Click chemistry may help treat dogs with bone cancer

In September, researchers from California and Denmark were awarded a Nobel Prize in Chemistry for their development of ‘click’ chemistry, a process in which molecules snap together like LEGO, making them a potentially more efficient transportation device in delivering pharmaceuticals to cancer tumors.

Now, in a recent study, a researcher at the University of Missouri has successfully shown for the first time how click chemistry can be used to more efficiently deliver drugs to treat tumors in large dogs with bone cancer — a process that had previously only been successful in small mice.

“If you want to attack a tumor using the immune system, an antibody is an extremely specific way to deliver a drug or radioactive payload to the tumor, but the problem with antibodies is they are huge molecules that circulate in the bloodstream for days or even weeks,” said Jeffrey Bryan, an associate professor in the MU College of Veterinary Medicine and author on the study. “If you put a drug or radioactive molecule onto the antibody, you leave radioactivity circulating in the bloodstream for a long time, which can spread to and negatively impact organs, bone marrow and the liver while not getting as much dose to the specific tumor as you were hoping for.”

The goal with click chemistry is to maximize the delivery of therapeutic drugs specifically to the cancer tumor to increase effectiveness while minimizing the circulation of those drugs throughout the bloodstream and causing dangerous side effects.

From mice to man’s best friend

For years, many chemists assumed that while click chemistry has been successful in mice, the strategy would not work in large dogs or people because the size of the body might be too big for the two sides of therapy-delivering molecules to find each other and snap, or ‘click,’ together. Bryan collaborated with Brian Zeglis, an associate professor at Hunter College in New York who specializes in click chemistry, to conduct the first-ever successful ‘proof-of-concept’ study at the MU College of Veterinary Medicine. Using click chemistry, doses of radiopharmaceuticals were delivered specifically to the tumors in five dogs that weighed more than 100 pounds and had bone cancer.

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