Treatment of feline intermediate to high‐grade alimentary lymphoma: A retrospective evaluation of 55 cats treated with the VAPC combination chemotherapy protocol (2017–2021)

Abstract The most commonly utilized protocols to treat lymphoma in cats employ vincristine, cyclophosphamide and prednisone; with additional drugs sometimes used including L‐asparaginase and doxorubicin. Medical records were reviewed for 55 cats with alimentary lymphoma treated with a novel multiagent protocol using prednisolone, L‐asparaginase, doxorubicin, vinblastine instead of vincristine, a higher dosage of cyclophosphamide and oral procarbazine (VAPC protocol). Outcomes evaluated were response to therapy, toxicity and progression‐free survival (PFS). Grade 3 or 4 neutropenia was the most common treatment‐related reason for chemotherapy dosage adjustment, occurring in 8 of 52 cats receiving vinblastine, 7 of 55 cats receiving cyclophosphamide and 1 of 40 cats receiving doxorubicin, but febrile neutropenia was identified in only two cats. Of 38 cats receiving chemotherapy for measurable disease, 26 (68.4%) achieved complete response (CR). Three cats achieved a partial response and 9 cats failed to achieve a remission. There were no identified factors influencing whether a cat was likely to achieve CR. For all 55 cats (including those receiving chemotherapy and surgery), median PFS was 184 days with 1, 2 and 3‐year survival rates of 35.4%, 26.5% and 26.5%, respectively. On multivariate analysis, 40 cats that achieved CR had a median survival time of 341 days (78 days for PR, 45 days for NR); PFS times were also significantly affected by lymphocyte:monocyte L:M ratio (>3.4 = 700 days vs. ≤3.4 = 126 days) and B‐cell versus T‐cell phenotype (220 days vs. 42 days, respectively).