Cori, a 15yo FS mixed breed canine, was presented to the PVESC oncology service in October 2024 for consultation regarding an oral amelanotic melanoma (MI >100) diagnosed via excisional biopsy completed by her rDVM. The tumor recurred rapidly over the next few weeks before presenting to PVESC.
Complete staging revealed a solitary soft tissue nodule in the right cranial lung lobe (top right) and a bladder mass (bottom left). Given these findings, the owner’s primary goal was to keep Cori as comfortable as possible without invasive procedures. At the time, Cori’s quality of life was most impacted by her oral mass. Consultation with our remarkable surgery department introduced the possibility of removing Cori’s oral mass without performing a complete hemi-mandibulectomy.
Cori underwent a CT with our surgery service, which revealed a soft tissue mass on the left mandible encompassing PM1 and PM2 with minimal bone involvement (below, middle). CT confirmed the presence of a solitary pulmonary mass, measuring 3cm in diameter and no other nodules. The oral tumor was removed via a left partial segmental marginal mandibulectomy from 304 to 307 (post-op, below, right). Histopathology confirmed a diagnosis of oral malignant melanoma (MI >40) and the margins were clear.
Cori’s tumor was submitted to FidoCure for genetic testing (profiling) and the results suggested a combination of injectable carboplatin and oral olaparib (PARP inhibitor) as an effective therapeutic approach. Cori experienced severe bone marrow toxicity secondary to injectable carboplatin therapy, so treatment with carboplatin was discontinued (per owner’s request) and continued treatment with single-agent olaparib was recommended.
Cori was restaged in February 2025 to assess her response to treatment. The changes noted on her chest X-rays were stable. Unfortunately, her bladder tumor had progressed (left). At this time, she was transitioned to an alternative oral chemotherapy drug called lapatinib (HER2 inhibitor). Cori developed persistent lower urinary tract signs that responded favorably to treatment with oxybutynin, a medication frequently used to help with “overactive bladder signs” that accompany bladder tumors.
Restaging in March 2025 revealed a stable lung nodule (top right) and partial remission of Cori’s bladder tumor (bottom left). Continued treatment with lapatinib was recommended and Cori continues to do well at home.
Canine oral malignant melanoma is an aggressive cancer with high rates of systemic metastasis and death due to cancer progression. Given the extremely high mitotic index (>100) of Cori’s primary tumor and the rate at which it recurred, rapid regrowth after marginal excision was expected and predicted survival was measured in months. At presentation, Cori’s quality of life was significantly impacted by her primary tumor, which limited acceptable treatment options to surgical removal or humane
There were multiple factors that made Cori a poor candidate for curative intent surgery, including but not limited to the lung nodule and bladder tumor identified during staging. Thus, we developed a treatment plan for Cori that involved removing her tumor without extensive jaw resection followed by systemic therapy with broad spectrum activity to improve our chances of being effective against all three tumor types: melanoma, pulmonary carcinoma (diagnosis not confirmed) and urothelial carcinoma (diagnosis not confirmed). Lapatinib is an oral targeted drug that blocks the effect of HER2, a protein involved in cancer progression. Ongoing studies support the use of lapatinib in dogs with high-grade pulmonary carcinoma as well as urothelial carcinoma. Treatment is well-tolerated with gastrointestinal upset and ALT elevations most commonly reported.
Although humane euthanasia would have been supported, Cori’s case is an excellent example of how our team at PVESC works together to formulate a treatment plan that is tailored to the individual patient while keeping the owners goals in mind. We encourage all owners to seek consultation with one of our three talented veterinary oncologists following a diagnosis of cancer in their pet, particularly when options seem limited.
Authored by: Brittanie Partridge, DVM, PhD, DACVIM (Oncology)