[Recent developments in anticancer photochemotherapy]

Abstract

The photodynamic therapy of cancer (PDT) by porphyrins is now at a turning point with the advent of phase III clinical trials. The transport of photofrin II and its delivery to tumor cells and vasculature is believed to be a determinant of tumor necrosis by suppressing the oxygen supply. However, this treatment must be improved by increasing the selectivity of the photosensitizer uptake by tumors and also by using photosensitizers absorbing in the 700-800 nm range where tissues have the highest transmittance. In addition, these new photosensitizers (chlorines, phthalocyanines...) should be rapidly excreted to avoid the only secondary effect of the PDT: the long-lasting photosensitivity of the patient skin. Finally, the combination of PDT with other therapies or its chemopotentiation by "bioreductive" drugs which interfere with the metabolism of hypoxic cells resulting from the PDT are potential means for improving the effectiveness of this new modality for cancer treatment.