Phase I dose escalating study of oral cyclophosphamide in tumour-bearing cats

•Currently no consensus maximum tolerated dose (MTD) of oral cyclophosphamide has been established in cats.•The maximum tolerated dose in tumour-bearing cats was 460 mg/m2 every 2–3 weeks.•The dose limiting toxicity was neutropenia with nadir at 7–21 days.•Haematology is recommended at day 0, 7 and 14 days after cyclophosphamide.•This dosage was safe in combination with prednisolone and L-asparaginase.