Investigators at Purdue University are reporting that significant progress has been made on developing a diagnostic technique to detect circulating neoplastic cells through noninvasive scanning. Predictably, the technology uses tumor-specific fluorescent probes for detection:
The technique uses a fluorescent tumor-specific probe that labels tumor cells in circulation. When hit by a laser, which scans across the diameter of the blood vessel 1,000 times per second, the tumor cells glow and become visible. The in vivo flow detection was performed on a two-photon fluorescence microscope in Cheng’s lab. [Ji-Xin Cheng is an assistant professor of chemistry and biomedical engineering at Purdue –ed.] The researchers compared several methods and found two-photon fluorescence provides the best signal to background ratio. The technology is able to scan every cell that is pumped through the vessel, He said.
Low’s team has developed two labeling agents that attach to different forms of cancer. One label targets ovarian, non-small lung, kidney and endometrial cancer, and the other targets prostate cancer. [Philip Low is Purdue’s Ralph C. Corley Distinguished Professor of Chemistry –ed.]
These labels would be administered through an injection. The first label has already been tested in humans and has no adverse side effects and could potentially be administered weekly, He said.
Computed tomography, or CT, scans and magnetic resonance imaging, or MRI, are the current methods used to track the spread of cancer. These methods have a limited resolution, and a 1 millimeter tumor could go undetected by CT or MRI. The Purdue-developed technology can achieve single-cell resolution and can detect rare cell populations.
“Our method can detect cancer cells early in disease development and the test can be conducted frequently,” Low said. “Discovering the cancer early and knowing whether it has metastasized, or spread, greatly improves a patient’s chance for successful treatment.”
The laser penetrates to a depth of 100 microns and is able to examine shallow blood vessels near the surface of the skin. Advanced optical technology could be incorporated into the technology platform and enable the method to reach deeper vessels that handle larger volumes of blood, Cheng said.
The Purdue team continues to work with the Mayo Clinic and is planning to initiate a clinical trial to further evaluate the technique.