SEATTLE: July 15, 2007 -- A tumor paint developed by researchers at Seattle Childrens Hospital Research Institute and Fred Hutchinson Cancer Research Center will help surgeons see where a tumor begins and ends more precisely by illuminating the cancerous cells. The study, published in the July 15, 2007 issue of Cancer Research, shows that the tumor paint can help surgeons distinguish between cancer cells and normal brain tissue in the operating room. The paint is a scorpion-derived peptide called chlorotoxin that is linked to the molecular beacon Cy5.5.Until now there has been no way to allow surgeons to see tumors live during surgery.

Chlorotoxin:Cy5.5 is a fluorescent molecular beacon that emits photons in the near infrared spectrum. This illumination gives surgeons a better chance of removing all of the cancerous cells during surgery without injuring surrounding healthy tissue. This is particularly significant in the brain, where approximately 80% of malignant cancers recur at the edges of the surgical site. Current technology, such as magnetic resonance imaging (MRI) can distinguish tumors from healthy tissue only if more than 1 million cancer cells are present. But Cy5.5 can identify tumors with as few as 2000 cancer cells, making it 500 times more sensitive than MRI.

"My greatest hope is that tumor paint will fundamentally improve cancer therapy, said James M. Olson, MD, PhD, of Seattle Childrens Hospital and The Hutchison Center who is the senior author of the study. By allowing surgeons to see cancer that would be undetectable by other means, we can give our patients better outcomes.

Olson led the team that included neurosurgeons, engineers and biologists. The bioconjugate, Chlorotoxin:Cy5.5 which, when injected, emits a near-infrared light, was created in his laboratory at the Hutchinson Center. In mouse models, the team demonstrated that they could light up brain tumors as small as 1 millimeter in diameter without lighting
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Contact: Jennifer Seymour
jennifer.seymour@seattlechildrens.org
206-987-5207
Children's Hospital and Regional Medical Center of Seattle
15-Jul-2007