- Email: [email protected]
Sonodynamic application of ultrasound in therapy
Abstracts Methods: Patients included in this series were treated with HIFU as primary care for localized prostate cancer, with a baseline PSA level ⬉30 ng/ml. All patients were treated under general or spinal anesthesia, using the Ablatherm® device (EDAP SA). The HIFU treatment was delivered in one or two sessions (mean: 1.4 ⫾ 0.8). Patient follow-up included sextant biopsies and PSA level measurements. Any positive biopsy or 3 consecutive increases in the PSA level were considered as a failure for the disease-free rate (DFR) calculation. Results: 245 patients fulfilled these inclusion criteria and were all considered for analysis. The main baseline characteristics before HIFU were: mean age 71.1 ⫾ 5.5 years, mean prostate volume 32.3 ⫾ 16.06 cc, mean PSA level 9.06 ⫾ 6.17 ng/ml, and all had positive biopsies. According to the usual definition of the disease risk level, 68 patients were classified as low-risk patients, 106 as intermediate-risk, and 67 as high-risk. The mean patient follow-up was 24 months (range: 3–103 months). In each risk group, the results of DFR survival curves obtained using the Kaplan-Meier method were 76.7%, 66.8%, and 55.6%, respectively (log-rank: p ⫽ 0.0331). Conclusions: The 5-year results observed after HIFU treatment of localized prostate cancer are similar to those reported after radiation.
Magnetic resonance imaging-guided and monitored focused ultrasound surgery Hynynen K, Radiology/MRI, Brigham and Women’s Hospital, Boston, MA, and Harvard Medical School, Boston, MA During the past few years, ultrasound phased arrays with large number of elements (up to several hundred) have been developed to control the focal exposures delivered into the tissue. These phased arrays can increase focal spot size thus making treatments of large tumors practical. In addition, they offer sharp focusing through highly distorting tissues such as skull. However, the exposure control becomes complex with these new arrays, and online monitoring is required to provide clinical safety. Magnetic resonance imaging methods have been developed for noninvasive temperature monitoring over the past 10 years. Both phantom and animal experiments have shown that the proton resonant frequency is temperature dependent and that maps of the temperature change can be obtained within seconds with phase subtraction methods during focused ultrasound exposure. Recent clinical treatments have verified the usefulness of large-scale phased arrays and temperature mapping during ultrasound surgery. New experimental studies show that these arrays guided by MRI may have many clinical applications beyond thermal ablation of tissues, for example in targeted drug delivery, gene therapy, vascular occlusions, and thrombolysis.
Ultrasound-targeted gene and drug therapy Unger EC,*1,2 Sweitzer R,1 1. ImaRx Therapeutics, Inc., Tucson, AZ, and 2. Radiology, University Medical Center, Tucson, AZ Objective: The aim of this study was to develop non-viral gene delivery to provide higher levels of expression and target selected tissues. Methods: Neutral (n) perfluoropropane-filled microbubbles (mb) and mb with cationic surface (c) charge were prepared. Mb vesicles (ves) filled with perfluorobutane, perfluoropentane (PF5), and perfluorohexane (PF6) were also tested. PF5 has a boiling point of about 28°C and PF6 of about 60°C. Therefore, PF5 exists as a liquid at room temperature and may become gas in vivo. PF6 should be a liquid in vivo. In vitro studies were performed to assess binding of DNA to the different mb formulations. Nude Balb/C mice were injected with plasmid (pCAT) DNA and the following groups tested (n ⫽ 3–5 animals per group): control, plasmid, plasmid ⫹ nmb, plasmid ⫹ cmb, plasmid ⫹
S41
cPF5 ves, plasmid ⫹ cPF6 ves. This was repeated in additional groups of animals with transdermal ultrasound application, frequency ⫽ 1.0 MHz, 1.5 W/cm2 for 5 min to the liver. Livers were removed 24 – 48 hrs later, and pCAT was assayed. Results: Mean size of the gas filled mb was about 1 , and mean size of the PF5 and PF6 ves was about 100 to 200 nm. The cmb and ves avidly bound DNA, but the nmb showed no affinity for DNA. Conclusions: There is synergy between US and cmb wherein the plasmid DNA is presumably bound to the bubbles. Nmb that do not bind the DNA do not have this synergistic effect. This suggests that the mb act as cavitation nuclei, and to maximize the effect, the genetic material should be complexed onto the mb. Liquid PFCs have applications for gene delivery irrespective of US. PFCs have lower surface tension and viscosity and may improve the fusogenic properties of the ves for gene delivery. The apparent decrease in gene expression with US with these carriers is perplexing, and we are conducting ongoing studies to try to understand this.
