Jianjun Cheng, a professor of materials science and engineering at the University of Illinois at Urbana-Champaign, has been working on a system for delivering high doses of the chemotherapy drug doxorubicin directly to bone tumors via tiny “nanoparticles.” But testing the technology in lab mice has been challenging, because mouse models of cancer don’t closely mirror what people with the disease experience.
So Cheng teamed up with University of Illinois veterinary clinical medicine professor Timothy Fan to test the particles in a more realistic model: pet dogs that have developed osteosarcoma. In a paper published recently in the Proceedings of the National Academy of Sciences, they demonstrated that the nanoparticles homed in on bone tumors and produced anticancer effects.
The nanoparticles, which are made of polylactide, carry a doxorubicin payload. They are coated with a drug called pamidronate, which targets degraded areas of bone and delivers the chemo drug directly to tumors. The treatment was well tolerated by the dogs, who suffered none of the toxicities normally associated with systemic doses of doxorubicin, Cheng and Fan reported. They are hoping to provide proof-of-concept that this delivery method might be able to be used in people with bone cancers that can’t be surgically removed.
Dogs are considered to be better models of human bone cancer than mice are, because dogs develop the disease naturally, and their tumors are often close in size to what people get.
“I would say that if you are able to demonstrate anti-cancer activity in a dog with very advanced disease, then it would be likely that you would have equivalent or better activity in people with a less advanced stage of the disease," Fan said in a press release from the University of Illinois.
The college’s research is one of several osteosarcoma studies taking place around the world in dogs with the disease. In March, for example, veterinarians at Colorado State University used tumor samples from dogs with osteosarcoma to map genes that they believe help predict how patients will respond to doxorubicin and another commonly used chemo drug, carboplatin. Since the genes are present in both dogs and humans, the model could be used to predict chemo response in people.
And in April, the National Cancer Institute’s Comparative Oncology Trials Consortium (COTC) deployed 20 veterinary schools to a study of the immunosuppressant rapamycin, which inhibits a mutated form of the protein mTor. The research is designed to test the theory that inhibiting the protein might help shrink tumors.
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