For decades, the definitive surgical treatment for prostate gland enlargement, or benign prostatic hyperplasia (BPH), has been a procedure called transurethral resection of the prostate (TURP), in which the inside part of the prostate gland is removed surgically via a scope inserted through the urethra. While frequently successful, TURP carries a significant risk of treatment-related complications, ranging from problems with urine control, loss of sperm fertility and erectile dysfunction, to retrograde ejaculation (passing of semen into the bladder rather than through the urethra) and urethral stricture (tightening of the urinary outlet from scar tissue).

Now, an alternative surgical technique called water ablation is among a number of minimally invasive options that are showing promise as alternatives to TURP for the treatment of BPH.

BPH, a common, non-cancerous condition in men over the age of 40, can cause a spectrum of lower urinary tract symptoms (LUTS), including frequent urination, inability to empty the bladder completely, incontinence, bladder stones, and/or painful or bloody urination. The causes of BPH is unknown, although high-fat diets, family history, and hormones have been suggested as risk factors. It is estimated that more than 12 million American men suffer from BPH, and 50 percent of these men struggle with LUTS.

An article first published online in the journal BJU International (formerly the British Journal of Urology), describes the first human study designed to demonstrate the safety and feasibility of a surgical method called Aquablation — a novel minimally invasive water ablation therapy combining image guidance and robotics (AquaBeam) for targeted and heat-free removal of prostatic tissue in men suffering from LUTS secondary to BPH.  The article, titled “Aquablation – Image Guided Robotically-Assisted Waterjet Ablation of the Prostate: Initial Clinical Experience” (x BJU Int. 2015 Oct 19. doi: 10.1111/bju.13358), appeared on Nov. 19, 2015.

The study co-authors, Peter Gilling, Rana Reuther, Arman Kahokehr, and Mark Fraundorfer — all of the Tauranga Hospital Department of Urology at Tauranga, New Zealand — explain that under real-time image-based ultrasonic guidance, AquaBeam technology enables surgical planning and mapping, and leads to a controlled heat-free resection of the prostate using a high-velocity saline stream.

In the prospective, non-randomized, single-center trial in men between the ages of 50 and 80 with moderate-to-severe LUTS, 15 patients were treated with Aquablation under general anesthesia. The mean age was 73 years and the mean prostate size was 54 ml (in a range of 27 to 85 ml). A significant median lobe was present in six of the 15 subjects, the mean International Prostate Symptom Score (IPSS) was 23, and peak urinary flow rate (Qmax) was 8.4 ml/s at baseline.

Time required to conduct the procedure averaged 48 minutes with a mean Aquablation treatment time of eight minutes. The co-authors report that procedures were technically successful, with no serious or unexpected adverse events. All but one patient had removal of the urinary catheter on day one, and the majority of patients were discharged on the first postoperative day. None of the patients required a blood transfusion, post-operative sodium changes were negligible, and no serious 30-day adverse events occurred. One patient underwent a second Aquablation treatment within 90 days of the first procedure.

In terms of results, the subjects’ mean IPSS score statistically improved from 23.1 at baseline to 8.6 at six months, and the Qmax increased from 8.6 ml/sec at baseline to 18.6 ml/sec. Also at six months, mean Pdet@Qmax decreased to 45 cmH2O from 66 cmH2O at baseline, and mean prostate size was reduced to 36 ml, a 31% reduction in size compared to the baseline. Moreover, no cases of urinary incontinence or erectile dysfunction were reported.

The co-authors conclude that based on preliminary results from this initial study, Aquablation of the prostate is technically feasible with a safety profile comparable to other BPH technologies. They also find that the combination of surgical mapping by the operating surgeon and the high-velocity saline constitutes a promising technique for heat-free prostate tissue removal, with advantages including a reduction in resection time compared to other endoscopic modalities as well as the potential to preserve sexual function.

An article published in the Journal of Endourology earlier this year, titled “Image-Guided Robot-Assisted Prostate Ablation Using Water Jet-Hydrodissection: Initial Study of a Novel Technology for Benign Prostatic Hyperplasia” (J Endourol. 2015 Jan;29(1):63-9. doi: 10.1089/end.2014.0304.), evaluated the safety and efficacy of the Aquablation system in a canine model. The researchers, from the University of Southern California Department of Urology at Los Angeles, California, note in their study that the Aquablation technology uses a high-velocity saline stream that aims to selectively ablate prostatic glandular tissue while sparing collagenous structures, such as blood vessels and capsule. Once the ablation is complete, a laser beam is captured by a low-pressure water jet to produce surface hemostasis, with the extent and depth of ablation predetermined by endoscopic and transrectal ultrasonography guidance.

An American Urological Society paper co-authored by researchers Lennart Wagrell and Magnus Tornblom of Sweden’s Uppsala University Department of Urology,  discusses a Convective Water Vapor Energy (WAVE) platform technology called the Rezūm System, which uses radio frequency energy to transform sterile water into stored thermal energy in the form of vapor, or steam. This water vapor is convectively delivered directly into the obstructive prostate tissue that causes BPH, where condensation releases enough thermal energy to gently and immediately denature the targeted prostate tissue cells to cause necrosis. The treated tissue is absorbed by the body’s immune system. Wagrell and Tornblom note that this targeted, rapid and efficient tissue treatment has the advantages of short procedure times and compartmentalization of the treatments to the transition zone. Their study is titled “Transurethral Convective Water Vapor Ablation Therapy for BPH; A Single Center’s Experience Using the Rezm System in an Office-based Setting.”

The study evaluating the Rezūm System, developed by NxThera, Inc., of Maple Grove, Minnesota, as an office-based treatment option for BPH enrolled 27 men who underwent the procedure, with standard outcome measures including IPSS, QOL, Qmax and PVR used. Based on data recorded, the co-authors determined that the treatment can be safely performed in an office setting. Wagrell and Tornblom report that rapid clinical improvement has been promising, with only minimal, transient adverse effects noted, concluding that the Rezūm System may be a promising treatment alternative to other BPH treatment options.

The Rezūm procedure is described by NxThera as “an effective, safe and minimally invasive BPH treatment option that gives urologists the opportunity to offer an office-based or outpatient treatment option that may provide relief to men who are looking for an alternative to currently available BPH treatment offerings.”

NxThera received 510(k) clearance for the Rezūm System in September. In a NxThera release, Dr. Kevin T. McVary, Professor and Chair, Division of Urology at Southern Illinois University School of Medicine, notes that, “The clinical data from the Rezūm II randomized, controlled clinical study demonstrated clinically and statistically significant BPH symptom improvement in as little as two weeks, as well as meaningful improvements in the quality of life for patients. The Rezūm therapy is performed in an office setting without the need for general anesthesia, while demonstrating minimal complications and preserving sexual function.”

“FDA clearance of our Rezūm System to treat BPH is a significant milestone for NxThera and our team of dedicated and passionate employees, and a testament to the vision and commitment of our many clinical advisors, clinical study investigators, investors, and our founder and Chief Technology Officer Michael Hoey,” said J. Robert Paulson, president and CEO of NxThera. “We now will shift our focus to accelerating and expanding access to and adoption of the Rezūm procedure in the U.S. during early 2016, and expanding into key international markets later in the year. We will support this commercial expansion by providing world-class clinical training and education programs to urologists and their practices who are committed to expanding the BPH treatment options they offer to meet the needs of their diagnosed but untreated patients.”

Sources:
U.S. National Library of Medicine
NxThera, Inc.
BJU International
Journal of Endourology
American Urological Society