A benign but invasive canine oral cancer is often mistaken for a very similar malignant one, leading to misdiagnoses in close to a third of cases, but a new diagnostic tool can now distinguish between the two, according to a new study that also identified a promising FDA-approved drug ready for clinical trials.

Canine acanthomatous ameloblastoma (CAA) is benign but also a locally aggressive, destructive and invasive tumor that is relatively common in dogs. Surgery is the standard treatment, often involving removing a section of the jawbone. Many features of CAA overlap with canine oral squamous cell carcinoma (COSCC), a malignant, metastatic canine oral cancer, making it challenging for clinicians to distinguish between the two.

The multidisciplinary research team used advanced high-resolution genomic techniques to isolate and profile single cells from tumor samples and identify a rare cell type that is unique to CAA, making it possible now to differentiate much more cleanly between the two cancers. They also discovered that these rare cells express a gene, called ERBB4, which belongs to a family of well-studied genes important in many human cancers, including certain forms of breast cancer. The team found an FDA-approved drug that targets ERBB4 shows promising results for reducing CAA tumor growth, opening the door for clinical trials in dogs.

“Now, with the advent of novel therapies, we are trying to not have to remove large portions of anatomy but instead shrink the tumors to a point where we can do minimal or no surgery at all,” said Dr. Santiago Peralta, associate professor of dentistry and oral surgery in the Department of Clinical Sciences in the College of Veterinary Medicine (CVM), and a senior author of the study. “That’s when it becomes super critical to have an absolutely accurate diagnosis because one molecule will be effective in one tumor but not in the other.”

The research resulted from the wide variety of expertise and advanced tools found at Cornell.

“There’s no way this could have been done without extensive collaboration across disciplines,” said Praveen Sethupathy, professor of physiological genomics and chair of the Department of Biomedical and Translational Sciences in CVM, and a senior author of the paper. Andreas Stephanou, a doctoral student, is first author of the study, which published July 21 in the journal Molecular Therapy Oncology. Stephanou works with Sethupathy and Iwijn De Vlaminck, professor at the Meinig School of Biomedical Engineering in Cornell Duffield Engineering, and a co-author of the paper. 

While Peralta is a clinician with experience diagnosing and treating CAA and COSCC and setting up clinical trials, Sethupathy’s lab brings genomic expertise, and Bill Katt, a senior scientist in the Department of Biomedical and Translational Sciences, lent his extensive knowledge of cell models of these cancers

The team wanted to see if they could locate rare cell types in CAA, which are often critical in cancer but can go unnoticed depending on the method used to detect them.

Peralta provided biopsy specimens from his lab, which Sethupathy, Stephanou and Bo Shui, a senior scientist in Sethupathy’s lab, processed and analyzed using single-cell RNA sequencing technology, where individual cells are separated and molecularly assessed. “We identified there was at least one population of rarer cells that exhibited this unexpected, neuron-like molecular signature,” Sethupathy said, adding that one of the genes that was expressed in those neuron-like rare cells was ERBB4.

Working with co-author Taranjit Gujral, a systems biologist at the Fred Hutchinson Cancer Center at the University of Washington, the team used live CAA tumor tissues and ran experiments using a panel of many dozens of therapeutic compounds. It turned out that neratinib, a drug known to inhibit ERBB4, effectively suppressed tumor growth.

The researchers aim to eventually test their results in clinical trials with canine patients. 

While there is a human analogue of CAA, it is relatively rare, which can make funding challenging. Also, human trials require stringent protocols and take years to start and complete. Dogs are much easier to work with, with the hope that a successful treatment could not only provide a treatment for CAA but also shed light on the analogous human cancer. The team’s collaboration is part of the growing Comparative Oral Oncology Laboratory initiative.

The study was funded by the Cornell Richard P. Riney Canine Health Center, the Joseph and Bessie Feinberg Foundation, the Morgan Cueman Cancer Research Fund and the National Science Foundation.