Just Like Us
A common feline cancer may hold the key to better treatments for humans
The traditional means of testing a potential treatment for cancer is to get a lab full of mice and conduct controlled experiments that attempt to prevent tumor growth. In the late 1990s, such studies produced a new medication that choked off the blood flow to malignant cells. It was hailed as a wonder drug.
“There was literally a headline in the New York Times saying scientists would cure cancer within two years,” says Elizabeth McNiel, a comparative oncologist whose research lab is based in the Molecular Oncology Research Institute of Tufts Medical Center and who conducts clinical research at the Cummings School of Veterinary Medicine on Tufts’ Grafton campus. “It was huge.”
But once researchers tested the drug outside the lab, in human clinical trials, it did not produce such miraculous results. Drugs that cut off blood supply to tumors “have been disappointing [in treating] many types of cancer,” says McNiel. “There seems to be a really big disconnect between what we observed in the mouse and what was observed in humans.”
In what could signal a new direction for cancer research, McNiel hopes to bridge that evident disconnect by studying the disease in cats. The work could produce breakthroughs to advance cancer treatment in cats and humans.
As companion animals, cats live in the same environments as their owners, and the cancers they develop tend to occur in similar ways to those in humans. Whereas mouse cancers usually are small and contained, feline cancers come in various sizes and spread throughout the body.
“We think that [human and feline cancers] may be parallel in their underlying causes,” says McNiel. Studying cancer in domestic cats may produce more reliable results than using lab mice and could result in more effective treatments in the long run.
McNiel studies squamous cell carcinoma, a cancer of the mouth typically caused in humans by tobacco use, though increasingly by human papillomavirus (HPV). It is also one of the most common feline cancers. Squamous cell carcinoma is usually quite aggressive.
Those grim statistics make this cancer a good candidate for study in a clinical environment, McNiel says, because pet owners might be more willing to consider a nontraditional therapy when faced with such dismal survival rates.
In research funded by the Morris Animal Foundation, McNiel is investigating the potential of a drug used to treat human cancer. The designer peptide called Anginex contains 33 amino acids that bind to another protein in the blood vessels that supply tumors with growth-promoting nutrients and oxygen. The bound drug helps switch off the flow of blood to the tumor cells, essentially severing their lifeline.
Thus far, McNiel and her colleagues have conducted successful safety trials to ensure that the drug won’t harm cats. They tested the drug in the laboratory, using feline blood vessel tissue, as well as in a dozen cats being treated for squamous cell carcinoma at the Foster Hospital for Small Animals at Tufts.
Michael Blanding is a freelance writer in Brookline, Mass.