Retrospective analysis of efficacy and safety of oral paclitaxel for treatment of various cancers in dogs (2017-2021)

Background: In humans, several safety evaluations have shown minimal adverse events with oral paclitaxel; however, its therapeutic efficacy and safety has not been well established in dogs with various cancers. Objectives: We aimed to retrospectively evaluate the efficacy and safety of oral paclitaxel in dogs with various cancers. Methods: Twenty-one dogs diagnosed with various cancers were administered several doses of oral paclitaxel three times a month (group 1) or six times a month (group 2). Results: The overall response rate was 6.25% (6.25%, complete response; 56.25%, stable disease; 37.5%, progressive disease) in dogs for which the treatment response could be evaluated. The median overall survival (OS) and progression-free survival (PFS) were 74 and 60.5 days, respectively. Regardless of the administration group, differences in OS and PFS of the two groups did not reach statistical significance. Most dogs tolerated the treatment regimen well, and although minor adverse events were observed in some dogs, they recovered after temporary drug discontinuation, dose reduction or symptomatic treatment. There was no significant difference in the prevalence of adverse events between the two groups. Conclusions: Based on the observed responses in certain types of cancers and the minimal adverse events, the study findings supported the efficacy and safety of oral paclitaxel administration in dogs. Thus, oral paclitaxel could play a role in the management of cancer in dogs.