the health system, pharmacists in Canada are not getting a lot of practice in interpreting test results. However, Bousman thinks this will change once payers see the value in covering the tests and begin reimbursing the expense. Dixon agrees and thinks that third-party insurance companies will get onboard once they see the cost savings possible by avoiding the expense and human downtime associated with multiple prescription trials.D’Angelo points out that there is still a lack of awareness about pharmacogenomics not only among the public, but also among healthcare providers, including pharmacists. However, she adds, pharmacogenomics is coming down the pipe, whether we like it or not.“I strongly believe pharmacists are the right provider to champion this and to be involved in the interpretation side,” she says. “It’s a medication issue, and we’re the drug experts.”Bousman agrees that pharmacogenomics should live with pharmacy. Even though pharmacogenomics is a matchup of medications, drugs and genetics, the pharmacist comes to the table with the drug expertise, and that’s arguably the harder half, he says. He adds that you don’t have to be a geneticist to understand the genes at the level that they are used in pharmacogenomics.Another big barrier to clinical implementation is the time factor of interpreting the results, and healthcare professionals are not paid for this time, D’Angelo says.“A lot of these tests can come with 30 to 50 pages of results, it’s pretty complex information,” she says. Tests give a list of medications and the gene variants and are classified in a traffic light system: red means don’t use the medication; yellow, use with caution; and green, use as prescribed.There are a lot of things to consider when interpreting the results, D’Angelo says, such as: What’s going on with the patient? What are the symptoms that are bringing them in for help? What are their comorbidities? Are there drug interactions we need to consider? What are their past medication experiences?To test or not to test?The test results give guidelines, but there are no guidelines for who and when to test, Bousman adds. “And that’s the tricky bit.”For example, a patient may ask about pharmacogenomic testing before starting a medication, and then the pharmacist or physician is left counselling the patient as to whether they should or should not have testing.“It’s probably the number one question I get asked by physicians,” Bousman says. “And it’s always an ‘it depends’ kind of an answer.”There are a lot of different factors involved in making the call on whether to test or not. For example, what drug is being considered? If there is not a lot of pharmacogenomic information about the drug, it may not be worth doing the test at the present time, Bousman says. Comorbidities and other drugs that the patient is taking are also considerations.Deciding who should have testing is challenging for pharmacists who are just new to pharmacogenomics, Bousman says. This is where you need a champion who you can reach out to and consult with, he says, adding that he doesn’t see any harm in doing testing.How to learn about pharmacogenomics can be another challenge for pharmacists because there is no formal Canadian course for community pharmacists.Today, while all Canadian pharmacy schools are offering pharmacogenomic courses, it might just be a one-off course, Bousman says. Practising pharmacists can take continuing education, but Bousman recommends they become familiar with current guidelines, particularly those that are relevant to their practice.The Pharmacogenomics Knowledge Base (PGKB.org) is the best place to start, Bousman says. He describes it as a one-stop shop and uses it every day. “It’s like the Wikipedia for pharmacogenomics; you type in a drug or a gene and away you go.”There is also the Clinical Pharmacogenetics Implementation Consortium (cpicpgx.org), which creates the dosing guidelines that are based on pharmacogenomics, and it provides a list of genes and the medications they affect. The U.S. Food and Drug Administration (FDA) also has free resources.The Pharmacogenomics Global Research Network is another resource for pharmacists. The word research shouldn’t scare pharmacists off, Bousman says, describing the organization as a network of people that are experts in the field of pharmacogenomics. They have weekly educational seminars, lots of resources and an annual meeting.For more information about pharmacogenomic testing, the Genome BC website has a handout for clinicians with a link to a list of PGx tests available to Canadians and information on how to identify a good PGx test.Katelnikoff recommends doing a pharmacogenetic self-test, as Dixon did, and looking for things that are in your past or could be in your future. That’s how her learning began.Bousman says the most important thing pharmacists can do is just start into pharmacogenomics in a targeted way. “Dive into a specific part of it,” he says. “Don’t try to learn everything in one big gulp, that’s not going to happen.”But get off the fence and get in!” he urges.

It’s time to dive into pharmacogenomics

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