By Dennis Thompson
FRIDAY, March 6, 2020 (HealthDay News) – Few heartbreaks are as devastating as when a beloved family dog becomes ill with cancer.
But new research work could spur the development of more and better treatments for a canine companion who has a brain tumor, because those same therapies may also help human children. Dog brain cancers are genetically similar to those found in children, according to a new study published in the journal. Cancer cell reports.
“These dog tumors were much more similar to the tumors we found in children than the tumors we found in adults,” said lead researcher Roel Verhaak, associate director of computational biology at the Jackson Laboratory in Farmington, Connecticut.
“This is important because it means that any results we find in preclinical experimental therapy studies involving canines will be more applicable, and perhaps even only applicable, to brain tumors in children,” he added.
The researchers concluded that striving to cure pets with brain tumors and learning which therapies work best and why they might inform cancer treatments for children with these tumors.
The family dogs were once thought to be better at testing experimental cancer drugs than laboratory animals like mice or monkeys, said Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society.
This is because dogs live closely alongside humans, sharing the same exposures from home and play, and often the same food from the table, he said.
“What we need to see are the similarities and differences between the canine tumor and the human tumor, and that is exactly what this research has done,” Lichtenfeld said. “I personally find this report very exciting and very important.”
The study focused on gliomas, a common type of brain cancer. Senators John McCain and Ted Kennedy died of gliomas, and a similar brain tumor claimed the life of Rush drummer Neil Peart in January.
Companion dogs develop gliomas almost as often as humans, the researchers said in the background notes. Dogs develop gliomas at an average age of 9 years.
Whether in humans or canines, gliomas are incredibly difficult to treat, Verhaak and Lichtenfeld said.
“They do not respond to chemotherapy and very minimally to radiation therapy,” said Verhaak. “When dogs have a brain tumor, their owners often choose compassionate euthanasia because there are minimal treatment options for these dogs and it is expensive to treat a dog for a brain tumor.”
Verhaak’s team collected brain tissue samples from 83 dogs that suffered natural deaths caused by gliomas. Heartbroken families donated all samples.
Humans tend to be diagnosed with brain tumors, either in childhood or between the ages of 40 and 70, Verhaak said.
Since dogs, on average, develop gliomas around age 9, the middle-age for canines, the researchers suspected that their tumors closely resembled those of adult humans.
Instead, they were surprised to find that the tumors in dogs were more like those in children, which are closer to their actual age.
The gliomas in the dogs had several mutations similar to pediatric brain cancers. Both are lower than the number of mutations found in adult gliomas, the findings showed.
The researchers also found that the immune systems of dogs with gliomas closely resembled those of human patients, meaning that immunotherapies that work against canine gliomas could also be effective in people.
“There are some very specific gliomas in children that don’t occur in adults that are incredibly difficult to treat. We don’t have any medications that are particularly successful,” Lichtenfeld said. “Having a model that could advance research on gliomas in children is huge.”
Comparing canine and human gliomas has also helped “fine-tune” researchers to focus on the genetic changes that are crucial in glioma development, Verhaak said.
“This research allowed us to get closer to parts of the genome where we see changes in both human and canine tumors,” he said. “It really reduced the number of disease pathways that are essential for dog tumors, childhood tumors, and adult tumors.”