A Case of Transitional Cell Carcinoma of the Bladder in a Dog Successfully Treated with HER2 and CCR4 Ingibitors

Abstract

Lapatinib, a molecular targeting inhibitor of human epidermal growth factor 2 (HER2), was used in a dog with transitional epithelial carcinoma located in the bladder triangle, and stability was obtained for 169 days. owing to a growth observed on day 200, mogamulizumab, a humanized monoclonal antibody with regulatory T-cell infiltration inhibitor (CCR4 inhibitor) properties, was added to the lapatinib treatment reginen. This resulted in shrinking of the tumor and partial remission, enabling survival for 334 days. The only side effect of concurrent administration of the two drugs was grade 1 anorexia in the VCOG-CTCAE, which was manageable, and the subject was in very good condition during treatment. Combination therapy including lapatinib and mogamulizumab for transitional epithelial carcinoma of the bladder in dogs can be considered a promising and effective treatment option in the future.