Researchers from California and Denmark were awarded the Nobel Prize in Chemistry in September for developing "click" chemistry, a process in which molecules snap together like LEGO, potentially making them a more efficient transportation device for delivering pharmaceuticals to cancer tumors.
'Click' chemistry may help treat dogs with bone cancer
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In a recent study, a University of Missouri researcher demonstrated 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, as per ScienceDaily.
If you want to use the immune system to attack a tumor, an antibody is an extremely specific way to deliver a drug or radioactive payload to the tumor, but the problem with antibodies is that they are huge molecules that circulate in the bloodstream for days or even weeks, according to Jeffrey Bryan, an associate professor in the MU College of Veterinary Medicine and study author.
The goal of click chemistry is to maximize therapeutic drug delivery specifically to cancer tumors to increase efficacy while minimizing drug circulation throughout the bloodstream and causing dangerous side effects.
For years, many chemists assumed that while click chemistry had been successful in mice, it would not work in large dogs or humans because the size of the body would be too large for the two sides of therapy-delivering molecules to find each other and snap, or "click," together.
Bryan worked with Brian Zeglis, an associate professor at Hunter College in New York who specializes in click chemistry, to carry out the first successful "proof-of-concept" study at the MU College of Veterinary Medicine.
Doses of radiopharmaceuticals were delivered specifically to the tumors in five dogs weighing more than 100 pounds and suffering from bone cancer using click chemistry.
Bryan has spent nearly two decades studying veterinary and comparative oncology.
He claimed that some dogs with one known bone tumor have additional bone tumors hidden within their skeleton.
Another advantage of studies involving imaging scans and click chemistry is the ability to determine whether additional cancer tumors are present in a dog's skeleton and affect its health.
The MU College of Veterinary Medicine, which received more than $14 million in federal research funding from the National Institutes of Health last year, is home to cancer clinical trials that draw people and their pets from California, Florida, New York, and other states across the country.
While this was a successful "proof-of-concept" imaging study involving click chemistry, Bryan's long-term goal is to develop a therapy involving radiopharmaceuticals, potentially involving an antibody-targeting molecule, to treat dogs with bone cancer that may not be well enough for other surgical treatments.
Bryan will collaborate with ELIAS Animal Health in 2020 to develop a precision medicine approach (a vaccine derived from a dog's tumor) to target and kill cancer cells in dogs suffering from osteosarcoma.
Because of the treatment's success in dogs, the Food and Drug Administration granted ELIAS Animal Health's parent company, TVAX Biomedical, a rare fast-track designation to study the ELIAS immunotherapy approach to treat glioblastoma multiforme, a cancerous brain tumor in humans.
The last dog in that study died a few weeks ago, five years after their initial diagnosis of bone cancer, and the dog never relapsed, so the dog was able to live the rest of its life cancer-free thanks to the immunotherapy, Bryan said.
Osteosarcoma is a type of aggressive bone cancer. It is the most common type of primary bone cancer in dogs, and it usually starts in the leg, as per The Pet Oncologist.
Large dog breeds are disproportionately affected by this cancer.
Although osteosarcoma is serious cancer, the vast majority of dogs can be significantly helped with treatment.
Most dogs with bone cancer in the leg will have a limp and swelling in the bone, which can lead to misdiagnosis as a soft tissue injury or orthopedic problem.
Cancer in the leg is excruciatingly painful because small fractures and bleeding put pressure on the sensitive nerve endings on the affected bone's surface.
Sometimes the fractures are more severe, resulting in a broken leg that cannot be repaired (called a pathological fracture).
Amputation is the most effective treatment for cancer of the leg in the vast majority of dogs and will relieve the pain caused by bone cancer while also preventing the leg from breaking.
Because amputation does not stop the spread of cancer, a therapy that can reach the lungs and other body sites are required to prevent or delay the spread of these cancers.
Chemotherapy after amputation is the most important advancement and gold standard treatment for osteosarcoma in dogs, as it can slow the spread of cancer, dramatically improve life expectancy, and, in some cases, result in a cure.
