Sustained Response of Carcinoma Ex Pleomorphic Adenoma Treated with Trastuzumab and Capecitabine

Background: Carcinoma ex pleomorphic adenoma is a rare histologic subtype of salivary gland cancer with an overall poor prognosis. Limited histopathologic analyses have shown that some such tumors exhibit significant HER2/neu immunoreactivity, suggesting a potential role for HER2-based therapy. We report here a case of a 58-year old man with metastatic carcinoma ex pleomorphic adenoma who achieved a sustained long term response to combination therapy with trastuzumab and capecitabine.

Case Presentation: A 58 year old man presented with T1N2bM0 carcinoma ex pleomorphic adenoma and underwent surgery followed by adjuvant radiation therapy. Multiple metastases to bone were documented one year later. Since the original tumor was strongly HER2/neu positive by immunohistochemistry, the patient was treated with trastuzumab, capecitabine, and zoledronic acid. He experienced total resolution of symptoms and repeat FDG-PET scan after three cycles revealed interval disease resolution. Continued treatment has resulted in maintenance of disease control for over 2 years.

Conclusion: This case illustrates the successful long term treatment of carcinoma ex pleomorphic adenoma with targeted therapy with trastuzumab in combination with chemotherapy. In the absence of definitive clinical trials which are unlikely to be performed due to the rarity of this tumor, case reports such as this one suggest potential utility for trastuzumab in combination with chemotherapy in the treatment of HER2/neu-overexpressing carcinoma ex pleomorphic adenoma.