High Drug Resistance in Feline Mammary Carcinoma Cell Line (FMCm) and Comparison with Human Breast Cancer Cell Line (MCF-7).

Drug repurposing and drug combination are important therapeutic approaches in cancer therapy. Drug repurposing aims to give new indications to drugs, rather than the original indication, whereas drug combination presupposes that the effect that is obtained should be more beneficial than the effect obtained by the individual drugs. Previously, drug repurposing and the combination of different drugs was evaluated in our research group against human breast cancer cells (MCF-7 cells). Our results demonstrated that the response obtained through the combination of drugs, when compared with the single drugs, led to more synergic responses. Therefore, using potential drugs for repurposing, combined with a reference drug in breast cancer (5-Fluorouracil), was the major aim of this project, but for the first time using the feline mammary carcinoma cell line, FMCm. Surprisingly, the feline neoplastic cells demonstrated considerable resistance to the drugs tested in isolation, and the combination was not effective, which contrasted with the obtained MCF-7 cells' response.