Ever wondered why a particular drug worked well for your friend but not for you? Turns out your genes are to blame.
Your body contains thousands of genetic combinations that you inherited from your parents when you were conceived. These genes provide the blueprint for everything that makes you unique. Moreover, some of these genes determine how your body processes and interacts with medications.
Pharmacogenomics studies your genetic information and looks for genetic variations that can influence your response to medication.
Currently, medicines are prescribed as though they work the same way for everybody. Of course, doses are typically adjusted according to the age, weight, and gender of a patient. However, this doesn’t account for genetic variations.
Depending on the gene variants you carry, you may or may not respond to a drug as others do. Likewise, you may experience more side effects than others.
With pharmacogenomics, your physician can design a treatment plan based on what will work best for you and not what works for everybody else.
The Inner Workings of Pharmacogenomics
When you take a drug, it goes through multiple pathways before your body can actually start using it. From absorption to transportation, attachment, and metabolism, your DNA can influence every part of this process.
For drugs to be effective, they need to be able to attach to cell receptors. Receptors are proteins located along the surface of cells. They are a crucial point of messaging between cells and are a starting point for biological activity.
As you may have guessed, your genes determine the type and amount of receptors you have. This can have significant effects on your treatment plan.
For example, HER2-positive breast cancers have higher than normal levels of the human epidermal growth factor receptor. This means that this type of breast cancer grows and multiplies faster than other types.
HER2-positive breast cancer doesn’t respond to any single chemo drug. So, women with HER2-positive breast cancer typically need one or two chemo drugs plus trastuzumab. Trastuzumab (Herceptin) is a monoclonal antibody that directly targets the HER2 receptor.
Some gene variants can directly affect the cellular uptake of drugs. Also, there are variants that influence how quickly some drugs are removed from their target cells. If they’re removed too quickly, they may not have a chance to work.
Let’s take selective serotonin reuptake inhibitors (SSRIs) as an example. SSRIs are the first line of treatment for depression. They work by increasing the levels of the happy hormone serotonin in the brain. To do this, they block the serotonin transporter.
This allows serotonin levels in the brain to remain higher for longer.
However, some pharmacogenomics studies suggest that a mutation in the serotonin transporter gene impacts the effectiveness of SSRIs. This might explain why less than 50% of individuals given SSRIs as first-line therapy for depression actually show improvement.
If you have lower CYP2D6 activity, you may achieve higher drug levels and more symptom relief. But, you may also experience magnified side effects even with normal doses.
In contrast, higher enzyme activity means you break drugs down too quickly. If you’re a rapid metabolizer, you won’t get as much out of a drug.
Pharmacogenomics vs Pharmacogenetics
Pharmacogenetics studies how a single gene influences disease risk and drug responses. On the other hand, pharmacogenomics is much broader. It studies how the entire genome simultaneously affects drug response.
Together, pharmacogenetics and pharmacogenomics are moving healthcare away from a one-size-fits-all approach.
Improving Patient Care Through Pharmacogenomics
Pharmacogenomics is driving healthcare from a one-size-fits-all approach to a targeted, more precise science. Here’s how it’s being used to advance patient care.
Pharmacogenomics has been most impactful in changing cancer care. Currently, pharmacogenomics testing is done to guide targeted cancer therapies based on tumor type.
Monoclonal antibodies are a prime example of targeted cancer therapy. By targeting key mutations and proteins that drive cancer growth, monoclonal antibodies have improved survival rates for many different cancers.
However, monoclonals don’t work for all types of cancer. The monoclonal antibodies gefitinib and erlotinib work best for patients with certain types of lung tumors. Meanwhile, cetuximab and panitumumab only work for colorectal cancers with EGFR mutations.
Furthermore, scientists have identified specific gene variants that can cause chemo toxicity. If you have one of these mutations, your oncologist will adjust the dose or choose another drug based on your genetic profile.
Prevention of Hypersensitivity Reactions
For certain drugs, routine testing for gene mutations can identify and avoid hypersensitivity reactions. For example, mutations in the HLA gene can cause severe side effects for patients taking abacavir. Abacavir is an antiviral drug used to manage HIV.
Hypersensitivity occurs in up to 8% of patients taking abacavir. Reactions can range from mild fever and rashes to severe toxic epidermal necrolysis.
Other drugs also associated with severe hypersensitivity reactions include allopurinol (used to treat gout and kidney stones) and carbamazepine (prescribed for seizures). Pharmacogenomics can help identify hypersensitive patients so providers can prescribe an alternative drug or treatment.
Pharmacogenomics testing is emerging as an important tool in cardiovascular care. Testing has become the standard of care at some healthcare institutions.
Practitioners routinely test for gene variants that can affect responses to three-widely used drugs. These include warfarin, clopidogrel, and simvastatin. Some people have certain mutations that affect their sensitivity to these drugs.
Meanwhile, others have mutations that affect their ability to remove them.
Testing for these mutations can help your physician calculate the dose that’s most effective and safest for you.
Finding a drug that works for you is just half the battle with chronic disease management. The other half is actually about complying with your treatment plan.
Pharmacogenomics can improve your adherence to a treatment plan by:
Genes can’t explain everything. Your genes determine how your body responds to many drugs. However, pharmacogenomics still can’t explain how the body interacts with the vast majority of drugs on the market (e.g., aspirin).
Cost. Although pharmacogenomics testing can reduce costs in the long term, the tests can be expensive. Public health plans in Canada currently don’t cover pharmacogenomic tests. So, you can expect to pay from $199 to $2,000 out-of-pocket.
Accessibility of relevant testing. Pharmacogenomics testing is not yet widely adopted in clinical care. Official guidelines for routine testing do exist. However, there are also no official guidelines that standardize what tests laboratories should do or how they should interpret the results.
Slow turn-around. Some patients must wait from 15 to 40 days for test results. This is hardly ideal for acute illnesses.
How Is Pharmacogenomics Testing Performed
Pharmacogenomic testing is simple and non-invasive. When you undergo a pharmacogenomics test, a laboratory technician swabs the inside of your cheeks to get a DNA sample. Then, your DNA sample is secured and sent for processing.
The sample collection shouldn’t take more than a few minutes. Alternatively, you can do it yourself with a direct-to-consumer pharmacogenomics test kit.
Truly Personalized Healthcare Is Just One Step Away
Modern healthcare saves millions of lives each day. But sometimes, even the most advanced diagnostic tools and strongest evidence-based care can miss their mark.
Pharmacogenetics shows us a better, more precise way of doing healthcare. At SRx Health, we strive to provide proactive, personalized patient-oriented care guided by your genes.
Learn how SRx Health can help you tap into your genome to optimize your health.
What if there was a precise science that could pinpoint the one drug that, at the right dose, could make all the difference? Enter pharmacogenomics.
One of the hardest parts of treating an illness is finding the medication that works for you. This is often a costly trial-and-error process.
You could go through different classes of drugs before the right one comes along. Sometimes, the first drug you try may be effective enough but also cause intolerable side effects.
Pharmacogenomics presents a viable solution to this problem. Let’s discover why.