A Case Report of Advanced Pulmonary Adenocarcinoma in a Dog Managed with Chemotherapy and Cytokine-Based Immunotherapy.

Pulmonary adenocarcinoma in dogs, particularly in advanced stages, carries a poor prognosis with limited therapeutic options. Immunotherapeutic approaches that activate natural killer (NK) cells may provide additional clinical benefit. This report describes the clinical response and survival outcome of a 9-year-old neutered male Welsh Corgi with late-stage pulmonary adenocarcinoma treated with combined chemotherapy and cytokine-based NK cell-activating immunotherapy. The dog presented with intermittent coughing, dyspnea, and cyanosis. Imaging revealed a large pulmonary mass with suspected nodal metastasis (stage III, T4N1M0). Cytology confirmed pulmonary adenocarcinoma. A splenic myelolipoma, unrelated to the primary pulmonary tumor, was identified incidentally and surgically removed. Treatment included vinorelbine-based chemotherapy and cytokine-based immunotherapy using interleukin (IL)-15, IL-12, IL-23, and selenium. After temporary discontinuation due to adverse events, cytokine monotherapy was administered, followed by resumed combination therapy upon stage IV progression with contralateral lung metastasis. Radiographic follow-up demonstrated disease stabilization during monotherapy and prolonged survival with combination therapy. The dog survived for 241 days, including 143 days after stage IV diagnosis, exceeding previously reported outcomes. Although NK cell function was not directly evaluated, these findings raise the possibility that cytokine-based NK cell immunotherapy, when combined with chemotherapy, could have contributed to disease control and prolonged survival in advanced canine pulmonary adenocarcinoma.