Response and outcome following toceranib phosphate treatment for stage four anal sac apocrine gland adenocarcinoma in dogs: 15 cases (2013-2017).

Abstract

To assess response and outcome in dogs with stage 4 anal sac apocrine gland adenocarcinoma (ASAGA) treated with toceranib phosphate as the sole chemotherapeutic agent. Retrospective case series. 15 client-owned dogs with stage 4 ASAGA treated with toceranib phosphate between March 2013 and June 2017. Medical records were reviewed, and data collected included signalment, clinical signs, results of physical examinations and diagnostic procedures, treatments, response, follow-up information, and outcomes. Adverse events and response to treatment were assessed according to standard guidelines, and the Kaplan-Meier product limit method was used for analyses of progression-free interval and survival time. No dogs had a complete or partial response to treatment with toceranib; however, 13 dogs had signs of clinical benefit. No dogs had signs of toxic effects related to toceranib or were withdrawn completely from treatment because of adverse events. Median progression-free interval and median survival time were 354 and 356 days, respectively. Results of the present study indicated that dogs with stage 4 ASAGA treated with toceranib had improved outcomes, compared with outcomes previously reported for dogs with ASAGA that had received non-tyrosine kinase inhibitor treatments. Some dogs had improvement in clinical signs, but euthanasia was often performed because of signs of locoregional failure; therefore, toceranib alone may not be an appropriate treatment for dogs with marked clinical signs attributed to ASAGA, particularly when signs suggest limited quality of life. Further study of toceranib in multimodality treatments for dogs with advanced ASAGA is warranted.