Outcome of treatment with a 10-week COP protocol in cats with intermediate or large cell lymphoma: 27 cases (2014-2023)

Objectives: The aim of this retrospective clinical study was to evaluate and report response to treatment with a 10-week maintenance-free COP (COP-10) protocol in a cohort of 27 cats with intermediate or large cell lymphoma. Additionally, to identify any potential prognostic factors for predicting the treatment response. Materials and Methods: The medical records of cats diagnosed with intermediate or large cell lymphoma in a single institution in the period 2014 to 2023 and treated with COP-10 as first-line treatment were reviewed. Results: Twenty-seven cats were included in the study. The median age was 10 years, 67% of the cats were in stages I to II and the most common anatomical location was alimentary (37%). The overall response rate was 65%, with 38% of cats achieving complete remission and 27% partial remission. For cats achieving complete remission, the median progression-free interval and the median lymphoma-specific survival time were both 1,139 days. For cats in partial remission, the median progression-free interval and the median lymphoma-specific survival time were 53 and 210 days, respectively. Clinical stage was significantly related to treatment response and survival time. Clinical Significance: Treatment with the short protocol COP-10 resulted in remission rates and durable first remissions for cats achieving complete remission comparable to responses seen with longer-duration chemotherapy protocols. The results from this study may impact economic and logistic decisions for owners, as well as the quality of life for patients in the future.