New Tumour Paint Illuminates Cancer Cells

Picture: A palette

Making tumour cells visible with
a new tumour paint; © Hemera

A tumour paint developed by researchers at Seattle Children’s Hospital Research Institute and Fred Hutchinson Cancer Research Center will help surgeons see where a tumour begins and ends more precisely by illuminating the cancerous cells. 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 tumours “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 percent of malignant cancers recur at the edges of the surgical site. Current technology, such as magnetic resonance imaging (MRI) can distinguish tumours from healthy tissue only if more than 1 million cancer cells are present. But Cy5.5 can identify tumours with as few as 2000 cancer cells, making it 500 times more sensitive than MRI.

"My greatest hope is that tumour paint will fundamentally improve cancer therapy,” said James M. Olson, MD, PhD, of Seattle Children’s 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.”

In mouse models, the team demonstrated that they could light up brain tumours as small as one millimetre in diameter without lighting up the surrounding normal brain tissue. In a prostate cancer model, as few as 200 cancer cells travelling in a mouse lymph channel could be detected.

Tumour painting has been successfully tested in mice and the pilot safety trials are complete. Olson and his team are preparing the necessary toxicity studies before seeking approval from the Food and Drug Administration to begin clinical trials.

MEDICA.de; Source: Children's Hospital and Regional Medical Center of Seattle