Researchers at the University of California, San Francisco (UCSF) and UC Davis have completed the first clinical trial of a promising new cancer drug in pet cats, providing hope for a disease that has long been nearly impossible to treat. The study found that 35% of cats with oral squamous cell carcinoma (SCC) who received the treatment had their disease controlled, with minimal side effects. The findings, published today in Cancer Cell, also suggest the drug could be effective for humans with head and neck squamous cell carcinoma (HNSCC).
A Cancer Hard to Treat
Oral SCC is one of the most aggressive cancers in cats, with most surviving only two to three months after diagnosis. Traditional treatments such as surgery, chemotherapy, and radiation typically do little to slow the disease.
“One of the struggles I’ve had my entire career is that cats with this cancer—there is really nothing we can do,” said Katherine Skorupski, a UC Davis veterinary oncologist and second author of the study. “We see these cats, give the bad news, and do our best to keep them comfortable until they are euthanized. So the fact that we now have something that might help is so exciting.”
The researchers anticipate the drug could eventually be used in combination with other therapies to enhance treatment effectiveness.
Targeting the STAT3 Protein
The drug, originally developed for human head and neck cancers, targets a protein called STAT3, which acts as a faulty switch that drives cancer growth.
“What’s exciting is that this study shows it’s possible to shut down a protein that drives cancer,” said Daniel Johnson, first author and UCSF researcher. “That has been notoriously difficult in the past.”
The trial also highlights the value of using companion animals as models for human disease, which may yield more reliable results than traditional mouse models.
Jak’s Story: Extra Time with Family
One cat who benefited from the trial was Jakiro (“Jak”), a 9-year-old black domestic shorthair. His owner, Tina Thomas, was devastated when told Jak had only six to eight weeks to live.
“It was just a gut punch. We wanted more time with him,” Thomas said. “When I found out about this clinical trial, I knew I wanted him to be a part of it.”
After receiving weekly treatments for a month, Jak’s symptoms improved, and he lived more than eight months longer, enough to enjoy one last Christmas with his family.
“It was invaluable to give him time where he was comfortable and could enjoy being around his family,” Thomas said.
Positive Results with Minimal Side Effects
Of the 20 cats enrolled in the trial, 7 showed either a partial response or stable disease. The average survival post-treatment for these cats was 161 days. Side effects were minimal, with only mild anemia reported in some cases.
The drug not only blocked STAT3 activity but also boosted proteins associated with the immune response to cancer, giving researchers insights into how the therapy fights tumors.
“By partnering with veterinary oncologists and conducting clinical trials in companion animals, we can learn an enormous amount about how these drugs work while also helping pets,” said Jennifer Grandis, first author and UCSF researcher. “None of the cats were harmed, and many benefited.”
Looking Ahead
Researchers are now working with a small biotech company to advance the compound for clinical trials in both pets and humans, aiming to offer hope for aggressive cancers in two species simultaneously.
The study was supported by the National Institutes of Health and the Center for Companion Animal Health at UC Davis.