How Dogs Are Advancing Human Cancer Research

Dogs have been helping humans for centuries. Whereas some participate in law enforcement, animal-assisted therapy, search and rescue, and other essential work, the goofy golden retriever who lives next door might be a hero too. Increasingly, family pets are improving human cancer therapies by participating in canine clinical trials.

“Dogs continue to be an incredibly valuable part of the biomedical research process,” said Amy LeBlanc, DVM, DACVIM, director of the Comparative Oncology Program at the National Cancer Institute (NCI). “They are a huge part of how safe and effective drugs are developed in this country.”

What is Comparative Oncology?

The NCI describes comparative oncology as “the study of naturally developing cancers in animals as models for human disease.” The dogs Dr. LeBlanc works with are not bred to live in laboratories or injected with tumor cells. They are family pets who receive a cancer diagnosis and have parents who love them.

“This is a dog that has developed cancer as a consequence of their environment, genetic background, and susceptibility,” Dr. LeBlanc explained. “They’ve slept on your couch. They’ve eaten your pizza. They are exposed to everything you are exposed to. And then, because of their compressed lifespan, those exposures are magnified.”

Some canine cancers that share features with human cancers include bladder cancer, non-Hodgkin lymphoma, melanoma, breast cancer, osteosarcoma, head and neck cancer, and even insulinomas. Genetic similarities between species help human and canine experts share notes and further research in both fields.

“We’re really trying to make sure that what we learn can be shared,” Dr. LeBlanc said. “My program only participates in trials specifically designed to advance human health. When we do that, we also help the veterinary community because we generate data that we then publish and share.”

To help with knowledge sharing, the NCI developed a public repository for canine cancer data called the Integrated Canine Data Commons. Researchers use this information to further human medicine too.

“It’s really important to the NCI that data is disseminated to the community, so it can help everybody who’s interested in canine cancer, whether they’re pro-human, pro-dog, or in our case, both,” Dr. LeBlanc said.

Family Pets Provide Unique Perspective

Although beagles have made headlines in recent years because of their widespread use as animal test subjects and the efforts of animal rights organizations to free them, dogs living as household pets can provide unique insights into human research.

“Their immune system is more a reflection of ours,” said Dr. LeBlanc of the dogs she works with.

Dr. LeBlanc explained that a beagle who lives in a laboratory housing unit and eats the same food, drinks the same water, and breathes the same air every day has an immune system with less real-world experience than a dog who goes to the dog park, gets vaccines, and encounters diverse environmental exposures. She explained that a 10-year-old Labrador retriever who lives with a family and develops cancer will respond to drugs differently than an 18-month-old beagle raised in a laboratory.

“Their cardiac, kidney, and liver functions are not normal,” Dr. LeBlanc said of older family pets. “They have lived to be like a sixth- or seventh-decade-of-life human. If you give the same drug at the same dose to the beagle and the 10-year-old Lab, their pharmacokinetic profiles are different. They don’t process, absorb, distribute, and metabolize drugs the same way.”

Dr. LeBlanc said that the goal of comparative oncology is not to replace the foundational part of studying and developing drugs, but to add to it. Studying a dog who has developed a tumor naturally provides insights that can’t be captured in a lab. Family pets may also be more effective communicators because of their deeply personal relationships with their owners.

“There’s no substitute for the bond between a human owner and a dog,” Dr. LeBlanc said. One of the most valuable lessons she learned as a young veterinarian was to listen to the dog or cat owner because they know better than anyone how their pet is feeling.

“You can’t appreciate those subtle changes that can be indicative of nausea, fatigue, and other side effects in purpose-bred dogs, and you absolutely can’t observe them in mice,” Dr. LeBlanc said. “It’s helpful when you can predict some of that based on drug class, and then it’s augmented by a really perceptive pet owner.”

Canine Clinical Trials

The American Veterinary Medical Association (AVMA) provides a free database of information about canine clinical trials in much the same way that ClinicalTrials.gov does for human trials. You can search the AVMA Animal Health Studies Database by animal species, location, and diagnosis. If you find a trial that looks interesting, speak with your veterinarian or veterinary oncologist.

“Typically, they need to work with their family veterinarian because we need to understand their eligibility for trial,” Dr. LeBlanc said. “It’s really an identical process to what happens for humans. There’s a screening process, and there’s eligibility and inclusion and exclusion criteria. The way we conduct our trials is modeled off the human experience because we hold ourselves to that standard.”

