For owners whose dog has been diagnosed with a glioma — or whose MRI indicates a suspected glioma brain tumor — deciding what to do next can be difficult. The UC Davis Weill School of Veterinary Medicine is recruiting dogs for two clinical trials designed to offer a spectrum of care while advancing research into canine brain tumors.

The CARE Trial is testing an experimental drug in combination with radiation therapy for dogs with glioma. A second study, the PRISM trial, includes both an observational/palliative pathway and a radiation therapy pathway. Together, the studies give families with different treatment goals and financial circumstances opportunities to pursue diagnosis or care and contribute to research.

What Is a Glioma in Dogs?

A glioma is a tumor that develops from glial cells, which support and protect nerve cells in the brain. Canine gliomas include astrocytomas and oligodendrogliomas. Because these tumors grow inside the skull, they can interfere with normal brain function and cause progressively worsening neurological problems.

Symptoms of a brain tumor in dogs can include seizures, disorientation, behavioral changes, vision loss and other neurological changes. The signs vary depending on the tumor's size and location. An estimated 6,500 dogs develop glioma in the United States each year.

MRI can identify a suspected brain tumor, while a biopsy allows veterinary specialists to confirm the diagnosis and examine the tumor's molecular characteristics. Current treatment options may include surgery, radiation therapy, chemotherapy or supportive and palliative care, depending on the dog and the family's goals. Unfortunately, gliomas are difficult to treat, and the disease is fatal for most dogs diagnosed with them

Two Clinical Trial Options for Dogs with Canine Glioma

The two UC Davis studies approach glioma from complementary directions to achieve one goal – to improve patient outcomes. The CARE trial is a treatment course that tests a strategy intended to make tumor cells more vulnerable to radiation. The PRISM trial is a research and monitoring trial that connects changes in each dog's symptoms and disease progression with the molecular signature of the tumor, helping researchers classify canine gliomas more precisely. Owners in this trial may or may not pursue traditional radiation treatment. Either way they are contributing to the knowledge of gliomas to potentially benefit future dogs and humans who develop glioma, while also having their dog monitored and cared for by the neuro-oncology team during treatment/palliative care.

CARE Trial: Experimental Drug and Radiation Treatment

The Combined Autophagy inhibition and Radiation to improve Efficacy in canine glioma, or CARE, trial is investigating whether an experimental drug can reach brain tumors after being administered intravenously and whether combining it with radiation may improve patient outcomes. The drug is designed to block autophagy, a cellular process that cancer cells can use to withstand stress and survive treatment.

By inhibiting that protective process while dogs receive radiation therapy, researchers hope to make tumor cells more vulnerable to treatment. Researchers will study whether the drug reaches the tumor and produces the intended biological effects when given alongside radiation.

Dogs enrolled in this trial will receive the experimental drug intravenously twice a week for four weeks while simultaneously undergoing standard radiation therapy.  Participants will receive a brain tumor biopsy before treatment and another after completing treatment. The biopsies will allow researchers to confirm the diagnosis and compare tumor tissue before and after therapy. Dogs will be closely monitored by a UC Davis veterinary neuro-oncology team throughout their participation, and the trial covers the cost of all study procedures. The only cost to the client is the cost for radiation therapy, but the study will provide $4,000 toward this treatment. Because the treatment is experimental, its safety and effectiveness have not yet been established. Determining safety, tumor uptake and biological response are among the study's central objectives.

PRISM Trial: Observational and Radiation Pathways

The Precision Research Integrating Symptoms and Molecular Biology in Canine Glioma, or PRISM, trial is recruiting 60 dogs for participation in two different pathways. Researchers will document how each dog's disease progresses and compare that information with a detailed molecular analysis of the tumor.

The findings will help researchers begin to identify distinct subtypes of canine glioma. A more precise classification system could guide future targeted therapies for dogs and help scientists determine which naturally occurring canine gliomas may be most relevant to pediatric or adult glioma in people.

