Inhibition of rat colon tumor isograft growth with dequalinium chloride.

In searching for a new approach to the systemic treatment of colorectal carcinoma, we have observed that certain lipophilic cationic compounds are accumulated and retained for a significantly longer period in the mitochondria of living carcinoma cells than in normal cells or sarcoma cells. We report the in vivo therapeutic effect of one of these compounds, dequalinium chloride, on the W163 rat colon carcinoma isograft, which grows rapidly in Wistar/Furth rats after primary tumor implantation, and which recurs rapidly after primary tumor resection. In the primary transplant model, tumors were implanted, and daily dequalinium chloride treatments were begun the following day in doses ranging from 1 to 10 mg/kg. In the recurrence model, isografts were implanted, allowed to grow for one week, and then all gross tumor was resected. Dequalinium chloride was administered in varying daily doses starting the day after resection. In both models, tumor was removed on day 11 after implantation or resection. At sublethal doses, dequalinium chloride significantly inhibited primary tumor growth to 60% that of controls and recurrent tumor growth to 50% that of controls. We propose that this unique biologic approach of targeting carcinoma mitochondria with lipophilic cationic compounds may provide a major new opportunity for treating colorectal carcinoma.