Scientists have shared the outcomes of the first-ever clinical trial utilizing a new category of targeted therapy in pet cats suffering from head and neck squamous cell carcinoma (HNSCC)—a deadly cancer that is especially challenging to treat. The study, published in Cancer Cell, discovered that 35% of treated cats showed disease control with minimal adverse effects—and this drug is expected to be effective for humans with HNSCC as well.
Cancer Cell"This research has two major takeaways," states senior author Daniel Johnson from the University of California, San Francisco Helen Diller Family Comprehensive Cancer Center.
"Firstly, it shows that targeting a transcription factor which promotes cancer, something notoriously difficult in past efforts, is achievable. Secondly, it demonstrates that pet cancers can effectively mirror human diseases and clinical trials in pets may provide more dependable insights than mouse model tests."
Originating from research aimed at treating human head and neck cancers, this drug uniquely targets the transcription factor STAT3. STAT3 is found in various solid and liquid tumors, including most HNSCC cases.
The inspiration to test this HNSCC drug on pet cats emerged from a conversation between first author Jennifer Grandis and her sister, a veterinarian, who informed Grandis about the difficulty of treating oral cancers like HNSCC in pet cats and their poor survival rates following diagnosis.
"There is striking similarity in clinical, histopathologic, and immunologic aspects between feline and human HNSCC," the authors note.
One beneficiary of this trial was a 9-year-old black domestic shorthair named Jak. When diagnosed with HNSCC, his veterinarian gave him only six to eight weeks to live.
"It was devastating," says his owner, Tina Thomas. "We wanted more time with him. Once I learned about the clinical trial, signing him up for it was an easy decision."Jak underwent weekly treatments over a month. His symptoms—predominantly watery eyes—greatly improved during this period. Ultimately, he lived more than eight months after diagnosis.
"It meant so much to us because he remained part of our lives," says Thomas. "During that timeframe, my son completed his college education and daughter finished her master's program. Jak celebrated another Christmas with us and cherished the holiday tree. He was worth every effort."- Jak, a research participant, during the clinical trial. Credit: Tina Thomas
- Jak, a research participant, laying in the sun. Credit: Tina Thomas
Beides mild anemia, no cats in the trial presented side effects attributable to the treatment. Out of 20 enrolled cats, seven demonstrated either a partial response or stable disease during the study period. Among these seven responders, the average post-treatment survival was 161 days.
Upon examining tumor and blood samples from treated cats, researchers found that the compound worked in two ways: It not only blocked STAT3 activity but also increased levels of PD-1, a protein associated with an immune response to cancer.
"This study underscores how we could be more selective about spending limited resources on lab mouse studies that aren't even the best models for human cancers," Grandis says."By collaborating with veterinary oncologists and conducting clinical trials in companion animals, we can learn immense quantities about how these drugs work while also aiding pet owners. No cats in these trials were harmed, yet many received benefits."
The researchers assert that drug testing in pets can provide a superior model for predicting human results compared to lab mice. They are currently collaborating with a small biotech company to advance the new compound through clinical trials for both pets and humans.
"These animals breathe our air, face similar exposures, and their tumors are much more diverse, making them better models of human disease," Johnson states.