Caroline Helwick

November 01, 2017

SAN ANTONIO — "Aquablation," an investigational nonthermal and robotically assisted means of treating benign prostatic hypertrophy (BPH) using a waterjet, has shown advantages over transurethral resection of the prostate (TURP) in a randomized phase 3 study.

"Aquablation provides TURP-like results despite the newness of the procedure in urology," said Christopher Tallman, MD, from Houston Methodist Hospital in Texas. Mohamed Bidair, MD, from San Diego Clinical Trials in California, was the first author of the study, presented here at the Sexual Medicine Society of North America (SMSNA) Fall 2017 Scientific Meeting.

Aquablation therapy (AquaBeam System, PROCEPT BioRobotics) is a robotically controlled high-pressure waterjet that can remove prostate tissue without the application of heat. It involves intraprocedural ultrasound imaging, real-time surgical planning, and robotic execution while the patient is under general anesthesia.

In the phase 3 WATER study, aquablation was compared with the gold standard BPH treatment, TURP, in 181 men aged 45 to 80 years enrolled from 17 sites across four countries. All had moderate to severe lower urinary tract symptoms associated with BPH.

Prostate resection for patients with lower urinary tract symptoms remains the gold standard for surgical treatment of BPH; however, as many as two-thirds of men will suffer from sexual dysfunction after TURP, primarily ejaculatory dysfunction, Dr Tallman noted. The hope is that aquablation may provide better sexual function outcomes.

Noninferiority Trial

The trial had a coprimary safety and efficacy endpoint, with the efficacy endpoint designed as a noninferiority comparison. The primary safety endpoint was the occurrence of Clavien-Dindo grade 1 symptoms (persistent ejaculatory dysfunction, erectile dysfunction, or urinary incontinence) or grade 2 or higher postoperative complications at 3 months. The primary efficacy endpoint was the reduction in International Prostate Symptom Score at 6 months.

Twenty-nine patients (25.0%) treated with aquablation experienced grade 1 or 2 safety issues meeting the primary endpoint compared with 26 patients in the TURP group (40.0%), showing a 15% difference favoring aquablation (noninferiority comparison, P < .001; superiority, P < .02). When counting only grade 1 events, the rates were 6.9% and 24.6%, respectively (difference, 17.7%; P < .001), Dr Tallman reported.

"This was a statistically significant difference favoring aquablation, with the primary safety endpoint more than met," he said.

For the 6-month efficacy data, both treatments demonstrated substantial improvement in symptom scores. In this comparison, aquabation proved noninferior to TURP. However, in a subset analysis that included only patients with larger prostate volumes (50 - 80 mL), superiority in both safety and efficacy (P < .01) was shown, Dr Tallman reported.

Table. Symptom Reduction, Aquablation vs TURP

Change in International Prostate Symptom Score Aquablation TURP
All Patients 50 to 80 mL Volume All Patients 50 to 80 mL Volume
30 days −12.5   −11.1  
90 days −16.0   −14.6  
180 days −16.9 −17.4 −15.1 −13.3

Sexual Parameters Better With Aquablation

Among men who were sexually active at both baseline and after treatment, ejaculatory function was significantly better with aquablation as measured by the Male Sexual Health Questionnaire for Ejaculatory Dysfunction (MSHQ-EjD). Scores increased slightly but not significantly from baseline levels in the Aquablation group (by 0.6 points), but deteriorated (by 1.7 points) in the TURP group (P < .05).

"Our analyses demonstrate that men undergoing aquablation show significantly less impact to ejaculatory function as compared to those undergoing TURP," Dr Tallman said.

Session attendee Ryan Terlecki, MD, from Wake Forest School of Medicine, Winston-Salem, North Carolina, who has treated patients with aquablation, said this finding "raises an eyebrow.... Not only are you saying that ejaculatory function did not get worse, but it got better. How do you explain this?"

"We think this is related to the preservation of the bladder neck and the ejaculatory ducts that are not destroyed.... It's not a difference in depth of penetration around the bladder neck; it's the velocity and high pressure of the saline," Dr Tallman suggested. "But there's really no good explanation. I'd say it's a modest overall improvement."

At 6 months, erectile function, an indication of overall satisfaction for patients, remained stable relative to baseline in the aquablation group but fell in the TURP group (P < .05), indicating superiority of aquablation. The International Index of Erectile Function (IIEF-5), or SHIM questionnaire, which measures the quality of erections, did not significantly change from baseline in either group at 6 months.

Altogether, the researchers determined that aquablation is associated with about four times fewer sexual adverse effects than TURP (P < .001).

Interest and Concerns

Dr Terlecki, who asked about ejaculatory function, also commented that he has seen some excess bleeding with ablation during studies in which he has participated. "These procedures can cause a lot of bleeding in select patients, such that you have to go in with a second modality to rescue them," he said during the discussion. He could not cite a percentage for this complication, "but even with a subset of patients less than 10, it's more than one case."

Session moderator Richard Santucci, MD, from Detroit Medical Center, said a 10% rate of bleeding, as observed by Dr Terlecki (but not reported in this study), may indicate "this is a good procedure that just needs to be changed a bit."

Overall, Dr Santucci told Medscape Medical News, he found the results "absolutely striking.... Basically, once you are set up, the robot moves the water pulse machine at its own speed, and it's only for a couple of seconds. A TURP operation, on the other hand, is about 1 hour," he said. "This is a whole new paradigm: a treatment that takes a few seconds, not 1 hour."

He continued, "This was a noninferiority study that shows it works well" and could take BPH treatment into the future. "We may think, in 10 years, that TURP is like riding a horse to work.

"But remember, it's only been studied to the level where it was shown not to kill anyone. We really don't know enough yet," he cautioned. "My memory is littered with the broken bodies of cool stuff that didn't work in the end".

Dr Tallman, Dr Terlecki, and Dr Santucci have disclosed no relevant financial relationships. The study was not industry supported.

Sexual Medicine Society of North America (SMSNA) Fall 2017 Scientific Meeting: Abstract 194. Presented October 27, 2017.

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