Toceranib phosphate for the treatment of dogs with high-risk adrenal gland tumours: 16 cases (2019-2023)

OBJECTIVES: The aims of this study were to evaluate the response rate, time to progression (TTP) and survival times of dogs with high-risk adrenal gland tumours (ATs) treated with toceranib phosphate, in both macroscopic and microscopic setting, and to report the adverse event (AE) profiles.

MATERIALS AND METHODS: Medical records of dogs diagnosed with a high-risk adrenocortical carcinoma (ACC) or phaeochromocytoma (PCC), treated with toceranib, were retrospectively reviewed. High-risk ATs were defined as inoperable and/or metastatic ATs or cortical tumours with high Utrecht score. Endpoints were response rate, TTP and overall progression-free survival time (PFST). Adverse events were reported according to VCOG-CTCAE.

RESULTS: Sixteen dogs were included: 10 diagnosed with PCC and six with ACC. All dogs with ACC received adjuvant toceranib due to a high Utrecht score or metastatic disease, while all dogs with PCC were treated with toceranib in the macroscopic setting. A clinical benefit was detected in 80% of dogs with PCC: four achieved stable disease for a median TTP of 176.5 days, and two achieved partial response for 182 and >100 days, respectively. Median PFST for dogs with PCC was 112 days. Among dogs with ACC, 3 (50%) progressed and were euthanized after 237, 364 and 273 days; the remaining 3 (50%) dogs were alive and disease free 382, 508 and 583 days after starting toceranib. Overall, toceranib was well-tolerated.

CLINICAL SIGNIFICANCE: Toceranib may offer clinical benefit and improve outcome in dogs with high-risk ATs in both the macroscopic and microscopic disease setting.