Photodynamic therapy and diagnosis of5-aminolevulinic acid for gastrointestinal cancer

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 16591309
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Digestive surgery
• Research Institution: Hamamatsu University School of Medicine
• Principal Investigator: TANAKA Tatsuo Hamamatsu University Hospital, assistant professor, 医学部附属病院, 講師 (90273185)
• Co-Investigator(Kenkyū-buntansha): KONNO Hiroyuki Hamamatsu Univ. Sch.of Med., professor, 医学部, 教授 (00138033)
• Project Period (FY): 2004 – 2006
• Keywords: Photodynamic therapy / 5-aminolevulinic acid / mono-L-aspartyl chlorine e6 (NPe6)

Research Abstract

Photofrin is the most commonly used photosensitizer for photodynamic therapy (PDT). The major side effect of Photofrin is cutaneous photosensitivity. 5-aminolevulinic acid (5-ALA) is potentially exploitable for PDT and does not cause the side effect of prolonged normal skin photosensitization. We investigated the anti-tumor effects and safety of 5-ALA in patients with gastrointestinal cancer. 5-ALA(30 mg/kg) was administrated orally. At 4 h after administration, laser beam was irradiated to the tumor site endscopically using a directional quartz fiber (energy level : 100 J/cm^2). The antitumor effects of 5-ALA PDT according to patients were one PR and two SD. We investigated antitumor effects of 5-ALA PDT for human gastric cancer by animal model. Nude mice were implanted subcutaneously MT2 tumor (human gastric cancer line) and 5-ALA PDT was done. The rates of tumor shrinkage after PDT were 0.40 (5-ALA) and 0.16 (Photofrin). Judging from these results, anti-tumor effect of 5-ALA PDT is not satisfaction in the clinical and basic research.
Next, we investigated antitumor effects of PDT using a fractionated dosing of mono-L-aspartyl chlorine e6 (NPe6) in a murine tumor. Eight nude mice with MT2 tumor were given 10 mg/kg NPe6 intravenously. Two hours later PDT was performed using a laser diode at a light dose of 100 J/ cm^2 and wavelength of 664 nm. Histological changes in tumors were examined 3 weeks after PDT. The CR rate was 87.5 % and the overall response rate was 100 %. The anti-tumor efficacy of NPe6 for human gastric cancer is very excellent correspond to it of Photofrin.