An inexpensive tracing agent used in combination with ultrasound can pinpoint how effectively drugs targeting pancreatic cancer work, researchers at UT Southwestern Medical Center have demonstrated for the first time.
The study, involving human pancreatic tumor cells implanted in mice, opens a new avenue for real-time imaging of a patient’s response to cancer therapies. It appears in the Jan. 1 issue of the journal Clinical Cancer Research.
The UT Southwestern research team focused on pancreatic cancer because it is one of the deadliest cancers, characterized by extensive local invasion and metastasis to the liver, said Dr. Rolf Brekken, assistant professor of surgery and pharmacology and the study’s senior author. The five-year survival rate ranges from only 1 percent to 4 percent for patients diagnosed with the most severe form of cancer of the pancreas called pancreatic andenocarcinoma.
“The current best therapy ? including surgery, radiation and chemotherapy ? has done little to alter cancer-related deaths of these patients, emphasizing the need for more effective treatment,” said Dr. Brekken, a researcher at the Nancy B. and Jake L. Hamon Center for Therapeutic Oncology Research at UT Southwestern.
The research team examined how pancreatic tumor cells respond to an experimental anti-cancer agent that targets vascular endothelial growth factor (VEGF), a protein responsible for triggering the development of blood vessels that deliver nutrients and oxygen to tumors, enabling them to grow and spread. Drugs that target VEGF are in a class called anti-angiogenic agents that are designed to choke tumor growth by reducing the number of blood vessels feeding the cancer.
“In general, it has been difficult to assess whether anti-angiogenic drugs are having an impact on tumors in human patients,” said Dr. Brekken. “The sooner we can measure the effectiveness of the treatment, the earlier we can intervene to change anti-cancer agents if a particular drug has no effect. This could be a lifesaving approach in patients with rapidly fatal disease.”
To find the answer, the UT Southwestern team resorted to an inexpensive and commonly used contrast, or tracing agent, called microbubbles. Each tiny bubble measures about one to two microns in diameter ? about a hundredth the width of a human hair ? and consists of albumin, sugar and an inert gas. Microbubbles are used routinely in echocardiography, for example, allowing cardiologists to see how efficiently and how much blood the heart pumps.