As insurance companies, governments, doctors, and patients debate who should pay for the screening and treatments of personalized medicine, many people feel that the greatest dilemma facing this new medical field is economic.
But the science behind targeted treatments, it turns out, still poses significant challenges all on its own.
The Genetic Testing Registry, a branch of the National Health Institutes, lists over 32,000 genetic tests that are available for doctors and patients to choose from. These tests look at how nearly 4,000 genes interact with nearly 6,000 diseases, in addition to testing how patients will respond to specific drugs or treatments.
These numbers are not static. In fact, they are growing every year as genome science advances and scientists learn more about how the human genotype affects health outcomes.
All this new information has the potential to completely alter how clinical medicine is practiced. But taking new discoveries in genome science and translating them into concrete therapies that doctors and patients can use is not a straightforward process.
As new genetic variations are discovered, they must first be studied and categorized. The effect they have on a patient’s health and any potential diseases must be researched and established. Only then can researchers begin to investigate how these new genetic sequences can be used to create precision therapies.
As an article published in the HUGO Journal notes, “The biological understanding of the human genome is far from complete and… the information would not be informative to the clinicians if the genes affected have not been studied so far or if the pathways they are involved in are unknown.”
In other words, it takes a lot of expensive research, trial, and error to translate new discoveries in genomic science into advancements in the field of personalized medicine.
Once researchers have identified new genomic discoveries, there are additional scientific challenges: regulation and testing.
In 2008 and 2010, reports on the state of personalized medicine noted that one of the biggest challenges facing the new field was regulating how genomic research is conducted and testing new therapies. Both reports noted that, while the number of known genetic markers that could be tested is growing rapidly, the clinical validation necessary to create treatments based on those markers goes much more slowly.
Why are regulation and testing such a challenge?
One reason is the newness of the field. The human genome was first successfully mapped in 2003, making genomic science — the foundation on personalized medicine — a very new branch of medical research. Standards for conducting research safely and ethically are being developed alongside genomic science itself.
Integrating this new research with current medical systems is even more complicated. In the United States, the Regulatory Science Initiative is part of a global push to standardize research, regulations, and clinical trials in personalized medicine, but even that has been in place only since 2010.
As with all new scientific fields, personalized medicine is still a largely uncharted territory, which creates challenges for both discovering and applying new information.
Another reason is the population size. Most countries require that a new drug undergo extensive clinical trials to prove that it is safe and effective. On top of that, most insurance companies will not cover experimental therapies, only treatments that have been thoroughly tested. A typical drug trial can take years and thousands of participants; a typical drug can take millions of dollars to develop.
When the vaccine for human papillomavirus was developed, more than 24,000 men and women in 33 countries participated in clinical trials. The test population was large, but so was the candidate pool: most healthy women and men between the ages of 16 and 33 were eligible to participate.
Precision treatments target a much smaller candidate pool. They are often intended for only 1 to 5 percent of the population, which makes finding participants for clinical trials much harder. Participants in these clinical trials have to have the same genetic markers as the intended recipients of the new drugs, and screening for those can be difficult and time consuming.
Gordon Mills, PhD, a researcher at the MD Anderson Cancer Center’s Institute for Personalized Cancer Therapy, recently spoke to the American Cancer Society about these challenges. “We need to emphasize to patients and to the public and funders and regulatory agencies that these are just very early days,” Mills explained.
And as with any new science, personalized medicine still has challenges to overcome before it can be fully integrated into everyday medical practice.
July 27, 2016
Christopher Nystuen, MD, MBA