Retrospective evaluation of nimustine use in the treatment of feline lymphoma

Background: Nimustine, similar to lomustine, is an alkylating agent from the nitrosourea family. There have been some reports regarding lomustine treatment for tumour-bearing cats. However, information regarding nimustine treatment for tumour-bearing cats is limited. Objectives: To retrospectively evaluate adverse events and clinical outcomes in tumour-bearing cats receiving nimustine. Methods: Information regarding diagnosis, treatment condition, adverse events, and clinical outcomes was collected in tumour-bearing cats receiving nimustine through reviews of medical records. Results: Nine cats with lymphoma were treated with nimustine in the primary therapy (n = 2) and in the rescue therapy (n = 7). Median starting dose of nimustine was 25 mg/m(2) (range: 20-30 mg/m(2)) with dosing interval of three weeks and 1-11 administrations. Adverse events were mild gastrointestinal toxicity (grade 1) including diarrhoea (n = 2) and vomiting (n = 2) and mild myelosuppression (grade 1 or 2) including thrombocytopenia (n = 3) and neutropenia (n = 1). No severe adverse events were observed. Progression-free survival durations among cats receiving nimustine in the primary therapy and in the rescue therapy were 274-688 days (median: 481 days) and 9-671 days (median: 102 days), respectively. Overall survival durations among cats receiving nimustine in the primary therapy and in the rescue therapy were 275-745 days (median: 510 days) and 14-671 days (median: 109 days), respectively. Conclusions: Nimustine was well tolerated and showed clinical outcomes similar to lomustine in cats with lymphoma. These findings suggest that nimustine might be an alternative to lomustine in the treatment of feline lymphoma.