Convective transurethral therapy reduces LUTS

New Orleans-A handheld transurethral therapy that delivers targeted sterile water vapor reduces lower urinary tract symptom severity in patients with BPH with no impact on sexual function. 

Dr. McVaryThe improvement in symptoms was durable and accompanied by an improvement in flow rate, reported first author Kevin T. McVary, MD, at the AUA annual meeting in New Orleans. 

He described the results of the use of the Rezum system (NxThera, Inc.) in a pivotal single-blind study of 197 men with BPH who were randomized 2:1 to treatment with the Rezum system or a control arm. NxThera announced in early September 2015 that the FDA granted 510(k) clearance for the device.

The Rezum system consists of a handheld device delivering energy (vapor) through a deployable needle at the tip, and a generator, said Dr. McVary, professor and chair of urology, Southern Illinois University School of Medicine, Springfield. Radiofrequency energy and sterile water are transferred from the generator into the hand piece, where the water is converted to steam, which is transferred down the beak to a retractable meter needle.

“As you increase the temperature, you have a small increase in thermal energy contained within the water, but when there’s a phase change, there's a dramatic increase in the energy carried as it converts from water to vapor,” he said. “When you convert back from vapor to water [condensation], that energy’s released. When it’s released into tissues, any tissue above 70 degrees is immediately and irreversibly going to die.”

In the procedure, vapor is injected into the transition zone, and the vapor intercalates throughout the transition zone tissues confined within the prostatic pseudocapsule of the transition zone, resulting in cell death within 9 seconds.

Convective energy, rather than conductive energy, is used.

“With conductive energy, there is a non-uniform kill zone near to the conductive source, while as you get further from the heat source, there is not as much,” he said.

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The study was conducted at 15 sites and included 197 men with symptomatic BPH, an International Prostate Symptom Score (IPSS) score ≥13, peak urinary flow rate (Qmax) ≥5 mL/sec to ≤15 mL/sec, with minimum voided volume ≥125 mL, and a prostate volume >30 but <80 cc. Middle lobes were included if encountered. The sham control had a robust mimicry, with the Rezum device operated external to the patient to mimic system sounds.

The blinding was effective; at the 3-month follow-up visit, 55.7% of the control subjects guessed incorrectly or didn’t know the arm to which they were randomized.

The median age of the cohort was 62.9 years and the median prostate volume was 45.4 cc. The mean IPSS was 21.9 and the mean Qmax was 10.1 mL/sec.

Ninety percent of patients required oral sedation only. The average treatment time was 5.3 minutes. About one-third (31.1%) of patients had a middle lobe.

NEXT: Improvement seen at 3 months post-treatment

Improvement seen at 3 months post-treatment

An improvement in lower urinary tract symptoms, as measured by the change in IPSS, occurred in the treatment arm compared with the control arm at 3 months post-treatment. The mean IPSS decreased from 22.0 at baseline to 10.7 at 3 months in the treatment arm, for a change of 11.3, compared with a reduction from 21.9 to 17.5 in the control arm, for a change of 4.3. The difference between the two groups in the change in IPSS was significant (p<.0001). The response in the treatment “looks to be durable for about a year at the study end,” said Dr. McVary.

A substantial improvement in Qmax was also observed in the treatment arm compared with controls. At 3 months, Qmax was 16.1 mL/sec in the active treatment group, an improvement of 6.2 mL/sec from baseline, and 10.8 mL/sec in the controls, an improvement of only 0.5 mL/sec from baseline.

The rate of the primary composite safety endpoints consisting of rectal injury, formation of fistula, or retention was ≤12% at 3 months, which met the primary safety endpoint. There was one only one patient with a serious adverse event, a patient with prolonged retention.

Patients with a middle lobe responded to treatment similarly as the entire cohort on the IPSS and Qmax endpoints.

Measurement of ejaculatory function and ejaculatory bother showed essentially no difference between the treatment and control arms. Changes in erectile function were similar between the two arms in all baseline erectile dysfunction conditions (severe, moderate, mild, or none).

Dr. McVary is a consultant/adviser and investigator for NxThera, Inc., which provided funding for the study. Several of Dr. McVary’s co-authors are also consultant/advisers for NxThera.

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