Researchers Develop Chlorotoxin:Cy5.5 Enabling Surgeons to See Cancer Cells
500 times better than an MRI
SEATTLE, July 15 /PRNewswire-USNewswire/ -- A tumor paint developed by
researchers at Seattle Children's 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 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 fewer than
2000 cancer cells, making it 500 times more sensitive than MRI under
operating conditions.
"My greatest hope is that tumor 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."
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 up the
surrounding normal brain tissue. In a prostate cancer model, as few as 200
cancer cells traveling in a mouse lymph channel could be detected.
Chlorotoxin:Cy5.5 is applicable to many cancers, but is especially
helpful to surgeons operating on brain tumors. Not only would it reveal
whether they'd left behind any bits of tumor, it would also help them avoid
removing normal tissue. Chlorotoxin:Cy5.5 begins binding to cancer cells
within minutes. The Chlorotoxin:Cy5.5 signal lasts for 14 days,
illuminating cancer cells. Contrast agents currently in use only last for a
few minutes.
"I feel fortunate to be working with gifted scientists to bring this
revolutionary imaging technique from the laboratory to the bedside," said
Richard Ellenbogen, MD, pediatric neurosurgeon, Seattle Children's Hospital
and co-investigator on the study. "This development has the potential to
save lives and make brain tumor resection safer."
Surgery remains a primary form of cancer therapy. Despite advances in
surgical tools, surgeons currently rely on color, texture or blood supply
to differentiate tumor from normal tissue, a distinction that is often
subtle and imperfect. The limitations of this method contribute to cancer
growth or patient mortality that is potentially preventable. The tumor
painting technique combines a visual guide for the surgeon with the
potential for significant improvement in accuracy and safety.
Tumor 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. Chlorotoxin:Cy5.5 could be used in
operating rooms in as little as 18 months. All clinical studies will have
consenting adult participants.
Olson and his team believe that Chlorotoxin:Cy5.5 has the potential to
be used in the future as a non-invasive screening tool for early detection
of skin, cervical, esophageal, colon and lung cancers. It is also useful in
identifying positive lymph nodes which could mean a significant advancement
for breast, prostate and testicular cancers.
Children's and the Hutchison Center's role as leading research
institutions is underscored by their membership in the Pediatric Brain
Tumor Consortium (PBTC), a group of 10 medical centers selected by the
National Cancer Institute (NCI). The consortium's members were chosen by
the NCI based on their experience, dedication to research and quality of
patient care.
Other Children's and Hutchison Center, and University of Washington
researchers on the team include Mandana Veiseh, PhD; Patrik Gabikian,
S-Bahram Bahrami, PhD; Omid Veiseh, Miqin Zhang, Robert C. Hackman, MD; Ali
C. Ravanpay, Mark R. Stroud, PhD; Yumiko Kusuma, Stacey J. Hansen, Deborah
Kwok, Nina M. Munoz, PhD; Raymond W. Sze, MD; William M. Grady, MD; and
Norman M. Greenberg, PhD.
About Seattle Children's Hospital Research Institute, Seattle, Wash.
At the forefront of pediatric research, the Seattle Children's Hospital
Research Institute at Children's Hospital and Regional Medical Center in
Seattle conducts research under nine major centers and is internationally
recognized for its discoveries in cancer, genetics, health services,
immunology, pathology, infectious disease and vaccines. Consistently ranked
as one of the best children's hospitals in the country by U.S. News & World
Report, Children's serves as the pediatric referral center for Washington,
Alaska, Montana and Idaho. Children's has been delivering superior patient
care for 100 years, including advancing new discoveries and treatments in
pediatric research, and serving as a primary teaching, clinical and
research site for the Department of Pediatrics at the University of
Washington School of Medicine. For more information about the Institute
visit http://research.seattlechildrens.org/.
At Fred Hutchinson Cancer Research Center, our interdisciplinary teams
of world-renowned scientists and humanitarians work together to prevent,
diagnose and treat cancer, HIV/AIDS and other diseases. Our researchers,
including three Nobel laureates, bring a relentless pursuit and passion for
health, knowledge and hope to their work and to the world. For more
information, please visit fhcrc.org.
Media Contacts:
Amy MacIver
Children's Hospital and Regional Medical Center
(206) 987-5210
(206) 469-3745 pager
amy.maciver@seattlechildrens.org
Dean Forbes
Fred Hutchinson Cancer Research Center
(206) 667-2896
(206) 605-0311 cell
dforbes@fhcrc.org
SOURCE Seattle Children's Hospital Research Institute
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Related links:
http://www.seattlechildrens.org
CONTACT:
Amy MacIver of Children's Hospital and
Regional Medical Center, +1-206-987-5210, +1-206-469-3745 pager,
amy.maciver@seattlechildrens.org; or Dean Forbes of Fred
Hutchinson Cancer Research Center, +1-206-667-2896,
+1-206-605-0311 cell, dforbes@fhcrc.org
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