ANTITUMOR EFFICACY OF THE COMBINATION OF PHOTODYNAMIC THERAPY AND CHEMOTHERAPY IN MURINE TUMORS

Photodynamic therapy (PDT) is based on the administration of tumor-loc alizing photosensitizers followed by light exposure of the tumor mass. The photocytotoxic effects are mainly caused by the generation of sin glet oxygen. Recently, PDT has been proposed for use in combination wi th anticancer chemotherapy with a view to exploiting any additive anti tumor effect. We investigated the effect of PDT with photoactivated al uminum disulfonated phthalocyanine (AlS2Pc) combined with the antiblas tic drugs Adriamycin (ADR) and cisplatinum (CDDP) on murine tumors. Mi ce bearing L1210 leukemia and P388 lymphoma were treated with ADR or C DDP and subsequently treated with PDT. Low chemotherapy doses were ine ffective, but the combination of antiblastic drugs + PDT had a signifi cantly additive antitumor effect. In conclusion, with this combined th erapy we were able to greatly reduce the effective doses of antiblasti c drugs, thus lowering their toxic effects on normal host tissues. (C) 1998 Elsevier Science Ireland Ltd.