Novel STAT3-Targeted Therapy Tested in Pet Cats With Oral Cancer
The investigational drug belongs to a new class of compounds that directly target a transcription factor, STAT3.
In a phase 1 clinical trial, researchers have tested a new STAT3-targeted therapy in pet cats diagnosed with head and neck squamous cell carcinoma (HNSCC), a type of oral cancer that is typically aggressive and difficult to treat. The study, published August 28 in Cancer Cell, reports that 35% of the animals responded to the experimental treatment, which also showed limited side effects.
The investigational drug belongs to a new class of compounds that directly target a transcription factor—STAT3—that is frequently activated in several solid and blood cancers. While the compound was originally designed for human use, cats with naturally occurring HNSCC were selected for the first clinical trial due to similarities between feline and human disease in terms of histology and immune response.
Results show partial disease control in subset of animals
Among the 20 cats enrolled in the trial, seven showed either a partial response or stable disease following treatment. For these animals, median survival after the start of treatment was 161 days. All cats underwent a four-week course of therapy, and most tolerated the compound well, with mild anemia reported as the only side effect potentially linked to the drug.
According to the investigators, this is the first study to demonstrate that direct inhibition of STAT3 activity in a naturally occurring animal cancer can result in a measurable therapeutic benefit. In addition to blocking STAT3, the compound also appeared to increase expression of PD-1, a checkpoint protein that plays a role in immune responses to cancer.
Companion animals as translational cancer models
The decision to launch the clinical trial in cats followed discussions between researchers and veterinary specialists who highlighted the lack of effective treatment options for feline HNSCC. In cats, survival after diagnosis is usually less than three months.
The team selected pet cats with advanced oral tumors that had few or no remaining treatment options. Unlike mouse models in laboratory settings, these animals live in real-world environments, making them potentially more relevant for assessing how drugs will perform in humans. Their tumors also tend to be genetically diverse, a characteristic shared with human cancers but absent from many inbred laboratory models.
Researchers are now collaborating with a small biotechnology company to further evaluate the compound in trials involving both humans and animals.
Implications for drug development
The study highlights the value of cross-species research and suggests that companion animals with cancer can serve as intermediate models between traditional preclinical studies in mice and full-scale human trials. This approach may reduce the time and cost associated with developing new cancer therapies, while also generating valuable biological data.
The drug used in the study is now being investigated in additional preclinical and clinical settings to determine its efficacy across a broader range of tumor types.
Reference: Grandis JR, Skorupski KA, Cheng N, et al. Safety and efficacy of a STAT3-targeted cyclic oligonucleotide: From murine models to a phase 1 clinical trial in pet cats with oral cancer. Cancer Cell. 2025. doi:10.1016/j.ccell.2025.07.015
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