Antitumor effect of photodynamic therapy in mice using direct application of photofrin dissolved in lidocaine jelly

Background/purpose: Photodynamic therapy (PDT) is a non-invasive cancer therapy that has a strong antitumor effect with intravenous administration of Photofrin. However, Photofrin causes light hypersensitivity that impairs the quality of life (QOL) of patients, and thus an improved method of administration is needed. Here, we report the antitumor effect of local administration of Photofrin in combination with a vasodilator, lidocaine hydrochloride. Method: The antitumor effect was investigated in nude mice transplanted with HeLa cells. An incision was made near the tumor and Photofrin dissolved in lidocaine jelly was applied directly to the tumor. The tumor was irradiated at 100 J/cm² with a yttrium aluminum garnet (YAG)-dye laser (630 nm) at 2 h after the direct application and the tumor volume was measured for 30 days after PDT to investigate the antitumor effect. In some mice, the tumor was excised 24 h after PDT and the depth of necrosis was measured in the excised specimen. Result: The tumor was mostly necrotized by PDT following direct application of 10 mg/ml Photofrin dissolved in lidocaine jelly and the effect was greater than with direct application of Photofrin alone. The increase in tumor volume observed in control mice was significantly inhibited in mice that received PDT after direct application of Photofrin in lidocaine jelly. Conclusion: PDTusing direct application of Photofrin in lidocaine jelly has a strong antitumor effect in mice and this approach may avoid the adverse effects of systemic Photofrin administration.