SECOND OPINION

Precision Medicine: What Challenges Lie Ahead?

Precision medicine, the targeted approach to treating a disease based on the unique characteristics of each individual's disease, is a rapidly growing field. Early successes, particularly in the treatment of cancer, point to continued growth in the field.

What are some of the challenges precision medicine faces moving forward?

2 Responses
Elaine Mardis, PhD
December 8, 2017

Precision medicine faces a number of challenges, but perhaps the most significant one is physician education about genomics and the role that it can play in offering additional precision to diagnostic medicine. In particular, most physicians who have been practicing medicine for more than ten years, unless they focus on genetics in their practice, are not aware of the advances in our understanding of the role of the genome in disease pathogenesis. This makes it difficult to conceptualize how adding genomic data to diagnostic evidence will help make treatment decisions more precise or personalized. On the flip side, there remains a lot we do not understand about the changes we see in an individual’s genome and how those relate to disease. So, we have to strike a careful balance that involves the initial application of genomics in medicine where it is most likely to be helpful in providing additional information pertinent to patients with specific challenges. Using a strategic and intelligent approach will provide powerful examples of how genomics leads to better diagnosis and treatment, which over time builds the case for its utility in medical practice.

About Writer

Elaine R. Mardis, PhD, is the co-executive director of The Genomics Institute at Nationwide Children’s Hospital. Dr. Mardis is an internationally recognized expert in cancer genomics who received the 2016 Morton K. Schwartz award from the American Association for Clinical Chemistry. She also was included on the 2013 Thomson Reuters’ list of most cited researchers, one of only two women listed. Among her several prominent roles, Dr. Mardis is a member of the Board of Directors for the American Association for Cancer Research and a member of the Supervisory Board of Qiagen N.V. She is editor-in-chief of Molecular Case Studies and an associate editor of Molecular Cancer ResearchDisease Models and Mechanisms and Annals of Oncology. In 2013 she was featured in Discover magazine’s “The Year in Science.” In 2017 she will be awarded the Luminary Award from the Precision Medicine World Conference.

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Timothy Cripe, MD, PhD
December 8, 2017

First, we need to be precise about what we mean when we say precision medicine. We all think we treat patients precisely, in terms of being as certain as possible about the diagnosis and best treatment. Some think of precision medicine as personalized medicine, and again we do as much as possible to tailor therapy to each patient, making everything we do personalized. The question really is asking about newer technologies that better define nuances of a patient’s diagnosis in new ways that were not previously possible, and which may guide us to prescribe specific therapies. Studies of genomics, in which we assess which genes are expressed or altered in a patient’s cancer, for example, may indicate which drug would be best for that individual patient.

By some measures, precision medicine has transformed cancer care, like it has for many other fields. In some patients, we can now precisely match the best treatment because we can detect what makes their cancers “tick.” For example, patients with a specific type of leukemia can be treated, and in many cases cured, using a drug that specifically targets the abnormal protein expressed in their cancer that drives the cancer cell to thrive.

Ultimately, precision medicine has not been the panacea for cancer many had hoped. First, even though they are supposedly targeted for specific proteins, most such proteins also have functions in normal cells so the drugs can cause “on target” side effects. They can also have effects on other functions of a cell, so-called “off target” side effects, so they are not as precise as we wish. Second, in many cases the positive effects of drugs that inhibit drivers are short-lived. Cancer cells are extremely adaptable, essentially evolving with each cell division. Often when exposed to a drug that slows or stops most of the cells from growing, one cell among many figures out how to avoid the effects of the drug by either mutating the driver so the drug doesn’t work on it anymore, or expressing other drivers that are not hit by the drug.

Despite its limitations, precision medicine undoubtedly will continue to play an important role in treating cancer. Certainly, for benign tumors that can’t adapt very well, targeted drugs should continue to be potent. But for more aggressive cancers, the challenges for the future will be to figure out how to combine different targeted therapies together, without multiplying their side effects, and hopefully making it harder for cancer cells to escape therapy.

About Writer

Dr. Cripe is chief of the Division of Hematology, Oncology and Blood and Marrow Transplantation at Nationwide Children’s Hospital. His clinical interests include gene and viral therapies for solid tumors in children, including brain tumors, neuroblastoma and bone and soft tissue sarcomas. Dr. Cripe’s current research focuses on developing and testing new therapies for pediatric solid tumors and translating those findings into clinical studies. He was among the first in the country to launch clinical trials of attenuated oncolytic viruses in children.

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