Efficacy of COP-based protocol used with raltegravir in treatment of cats with mediastinal lymphoma and progressive viral leukemia

Mediastinal lymphoma is a common disease in both human and veterinary medicine and is frequently diagnosed in cats infected with feline leukemia virus. The disease is considered a negative prognostic factor for affected animals. The retrospective research included 5 FeLV-positive cats with confirmed mediastinal lymphoma and progressive viral leukemia. The purpose was to study the response of FeLV-positive cats to standard chemotherapy protocol: cyclophosphamide 250 mg/m² IV, vincristine 0.5 mg/m² IV, prednisolone 20…40 mg/m² orally (COP), survival of animals and side effects associated with chemotherapeutic treatment. All studied cats received raltegravir (Isentress, MSD, USA) orally at a dose of 20 mg/kg every 12 hours. Improvement in clinical signs associated with mediastinal lymphoma was observed after the 3rd course of chemotherapy. The clinical response rate was 80 % (40 % full remission, 40 % partial remission, 20 % unchanged status). The average lifespan of FeLV-positive cats treated with chemotherapy for mediastinal lymphoma was 1091.2 days, with a maximum lifespan of 1364 days and a minimum lifespan of 775 days. Rate of clinical response, as well as lifespan expectancy of affected cats, was higher than in previous studies. This is probably due to raltegravir, which can reduce the viral load and thus control the course of progressive infection. Side effects were found in 100 % of FeLV-positive cats: with anorexia — in two animals (60 %), vomiting — in two (40 %), neutropenia — in four (80 %), thrombocytopenia — in all cats (100 %), anemia — in three (60 %) and azotemia — in one animal (20 %). Overall, the efficacy of the COP protocol was satisfactory, and chemotherapy treatment can be offered to owners of FeLV-positive cats with mediastinal lymphoma, if the owner is reluctant to opt for euthanasia of the affected animal.