Comparing vincristine and vinblastine chemo side effects in cats

Abstract

BACKGROUND: Current standard chemotherapy protocols for lymphoma in cats carry risks of gastrointestinal toxicity, which can decrease quality of life and complicate response assessment. Protocols with less gastrointestinal toxicity may improve treatment tolerance. HYPOTHESIS/OBJECTIVES: The study purpose was to compare response rate, outcome, and toxicity between cats that received vincristine or vinblastine as part of combination chemotherapy for lymphoma. We hypothesized that vinblastine would have similar efficacy, but less gastrointestinal toxicity, compared with vincristine. ANIMALS: Forty client-owned cats with confirmed diagnosis of lymphoma. METHODS: Cats were randomized to 1 of 2 treatment arms and received weekly COP-based chemotherapy for 6 months or until disease progression. Response rate, progression-free survival (PFS), lymphoma-specific survival (LSS), and incidence and severity of gastrointestinal and hematologic toxicity were compared between arms. Arm cross-over occurred if specific gastrointestinal toxicity criteria were noted. RESULTS: Cats in both arms had similar response rates, PFS, and LSS (48 versus 64 days, P = .87; 139 versus 136 days, P = .96). Cats that received vincristine were significantly more likely to switch arms based on gastrointestinal toxicity than cats that received vinblastine (44.4 versus 10.5%, P = .02). Lower baseline weight was significantly negatively associated with PFS and LSS (P = .01, P = .003, respectively). Baseline anemia was significantly negatively associated with LSS (P = .04). CONCLUSIONS AND CLINICAL IMPORTANCE: Results suggest that vinblastine is a reasonable alternative to vincristine in the treatment of some cats with lymphoma. Baseline body weight remains a significant prognostic factor for cats with lymphoma.