UNH chemists invent molecules for cancer imaging
“Clamshell” could allow earlier tumor detection with PET scans

UNH chemists Gary Weisman and Ed Wong designed the new class of “clamshell” molecules that are the basis of new imaging compounds for Positron Emission Tomography, or PET scans. By providing sharper images, these compounds could allow doctors to see smaller tumors, treat patients sooner and save lives. One of the new imaging compounds is currently being tested in rats and preliminary results are very promising.

“Our collaborator Carolyn Anderson told us that it lights up tumors like a Christmas tree,” said Wong. “She said that it produced the nicest, sharpest images they’d ever seen.”

PET scans produced with conventional copper-based imaging agents appear hazy because proteins in the body hijack the positron-emitting copper isotope from the imaging agent. The clamshell molecules, however, hang on to metal ions by embracing them snuggly in a protective shell. Anderson and co-workers attach the clamshells to polypeptides that target specific tumors and then “tag” the composite molecule with a copper radioisotope.

“The use of the clamshell molecules developed by Drs. Wong and Weisman for complexing copper radionuclides for PET imaging is a major advance for PET radiopharmaceuticals,” said Anderson, a professor at Washington University (St. Louis) and the medical school’s Mallinckrodt Institute of Radiology, where the first usable PET scanner was developed in 1970. “The sky’s the limit for the uses of the clamshell molecules for binding copper and other metal radionuclides to a multitude of targeting molecules for imaging and therapy of cancer and other diseases.”

Anderson, Weisman, and Wong’s collaborative research efforts in this area are currently funded by a grant from the National Cancer Institute of the National Institutes of Health. Their research progress has been reported in a series of journal articles, the latest appearing in the Dec. 15 issue of Clinical Cancer Research.

To see their work result in a potential biomedical application is an added bonus for Wong, an inorganic chemist, and Weisman, an organic chemist. Their 16-year collaboration has focused primarily on basic, rather than applied research.

“We’re academics and most of the breakthroughs in science have been from basic research,” said Weisman. “And basic research provides problems for students to work on and mature into scientists themselves.”

Both of these teacher-scholars have involved undergraduates as well as graduate students in their research for many years. “Our goal in all of our research programs has always been to turn students into professionals,” said Wong. “That’s as important a goal as doing good science.”

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