Establishment of two vaccine-associated feline sarcoma cell lines and determination of in vitro chemosensitivity to doxorubicin and mitoxantrone

Objective-To establish 2 vaccine-associated feline sarcoma (VAFS) cell line s and to determine their in vitro sensitivity to the chemotherapeutic agent s doxorubicin and mitoxantrone. Sample Population-Tumor specimens collected from 2 cats undergoing surgery for removal of vaccine-associated sarcomas. Procedures-Tumor specimens were minced and treated with trypsin under asept ic conditions to obtain single-cell suspensions, which were then cultured i n vitro in medium supplemented with 5% heat-inactivated fetal bovine serum. Growth rates and sensitivity after 24 hours of exposure to various concent rations (0.1 to 100 mug/ml) of doxorubicin and mitoxantrone were assessed f or each cell line. Survival of cells was estimated 3 days after exposure to the 2 agents, and the concentration of each drug that resulted in a 50% re duction in the number of viable cells (IC50) was calculated. Results-Two tumor-derived cell lines (FSA and FSB) were successfully establ ished and determined to be sensitive to doxorubicin and mitoxantrone. Under the conditions tested, the IC50 of doxorubicin were 0.6 and 1.5 mug/ml for cell lines FSB and FSA, respectively. The IC50 of mitoxantrone was 0.4 mug /ml for both cell lines. Conclusions and Clinical Relevance-The establishment of VAFS cell lines pro vides a tool for the in vitro screening of antitumor drugs. Doxorubicin and mitoxantrone were effective in decreasing the number of viable cells in th e 2 cell lines tested. Both of these anthracycline antibiotics have been us ed to treat various neoplasias in cats, and their efficacy for adjuvant tre atment of vaccine-associated sarcomas should be further evaluated.