After positive initial results, they led the City of Hope arm of a large, multisite Phase 2b trial of the technology, providing important data (published in Lancet Oncology in July 2022) that led to its recent approval by the Food and Drug Administration (FDA). The exciting platform, called Exablate Prostate, is now available to qualifying patients.
Exablate Prostate, developed by the health care technology company Insightec, uses high-intensity sound waves, or ultrasound, to target and destroy cancer cells within the prostate while leaving surrounding healthy tissues unaffected. Guided by magnetic resonance imaging (MRI) to help navigate a small, ultrasound wand through the rectum and around the gland, the acoustic ablation technique does not require any incisions or radiation.
“I was very interested in this new approach using ultrasound energy, instead of radiation imaging, to get rid of cancers within the prostate,” says Wong, who had led City of Hope’s Department of Radiology for more than 25 years and is currently co-director of the Center for Theranostic Studies, which aims to develop methods to diagnose and treat tumors at the same time. “What was intriguing, and different from the previous generations of ultrasound devices, is that it uses real-time MRI imaging to target the energy and, at the same time, give temperature feedback.”
The way it works is the ultrasound device is set to a particular setting that generates just enough heat to destroy cancer cells. Using MRI imaging, the device is positioned to treat just the areas in the prostate that contain tumor cells. At the same time, precise temperature readings ensure that the surrounding tissue isn’t being damaged. Algorithmic software gives real-time feedback and adjusts the focus area of the ultrasound device as areas are successfully treated.
“The Exablate technology is able to mark areas as treated, monitor temperature changes, and adapt or change treatment plans every step of the way as it works to destroy the cancer,” says Wong. “One of the biggest benefits of this precision treatment method is that it reduces the chance of erectile dysfunction, a common side effect of more traditional approaches like surgery and radiation.”
While the initial trial enrolled men with Gleason 6 scores — meaning their cancers were low-grade — the larger, multiphase study tested the technology in men with a Gleason 7 score, one of the most commonly diagnosed stages and considered intermediate-risk. The Gleason system aims to rate the aggressiveness of a patient’s prostate cancer, with 6 and below being the least aggressive and 8 to 10 being high-grade cancers. Because most patients with a Gleason 6 score are now considered candidates for a “watch and wait” approach, the Exablate platform was approved using just the data from Gleason 7 score trial participants. Current guidelines suggest it should be used only in that population.
Encouraging Results
Of the 101 men ages 50 and older treated at the eight sites, 88% had no evidence of cancer in the treated area 24 months following therapy.
“Eventually, there will probably be an increased use in patients who are outside the initial guidelines of the protocol,” says Wong. “But at this point, we at City of Hope will stick to the guidelines of treating patients who have a very isolated tumor in just one side of the prostate gland.”
Wong says that one of the challenges of expanding use of the technology is figuring out where focal therapy for prostate cancer fits in the spectrum of care.
“At this moment in time, especially in this country, there are traditionalists who advocate for whole gland therapy or gland removal, versus this particular approach,” Wong says. “There are physicians and even patients who are not completely convinced that focal therapy is an option for them. The other potential downside is that not every patient is the appropriate candidate for this. You have to have disease just in one portion of the gland, and a certain percentage of patients present with both sides of the gland involved, for example.”
Nonetheless, he says that preservation of erectile function is a major benefit of the method. And there were no reports among trial participants of urinary leakage requiring use of a pad, which is often a side effect of prostate surgery. Furthermore, the Exablate approach has been shown to be effective in delaying or eliminating the need for whole-gland treatments, such as surgery or radiation.
“I’ve always been interested in finding ways to advance the field and push the leading edge of cancer care,” says Wong. “Exablate fits an exciting paradigm of a new technology that creates novel opportunities for treatment without some of the side effects that can have a major impact on quality of life.”
After helping Exablate gain FDA approval, Wong continues to seek new treatment options both in the lab and through clinical trials. One of his current trials is testing the safety and efficacy of a monoclonal antibody in treating patients with colorectal cancer that has spread to other areas of the body, including the prostate. Developed at City of Hope, the monoclonal antibodies attach to cancer cells and deliver a radioactive agent called Ac225 to destroy them. Wong has long studied targeted radiopharmaceuticals and is involved in several additional trials testing different methods of Ac225 delivery in prostate and other cancers.
“Being at City of Hope gives me the opportunity to participate in important translational research that has the potential to change people’s lives for the better,” he says. “I’m thrilled that I got to play a role in bringing Exablate to patients, and look forward to finding new, more precise, ways to treat cancer while also reducing side effects.”
Main image of Exablate Prostate courtesy Insightec.