COMPARING THE ANTITUMOR EFFECT OF SEVERAL BIOREDUCTIVE DRUGS WHEN USED IN COMBINATION WITH PHOTODYNAMIC THERAPY (PDT)

Purpose: To compare the effect on the RIF-1 murine sarcoma of nine bioreductive agents from five different classes when used in combination with either photodynamic therapy or clamping. Methods and Materials: RIF-1 tumors implanted intradermally in C3H mice were treated with either 50J photodynamic therapy or with 120 min clamping in combination with either misonidazole, pimonidazole, metronidazole, nimorazole, RB6145, RSU1069, SR4233, mitomycin-C, or RB90740. The tumors were measured 3 times-per-week until reaching 4 X their initial treatment volume. Results: RSU1069 produced the greatest anti-tumor activity in combination with both photodynamic therapy and clamping. RB6145 also substantially enhanced the effect of photodynamic therapy and clamping whereas misonidazole induced a smaller, but significant increase. Mitomycin-C had no effect under cramped conditions, but greatly increased the tumorcidal effect of photodynamic therapy. Mitomycin-C also induced an effect when given with light alone. None of the other agents showed any augmentation of the tumor cell killing induced by photodynamic therapy. Conclusion: Of the bioreductive agents studied RSU1069, RB6145 and mitomycin-C showed the greatest antitumor response in combination with photodynamic therapy.