In studies in laboratory mice with implanted human brain tumors, the new device clearly delineated tumor tissue from normal brain tissue. Also, with near-infrared light's ability to penetrate deep into the tissue, the system identified tumors that had migrated away from the main tumor and would have evaded detection.
Pramod Butte, MBBS, PhD, research scientist and assistant professor in the Department of Neurosurgery, the article's first author, said the tumor-imaging process consists of two parts: deploying a fluorescent "dye" that sticks only to cancer cells, and using a laser and a special camera to make an invisible image visible.
To get the dye to the tumor, it is linked to a peptide called chlorotoxin, which, contrary to its name, is not toxic. It completely ignores normal tissue but seeks out and binds to a variety of malignant tumor cells. It first was derived from the venom of the yellow Israeli scorpion, also called the deathstalker. Article co-author Adam Mamelak, MD, professor of neurosurgery and director of functional neurosurgery, has studied the synthetic version of chlorotoxin and its tumor-targeting properties for more than a decade.
In this study, chlorotoxin was bonded to a molecule, indocyanine green, a near-infrared dye, a version of which already is approved by the Food and Drug Administration. The chlorotoxin-indocyanine green combination Tumor Paint BLZ-100 emits a glow when stimulated by near-infrared light.
"Injected intravenously, the chlorotoxin seeks out the brain tumor, carrying with it indocyanine green, which has been used in a variety of medical imaging applications. When we shine a near-infrared laser on the tissue, the tumor glows. But the glow emitted by the tumor is invisible to the human eye," said Butte, whos
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Cedars-Sinai Medical Center