In vitro and in vivo experiments on electrochemotherapy for bladder cancer

BACKGROUND: Electrochemotherapy is widely used for treatment of solid tumors; however experience in bladder cancer is limited.

PURPOSE: To investigate mitomycin C (MMC) and cisplatin (CIS) for their use with electrochemotherapy in bladder cancer in-vitro and in-vivo.

MATERIALS AND METHODS: The human bladder cancer cell line SW780 was used. Cells were treated with electroporation (EP), drug alone or EP+drug respectively, in increasing concentrations of either MMC or CIS ranging from respectively 0.001μM to 2000μM and 1.56μM to 300μM. EP parameters: eight pulses of 1.2kV/cm, 99μs, 1Hz. Survival and apoptosis (caspase activity) were investigated. Nude mice (NMRI-Fox1nu) were inoculated subcutaneously and randomized to: a) EP+NaCl, b) NaCl alone, c) EP+drug, d) drug alone. Drugs were: MMC (5mM) and CIS (250mM). Tumors were measured thrice weekly. A similar experiment investigated necrosis by histology at days 2 and 6.

RESULTS: and conclusions: In vitro, MMC cytotoxicity (p=0.9057) and caspase activity (p=0.53) was unaffected by EP. However, EP caused a 6.6-fold increased cytotoxicity (p<0.0001) and a higher caspase activity (p<0.001) with CIS. In-vivo "EP+MMC" showed tumor volume reduction (p<0.0005). Survival for "EP+MMC" and "MMC alone" were higher than controls (p=0.0004). Tumor response: "EP+MMC" (100%), "MMC alone" (53%), "EP+NaCl" (14%), "NaCl alone" (0%). In-vivo "EP+CIS" showed slower tumor growth (p=0.0005) over other combinations with significantly higher survival (p=0.0003). Tumor response: EP+CIS" (47%), "CIS alone" (0%), "EP+NaCl" (0%), "NaCl alone" (8%). In-vivo electrochemotherapy with MMC or CIS is more effective than chemotherapy alone in a bladder cancer tumor model, opening new perspectives in bladder cancer therapy.