Electrochemical red-ox therapy of prostate cancer in nude mice.

Minimally invasive therapies are increasingly in demand for organ-confined prostate tumors. Electrochemical therapy (EChT) is attractive, as it relies on locally-induced reduction-oxidation reactions to kill tumor cells. Its efficacy for prostate cancer was assessed in human PC-3 and LNCaP tumor xenografts growing subcutaneously in nude mice (n = 80) by applying 2 Stainless Steel vs. 4 Platinum-Iridium (Pt-Ir) electrodes to deliver current densities of 10 to 35 mA/cm(2) for 30 or 60 min. The procedure was uneventful in 90% of mice. No difference in tumor vs. body temperature was observed. Changes at electrode-tumor junctions were immediate, with dryness and acidity (pH2-3) at the anode and oedema and alkalinity (pH10-12) at the cathode. This was accompanied by cellular alterations, found more pronounced at the cathode. Such acidic and alkaline conditions were cytotoxic in vitro and dissolved cells at pH>10. In mice, tumor destruction was extensive by 24h with almost undetectable blood prostate specific antigen (LNCaP model) and covered the whole tumor surface by 4 days. EChT was most efficient at 25-30 mA/cm(2) for 60 min, yielding the longest recurrence-free survival and higher cure rates, especially with 4 Pt-Ir electrodes. EChT is a promising option to optimize for organ-confined prostate tumors.