Figuring out whether a patient will benefit from a cancer drug can prove challenging for physicians striving to defeat the disease.

Tumor cells that heavily express the HER2 protein glow under positron emission tomography scanning. (Image courtesy of Joanne Mortimer)

Take breast cancer, for example. Patients diagnosed with what is called HER2-positive breast cancer — tumors that heavily express the HER2 protein — often get the drug Herceptin to combat this aggressive, potentially fatal disease. Herceptin sticks to the HER2 protein, which stops these cancer cells from reproducing.

But the drug does not help everyone. Sometimes HER2-positive tumors behave in unexpected ways.

“We don’t really know in advance who will benefit from Herceptin or not,” said Joanne Mortimer, M.D., director of the Women’s Cancers Program at City of Hope.

A technology in development at City of Hope may help doctors answer that question before patients get treated. Researchers are developing a way to use imaging to learn more about the biology of breast cancer.

The Department of Defense’s Breast Cancer Research Program recently funded ongoing studies by Mortimer and James Bading, Ph.D., research professor in the Department of Cancer Immunotherapeutics and Tumor Immunology. The research team also includes Andrew Raubitschek, M.D., chair of the Department of Cancer Immunotherapeutics and Tumor Immunology, and David Colcher, Ph.D., deputy director of the Division of Radioimmunotherapy.

The project takes advantage of the imaging tool called positron emission tomography, or PET.

PET scanning uses small amounts of radiation to help doctors see how cancers function. In the study, scientists use Herceptin that has been tagged with radiation. Doctors inject the Herceptin into the patient. If the patient’s tumors need HER2 protein to grow, the radiation on the tagged Herceptin will light up the tumors on the PET scan.

“Patients with this disease are likely to benefit from Herceptin treatment,” Mortimer explained.

If the technology works, and patients receive the PET scans before starting therapy, the patients whose tumors would not respond to Herceptin could be steered to other medications instead. “In theory, this could spare these patients the toxicity, cost and inconvenience of getting that drug,” Mortimer said.

Their findings also may point to other patients who could benefit from Herceptin. “There’s a varying degree of HER2 protein in other breast cancers, and it’s conceivable that the imaging might show that other patients could benefit from Herceptin — patients we would not have thought were appropriate for the drug,” she said.

The imaging also might help doctors understand whether a woman’s breast tumors are all the same. If a woman has HER2-positive breast cancer that has spread to other locations in the body, do the other tumors act like HER2-positive cancers?

“By using this agent with PET imaging, hopefully we’ll be able to answer some of those questions,” Mortimer said, “allowing us to focus our treatment strategies more specifically to each woman’s cancer.”

To learn more about City of Hope research into women’s cancers, visit www.cityofhope.org/womenscancers. To learn about the Department of Defense Breast Cancer Research Program, visit http://cdmrp.army.mil/bcrp.