Electrochemotherapy can eradicate established colorectal carcinoma and leaves a systemic protective memory in mice

Mice bearing subcutaneously established colorectal carcinoma (CRC) were given intratumoral, intravenous or intraperitoneal injection of various doses of bleomycin (BLM), followed by the delivery of direct current, square wave electric pulses to the tumor. Approximately 50% of animals treated with electrochemotherapy with BLM had completely eradicated established CRC tumors. Importantly, it was shown that CRC-specific cytotoxic T lymphocytes were elicited in the spleens of cured animals, resulting in the protection of the rechallenge with CRC. These results indicate that electrochemotherapy with BLM is promising for the treatment of metastatic CRC as well as the original lesion.