A New Cancer Therapy with a Resonance Nuclear Reaction between ¹⁵n-5-ALA and Proton Beam: iPDT

A super-aged society, the prime example of which is Japan, is being flooded with increasing in numerous numbers of aged cancer patients, who often take anti-coagulant medicines to prevent the attacks of ischemic heart diseases and/ or strokes. Since they have diseases with bleeding tendency induced by the medicines, it’s hard for them to receive surgical operations. Thus, low invasive cancer treatments without bleedings are abundantly desired. In this study, the applicant will establish a new proton therapy, in which a resonance nuclear reaction (RNR) induced by collision of a proton with a stable nitrogen isotope ( 15 N), can be a clue to injure cancer-cells specifically. The LET of the product ions ( 12 C 6+ , 4 He 2+ ) of the 15 N RNR is above 50 times in comparison with the LET of proton. To establish the cancer-specific 15 N delivery, 15 N-aminolevulinic acid ( 15 N-ALA) will be used. This reagent has been already used and obtained regulatory approvals as a diagnostic medicine for the location of the glioblastoma in Japan. In this study, a pair of rat gastric epithelial cells, one is normal cell, and another is cancerous characteristics cells were used, 15 N-ALA treated porphyrin fluorescent intensity of these cells will be compared with 14 N-ALA treatment. The cells will be irradiated with a proton beam generated by an electrostatic accelerator and 4.43 MeV gamma-rays will be measured to demonstrate the amount of 15 N collected specifically in the tumour cells. Such quantitative analysis of 15 N in the tumour cells can be a new pre-diagnosis of iPDT.