Antitumor Effect Sonodynamically Induced by Focused Ultrasound in Combination with Ga‐Porphyrin Complex

The antitumor effect of focused ultrasound in combination with Ga‐porphyrin complex, 7,12‐bis(1‐decyloxyethyl)‐Ga(III)‐3,8,13,17 tetramethylporphyrin‐2,18‐dipropionyl diaspartic acid (ATX‐70), on the growth of experimental murine tumors was examined. Walker 256 tumors implanted in rat kidneys were exposed in a progressive wave field for 5 min to focused ultrasound at 500 kHz with the second harmonic (at 1 MHz) superimposed after administration of ATX‐70 to the rats. A significant antitumor effect was obtained at a focal‐spot average acoustic intensity of 12 W/cm(2) or higher with an ATX‐70 dose of not less than 2.5 mg/kg. When the acoustic intensity was 8 W/cm(2) or lower, no significant effect was observed even at an ATX‐70 dose of 2.5 mg/kg. Also when the ATX‐70 dose was 1.0 mg/kg or lower, no significant effect was observed even at a focal‐spot average acoustic intensity of 40 W/cm(2).