From Bench to Bedside: New Tools Push Veterinary Oral Cancer Toward Targeted Therapy

Oral squamous cell carcinoma is one of the most formidable malignancies that veterinary oncologists face. In dogs, canine oral squamous cell carcinoma, or COSCC, and in cats, its feline counterpart FOSCC, these tumors of the oral cavity often behave aggressively, resist conventional treatments, and leave clinicians with a limited arsenal of genuinely effective options. A recent editorial spotlight published in the journal Veterinary Oncology by Matthew J. Atherton of the University of Pennsylvania surveys four new studies that, taken together, signal a turning point. Rather than isolated incremental gains, the work describes a coherent pipeline: new molecular mapping technologies, freshly derived laboratory models, a targeted drug already approved for human use, and a comparative clinical trial that spans species. The through-line is precision medicine, an approach that identifies the specific molecular drivers of an individual tumor and matches them with therapies designed to shut those drivers down.

The first of the highlighted studies tackles a long-standing obstacle in cancer biology: the difficulty of studying tumors in their native spatial context. Goldschmidt and colleagues applied state-of-the-art spatial transcriptomics to formalin-fixed paraffin-embedded biopsy samples from nine dogs diagnosed with COSCC. Spatial transcriptomics is a technique that measures gene expression while preserving the physical location of each cell within the tissue, allowing researchers to see not just which genes are active but where that activity occurs. This matters because tumors are not uniform masses; they contain distinct compartments, including normal epithelium, pre-malignant dysplastic epithelium, the tumor microenvironment, and regions of surface and deep tumor, each of which may behave differently and respond differently to therapy.

The spatial analysis revealed striking molecular patterns. Gene signatures associated with EGFR, the epidermal growth factor receptor, a well-known driver of cell proliferation in many human cancers, and with epithelial-to-mesenchymal transition, a process by which cancer cells acquire invasive, migratory properties, were increased and shared between dysplastic epithelium and tumor samples. This suggests that the molecular changes driving malignancy begin early, before full transformation. Within the cancer samples themselves, the researchers found enrichment of KRAS gene sets, along with the transcripts KRT17 and SPP1, markers often associated with aggressive tumor behavior. Perhaps most intriguing were the findings in the tumor microenvironment, defined in the study as peritumoral mesenchymal stromal tissue infiltrated with leukocytes. There, the team detected signals associated with an increased presence of tumor-associated macrophages, immune cells that tumors frequently co-opt to suppress anti-cancer immunity, and induction of IL10, an immunosuppressive signaling molecule. Enrichment of ICOS and CTLA4 was also noted, and these signals correlated with CD4-positive T cell transcripts in the microenvironment, hinting at a complex immune landscape that could be exploited therapeutically.

The second and third studies demonstrate how such molecular insights can be translated directly into new treatments. Katt and co-workers established several new COSCC cell lines using a combination of patient-derived xenografts and tissue-cultured cell lines created directly from COSCC biopsies. Patient-derived models are prized in oncology research because they preserve more of the biology of the original tumor than long-established laboratory lines. When the team investigated these new models, they uncovered evidence of RAS activation in every one of them. RAS is a signaling protein that, when switched on, drives cells to proliferate uncontrollably, and it sits upstream of MEK1/2, a pair of serine/threonine kinases that relay the growth signal deeper into the cell.

That molecular logic pointed straight at a drug. Trametinib is a small-molecule inhibitor of MEK1/2, already used in human medicine for cancers with activated RAS pathway signaling. The researchers screened trametinib against other cytotoxic and targeted agents using their novel cell lines and found, as predicted, that it exerted anti-tumor activity both in vitro and in a canine xenograft model. These preclinical results were compelling enough to justify testing the drug in pet dogs with COSCC. In a preliminary study of four dogs, objective responses were documented in two of the treated patients. A subsequent dose-escalating study of twenty dogs with COSCC confirmed that trametinib was well tolerated and showed a thirty percent objective response rate, with a further twenty-five percent of dogs exhibiting stable disease, meaning their tumors neither grew nor shrank significantly.

