When a patient has breast cancer, doctors usually recommend therapies that target certain characteristics of the primary tumor. But as metastasized breast cancer cells travel through the bloodstream, they form deposits elsewhere — and in 25 to 50 percent of cases, these tumors have characteristics different from the original breast tumors.
That means that treatments might not work as well against these metastatic tumors as they would against the original breast cancer.
|George Somlo seeks better strategies for breast cancer. (Photo by p.cunningham)|
Researchers at City of Hope and Palo Alto Research Center (PARC) are studying the molecular characteristics of these “circulating cancer cells” to see if that information could result in better therapy strategies. They are using a tool developed at PARC: Fiber Array Scanning Technology, or FAST.
George Somlo, M.D., co-director of City of Hope’s Breast Cancer Program, presented the group’s findings in December 2009 at the 32nd annual San Antonio Breast Cancer Symposium.
“What’s novel in our approach is that we’re not just trying to find these cells, but also characterize them to find out how we can treat patients according to the variations between circulating tumor cells and the primary tumor and metastatic sites,” said Somlo, the study’s lead author. His team is working with Richard Bruce, Ph.D., director of the Scripps-PARC Institute for Advanced Biomedical Sciences. Bruce was senior author on the study.
Patients with metastatic breast cancer typically survive less than two years. About 40,000 people die from breast cancer every year in the U.S. due to complications from metastatic sites, said Somlo, so there is an urgent need to improve the ability to deliver individualized targeted therapies.
In the study, researchers took blood samples from newly diagnosed or relapsed stage IV metastatic breast cancer patients before they began treatments or changed therapy. Then they sent the samples to PARC for FAST processing and analysis of expression of target proteins. These include the estrogen and HER2 receptor proteins and ERCC1, a protein implicated in repairing DNA after exposure to certain chemotherapeutic agents such as cisplatin.
Somlo noted that studying patients’ circulating cancer cells could help physicians better understand what drives each patient’s metastatic tumors and may lead to the selection of therapies more likely to work against their specific metastatic cancer.
Other contributors to the study included Ben Hsieh, Ph.D., Robert Krivacic, M.S., and Douglas Curry from PARC, and Paul Frankel, Ph.D., Sean Lau, M.D., Norma Baker, R.N, and Susan Swain-Cabriales, R.N., from City of Hope.
Somlo and Bruce also shared findings about circulating tumor research in 2009 at the American Society of Clinical Oncology Breast Carcinoma Conference in San Francisco, and at the National Institutes of Health (NIH) Circulating Tumor Conference in Bethesda, Md.
The NIH has supported the circulating tumor cell research, and as a result of the most recent NIH presentation, the researchers were awarded a supplementary NIH grant under the American Recovery and Reinvestment Act of 2009.
The two-year, nearly $668,000 grant will be divided between Somlo and Bruce to fund future research studies on circulating tumor cells.
Looking for cancer cells
Locating metastasized circulating cancer cells in the bloodstream may truly be like finding a needle in a haystack. Scientists estimate that only one such cancer cell floats amid every 1 million to 10 million blood cells.
The investigational FAST system uses laser-printing optics to quickly scan blood samples (300,000 cells per second) for cancer cells labeled through immuno-fluorescence.