Results of a phase II clinical trial on the use of ifosfamide for treatment of cats with vaccine-associated sarcomas.
OBJECTIVE
To determine clinical activity and toxic effects of ifosfamide when used to treat cats with vaccine-associated sarcoma (VAS).


METHODS
27 cats with a nonresectable, recurrent, or metastatic VAS.


METHODS
Each cat received ifosfamide (900 mg/m(2) of body surface area) as an IV infusion during a 30-minute period. Diuresis by infusion of saline (0.9% NaCl) solution and administration of mesna were used to prevent urothelial toxicosis. Treatments were administered every 3 weeks, and tumor response was assessed after the second treatment. All ifosfamide-associated toxic effects were graded in accordance with predetermined criteria.


RESULTS
61 treatments were administered to 27 cats (median, 2 treatments/cat; range, 1 to 4 treatments/cat). After ifosfamide treatment, 1 cat had a complete response and 10 had partial responses for an overall response rate of 11 of 27 (41%; 95% confidence interval [CI], 25% to 59%). Responses lasted from 21 to 133 days (median, 70 days; 95% CI, 60 to 113 days). The acute dose-limiting toxicosis was neutropenia, which was detected 5 to 28 days (median, 7 days) after treatment. Median nadir neutrophil count was 1,600 cells/muL (range, 200 to 5,382 cells/microL). Nine (33%) cats had adverse gastrointestinal effects (primarily salivation during the ifosfamide infusion and inappetence after treatment). Two cats were euthanatized because of severe nephrotoxicosis, and 1 cat developed pulmonary edema during diuresis.


CONCLUSIONS
Ifosfamide has antitumor activity against VAS in cats and is tolerated well by most cats. Ifosfamide should be evaluated as an adjuvant treatment for cats with VAS.
Rassnick
Kenneth M
KM
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Rodriguez
Carlos O
CO
Khanna
Chand
C
Rosenberg
Mona P
MP
Kristal
Orna
O
Chaffin
Kelly
K
Page
Rodney L
RL
D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000009:adverse effects / Q000627:therapeutic use*; D002371:Cat Diseases / Q000188:drug therapy*; D002415:Cats; D004334:Drug Administration Schedule; D005260:Female; D007069:Ifosfamide / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D015080:Mesna; D012509:Sarcoma / Q000139:chemically induced / Q000188:drug therapy / Q000662:veterinary*; D012965:Sodium Chloride; D014612:Vaccines / Q000009:adverse effects*
D018906:Antineoplastic Agents, Alkylating; D014612:Vaccines; D012965:Sodium Chloride; D015080:Mesna; D007069:Ifosfamide