Cisplatin enhances the efficacy of 5-aminolevulinic acid mediated photodynamic therapy in human head and neck squamous cell carcinoma.

Photodynamic therapy (PDT) has become a promising option for the treatment of head and neck, and other forms of cancer. 5-Aminolevulinic acid (ALA) is one of the popular photosensitizers used in PDT. It is a heme precursor and is converted to a photosensitizer protoporphyrin IX. In this present study, the combination of anticancer drug cisplatin (CDDP)- and ALA- mediated PDT was used to study the cytotoxicity in vitro as well as in vivo. Human head and neck cancer cells AMC-HN3 were treated with cisplatin- and ALA-mediated PDT individually, and also in combination. Several approaches like confocal microscopic study, cytotoxicity assay, etc have been performed to study the intracellular accumulation of protophorphyrin IX in cells and its effectiveness in PDT, when treated in combination with chemotherapy drug, cisplatin (CDDP). The combination of treatments efficacy was also studied in tumor xenograft model. Compared to the individual treatments, combination of CDDP and PDT was found to be more cytotoxic in AMC-HN3, and also more effective in reducing the tumor volume in mice xenograft. Thus, with the combined therapy, not only the efficacy of treatment can be enhanced, but the doses of the drugs can also be lowered. This in turn can reduce the side effects of the chemotherapy drugs. Therefore, this study may lead to a potential drug-PDT combination that may be a useful treatment modality for human head and neck cancer.