Photodynamic therapy (PDT) is an effective cancer treatment modality that allows selective destruction of malignant tumor
cells. We asked whether PDT could inhibit in vivo and in vitro growth of synovial sarcoma cells. We analyzed PDT using ATX-S10·Na(II)
and a diode laser for a synovial sarcoma cell line (SYO-1). Photodynamic therapy with ATX-S10·Na(II) showed an in vitro cytotoxic
effect on the cultured SYO-1 cells. The in vitro effect of PDT depended on the treatment concentration of ATX-S10·Na(II) and
the laser dose of irradiation. ATX-S10·Na(II) was detected in the tumor tissue specimens that were excised from nude mice
bearing SYO-1 within 6 hours after intravenous injection, but it was eliminated from the tumor 12 hours after injection. Photodynamic
therapy suppressed the tumor growth of nude mice bearing SYO-1, and high-dose irradiation induced no viable tumor cells in
histologic specimens. Photodynamic therapy performed after marginal resection of the tumor of nude mice bearing SYO-1 reduced
the rate of local recurrence of the tumor. Our results suggest PDT using ATX-S10·Na(II) and laser irradiation may be a potentially
useful treatment for synovial sarcoma, especially to reduce the surgical margin and preserve critical anatomic structures
adjacent to the tumor.
One or more of the authors (TK, TO) have received funding from Grants-in-aid for Young Scientists (B) from the Ministry of
Education, Culture, Sports, Science and Technology (18791040 and 15790792), by a grant from the Japan Orthopaedics and Traumatology
Foundation Inc (0158), by Grants-in-Aid for Clinical Cancer Research and Grants-in-Aid for Cancer Research (14S-4 and -5)
from the Ministry of Health, Labor and Welfare, and by a grant from the JSPS Fujita Memorial Fund for Medical Research.
Each author certifies that his or her institution has approved the animal protocol for this investigation and that all investigations
were conducted in conformity with ethical principles of research.