Observational/Palliative Pathway

Dogs in this PRISM pathway do not receive an experimental therapy through the study. Instead, they return for monthly hospital visits and brain MRI examinations so researchers can characterize how the tumor and the dog's clinical signs change over time.

The observational pathway is intended in part for families that cannot or do not plan to pursue advanced treatment but want a definitive diagnosis and an opportunity to contribute to research. The study provides $3,000 toward the initial diagnostic workup, which costs approximately $7,000, and covers trial-related follow-up care.

Radiation Therapy Pathway

Dogs participating in PRISM while receiving radiation therapy return for follow-up visits and brain MRI examinations every three months. The study provides $3,000 toward radiation treatment and covers trial-related follow-up care.

Both PRISM pathways involve a brain tumor biopsy at the start of the study. Participation also includes a postmortem examination when the family chooses to say goodbye to the dog. The tissue and clinical information collected throughout the study will allow researchers to compare tumor biology with each dog's course of disease.

Frequently Asked Questions About the Canine Glioma Trials

Does my dog need a confirmed glioma diagnosis to be screened?

Dogs with a suspected glioma may be considered for screening. The UC Davis clinical trial team will review each dog's diagnosis, condition and medical history. A biopsy performed through the study can confirm the diagnosis and provide tissue for molecular analysis.

Does my dog have to receive radiation therapy?

No. The CARE trial requires standard radiation therapy, and PRISM has a pathway for dogs receiving radiation. However, PRISM also offers an observational/palliative pathway in which no experimental study therapy is administered.

What costs do the studies cover?

The CARE trial provides $4,000 toward radiation therapy and covers study procedures. PRISM provides $3,000 toward either the initial diagnostic workup or radiation treatment, depending on the pathway, and covers trial-related follow-up care. Families remain responsible for expenses not covered by the applicable study.

Can my veterinarian refer my dog?

Yes. Dog owners or referring veterinarians may contact the UC Davis clinical trial team to request screening. The team will determine whether a dog meets the requirements for either study.

Where do the clinical trial visits take place?

Screening, study procedures and follow-up visits take place through UC Davis in Davis, California. Families should discuss the expected number and timing of visits with the clinical trial team before enrolling.

Will participating improve my dog's outcome?

There is no guarantee that participating in a clinical trial will improve an individual dog's outcome. The CARE trial is experimental, and its safety and effectiveness have not been established. The observational PRISM pathway is designed to collect information and does not provide an experimental therapy.

How Can Canine Glioma Research Help Dogs and People?

Naturally occurring gliomas in dogs share important biological characteristics with human gliomas. Unlike experimentally induced tumors, cancers in companion dogs develop spontaneously in animals with intact immune systems and the genetic and environmental diversity found in a clinical population.

This makes canine glioma research valuable not only for improving veterinary care but also for exploring treatments and tumor classifications that could eventually inform human medicine.

"Companion canines with glioma are becoming more readily acceptable as a translational model for human glioma," said Christine Toedebusch, director of the newly established UC Davis Translational Brain Tumor Center and an associate professor at the veterinary school. "Trials like this potentially open up new treatments for both dogs and humans."

Both of these trials are funded by the National Cancer Institute, underscoring the increasing importance of companion dogs in the search for a cure for glioma brain tumors across species. 

Dr. Yuanpei Li, lead investigator supporting the CARE trial, professor of biochemistry and molecular medicine and associate director of investigational therapeutics for the UC Davis Translational Brain Tumor Center, developed the investigational agent for the CARE trial. In collaboration with Toedebusch, he is testing the safety and preliminary efficacy in companion dogs through the CARE Trial. 

The PRISM trial, led by Dr. Christine Toedebusch, is supported by her recent R37 award from the National Cancer Institute.

Ask About a Glioma Clinical Trial for Your Dog

You can learn more about the CARE trial and sign up at this page.

You can learn more about the PRISM trial at this page.

For additional information, owners and veterinarians may email Dr. Christine Toedebusch or contact the Veterinary Center for Clinical Trials at (530) 754-1954. Please visit the UC Davis Translational Brain Tumor Center website to learn more.

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