Photochemotherapy in the treatment of cancer

The development of therapies which are selective for tumor tissues is one o f the most important goals in anticancer research. Within this framework ph otochemotherapy can be considered a very promising approach. Its therapeuti c effectiveness depends on two connected factors: drug and light. The drug (photosensitizer) is able to exert an antiproliferative effect only after i nteraction with suitable light. Both the photosensitizing drug and light al one are ineffective at doses used for these treatments. Nowadays, photochem otherapy is used in the treatment of cutaneous T-cell lymphoma and cavitary tumors. In the first case the photosensitizer is a psoralen derivative (P) and long-wavelength ultraviolet radiation (UVA) is used (PUVA therapy). In the second case, the treatment with porphyrins, porphyrin-based and non po rphyrin-based photosensitizers is followed by irradiation with 600-1000 nm light (photodynamic therapy, PDT). This review is concerned with PUVA and P DT treatments of cancer, The molecular mechanisms considered accountable fo r the photochemotherapeutic effects are discussed, the development of new c hemical structures aimed at improving the effectiveness and/or overcoming s ome undesired side effects will also be reported. Moreover, some clinical a pplications will be described.