Use of Cyclophosphamide, Vincristine, Prednisolone and Vinblastine for the Treatment of Large Cell Lymphoma in Cats

Background: The standard chemotherapy treatment for large-cell lymphoma in cats is CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) or COP (cyclophosphamide, vincristine, and prednisolone) chemotherapy protocols. Substituting vinblastine for vincristine might have similar efficacy, with lower severity of gastrointestinal adverse events. Hypothesis/Objectives: To evaluate whether the addition of vinblastine to a low-dose vincristine COP protocol could reduce the frequency and severity of adverse gastrointestinal effects while maintaining or increasing efficacy. Animals: Medical records of 41 cats with large-cell lymphoma treated with the modified COVP protocol at one veterinary referral institution. Methods: Retrospective case series study. All relevant clinical data were retrospectively collected. Median progression-free survival, disease-free interval, and survival time were calculated using the Kaplan–Meier Method. Differences between groups were analyzed using the log-rank test, and adverse events were graded using VCOG-CTCAE v2. Results: Progression-free survival was 264 days (range, 6–1486 days), the disease-free interval was 812 days (range, 39–1486 days) and the median survival time for all cats was 412 days (range, 7–1772 days). Complete response was achieved in 59% of the cases, and partial response was observed in 17%. Cats that achieved CR lived significantly longer, 838 days (range, 81–1772 days) versus 143 days (range, 10–798 days; p = 0.0018). The COVP protocol was generally well tolerated, and the most common adverse effects were mild signs of gastrointestinal disease and hematological abnormalities that did not require a pause in treatment. Grade-1 vomiting was the most common (24%), followed by grade-2 (22%) and grade-1 reduced appetite (20%). Conclusion: Cats with lymphoma treated with COVP seem to achieve acceptable survival and response rates compared to traditional chemotherapy protocols. © 2025 The Author(s). Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.