Precision Medicine vs Trial and Error: Why Pharmacogenomics is Increasingly Relevant

Pharmacogenomics looks at how genetic influences affect an individual’s response to therapeutic medications. Rather than taking the approach that therapy for all people with a certain health condition should begin with the same medication at the same dose, pharmacogenomics has the potential to enable personalized medicine selection and dosing to a degree not previously possible.

As of late 2021, 180 approved drugs were labeled by the U.S. Food and Drug Administration (FDA) with genetic factors. While many pharmaco-economic studies suggest that pharmacogenomic testing is cost-effective, a growing body of evidence also highlights the clinical impact of pharmacogenomics.

Estimates indicate that more than 98% of people in the U.S. carry at least one high-risk genomic variant in one of the 12 most-tested pharmacogenetic genes. Presence of such variants suggests that treatment with relevant medicationsmay need to be altered to avoid side effects or optimize efficacy. Therefore, the traditional one-size-fits-all, trial-and-error approach to medication management is inherently risky.

For these reasons and more, providers and payers are increasingly leaning into the potential of pharmacogenomics to select the best therapy for a patient, improve outcomes, reduce downstream costs, and deliver higher-value care.

Care costs reflect care effectiveness

Providers have known for years that two patients on the same drug regimen may respond very differently. One patient may clearly improve, while the other doesn’t, or may even suffer an adverse drug reaction. Prescription drugs in the U.S. cause an estimated 2.74 million adverse drug reactions and 128,000 deaths annually

Additionally, prescription drug-related morbidity and mortality resulting from non-optimized medication therapy costs an estimated $528.4 billion annually in the U.S. These data demonstrate that patients can suffer both clinically and financially when a new prescription results in treatment failure and/or new medical problems that cost $2,610 on average.

It’s not just researchers taking notice of the clinical and financial costs of this situation. U.S. Congressional delegates recently introduced legislation aimed at helping patients avoid adverse drug reactions, emergency room visits, and worsening illnesses related to being on a medication or a dosage that is incompatible with their genotype.

The Right Drug Dose Now Act (H.R.6875) was introduced on Feb. 28, 2022. Its goal is to update the National Action Plan for Adverse Drug Event Prevention with education about how pharmacogenomic testing can help reduce adverse drug events. It also includes funding to integrate pharmacogenomic information into electronic health records (EHRs) so that when providers are prescribing medications for their patients, they can access and utilize information about thepatient’s genotype and potential outcomes at the point of decision-making.

Pharmacogenomics can advance precision medicine

Knowing a patient’s pharmacogenomic profile can add valuable information when trying to decide the right treatment. That’s because ourgenetic variants or differences determine the way our body metabolizes medications, impacting whether we will respond well and reap the intended therapeutic benefit or not, as well as the potential to experience drug toxicity. Does my metabolism break down this drug quickly or slowly? Having this information at the point of care can help identify the right drug and the optimal therapeutic dosage.

Understanding a person’s pharmacogenomic profile including specific gene changes associated with drug metabolism cannot only guide providers regarding the optimal therapeutic dose, but also which drug or drug classes might have increased toxicity. For example, CYP2D6, an enzyme within the Cytochrome p450 family, converts the common pain reliever codeine into morphine in the body. A person found to have a CYP2D6 gene variant that makes them a rapid metabolizer of codeine could be at increased risk of an adverse drug event associated with morphine toxicity. Knowing this ahead of time could help a provider treating a patient identified as a rapid metabolizer avoid a medication that poses danger for them and opt for a different pain reliever instead.

Precision medicine is based on this very idea—that we can integrate personalized health information, including a person’s specific DNA profile into clinical decision-making. Pharmacogenomics is part of that vision, specifically as it relates to medication selection, dosage, and management. However, for pharmacogenomics to be a valuable part of precision medicine, it needs to be accessible and understandable at the point of care and integrated with other relevant information for that patient, such as what health conditions the patient has, what other prescription and over-the-counter medications and supplements they are taking, and other demographic, dietary and lifestyle factors that can also influence drug response.

Accurately interpreting complex genomic testing data takes expertise and integrating it with other relevant health information is critical. Thus, pharmacogenomic test findings must be presented in useful terms, not buried in scientific jargon or conveyed as just a laundry list of genetic variants. Most healthcare providers have no training in pharmacogenomics and a real need for decision support. To ensure that pharmacogenomic testing leads toclinical actions that positively impact patient outcomes, a carefully designed approach is needed and the tools for such an approach exist. Some models are emerging.

Insights deliver value across the healthcare continuum

The most advanced use cases for pharmacogenomic testing currently are in specialties such as oncology, pain management, and polypharmacy. The connection between some pharmacogenomic targets and positive health outcomes in these fields is beginning to be more widely accepted, so the adoption of pharmacogenomic testing in these areas is likely to pick up speed.

Meanwhile, potential opportunities are growing—but largely untapped—for pharmacogenomics to improve the cost and quality of patient care for an increasing number of conditions. As our understanding expands regarding the impact that a patient’s pharmacogeneticprofile can have on their likelihood of an adverse drug reaction, we will see a world where precision medicine can further enable providers to confidently choose treatments that will have the desired therapeutic effects. The appropriate utilization of pharmacogenomics in clinical practice can be one way to mitigate the prevalence of adverse drug reactions, worsened health conditions, and medication-driven visits to the emergency department.

Pharmacogenomics has the potential to reduce costly prescription risks and revolutionize the way we think about the delivery of high-value care. The benefits of pharmacogenomics can extend to providers and payers—and most of all, to the patients we all serve.

Sobha Pisharody, Ph.D., is chief strategy & product officer of InformedDNA.