FDA grants de novo clearance to Stone Clear device

The FDA has granted de novo clearance to the Stone Clear device, which delivers non-invasive ultrasound pulses to patients to facilitate passage of residual kidney stone fragments post-lithotripsy, SonoMotion announced in a news release.¹

Data on ultrasonic propulsion were published in The Journal of Urology.

Stone Clear is designed to manage kidney stones in the clinic setting without requiring anesthesia.

"Patients with post-lithotripsy residual fragments are more likely to have complications, emergency department visits, or repeat procedures, yet they have no reliable non-invasive option aside from passive observation," said James E. Lingeman, MD, a clinical professor of urology at Indiana University School of Medicine, in the news release.¹ "The Stone Clear device provides patients with a non-invasive option to reduce their residual fragment stone burden in the clinic environment while being fully awake."

Data on the safety and effectiveness of ultrasonic propulsion were recently published in The Journal of Urology.² Overall, the prospective, open-label, randomized, controlled study (NCT02028559) showed that ultrasonic propulsion reduced relapse (defined as stone growth, a stone-related urgent medical visit, or surgery) and added minimal risk in facilitating kidney stone fragment clearance compared with observation.

Data at 5-year follow-up showed that the time to relapse was longer for those in the ultrasonic propulsion arm compared with those in the control arm (P < .003). Specifically, the restricted mean time-to-relapse was 1530 days (± 92 days) for patients in the ultrasonic propulsion arm compared with 1009 days (± 118 days) in the observation arm, translating to a 52% longer restricted average time to relapse with the intervention.

Overall, 8 of 40 patients in the ultrasonic propulsion arm and 21 of 42 patients in the observation arm experienced relapse (HR, 0.30; 95% CI, 0.13-0.68), translating to a 70% lower risk of relapse in the treatment arm. Additionally, 63% of patients (n =24) in the treatment arm and 5% of patients (n = 2) in the control arm visually passed kidney stone fragments within 3 weeks of treatment.

Regarding safety, 63% of patients (n = 25) in the ultrasonic propulsion cohort and 40% of patients (n = 17) in the observation cohort experienced an adverse event (AE) (OR, 2.45; 95% CI, 1.01-5.96). All AEs were mild, transient, and self-resolving, according to the authors.

In total, the study randomly assigned 40 patients to receive treatment with ultrasonic propulsion and 42 patients to undergo observation. To be eligible for enrollment, patients needed to have at least 1 suspected stone remaining following lithotripsy and individual stone fragments of 5 mm or smaller in largest dimension. Additionally, patients need to be at least 4 weeks post-lithotripsy.³

The median follow-up was 3.0 years (IQR, 1.8-3.2). The primary outcome measure was relapse, defined as stone growth, a stone-related urgent medical visit, or surgery by 5 years or study end.

Based on these findings, the authors wrote, “When combined with recent evidence that removal of secondary, small, asymptomatic kidney stones during surgery for a primary stone reduced relapse by 82%, these current data suggest ultrasonic propulsion may be an option to remove small stones or residual fragments, especially when combined with another ultrasound and clinic-based investigational technology, burst wave lithotripsy, to break and expel stones potentially too large to pass asymptomatically.”

Break Wave, SonoMotion’s second solution, is currently undergoing clinicals trials in the United States and Canada.

References

1. Sonomotion announces FDA de novo clearance for its Stone Clear device. News release. SonoMotion, Inc. Published online and accessed November 13, 2024. https://www.prnewswire.com/news-releases/sonomotion-announces-fda-de-novo-clearance-for-its-stone-clear-device-302303764.html

2. Sorenson MD, Dunmire B, Thiel J, et al. Randomized controlled trial of ultrasonic propulsion-facilitated clearance of residual kidney stone fragments vs observation. J Urol. 2024:101097JU0000000000004186. doi:10.1097/JU.0000000000004186

3. Safety and effectiveness of the ultrasonic propulsion of kidney stones. ClinicalTrials.gov. Last updated February 2, 2024. Accessed November 13, 2024. https://clinicaltrials.gov/study/NCT02028559