Metronomic Chemotherapy in a Lion (Panthera leo) with Spindle Cell Sarcoma: Continuous Low-Dose Antiangiogenic Protocol
American Association of Zoo Veterinarians Conference 2011
Nancy C. Boedeker1, DVM; Anthony Calo4, DVM; David K. Saylor4, VMD; Rebecca K. Stites2, BS; Margarita Woc Colburn1, DVM; Tabitha C. Viner3,5, DVM, DACVP
1Department of Animal Health, Smithsonian National Zoological Park, Washington, D.C., USA; 2Department of Animal Care, Smithsonian National Zoological Park, Washington, D.C., USA; 3Department of Pathology, Smithsonian National Zoological Park, Washington, D.C., USA; 4VCAVRA, Gaithersburg, MD USA; 5National Forensics Laboratory, U.S. Fish and Wildlife Service, Ashland, OR, USA


A dorsal subcutaneous mass was excised from an 18-yr-old female lion. Histopathology revealed spindle cell sarcoma with necrotic center, high mitotic index, and narrow surgical margins. Similar tumors have been reported in other non-domestic felids.7,9,12 A continuous, oral, metronomic, antiangiogenic chemotherapeutic protocol was initiated post-operatively: cyclophosphamide (Roxane Laboratories, Columbus, OH) 25 mg/m2 PO EOD, piroxicam (TEVA Pharmaceuticals, Sellersville, PA) 0.27 mg/kg PO SID, and doxycycline (West-ward Pharmaceutical Corp. Eatontown, NJ) 4.5 mg/kg PO BID. Periodic urinalyses, complete blood counts, and chemistry panels were monitored for evidence of side effects. The surgical site healed without significant complications. The lion was euthanatized 7.5 mo post-operatively for disease unrelated to the tumor; no neoplasia was identified on gross or microscopic evaluation.

In domestic cats, a combination of aggressive surgical excision, radiation therapy, +/- intravenous chemotherapeutics is the recommended treatment for soft tissue sarcomas; recurrence with local invasiveness is common although metastasis is relatively rare.4,5,10 Metronomic antiangiogenic chemotherapy uses chronic administration of chemotherapeutic agents at low, minimally toxic doses with no drug-free breaks to overcome drug resistance by shifting the therapeutic target from tumor cells to tumor vasculature.11,13 Metronomic protocols incorporating oral cyclophosphamide and piroxicam have shown promise for treatment of sarcomas in domestic dogs; doxycycline has demonstrable antiangiogenic properties.1,2,8,14 Metronomic antiangiogenic therapy has not been previously reported in Panthera species and warrants further evaluation for management of neoplasia in carnivores. If effective, it could improve outcome while minimizing anesthetic events and undesirable side effects associated with chemotherapy.3,6


The authors thank the staff of the Departments of Animal Health, Pathology, and Animal Care at the Smithsonian Institution’s National Zoological Park for assistance with this case.

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Speaker Information
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Nancy C. Boedeker, DVM
Department of Animal Health
Smithsonian National Zoological Park
Washington, D.C., USA

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