What Does Personalized Medicine Really Mean?
Precision treatment focuses on the genetic ‘fingerprint’ of cancer.
If you have cancer, “it’s a match,” is major news when the genetic makeup of your tumor makes it vulnerable to a targeted treatment.
One size doesn’t fit all is a tenet of personalized medicine, also called precision medicine. Even within a single type of cancer, tumor types differ from one patient to another. It makes sense that treatment should be individualized, as well.
Personalized medicine also has implications for noncancer conditions. In addition to being more effective, a targeted approach can spare patients from debilitating side effects of standard treatments. However, it’s important to realize that targeted drugs have side effects, too.
For Janice King Poulsen, 71, of Sandy, Utah, the crucial treatment match involved the “ALK” genetic mutation. Poulsen, a lifelong nonsmoker, was diagnosed with Stage IIIA lung cancer in May 2007. That lung cancer spread to her brain. Home radon exposure, it later turned out, was the likely culprit.
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Poulsen had to retire from work as a travel agent and from managing a synchronized skating program. Cancer became the priority. She went through a grueling array of standard treatments: radiation, chemotherapy, brain surgery and gamma knife therapy, or stereotactic radiation, as new brain tumors developed.
Eventually, Poulsen connected with the Huntsman Cancer Institute at the University of Utah. She learned she might benefit from a targeted drug called Zykadia, or ceritinib, for treating non-small cell lung cancer. Genetic testing of her tumor revealed the ALK mutation, she says – the right type for the drug.
It’s been three years since Poulsen started her precision therapy. She takes three capsules daily, with minimal side effects of nausea and diarrhea. She says she feels great. Her cancer appears to be under control.
Insurance helps pay for the expensive medication, which costs about $13,000 a month, and Poulsen’s family pays roughly $460 a month out of pocket. “Cancer isn’t cheap,” she says. In comparison, Poulsen, who now advocates for stronger home radon-testing policies, notes: “If you put in a radon mitigation system, it’s about $1,500.”
Targeted Therapies Today
For precision medicine to work on cancer, it requires two essential pieces.
“You have to have both an understanding of the genetic changes and also a targeted therapy that matches those genetic changes and goes after [them],”
says Mary Beckerle, CEO and director of the Huntsman Cancer Institute at the University of Utah.
Cancer isn’t a single disease, but hundreds of different diseases, Beckerle explains. Finding a treatment-to-tumor match – as in Poulsen’s case – is far from guaranteed.
“One of the interesting challenges is that only about 5 percent of lung cancer patients have the ALK mutation in their tumors,”
Beckerle says. “So, now we have this very promising treatment and we have to find the patients who will benefit from it. To do that, we conduct genetic testing on the tumors of 100 patients in order to find, on average, five patients who would benefit from this treatment.”
Here are just some of the medical conditions for which targeted therapies are currently available for matching genetic types:
Leukemia: Among the first targeted therapies developed, Gleevec inhibits a specific protein created by what’s known as the Philadelphia chromosome abnormality in some types of leukemia. The Food and Drug Administration approved Gleevec in 2001.
Cystic fibrosis: Two FDA-approved drugs – Kalydeco and Orkambi – work by affecting a defective protein created by the cystic fibrosis gene. These drugs only work for a subset of CF patients. When there is a match, patients on targeted treatment have seen significant improvement in their lung function.
Breast cancer: For patients with a type of breast cancer involving higher levels of the “HER2” protein, the drug Herceptin can be effective. However, heart failure has been a particularly concerning side effect for a small percentage of women taking this intravenous drug. Women on Herceptin should be closely monitored for cardiac function.
Colon cancer: With advanced colorectal cancer, a type of targeted drug treatment called “monoclonal antibody therapy” uses drugs such as Avastin or cetuximab to stop tumors from growing and spreading. Other targeted drugs use different mechanisms to combat tumors.
The National Cancer Institute offers a comprehensive rundown of targeted cancer treatments approved by the Food and Drug Administration to date.
Not Just Genetics
Precision medicine encompasses far more than genetics, says Eric Dishman, director of the All of Us research program – an ambitious new effort to gather health and genomic data from 1 million or more U.S. residents – at the National Institutes of Health. Truly personalized treatment involves pulling together a rich collection of your individual health data, including but not limited to your genome sequence.
The All of Us program is intended to accelerate research and improve health. Goals include delivering precision medicine and finding medical breakthroughs by taking individual differences in lifestyle, environment and biology into account.
The broad scope of All of Us will enable research for both common and rare diseases, according to the NIH website. One focus is pharmacogenetics – why individuals respond differently to commonly used drugs.
Participants who volunteer can benefit by the ongoing collection of data and information about their personal health. Although enrollment is currently limited during the project’s beta phase, the full-scale public launch is expected to take place this spring.
Dishman is passionate about the need for personalized medicine, and no wonder – he was an early beneficiary. Diagnosed at 19 with kidney cancer followed by more than two decades undergoing chemotherapy, immunotherapy and more, about five years ago he found himself in kidney failure, about to start dialysis and with little hope to survive.
Unbeknown to Dishman at the time, his medical team had made an unprecedented, four-month effort to compile every bit of information from 23 years of his disease-treatment course. They also analyzed his genetic information. What they found was surprising: His kidney cancer might best respond to chemotherapy typically used for pancreatic cancer.
The experiment worked, putting Dishman’s cancer in remission and allowing him to undergo transplant with a kidney donated from a colleague at Intel, where Dishman was then working as vice president of the health and life sciences group.
Although exciting, precision treatments still have a long way to go. While they’re incredibly promising, Beckerle says, “We also know that tumors can evade our best targeted therapies.” In some cases, a patient’s cancer can return and become resistant to drugs that used to work. For example, she says, patients with acute lymphoblastic leukemia who are treated with Gleevec can experience a relapse, with their disease no longer sensitive to the drug.
Cost and the opportunity to receive these treatments are also issues, especially for people who don’t have access to a dedicated cancer center. If you or a family member receive a cancer diagnosis, speak up, Beckerle advises: “Don’t hesitate to ask your oncologist if there are any targeted therapies available for your particular type of cancer.” If not, she adds, also ask about emerging therapies that might be available in clinical trials.