Scientists at the University of California, San Francisco and the University of California, Davis have completed the first clinical trial of a groundbreaking cancer drug in pet cats, demonstrating significant therapeutic potential for one of the most aggressive feline cancers while offering promising implications for human head and neck cancer treatment. The study, published in Cancer Cell, found that 35 percent of cats with oral squamous cell carcinoma who received the experimental treatment had their disease controlled with minimal side effects.
Breakthrough in STAT3 Targeting
The drug represents a significant scientific achievement as the first of its kind to successfully target STAT3, a protein that functions as a faulty molecular switch directing cancer cells to continue proliferating. "What's exciting is that this study shows it's possible to shut down a protein that drives cancer," said first author Daniel Johnson with the University of California, San Francisco Helen Diller Family Comprehensive Cancer Center. "That has been notoriously difficult in the past."
The therapeutic approach addresses a critical unmet medical need in feline oncology. Oral squamous cell carcinoma is one of the most aggressive cancers in cats, with most patients surviving only two to three months after diagnosis. Traditional interventions including surgery, chemotherapy, and radiation therapy typically provide minimal benefit against this devastating disease.
Clinical Trial Results
The trial enrolled 20 cats with oral squamous cell carcinoma, with seven animals exhibiting either partial response or stable disease during the study period. Among the responding cats, the average survival post-treatment extended to 161 days. Importantly, the treatment demonstrated a favorable safety profile, with only mild anemia observed and no other side effects attributable to the therapy.
"One of the struggles I've had my entire career is that cats with this cancer—there is really nothing we can do," said second author Katherine Skorupski, a professor of clinical medical oncology with the UC Davis School of Veterinary Medicine. "We see these cats, we give the bad news, and we do our best to keep them comfortable until they are euthanized. So the fact that we would have something, anything, that might help these cats is so exciting."
Translational Research Model
The study emerged from collaborative discussions between researchers and veterinary professionals, highlighting the potential of companion animals as disease models. First author Jennifer Grandis of UCSF conceived the feline trial approach through conversations with her veterinarian sister, who emphasized the extreme difficulty in treating oral cancers in cats.
The research demonstrates that pets with cancer may serve as more reliable disease models compared to traditional mouse studies. "By partnering with veterinary oncologists and doing clinical trials in companion animals, we can learn an enormous amount about how these drugs work while also helping people's pets," Grandis noted. "None of the cats in these trials were harmed, and many of them benefited."
Mechanism of Action and Immune Response
Beyond its direct anti-cancer effects, the treatment appeared to modulate immune system activity. The therapy not only blocked STAT3 activity but also elevated levels of proteins associated with immune responses to cancer, suggesting a dual mechanism of action that could enhance therapeutic efficacy.
Clinical Impact and Patient Stories
The trial's real-world impact is exemplified by cases like Jakiro, a 9-year-old black shorthair whose owner, Tina Thomas, was initially told he had only 6 to 8 weeks to live. Following weekly treatments for one month, Jakiro's symptoms improved significantly, and he survived more than eight months—sufficient time to spend another Christmas with his family.
"It was invaluable to us to give him time where he was comfortable and could enjoy being around his family," Thomas said. "He loved being under our Christmas tree and giving him that one more Christmas, which I don't think he would have had otherwise, just made us feel good."
Future Development
Researchers are currently collaborating with a small biotech company to advance the compound through clinical trials for both veterinary and human applications. Skorupski indicated that future therapeutic strategies will likely incorporate the drug alongside other treatment modalities to maximize clinical benefit.
The research was supported by the National Institutes of Health and the Center for Companion Animal Health at UC Davis, with additional UC Davis contributors including Robert B. Rebhun, Daniel York, Hong Chang, and Ellen E. Sparger.