Control Plasmid w/wo US Nmb w/wo US Cmb Cmb ⫹ US CVES ⫹ PFC Cves ⫹ PFC ⫹ US
pg CAT/g 0 0 0 0 113.25 333.74 164.13
Sonodynamic application of ultrasound in therapy Umemura S,*1 Kawabata K,1 Sasaki K,1 Sugita N,1 Azuma T,1 Yumita N,2 Sanghvi NT,3 1. Central Research Laboratory, Hitachi Ltd., Kokubunji, Tokyo, Japan, 2. Pharmaceutical Science, Toho University, Funabashi, Chiba, Japan, and 3. Focus Surgery, Indianapolis, IN
We have proposed “sonodynamic therapy” on the finding that certain chemicals such as hematoporphyrin were activated by acoustic cavitation and thereby induced a significant antitumor effect. We also found that sonodynamically active cavitation was induced at a relatively low ultrasonic intensity through superimposing the second harmonic onto the fundamental. The intensity threshold for producing focal damage in murine liver was reduced by orders of magnitude through secondharmonic superimposition especially in combination with administration of a certain xanthene, which seems to be stabilizing microbubbles. The effect was maximized at a second-harmonic phase emphasizing the peak rarefaction, which is consistent with the hypothesis that microbubble growth rather than collapse was accelerated. A tumor-selective amphiphilic xanthene was synthesized by modifying a side chain of rosebengal. Significant reduction in murine tumor volume was observed with focused wave insonation at a combination of 0.5 and 1 MHz after administration of the rosebengal derivative. Use of a stabilized microbubble agent to enhance the heating effect of focused ultrasound has also been studied. An exteriorized murine kidney was insonated with focused ultrasound at 3.2 MHz, and the tissue temperature change was measured. With administration of Optison at a dose of 0.2 ml/kg, the temperature elevation induced by ultrasonic exposure was significantly multiplied. Although it is thought to be difficult to deliver a stabilized microbubble agent beyond capillary walls to intercellular spaces in tumor tissue, the ultrasonically generated heat enhanced with microbubbles in capillaries can be easily delivered to tumor cells by conduction. This work is supported in part by the National Research and Development Program for Medical and Welfare Apparatus, Japan.
Magnetic resonance imaging-guided and monitored focused ultrasound surgery Hynynen K, Radiology/MRI, Brigham and Women’s Hospital, Boston, MA, and Harvard Medical School, Boston, MA During the past few years, ultrasound phased arrays with large number of elements (up to several hundred) have been developed to control the focal exposures delivered into the tissue. These phased arrays can increase focal spot size thus making treatments of large tumors practical. In addition, they offer sharp focusing through highly distorting tissues such as skull. However, the exposure control becomes complex with these new arrays, and online monitoring is required to provide clinical safety. Magnetic resonance imaging methods have been developed for noninvasive temperature monitoring over the past 10 years. Both phantom and animal experiments have shown that the proton resonant frequency is temperature dependent and that maps of the temperature change can be obtained within seconds with phase subtraction methods during focused ultrasound exposure. Recent clinical treatments have verified the usefulness of large-scale phased arrays and temperature mapping during ultrasound surgery. New experimental studies show that these arrays guided by MRI may have many clinical applications beyond thermal ablation of tissues, for example in targeted drug delivery, gene therapy, vascular occlusions, and thrombolysis.
