Final results from the pivotal PRESERVE trial have been published in European Urology, demonstrating that irreversible electroporation (IRE) with the NanoKnife System is a safe and effective method for prostate tissue ablation in patients with intermediate-risk prostate cancer. The FDA granted the NanoKnife System 510(k) clearance in December 2024 based on these findings.
Trial Results Meet Primary Endpoints
The prospective, single-arm PRESERVE trial enrolled 121 adult patients with intermediate-risk prostate cancer across 17 clinical trial sites in the US. The trial met its primary endpoint by demonstrating a negative in-field biopsy rate of 71% (95% CI, 62 to 79) at 12 months. When excluding patients without 12-month biopsy data, 80% (95% CI, 72 to 87) had a negative in-field biopsy at 12 months. The negative in-field biopsy rate per Delphi consensus criterion was 84% (95% CI, 76 to 90).
The negative out-of-field biopsy rate was 64% (95% CI, 54 to 73) at 12 months. At baseline, the median prostate-specific antigen (PSA) level was 5.8 ng/mL. At 12 months following the procedure, the median decrease in PSA level was 3.4 ng/mL, with 95% of patients experiencing a PSA reduction by 12-month follow-up.
Quality of Life Preservation
The study demonstrated strong preservation of urinary and sexual function. From baseline to 12 months, the mean change in urinary function was 3 per the University of California Los Angeles Expanded Prostate Cancer Index Composite (UCLA-EPIC) urinary domain total score and −2 per the International Prostate Symptom Score (IPSS) total symptom score.
According to the authors, "The mean UCLA-EPIC urinary domain total score improved significantly by 6 months after the procedure, and the total IPSS improved significantly by 3 months." Improvements in urinary function were maintained through 12 months, with 96% of patients who were pad free at study entry remaining pad free at 12 months following the procedure.
Regarding sexual function, data showed that erectile function declined overall but approached baseline by 12 months. "At 12 [months], 84% of patients with good baseline sexual function maintained erections sufficient for penetration," the authors reported.
Safety Profile
The treatment demonstrated a favorable safety profile, with 86% of patients experiencing an adverse event (AE), most being grade 1 to 2. The most common AEs included hematuria (44%), erectile dysfunction (18%), dysuria (16%), urinary retention (15%), micturition urgency (14%), pollakiuria (12%), and hematospermia (12%).
AEs of grade 3 or higher were reported in 12% of patients (n = 14), with procedure-related grade 3 AEs occurring in only 3 patients.
Study Design and Patient Population
To be eligible for enrollment, patients needed to be at least 50 years of age with histologically confirmed organ-confined prostate cancer staged ≤T2c and at least a 10-year life expectancy. Patients also had to have a Gleason score of 3+4 or 4+3 and a PSA level of 15 ng/mL or lower or a PSA density lower than 0.15 ng/mL². Additionally, patients could not have evidence of extraprostatic extension or seminal vesicle invasion by mpMRI.
For the study, all patients received IRE of the prostate with high voltage (2-3 kV) pulses lasting up to 100 microseconds through 2 to 6 monopolar probes. The primary efficacy endpoint was the rate of negative in-field biopsy at 12 months, and the primary safety endpoint was the incidence of AEs through 12 months.
Clinical Significance
"The publication of the PRESERVE study in European Urology provides strong supporting evidence for the use of Irreversible Electroporation as a focal therapy in prostate treatment," said Juan Carlos Serna, AngioDynamics Senior Vice President of Scientific and Clinical Affairs. "This is an important milestone for patients and providers seeking new options beyond traditional whole-gland therapies. These results reinforce the NanoKnife System's role in helping patients receive effective treatment while preserving quality of life, particularly urinary and sexual function, which are often impacted by conventional treatments."
The NanoKnife System uses a non-thermal technique called irreversible electroporation to ablate targeted prostate tissue while sparing critical structures. Unlike thermal ablation, IRE avoids damaging critical structures, helping preserve urinary and sexual function.
Overall, the authors concluded, "The promising short-term oncological outcomes of the study provide supporting evidence for IRE as a viable treatment for select cases of localized [prostate cancer]."
