Effects of combined sonodynamic and photodynamic therapies with photolon on a glioma C6 tumor model

The aim of this study was to investigate the low-power density sonication, sonodynamic therapy (SDT) with Photolon and combination of SDT and photodynamic therapy (PDT) with Photolon for the ablation of glioma C6 tumor model in rats. The study was performed on 50 rats bearing glioma C6. The tumors were sonicated with/without prior intravenous injection of photosensitizer (PS) Photolon (2.5 mg/kg b.w). Sonication was performed with 0.4; 0.7 and 1.0 W/cm² power density at 1 MHz frequency for 10 min, 2.0 h after Photolon administration using BTL-5710 Sono (BTL Industries Limited, Great Britain). PDT was carried out 2.5 h after Photolon administration using diode laser with 661 nm wavelength (IMAF-AXICON, Minsk, Republic of Belarus) at doses of 50 and 100 J/cm² with 0,17 W/cm² fluence rate. Assessment of tumor response was performed by vital staining with Evans blue and pathologic examination. The maximal tumor necrosis area that underwent sonication (1 MHz; 0.7 W/cm²; 10 min.) followed by PDT at a dose of 100 J/cm² was 100%. This is the first report to demonstrate the benefits of sono-photodynamic therapy (SPDT) consisting of low-power density ultrasound and PDT for the treatment of malignant glioma models.