Targeted Treatments Show Mettle Against Advanced Cancers
SUNDAY April 19, 2009 -- Patients with a variety of advanced cancers who had been faring poorly on less finely tuned therapies did better when they received treatments that were targeted to their tumors' specific characteristics.
The findings, which were to be presented Sunday at the American Association for Cancer Research annual meeting, in Denver, fit into the current framework of "personalized" medicine, explained Dr. Minetta Liu, a translational researcher/breast oncologist at Georgetown University's Lombardi Comprehensive Cancer Center in Washington, D.C.
That, of course, means being able to predict which drugs will do best for a particular person's cancer. "In breast cancer in particular, we have a lot of therapeutic options, but we pick our drugs based on large clinical trials of hundreds of women, so we're not individualizing therapy," she explained. "The desire is to come up with better ways to predict who will respond to which drug."
For this study, Arizona researchers searched for molecular targets in 66 patients who had failed an average of five therapies for a variety of different cancers.
"Such patients would normally be offered a trial with a new [experimental] anti-cancer agent, [but] we used fairly standard techniques and looked for conventional targets for conventional agents. For example, for estrogen receptor-positive cancer, we would use an anti-estrogen agent," explained study senior author Dr. Daniel Von Hoff, physician-in-chief at TGen, a nonprofit research institute in Phoenix, and chief scientific officer at Scottsdale Healthcare and U.S. Oncology Research. "We treated them according to the best target they had."
Researchers actually found a target in 98 percent of the group. Eighteen patients saw a benefit in progression-free survival, compared to how they had done on previous therapies.
Forty percent of patients in the trial survived at least 15 months, compared to 20 percent of the more general population, Von Hoff stated. The greatest benefits were seen in breast cancer.
The targets and therapies chosen were different from what the patients' doctors said they would have tried.
"We feel that this can help people who have progressed on everything else," Von Hoff said.
A second study from Italian researchers found that specific genetic mutations in patients with advanced colorectal cancer could indicate that the tumor will not respond to two monoclonal antibodies, Erbitux (cetuximab) and Vectibix (panitumumab).
Two studies also to be presented at the meeting focused on the brain tumors known as glioblastomas.
One from researchers at the University of Pennsylvania indicated that an imaging technique known as magnetic resonance perfusion-weighted imaging may be able to identify genetic mutations which could then help guide treatment choices. With further validation, these findings may result in use of the procedure in clinical trials and, further down the line, actual practice, said Dr. Deepa Subramaniam, director of the brain tumor center at Lombardi Comprehensive Cancer Center, Georgetown University, in Washington, D.C.
The second glioblastoma study, from doctors at Massachusetts General Hospital in Boston, identified a biomarker which could select out patients with brain tumors that would respond better to cediranib, a drug targeting the anti-vascular endothelial growth factor, which is in the research pipeline.
"This sounds very exciting and is going to become a standard marker in clinical trials," Subramaniam said.
The U.S. National Cancer Institute has more on tumor markers.
Posted: April 2009