Ultrasound-targeted gene and drug therapy Unger EC,*1,2 Sweitzer R,1 1. ImaRx Therapeutics, Inc., Tucson, AZ, and 2. Radiology, University Medical Center, Tucson, AZ Objective: The aim of this study was to develop non-viral gene delivery to provide higher levels of expression and target selected tissues. Methods: Neutral (n) perfluoropropane-filled microbubbles (mb) and mb with cationic surface (c) charge were prepared. Mb vesicles (ves) filled with perfluorobutane, perfluoropentane (PF5), and perfluorohexane (PF6) were also tested. PF5 has a boiling point of about 28°C and PF6 of about 60°C. Therefore, PF5 exists as a liquid at room temperature and may become gas in vivo. PF6 should be a liquid in vivo. In vitro studies were performed to assess binding of DNA to the different mb formulations. Nude Balb/C mice were injected with plasmid (pCAT) DNA and the following groups tested (n ⫽ 3–5 animals per group): control, plasmid, plasmid ⫹ nmb, plasmid ⫹ cmb, plasmid ⫹
S41
cPF5 ves, plasmid ⫹ cPF6 ves. This was repeated in additional groups of animals with transdermal ultrasound application, frequency ⫽ 1.0 MHz, 1.5 W/cm2 for 5 min to the liver. Livers were removed 24 – 48 hrs later, and pCAT was assayed. Results: Mean size of the gas filled mb was about 1 , and mean size of the PF5 and PF6 ves was about 100 to 200 nm. The cmb and ves avidly bound DNA, but the nmb showed no affinity for DNA. Conclusions: There is synergy between US and cmb wherein the plasmid DNA is presumably bound to the bubbles. Nmb that do not bind the DNA do not have this synergistic effect. This suggests that the mb act as cavitation nuclei, and to maximize the effect, the genetic material should be complexed onto the mb. Liquid PFCs have applications for gene delivery irrespective of US. PFCs have lower surface tension and viscosity and may improve the fusogenic properties of the ves for gene delivery. The apparent decrease in gene expression with US with these carriers is perplexing, and we are conducting ongoing studies to try to understand this.
Control Plasmid w/wo US Nmb w/wo US Cmb Cmb ⫹ US CVES ⫹ PFC Cves ⫹ PFC ⫹ US
pg CAT/g 0 0 0 0 113.25 333.74 164.13
Sonodynamic application of ultrasound in therapy Umemura S,*1 Kawabata K,1 Sasaki K,1 Sugita N,1 Azuma T,1 Yumita N,2 Sanghvi NT,3 1. Central Research Laboratory, Hitachi Ltd., Kokubunji, Tokyo, Japan, 2. Pharmaceutical Science, Toho University, Funabashi, Chiba, Japan, and 3. Focus Surgery, Indianapolis, IN
We have proposed “sonodynamic therapy” on the finding that certain chemicals such as hematoporphyrin were activated by acoustic cavitation and thereby induced a significant antitumor effect. We also found that sonodynamically active cavitation was induced at a relatively low ultrasonic intensity through superimposing the second harmonic onto the fundamental. The intensity threshold for producing focal damage in murine liver was reduced by orders of magnitude through secondharmonic superimposition especially in combination with administration of a certain xanthene, which seems to be stabilizing microbubbles. The effect was maximized at a second-harmonic phase emphasizing the peak rarefaction, which is consistent with the hypothesis that microbubble growth rather than collapse was accelerated. A tumor-selective amphiphilic xanthene was synthesized by modifying a side chain of rosebengal. Significant reduction in murine tumor volume was observed with focused wave insonation at a combination of 0.5 and 1 MHz after administration of the rosebengal derivative. Use of a stabilized microbubble agent to enhance the heating effect of focused ultrasound has also been studied. An exteriorized murine kidney was insonated with focused ultrasound at 3.2 MHz, and the tissue temperature change was measured. With administration of Optison at a dose of 0.2 ml/kg, the temperature elevation induced by ultrasonic exposure was significantly multiplied. Although it is thought to be difficult to deliver a stabilized microbubble agent beyond capillary walls to intercellular spaces in tumor tissue, the ultrasonically generated heat enhanced with microbubbles in capillaries can be easily delivered to tumor cells by conduction. This work is supported in part by the National Research and Development Program for Medical and Welfare Apparatus, Japan.