HEMATOLOGICAL AND CLINICAL-RESPONSES TO COMBINED MITOXANTRONE AND CYCLOPHOSPHAMIDE ADMINISTRATION TO NORMAL CATS

The purpose of this study was to examine the feasibility of a combinat ion chemotherapy protocol (''CYCLONE'') in cats, utilizing mitoxantron e and cyclophosphamide. Three normal adult cats were administered mito xantrone (6.5 mg/m2 intravenously) and cyclophosphamide (100 mg/m2 int ravenously) every 21 days for a total of three doses. Individual white blood cell count nadirs (range, 2.0-9.5 x 10(9)/L) and neutrophil cou nt nadirs (range, 0.3 to 5.0 x 10(9)/L) occurred between days 2 and 10 after each dose of chemotherapy. Mean white blood cell count nadirs ( range of mean, 5.5 to 8.4 x 10(9)/L) occurred between days 6 and 8, as did the mean neutrophil count nadir (range of mean, 1.7-4.0 x 10(9)/L ). Side effects were limited to transient appetite suppression in one cat and loose stools in two cats. Myelosuppression and gastrointestina l side effects were comparable to those observed with single-agent mit oxantrone protocols. Further investigation of this protocol is warrant ed.