Meloxicam in Combination with Mitoxantrone or Vinblastine as First-Line Treatment for Non-Resectable Urothelial Cell Carcinoma in Dogs

SIMPLE SUMMARY: Meloxicam is a readily available non-steroidal anti-inflammatory medication that is commonly used in clinical practice. It has been associated with a low incidence of gastrointestinal adverse effects in comparison to other non-steroidal anti-inflammatory medications and it has also demonstrated anti-tumour activity in vitro. In this study we describe the efficacy of meloxicam in combination with either mitoxantrone or vinblastine as a first-line treatment for non-resectable canine urothelial cell carcinoma (UCC), as well as the incidence of gastrointestinal adverse effects associated with this treatment combination. The results of this study suggest that meloxicam in combination with mitoxantrone or vinblastine, as a first-line treatment for non-resectable UCC, is well-tolerated and potentially effective in inducing cancer response. ABSTRACT: Cyclooxygenase (COX) inhibitors have been demonstrated to have antitumour activity in canine urothelial cell carcinoma (UCC), given as a sole treatment or in combination with chemotherapy. The purpose of this retrospective multi-institutional study was to assess the efficacy of meloxicam in combination with mitoxantrone or vinblastine as a first-line treatment for non-resectable canine UCC. Gastrointestinal adverse effects (AEs) of these treatment combinations were also assessed. A total of 28 dogs met the inclusion criteria, 21/28 dogs received mitoxantrone and meloxicam, and 7/28 received vinblastine and meloxicam. Tumour response (TR) and AE were evaluated according to Veterinary Co-Operative Oncology Group (VCOG) criteria. The endpoint of the study was the time to tumour progression (TTP). The mitoxantrone-group induced 24% partial response and 62% stable disease, while the vinblastine-group induced 14% and 86%, respectively. Median TTP was 84 days (mitoxantrone and meloxicam, 70 days; and vinblastine and meloxicam, 178 days). The presence of metastatic disease significantly decreased TTP (p = 0.007). Gastrointestinal AEs were reported in 21.4% of the patients, with the most common being VCOG grade 1–2 diarrhoea. Meloxicam is a well-tolerated NSAID when combined with mitoxantrone or vinblastine as first-line treatment for non-resectable canine UCC.