Has precision medicine’s time arrived?

Dr. Jennifer McClure reflects on using personalized genetic knowledge to improve health and health care.

by Jennifer McClure, PhD, Senior Investigator and Director of Research, Faculty & Development, Kaiser Permanente Washington Health Research Institute

Precision medicine, also called personalized medicine, refers to tailoring medical advice and treatments to the individual characteristics of a person. The hope is that by doing so, we can improve the safety and effectiveness of these interventions. This concept is not new to me. In fact, understanding how best to personally tailor behavioral interventions based on an individual’s psychological characteristics has been a focus of my research for nearly 20 years. But more recently, the term precision medicine commonly refers to tailoring health advice and treatments based on one’s genes. It is grounded in our rapidly evolving understanding of the human genome and the fact that genes play an important role in whether we will develop disease and how we individually respond to different therapeutic treatments.

An important and related field to precision medicine is epigenetics. Epigenetics help explain how environmental exposures, ranging from the nutrients we eat to the toxins we breathe or ingest, switch individual genes on and off, affecting how the genes express themselves. This, in turn, influences our genetic risk of disease and treatment response.

Given the complex interaction between our genes and environment, it will be difficult to reach the true potential of precision medicine. Simply taking a DNA test and knowing one’s gene variants is not enough. We need to better understand how individual genes function — alone and in combination. Perhaps due to this complexity, the American College of Medical Genetics and Genomics currently only recognizes 59 of the estimated 20,000 to 25,000 genes in the human genome as “medically actionable.”

Has the time come for precision medicine?

Despite the many challenges and unknowns in genomic medicine, I can’t help but wonder if the time for precision medicine has finally come. Upon reflection, I think it has. The question is whether we are ready for it.

As of April 2018, more than 5 million people worldwide were customers of 23andMe, a popular direct-to-consumer “Personal Genome Service.” Similar services are offered by Ancestry.com and others. Recently, 23andMe received approval from the U.S. Food and Drug Administration to market an at-home breast cancer risk test. Customers can also receive reports that summarize their known risk of developing diseases such as Alzheimer’s, celiac, and Parkinson’s diseases and age-related macular degeneration based on the specific gene variants included in the 23andMe DNA test. These at-home tests have limitations, but they have not stopped the consumer demand.

In fact, it’s hard to tell if the growth of at-home genetic testing is the driver of or a response to the increasing consumer demand for personalized health information. Either way, the demand is real. I see increasing evidence of this in the discussion threads of online patient forums and hear about it in conversations with friends and family. People want to understand their personal disease risk and to make medical decisions based on this information.

Personalized medicine is also gaining attention in the research community. While attending the annual meeting of the Society for Research on Nicotine & Tobacco, I heard one of the keynote speakers not only call for continued research on the genetic bases of smoking and nicotine dependence, she issued a challenge for us to start applying the information we’ve accumulated over the past 20+ years to clinical practice.

A time for action

To be clear, we still have a lot to learn about the role that genes play in health and individual treatment response. However, we also know a lot and the evidence base is evolving rapidly — faster than most clinicians can keep up. This is a realistic concern for both patients and providers. Another concern is that much of what we think we know now will be proven wrong in the future. The same can be said for all medical knowledge. But it is now possible to tailor some treatments based on individuals’ genetic makeup in ways that may improve the safety and effectiveness of these interventions. When this information is actionable, I believe it is time to take action.

As a behavioral scientist and researcher, I am also excited by the possibility that personalized medical information could help motivate and sustain important lifestyle changes — changes that will influence individual epigenetics and gene expression. To date, the evidence base is weak that simply knowing one’s genetic risk motivates behavior change, but far less research has been devoted to this than to understanding the human genome and its role in disease. With time, I am confident we will understand how best to harness this knowledge to promote behavior change and better health, and I hope to contribute to this knowledge base through my own research.

In the meantime, I am excited to see the promise of precision medicine finally starting to come into its own.