“MR Directed Focal Hyperthermia for Pelvic Disease” by Chris J. Diederich, PhD, et al. from the University of California San Francisco.
Along with primary investigators Drs. Vasant Salgaonkar, Eugene Ozhinsky, and Viola Rieke (Radiation Oncology and Radiology), Dr. Diederich and the team from the University of California San Francisco implemented sonication and feedback control strategies for targeted prostate hyperthermia with InSightec’s ExAblate 2100 endocavity focused ultrasound system.
The team devised specific beamforming, sonication, and control strategies to overcome the current software limitations of the system, with the goal of delivering long duration (15 to 30 minutes) and diffusely large continuous volumes of hyperthermia in prostate quadrants or hemi-gland targets.
“This proof-of-principle study demonstrated the feasibility of building onto clinical focused ultrasound equipment to enable hyperthermia via closed-loop temperature feedback,” said the Foundation’s Director of Extramural Programs, Matt Eames, PhD. “It is a technique that the Foundation hopes to bring to preclinical brain studies later this year.”
They used simulations to determine optimal beam forming strategies to defocus or control the ultrasound energy, and followed with patient-specific modeling to compute 3D thermal distributions. The data were implemented on the ExAblate prostate array, and experiments were conducted to confirm delivery of hyperthermia in vivo, to emulate targeted regions of focal cancer volumes or whole gland. They hope that their work will translate into having several different beam patterns available for clinical applications as well as better control, monitoring, and feedback.
We interviewed Professor Chris J. Diederich about his work to expand the capabilities of the system to better treat prostate cancer:
Q. Was the goal of your research to create parameters for using the InSightec prostate platform for hyperthermia rather than ablation? Did you get the results that you needed/wanted? Any disappointments or surprises?
UCSF Radiation Oncology has a comprehensive hyperthermia program using several modalities for hyperthermia therapy. The InSightec ExAblate prostate platform, although designed specifically for ablation therapy, appeared to us to have potential to be used to provide accurate hyperthermia delivery to the prostate, as well as other regions adjacent to the rectum, and accentuate our hyperthermia program.
We initiated this collaboration between Radiation Oncology and Radiology, with the generous support of the Foundation, to provide a platform for prostate hyperthermia, with the inherent MR temperature monitoring capabilities and beam forming, to precisely control or target heating for radiosensitization, drug delivery, and possibly immunotherapy. We have made significant progress to demonstrate hyperthermia delivery using our approach is feasible and could be realized; however, we need to complete integration of control strategies and additional experiments within animals, prior to use in patients.
Q. What comes next? - Are you ready to begin using the prostate platform for hyperthermia? If so, which area would you like to pursue first? Drug delivery, with radiation therapy, or immunotherapy?
We need to streamline the control feedback and continue to work with InSightec engineers to better facilitate our control schemes and hyperthermia monitoring. We will most likely pursue a clinical study of prostate hyperthermia in combination with hypofractionated radiation therapy and an immunotherapy agent. We are also investigating adapting this approach to the ExAblate table array for abdominal and superficial hyperthermia.
Q. Do you have new follow-up funding opportunities to continue this work?
A. That is now in process, and our plan is to fund a clinical study.
Q. Besides helping to fund the project, has the Focused Ultrasound Foundation helped advance your research in other ways?
A. Yes, the Foundation has given us exposure to other scientists and colleagues for constructive feedback. The clarity provided helped us broaden the scope of our work and improved the significance of our results.