Toxicity of Cytarabine Intravenous Constant Rate Infusion in Cats With Lymphoma

Cytarabine intravenous constant rate infusion (IV CRI) toxicity in cats with lymphoma has not been well documented. We aimed to assess toxicities following cytarabine IV CRI as a single-agent or within a multiagent protocol in cats with lymphoma. Medical records of cats with lymphoma treated with cytarabine IV CRI, with documented dose, route, duration and at least one follow-up visit between 1990 and 2024, were retrospectively reviewed. Adverse events (AEs) were retrospectively graded according to VCOG-CTCAE v2. Thirty-eight cats were included, and 70 doses were evaluated for AEs. Median cytarabine dose was 389.8 mg/m² (range 100.1-697.3 mg/m²) over a median infusion duration of 6 h (range 2-17 h). A total of 103 AEs were documented across 70 administrations. Gastrointestinal AEs were the most common category: altered appetite (21/38 cats, 55.2%), vomiting (9/38, 23.7%; one grade 3, the rest grades 1-2), diarrhoea (2/38, 5.3%) and dysphagia (2/38, 5.3%). Anaemia was the most common hematologic AE (14/38 cats, 36.8%; five grade 1, two grade 2, five grade 3, two grade 4); six cats (15.8%) developed thrombocytopenia (four grade 1, two grade 2), and one cat (2.6%) developed grade 2 neutropenia. Lethargy was the most common constitutional AE (12/38 cats, 31.6%). IV CRI of cytarabine was generally tolerated, with predominantly low-grade AEs, although grade 3-4 anaemia was not uncommon. Response rate and clinical benefit remain unknown; investigation of alternative dosing regimens may help clarify its therapeutic potential.