High-Intensity Ultrasound Device for Prostate Surgery Clears FDA Hurdle

Herbert Lepor, MD

The FDA has issued a de novo clearance for a minimally invasive high-intensity focused ultrasound (HIFU) device called Sonablate 450 for prostate tissue ablation. The device is intended for patients with low- to high-risk prostate cancer with a PSA lower than 10 ng/mL who have progressed on external beam radiation therapy 

The FDA’s decision marks the first approved device to use HIFU technology in the United States, despite its approval in 49 other countries around the world, according to a statement issued by SonaCare Medical, the company manufacturing Sonablate 450.

“Until now, this technology was not available in the United States,” said Herbert Lepor, MD, professor and Martin Spatz Chairman, Department of Urology, New York University School of Medicine, in a statement. “It is anticipated that ablative urological surgeons in the US will quickly master and adapt this technology for their patients. HIFU offers the opportunity for the precise delivery of ablative energy to the prostate. Thus, it can be adapted to whole gland or focal gland ablation.”

Sonablate 450 features a fully integrated probe with dual ablation transducers. With the device, ultrasound energy is focused at a specific location in the prostate gland called the focal point, which is heated to nearly 195 degrees Fahrenheit (90 degrees Celsius). The tissue at the focal point is destroyed, but the tissue surrounding the area remains unharmed. Because the technology uses ultrasound energy not radiation to destroy targeted tissue the procedure can be repeated, if necessary. 

The minimally invasive procedure can be used to perform prostate ablations that urologists routinely perform on prostate glands up to 40cc without previously performing a TURP (transurethral resection of the prostate) procedure. Tissue analysis is conducted via radio frequency (RF). An RF signal is sent to a targeted ablation site prior to delivery of HIFU and then another signal is sent after delivery of HIFU to the same site. The device calculates the change that took place and displays it on the screen. Tissue changes are quantified based on a comparison of RF ultrasound pulse-echo signals at each ablation site.

"I believe that we are at a pivotal point in prostate care," said Michael Koch, MD, who was a clinical trial investigator and is chairman of the Department of Urology at Indiana University, said in a statement. "Simultaneous advances in imaging, fusion technologies, and now more focused therapies are going to allow us to precisely diagnose prostate conditions, and ablate these targeted areas rather than perform whole gland prostate surgery, which carries a significant burden on quality of life. HIFU will become the work-horse of subtotal prostate therapy."

The positive decision for Sonablate 450 was preceded by a negative vote from the FDA's Gastroenterology and Urology Devices Panel in October 2014. At this hearing, the panel expressed desires to review further data on the HIFU device. Data reviewed by the FDA and its advisory panel were from the first 100 patients in a 200 patients trial. The mean age of patients in the trial was 69.7 years and the mean pretreatment PSA was 4.9 ng/mL.

In those treated with Sonablate 450 (n = 100), 50% obtained local control of the disease, which was defined as a PSA nadir of 0.5 ng/mL or lower along with a negative biopsy at 12 months (97.06% CI, 0.39-0.61; P = .0206). In those with biopsy results at 12 months (n = 78), the local control rate jumped to 64.1% (97.06% CI, 0.52-076; P = .0001), which passed the bar for significance, which was set at a local control rate of 40%. 

Grade I adverse events (AEs) related to HIFU were seen in 67.2% of participants. Grade 2 AEs were experienced by 81% and grade 3 AEs were seen in 23.3% of patients. The most common all-grade AEs were urinary tract infection (49.1%), incontinence (44.8%), urinary retention (41.4%), and hematuria (40.5%). 

The most common grade ≥3 AEs, at 5.2% each, were stricture, which included urethral stricture and bladder neck contracture, and urinary tract infection. Severe incontinence related to the device was experienced by 3.4% of patients. 

The combined fistula rate was 6.6% and 3 patients experienced osteomyelitis. After retaining on proper management techniques, the fistula rate dropped to 1.7% and there were no cases of osteomyelitis. 

"The FDA's decision on Sonablate is an important step in providing men with prostate conditions access to this less invasive approach," said Neal Kassell, MD, chairman of the Focused Ultrasound Foundation, in a statement. "We hope that focused ultrasound will eventually become a standard of care for treating the prostate." 

Larger studies are attempting to validate the efficacy and safety of Sonablate. Additionally, another HIFU device, Ablatherm, which is marketed by EDAP TMS, is undergoing a phase III clinical trial. Patient recruitment and follow-up phases of the study are now completed, according to the company. The pre-market approval file is currently under review by the FDA.