Lomustine, methotrexate and cytarabine chemotherapy as a rescue treatment for feline lymphoma

Objectives The aim of this study was to assess the efficacy and tolerability of lomustine, methotrexate and cytarabine chemotherapy as rescue treatment for feline lymphoma. Methods The medical records of 13 cats treated with lomustine, methotrexate and cytarabine for relapsed high-grade feline lymphoma, at a single institution between 2013 and 2018, were examined. All anatomical types were included. Data were analysed using descriptive statistics. Results Nine cats received all three drugs and four cats received only two drugs owing to progressive disease. In cats that received (or in which there was intention to treat with) all three drugs, 6/13 (46%) demonstrated a complete or partial response to chemotherapy. Treatment was generally well tolerated, although two cats experienced Veterinary Comparative Oncology Group (VCOG) grade 3 neutropenia and one cat experienced VCOG grade 3 thrombocytopenia. The median progression-free survival was 61 days (range 16–721 days). Conclusions and relevance CHOP-(cyclophosphamide, doxorubicin, vincristine, prednisolone) and COP-based protocols are established first-line chemotherapy for feline lymphoma, but standard rescue protocols are lacking. Lomustine has become a popular single-agent option, but prolonged or cumulative myelosuppression can result in treatment delays, risking relapse. Therefore, a multidrug lomustine-based protocol may be advantageous, and, from first principles, should also better overcome resistance. This study suggests that lomustine, methotrexate and cytarabine may represent an efficacious and well-tolerated protocol for feline lymphoma rescue.