Sonodynamic therapy: activation of anticancer agents with ultrasound

VX2 carcinoma was introduced into the right rear thigh of rabbits. The tumors were exposed to ultrasound (US; 1.97 MHz; 1.35 W/cm² ) for ten minutes, 24 hours after intravenous injection of hematoporphyrin (Hp; 20 mg/kg). Tumor damaging effects were evaluated by measuring the tumor diameter every three days following treatment. Any effect on the tumor growth caused by US alone or by Hp alone could not be statistically distinguished from the control; however, the combination of US and Hp did temporarily retard tumor growth. These results suggest that Hp enhances the tumorcidal effect of ultrasound. Since hematoporphyrin derivative (HpD) is one of several drugs which may be of interest in sonodynamic therapy, the authors also examined the cytotoxic effects of HpD alone and HpD with ultrasound exposure on HL-60 promyelocytic leukemia cells grown in suspension culture. Reproductive survival was evaluated by colony formation assays resulting in a plating efficiency for cells treated with HpD and ultrasound which was significantly lower than for ultrasound alone. Cells treated with HpD alone had a plating efficiency equal to sham treatments