Crucially, the correlative analyses in that trial revealed a biomarker that could transform how dogs are selected for treatment. Dogs whose tumors carried BRAF p.V595E mutations responded significantly better to trametinib than dogs with BRAF wild-type tumors. This alignment with trametinib’s known mechanism of action in activated RAS signaling illustrates the essence of precision oncology: rather than treating every patient identically, clinicians can profile a tumor’s mutations and predict which patients are most likely to benefit. Together, the cell line work and the clinical trials illustrate a rational pathway for introducing new targeted therapies in COSCC, moving systematically from bench to patient-side, a journey that in human oncology often takes many years but here was compressed into a remarkably short arc.

The fourth study extends the comparative approach to feline patients and to immunotherapy-adjacent territory. Signal transducer and activator of transcription 3, or STAT3, is a transcription factor that is hyperactivated in many cancers, including FOSCC, where it drives tumor cell proliferation, immunosuppression, and drug resistance. A prior phase 0 trial in humans with head and neck squamous cell carcinoma had shown that a STAT3 decoy, an engineered molecule that binds and sequesters the transcription factor’s activation machinery, could downregulate STAT3 target genes. Building on that human data, Grandis and colleagues evaluated a systemically administered linear STAT3 decoy in multiple preclinical murine models of head and neck squamous cell carcinoma and then undertook a phase 1 clinical trial of twenty cats diagnosed with FOSCC.

The feline trial produced results that are encouraging for one of the most aggressive malignancies in companion animal medicine. A thirty-five percent disease control rate was documented, comprising two partial responses and five cases of stable disease. Importantly, the favorable responses were accompanied by measurable biological changes: shifts in peripheral blood immune parameters and increased intratumoral expression of PDCD1, the gene encoding the PD-1 immune checkpoint protein. That last finding is particularly significant because PD-1 expression within tumors is a marker of T cell exhaustion, the state in which anti-tumor immune cells become dysfunctional. Its increase in responding patients suggests the STAT3 decoy may be relieving one layer of immunosuppression and potentially sensitizing tumors to checkpoint blockade, a class of drugs that releases the brakes on anti-tumor immunity. Beyond its clinical promise for cats, the study exemplifies the power of a comparative approach in cancer research, in which findings in one species inform and accelerate progress in others, with the aim of benefiting multiple species simultaneously.

Weaving these threads together, Atherton’s editorial argues that veterinary medicine is now entering the age of immune oncology, heralded in part by the roll-out of checkpoint blockade. The identification of CTLA4 upregulation within COSCC by the spatial transcriptomics study, alongside the prognostic implications of increased PDCD1 expression in FOSCC patients treated with the STAT3 decoy, provides impetus to investigate these molecules as mediators of T cell exhaustion. That, in turn, may set the scene for future trials of anti-CTLA-4 or anti-PD-1 therapy in oral squamous cell carcinoma patients of both species. Meanwhile, the early but encouraging clinical data from dogs treated with trametinib offers cautious optimism that this targeted therapy could be added to the currently limited arsenal of useful anti-cancer drugs for COSCC.

Ongoing studies are expected to determine the optimal way to incorporate trametinib into treatment regimens. The editorial notes several plausible roles: the drug could be applied in a neo-adjuvant setting, given before definitive surgery or radiation with the aim of improving the tolerability and outcomes of conventional treatment, or it could serve as an additional palliative option for more advanced COSCC cases where curative intent is no longer feasible. What makes this moment notable is not any single result but the demonstration that the full precision-oncology workflow, from spatially resolved molecular profiling through patient-derived models to biomarker-guided clinical trials, now functions in veterinary patients. For the dogs and cats facing these cancers, and for the humans whose head and neck cancers share many of the same molecular vulnerabilities, the comparative road ahead looks considerably brighter than it did only a few years ago.

Subject of Research: Recent advances in the diagnosis and targeted therapy of canine and feline oral squamous cell carcinoma

Article Title: An editorial spotlight on recent progress in veterinary oncology

Article References: Atherton, M. J. (2025). An editorial spotlight on recent progress in veterinary oncology. Veterinary Oncology, 2(1), Article 30. https://doi.org/10.1186/s44356-025-00047-y

Image Credits: AI Generated

DOI: 10.1186/s44356-025-00047-y

Keywords: veterinary oncology, oral squamous cell carcinoma, spatial transcriptomics, trametinib, MEK inhibitor, STAT3 decoy, tumor microenvironment, checkpoint blockade, BRAF mutation, comparative oncology, precision medicine, immunotherapy