Dr. LeBlanc recently led a clinical trial investigating a new treatment (CB-5339) for multiple myeloma. The study found that dogs tolerated the drug well, and it was effective enough to warrant further research. Now, human trials are investigating it too.

“Dogs with naturally occurring myeloma are a wealth of information data, and maybe, most importantly, enthusiasm,” Dr. LeBlanc said. “There are so many potentially promising cancer drugs – not just for multiple myeloma, but for all cancers – that don’t get a chance to move forward because there isn’t the necessary sort of nexus of enthusiasm around them.”

She said that the canine multiple myeloma trial helped garner enough interest to explore the drug in humans, but sometimes the opposite outcome can be just as informative.

“We’ve also done studies that have been negative, and the message has been, ‘Don’t get enthusiastic about this, and don’t waste any more money or time on this approach.’ In the eyes of pharmaceutical companies, this may be even more valuable,” Dr. LeBlanc explained. “They can stop spending resources on things that are not going to go anywhere.”

Dr. LeBlanc is passionate about the work she does, and she wants people to know that not only can dogs participate in clinical trials at a high level, but they are treated well when doing so.

“Some people have mental images of dogs in kennels and dark, dim spaces where there’s no care,” Dr. LeBlanc said. “That is so not what we do. It is a warm, supportive hospital clinic environment with people who are genuinely interested in making sure the dog’s best interests are met. And then, joint decision making occurs between the veterinarian and the family. These canine clinical trials look like human trials,” in that they are designed by similar guidelines and inclusion/exclusion criteria.

A Pet Parent’s Experience

Alan Smith and his wife, Nathalie, adopted a golden retriever/cocker spaniel mix they named Truffle from a shelter when she was a puppy. After five years of love and adventures, they noticed a concerning spot developing between two of Truffle’s front toes.

“She had this spot that looked irritated,” Smith said. “At first, I thought it was a blackberry thorn or something else she picked up on a hike. But over the course of a few days, it went from a raised red spot to the size of half a grape. When we took her to the vet, they aspirated it and told us it was a mast cell tumor.”

Mast cell tumors is a type of cancer that originates from mast cells, a type of immune cell found in various tissues throughout the body, and can be aggressive in dogs. Depending on the tumor grade and location, the prognosis can be as short as four to six months. The only treatment the Smiths’ veterinarian could offer was surgery, and they said Truffle would lose at least one toe, maybe two, to ensure good margins. For a dog who loved joining her parents on outdoor adventures, this outcome would be less than ideal. The Smiths asked for a referral.

“Our vet recommended an oncologist who might have other options,” Smith said. “When we went to see her, she offered a surgical option but was actually quite excited about Truffle because of her age and the location of the tumor. She felt like Truffle was a very good fit for a clinical trial she was involved with.”

The Smiths asked for more information and did their own research before enrolling Truffle. Because the trial did not involve surgery, it seemed like an opportunity to save Truffle’s toes. They also liked that it was a clinical trial for human treatments, so whatever the researchers learned might also benefit people.

“I felt like our primary responsibility was to Truffle and providing her with the best option,” Smith explained. “And it seemed like the clinical trial was the best option. But the fact that it was also potentially going to help people was also a significant factor in our decision.”

The clinical trial moved quickly. Truffle received intravenous and laser therapy once a week for three weeks at a center close to home. The Smiths dropped her off in the morning and picked her up in the afternoon. For Truffle and her parents, the trial was a success. The cancer disappeared and never returned, leaving Truffle cancer-free and with all her toes and full mobility.

“Truffle was my hiking buddy,” Smith said. ”Keeping her toes gave us several more years of mountain climbing, swimming, and exploring.” Although clinical trials don’t always have positive outcomes, in this instance, doing what was best for Truffle furthered human oncology research too. Smith encourages other dog parents to keep an open mind, advocate for their dogs, and explore treatment options and alternatives.

“It seems like dogs and people have been adapting to the world together for thousands of years,” Smith said. “It’s kind of cool that we are still doing that.”

To learn more about the NCI’s Comparative Oncology Program, click here. To enroll your dog in a clinical trial, start by talking to your veterinarian.