Activation of anti-cancer drugs with ultrasound: Sonodynamic therapy

The effect of porphyrin photosensitizing agents on the HL-60 human promyelocyte leukemia cell line in culture and a rabbit VX2 carcinoma in vivo was examined with ultrasound as the "activating" agent. Hematoporphyrin plus ultrasound significantly reduced growth rate of the VX2 tumors when compared to drug only, ultrasound only, and sham treated controls. In an in vitro exposure system, HL-60 cell killing was significantly increased with ultrasound plus mesoporphyrin but only in the presence of albumin stabilized microbubbles suggesting that acoustic cavitation is responsible for the sonochemical activation of the sensitizing agent.