Hank is a golden retriever that owner Molly Weiss describes as a 100-pound lap dog— lazy, snuggly, and ”an old man since birth.” Finn is a busy miniature Australian shepherd who loves to swim and is “a little high-strung,” according to owner Diana Busby. 

In all the obvious ways, Hank and Finn couldn’t be more different. But they share something that makes them part of an unfortunate club: both received a diagnosis of malignant melanoma.

Common to dogs and people alike, melanoma is a cancer that can develop in the cells of the skin and mucous membranes. Malignant melanomas develop quickly and have a high risk of spreading to other organs. The current standard treatment for dogs like Hank and Finn involves surgery or radiation to remove or shrink the tumor, sometimes followed by chemotherapy. Survival times range from four months to one year post-treatment, in part depending on how advanced the cancer is when diagnosed.

And the signs often aren’t easy to spot.

Finn developed a large mass in the back corner of his mouth, not visible from the outside. Busby only became aware of it when she came home one day to find him panting and drooling and checked his mouth to see if she could find a problem.

Hank’s tumor started as a small bump on his left hip—not unlike other benign cysts that he, like many older dogs, experienced. It didn’t raise any red flags for Weiss or for their vet until it grew significantly in the six months after his regular checkup.

Both families were faced with difficult choices.

Hank’s primary care vet, Dr. Danielle Hill at Banfield Eagan, referred him to the oncologists at the University of Minnesota (UMN) Veterinary Medical Center (VMC). After reviewing the X-rays and tests, they discussed the options. 

“Most, unfortunately, came with a very high cost, which puts you in a moral dilemma,” Weiss says. “Plus, his quality of life was the most important thing. At that time he was completely normal and we didn’t want to disturb things—we didn't want to make him sick with treatment.”

“It was incredibly devastating,” Weiss adds. “He’s my best friend—we have a really special bond.”

When Finn was diagnosed, doctors at BluePearl quickly determined that because of the tumor’s size and location, it couldn't be removed surgically. They were referred to the VMC to discuss the possibility of radiation treatment, which, they learned, wouldn’t be curative for Finn, and would come with costs that were prohibitive for them.

“We were panicked,” Busby says. “There seemed to be no good options.”

At those visits, however, both families also found out about an ongoing clinical trial aimed at finding better treatments for malignant melanoma. The VMC is part of the UMN College of Veterinary Medicine, which also is home to the Veterinary Clinical Investigation Center (CIC). The CIC supports more than 40 clinical trials that may lead to new drugs, devices, procedures, and treatments. Several of these trials focus on helping dogs diagnosed with cancer.

This particular study investigates a strategy to help the body’s immune system fight malignant melanoma using a combination of two drugs. The first drug is derived from a virus called VSV-IFNß-CSDE1WT (“VSV”) that has been modified in the laboratory so that it can kill cancer cells. VSV has been found to be safe and is even being used in cancer trials for people. 

To enhance the effectiveness of the VSV, the trial adds an additional drug to the treatment regimen called CD200AR-L. This drug stimulates immune cells (called T cells) by suppressing control mechanisms that “put the brakes” on the immune system. While in normal conditions these control mechanisms are important to regulate immune responses, their activation in the presence of cancer can prevent the body’s immune system from effectively fighting against the cancer. By “releasing the brakes,” the immune system has more power to fight the cancer.

Both Hank and Finn were good candidates for the trial, and both families ultimately decided to enroll them. Weiss described, “The importance of the information they get—if it helps them even a little bit to know what to do going forward, it’s totally worth it. Even if we knew we might be at the end of the line with Hank, we were totally willing to give it a go.”

Hank had surgery to remove the tumor along with a stay at the VMC to receive an initial round of treatment, with follow-up visits for additional treatment injections and testing. Finn underwent radiation as well as the same drug treatment and follow-up.

Months later, both dogs are doing great. 

Busby says, “If you look into Finn’s mouth there’s really no sign of the tumor, which is crazy. He’s really back to his normal self at this point—his quality of life is great, and we have so much more peace of mind.”

Hank is considered to be in remission and is also back to full health. 

“It was a complete blessing that study happened to be going on when he was diagnosed,“ Weiss says. “Everyone at the U of M has been so transparent and open—about the financial side, about risks, about potential side effects. They had constant communication with us.“

Dr. Antonella Borgatti, the study’s principal investigator, says, “Our patients and their owners are an essential part of the team and we could not do what we do without their commitment and participation. I am very grateful for the relationships we have built and for the opportunity to learn from our patients every day.”

The trial, which is a collaboration between the University of Minnesota and the Mayo Clinic, was made possible by a Minnesota Partnership grant. 

“I feel privileged to be a part of this multi-institutional team whose goal is to develop safe and effective novel immunotherapy approaches for the treatment of malignant melanoma in dogs,” Borgatti says.