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THE CANCER ISSUE

Tailor-made treatment

People are different -- their cancers too. Therapy starts to get personal.

October 20, 2008|Shari Roan | Times Staff Writer
  • Six years ago, a vaccine designed specifically for musician Kevin Carlberg, shown with his daughter, helped him beat back an aggressive type of brain cancer.
Six years ago, a vaccine designed specifically for musician Kevin Carlberg,… (Jay L. Clendenin / Los Angeles…)

The one thing Kevin Carlberg refused to face after his diagnosis with brain cancer in 2002 was anyone's estimate for how long he might live.

His doctors and his family all knew the number: six to 18 months.

"I understand the averages," says Carlberg, a rock musician who had just released a CD and was two months from his wedding date when he was told he had the worst stage of the worst kind of brain cancer, glioblastoma. "But every person is different."

Those words could serve as the new mantra in medicine. After having his tumor removed and undergoing chemotherapy and radiation, he received a novel treatment that was designed using his own white blood cells and proteins taken from his tumor to prod his immune system into recognizing and attacking more cancer in his body. It's an example of a growing healthcare strategy known as personalized medicine.

In the traditional medical model, patients diagnosed with cancer in a particular organ receive the same medications -- usually chemotherapy -- delivered in an average dose. But some estimates suggest that as many as 70% of cancer patients don't respond to this standard approach. The treatment fails and then doctors go back to the drawing board.

Personalized medicine aims to minimize that one-size-fits-all approach by matching each patient to a specific treatment based on the genetic and molecular characteristics of that person's tumor. Doctors can use genetic information gleaned from the tumor itself to choose -- or avoid -- certain medications for that patient or, as in Carlberg's case, create a treatment specifically for that person.

Not so long ago, "most lung cancers were treated the same way; colon cancer the same way. Breast cancer was treated one of two ways," says Dr. Dennis Slamon, director of clinical and translational research at UCLA's Jonsson Comprehensive Cancer Center and a pioneer of personalized cancer care. "But that was as sophisticated as it got, and we had huge variations in patients' outcomes. That should have told us we were dealing with different diseases."

Personalized medicine is gaining momentum in many areas of treatment. But its greatest application may be in the complex field of cancer, says Dr. Robert Figlin, director of the City of Hope Comprehensive Cancer Center in Duarte.

"Cancer is a disease which has been misnamed," Figlin says. "It's not a disease. It's hundreds of diseases."

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Molecular 'revolution'

Personalized medical care is a practical benefit from the Human Genome Project, the 13-year project, completed in 2003, that gave scientists a precision map of the genetic information of humans. Completion of the genome project allowed them to easily locate genetic differences between individuals, including gene variations that cause disease, as well as molecular changes that sometimes turn cells rogue.

"This revolution in molecular biology has translated to understanding . . . the reasons why cancer grows," says Dr. Roy S. Herbst, chief of the section of thoracic medical oncology at the M.D. Anderson Cancer Center in Houston.

For example, he says, in traditional practice, doctors removing a tumor send it to a lab to be categorized by size and shape.

But now in some cancers -- not yet all -- doctors can examine the tissue for specific genes and molecular processes that suggest the cause of a cancer, its potential to grow and what it might take to subdue it.

Personalized medicine -- luckily -- doesn't mean that every cancer is unique and must be treated in a unique way, Slamon says. In a group of 1 million people with breast cancer, for example, there are not 1 million types of cancer. Rather, "There may be seven or eight different subgroups," he says, each with a different molecular cause that warrants a different approach to treatment.

To identify these sub-types of cancer, doctors search for biomarkers, molecular indicators of how that tumor will respond to various drugs. Slamon, for example, worked for more than a decade trying to understand a protein biomarker called HER2.

About 25% of women with breast cancer carry a gene mutation that triggers an excess production of HER2. This protein makes the cancer more aggressive and difficult to treat. The discovery led to a drug called Herceptin, approved in 1998, which specifically targets HER2 and decreases cancer recurrences in these women by as much as 50%.

"The science is in its infancy," Slamon says. "Breast cancer is about seven to 10 years ahead in terms of appreciating the diversity of the disease. But those lessons are being applied to other cancers now."

Targeted therapies are now in use for certain types of colon, lung and ovarian cancers, and research is underway in many other types.

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