How Personalized Medicine Works

By: Marianne Spoon

By focusing on an individual’s medical history and genetics, health care professionals can better tailor treatments and maximize their benefits.
By focusing on an individual’s medical history and genetics, health care professionals can better tailor treatments and maximize their benefits.
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When a young boy from Utah with a defective windpipe faced life-threatening breathing challenges in spring 2014, his doctors turned to an exploratory option: Customize and 3-D print an entirely new organ for him.

The treatment, which saved the child's life, not only points to the potential of new medical tools, but also shows treatment options are increasingly custom-tailored to a person's biology [source: Stein].

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This idea, called personalized medicine, draws from biological information such as medical history, genetics and the uniqueness of a person's body to maximize benefits of medical treatments while reducing side effects and costs. In short, personalized medicine helps give "the right dose to the right patient at the right time" [source: FDA].

And a handful of screening tools are making their way to doctors' offices near you, such as a biomarker test for cancer or a genetic screening method to learn a safe and effective dose for blood-thinning drugs.

While we still have much to learn about the human body and basic biology, researchers are looking more closely at how diseases work at a genetic level, unveiling biological explanations rather than relying on symptoms alone.

As we'll learn, personalized medicine has come a long way from traditions of health care centuries ago to the high-tech tools we use today. We're also learning that with personalized medicine's lifesaving potential come challenges and ethical considerations.

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History of Personalized Medicine

Studying the human genome and mapping genes that were linked with disease brought us into the modern era of personalized medicine.
Studying the human genome and mapping genes that were linked with disease brought us into the modern era of personalized medicine.
iStockphoto.com/isak55

Though our current definition of personalized medicine has evolved with our understanding of the human genome, or the set of genetic information in our cells and bodies, the principles behind the term have been around for centuries.

More than 2,000 years ago, Hippocrates, known as the father of Western medicine, shared the notion that people have different ailments, symptoms and responses to treatments — the idea that a one-size-fits-all approach isn't always the best way to care for each patient [source: Sykiotis et al.].

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Later, medical pioneers such as Reuben Ottenberg and Ludvig Hektoen developed a more personalized approach after working on blood transfusions. In 1907, Ottenberg and Hektoen built upon knowledge that people had different blood types. They determined that matching them increased the chances for successful transfusions and lowered the risk of the body rejecting transfused blood [sources: FDA and ARC].

In the 20th century, doctors and researchers continued to personalize medicine by documenting and probing people's family health histories for diseases that were likely to have a genetic component, or to be passed on from generation to generation.

But it wasn't until the advent of the Human Genome Project that personalized medicine took on its current meaning, with a larger focus on the links between genetics and health. This international effort opened the door to mapping series of genes switched "on" or "off" during cancer or disease. Over time, scientists began to build side-by-side comparisons to generalize which sets of genes are involved in diseases among people of diverse ages, backgrounds and heritages through genome-wide association studies.

In 1998, the U.S. Food and Drug Administration — the regulating entity for approving and overseeing drugs, devices and medical treatments — used a personalized medicine approach to approve Herceptin, a drug that targets breast cancer in people whose tumors produce a specific protein [source: FDA]. Because researchers successfully identified what made the drug useful for a subset of people, the treatment gained approval and a place in standard medical practice.

Though population-level studies provide a comparison for personalized medicine, they're only one piece of the puzzle. In order for these studies to take a personalized medicine approach, each person's individual biology also should be explored.

Let's examine this notion and how personalized medicine differs from traditional medicine.

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What Makes Medicine 'Personalized?'

Personalized medicine recognizes that each patient might respond to treatments differently.
Personalized medicine recognizes that each patient might respond to treatments differently.
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Isn't medicine – and seeing a doctor when you're sick – a personal experience in itself? After all, you're being asked questions that are unique to you, right?

True, but personalized medicine goes a step beyond this and tailors treatment based on your individual biology. A personalized medicine approach might include gathering information about your genome (say, from a saliva sample) to understand whether you are more or less likely to respond to a type of drug or treatment.

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Pharmacogenetics gleans insight from a person's genes to improve the effectiveness of a given dose of a drug or treatment of a disease. Differing from a one-size-fits-all approach of traditional medicine, personalized medicine takes into account the specifics of each person's biology [source: Krimsky].

Let's say a group of 10 people from diverse backgrounds has been prescribed the same dose of the same drug for the same health problem, but it only works in treating seven people.

At a genetic and biological level, tremendous variation could exist within the group that might account for why it works for some but not for others. Traditional medicine has relied on a trial-and-error approach, which focuses on the idea that this given treatment works for most people (seven out of 10), so chances are it will work for you.

But your genetics and biology might be more similar to the three people for whom it didn't work, and as a result, you might experience negative side effects from trying the drug in addition to wasted time and resources. Through personalized medicine, you would be screened before being given a drug, and doctors would not recommend the treatment if you have specific biological similarities with the three people who didn't respond to that medication.

These key pieces of information in our biology, called biomarkers, are measurable signs associated with a given disease at a molecular level. They help pinpoint the type of cancer or tumor a person might have and can increase the chances he or she will get the most effective treatment.

In addition to looking at a person's genome, medical devices and regenerative biology are growing areas of personalized medicine.

For people needing prosthetics or medical devices to serve a certain function, health professionals and researchers custom-tailor those devices to get the job done. One man even had 75 percent of his skull reconstructed and implanted with help from a 3-D printer [sources: news.com.au and Oxford Performance Materials].

