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/cm2 or higher with an ATX-70 dose of not less than 2.5 mg/kg. When the acoustic intensity was 8 W/cm2 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/cm2.