Another area of personalized medicine making headlines is regenerative biology, or using cells derived from a patient's body for therapy. Once the stuff of science fiction, growing your own healthy tissue in a petri dish is becoming a possibility by taking skin cells and reprogramming them into specialized cells in the body.

And with these advances come a lot of data, requiring many experts working together to make sense of it all, including geneticists, biologists, doctors, cancer researchers, chemists, computer scientists and statisticians. The list of experts will continue to grow in the future, as the U.S. Food and Drug Administration envisions gaining more perspectives from experts in ethics, sociology and psychology to further the field [source: FDA].

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Early Success Stories

Taking our health into our own hands with products like activity trackers is one way personalized medicine is being integrated into our daily lives already.
Taking our health into our own hands with products like activity trackers is one way personalized medicine is being integrated into our daily lives already.
Christopher Ames/E+/Getty Images

Personalized medicine has drawbacks that we'll discuss later, but it also has success stories that have saved and improved people's lives.

For instance, the U.S. Food and Drug Administration approved the drug Kalydeco in 2012 to treat a rare form of cystic fibrosis, a potentially deadly lung condition. People with a certain genetic mutation did not respond to other drugs, and a personalized medicine approach enabled researchers to develop a drug that worked for that subset of people who didn't respond to existing treatment options [source: FDA].

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And with more than 347 million people worldwide living with diabetes, an artificial pancreas device system is another successful product of personalized medicine [sources: WHO, FDA]. It uses a computer to calculate the optimal amount of insulin based on a person's glucose levels. Personalized medicine has also come in handy for prescribing safe doses of warfarin, a drug that combats blood clots that can lead to heart attacks and strokes.

Doctors and researchers studying cancer have had multiple success stories with personalized medicine, too. In colorectal and breast cancers, doctors search for proteins from specific genes that increase the chance certain drugs will help [source: The Jackson Laboratory].

Personalized medicine has also helped improve quality of life for people living with tinnitus — a condition that causes ringing in the ears and affects one in five people. People with the condition have benefited from a customizable device that adjusts audio signals to their unique hearing situations [sources: FDA, Mayo Clinic].

We're already seeing personalized medicine make its way into our own hands for a more proactive approach to health, whether it's an activity tracker or at-home DNA sequencing kits. But with these advances also come obstacles.

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Obstacles of Personalized Medicine

Cost is a major obstacle for personalized medicine. Sequencing genomes can cost thousands, and insurance companies have been slow to cover the bulk of tests and products.
Cost is a major obstacle for personalized medicine. Sequencing genomes can cost thousands, and insurance companies have been slow to cover the bulk of tests and products.
iStockphoto.com/4774344sean

Personalized medicine can improve health care, but it can also complicate it.

One challenge is the temptation to overstate the impact of a given research finding or product. Even if biomarkers are established for a particular disease or treatment, they're not always proven to be the key to better treatment in clinical trials — medicine's gold standard of determining the effectiveness of a medical approach in an unbiased manner with real people [source: Pray].

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In addition, the field — and the ability to regulate it in the United States — has posed problems for the Food and Drug Administration, which is focusing on building the infrastructure to keep up with new companies and products.

Personalized medicine also relies heavily on basic science, which takes money and time. The more researchers study cancer and diseases, the more they realize these conditions are complex and shaped by a person's lifestyle and environment.

The epigenome– a layer that sits on top of our genome that turns genes "on" or "off" based on diet, exercise and the environment – adds this complexity to the mix, reflecting the impact a person's lifestyle and environment have on his or her predisposition for illness or disease.

Affordability remains another obstacle. Sequencing and analyzing a person's genome takes more money and time than experts initially predicted.

In order to use genetic information to make an informed clinical decision, one estimate says it will cost at minimum $17,000 per person to sequence a genome and professionally follow up on data of importance for that person [source: Conger]. Hefty price tags for professional genetic testing beyond cancer treatments are likely unaffordable for the average person.

In addition, insurance companies have been slow to cover the vast majority of personalized medicine tests and products because many devices and tests lack the clinical studies to prove effectiveness [source: Hresko and Haga].

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Ethical Considerations

While knowing you carry genes for a disease can be empowering, there’s a chance you’ll never develop the condition.
While knowing you carry genes for a disease can be empowering, there’s a chance you’ll never develop the condition.
iStockphoto.com/4774344sean

Would you want to know whether your genome contained information that suggested you were at a greater risk for cancer or disease, even if there's a chance it won't happen?

Knowledge can be empowering, but it can also create challenges when balancing health outcomes. In medical research, biomarkers are not always exact, and just because a person has a predisposition or the right combination of genes for a given health condition doesn't mean he or she will develop it.

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For example, some forms of breast cancer are associated with specific genes. If a person knows he or she has the genetic makeup conducive to developing cancer, but it hasn't happened yet, should he or she take action such as having a mastectomy (surgical removal of the breast)? These are ethical debates researchers, doctors and patients are weighing together.

Data created from personalized medicine has become a source of ethical debate, too. To prevent employers and health insurance companies from discriminating against people based on genetic information, the U.S Congress passed the Genetic Information Non-Discrimination Act in 2008 [source: U.S. Equal Employment Opportunity Commission].

Then there's the issue of intellectual property, or determining who owns the rights to findings and data generated from personalized medicine. Because a company finds a biomarker for a specific illness, can that company patent it? That was a real concern just a few years ago, but according to the Supreme Court of the United States, genes with discovered links to disease cannot be patented [source: Liptak].

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Author's Note: How Personalized Medicine Works

Looking to the future, I'm curious to see what will happen when personalized medicine and the Internet of Things collide: Will our thermostats monitor our biology in addition to the temperature?

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