Targeted microwave ablation shows precision, safety in localized prostate cancer

Initial data from the phase 2 VIOLETTE trial (NCT04582656) suggest that targeted microwave ablation (TMA) using organ-based tracking (OBT) fusion is precise and safe in patients with intermediate-risk prostate cancer.¹

The VIOLETTE trial remains ongoing.

The data were recently published in BJUI Compass, and the study has since reached its target enrollment.

“We are delighted to have completed the enrollment of the VIOLETTE trial. 76 patients with a single focus of prostate cancer visible on MRI were meticulously selected,” said lead author Nicolas Barry-Delongchamps, MD, PhD, in a news release on the findings.² “The Koelis technology not only helped to detect and characterize these tumors but also allowed precise planning for targeted treatment. As we look forward for the final oncologic results, we believe this new image-guided, needle-based technology is deemed to become an efficient and safe management option for selected patients.”

At the time of data report, the trial had enrolled 37 patients with intermediate-risk prostate cancer across 5 clinical trial sites in France and Belgium. The median age of participants was 68 years (IQR, 63-72).

Patients enrolled in the study underwent TMA with either general anesthesia or conscious IV sedation in an outpatient setting. The median duration for anesthesia was 78 minutes. The majority of procedures (70%) were completed transperineally.

According to the authors, “A median number of 3 (2–4) 12-W ablations of 2 to 5 min were performed per patient.”

Median follow-up was 6 months.

In total, there were 58 adverse events (AEs) reported in 22 patients. Of these, 74% were grade 1, 22% were grade 2, and 4% were grade 3. Among all AEs, 32 were considered to be possibly related to treatment. Six patients experienced acute urinary retention, of whom 5 were hospitalized and were thus considered to have severe AEs.

The investigators observed no significant difference between baseline to last follow-up in International Prostate Symptom Score, Male Sexual Health Questionnaire-ejaculatory dysfunction, and International Index of Erectile Function.

At 7 days following the procedure, 36 of 37 evaluable patients (97%) demonstrated visible non-vascularized prostatic tissue on DCE MRI. In these patients, the non-vascularised area was covering more than 100% of the targeted tumor index, with a median IQR value of 6 mL.

Additionally, the median prostate-specific antigen (PSA) density decreased from 0.2 ng/mL at baseline to 0.1 ng/mL at 12-month follow-up.

In the recent news release on the findings, Koelis reported that the final patient (of 76 total) was enrolled in the study in September 2024. The VIOLETTE trial remains ongoing to assess outcomes in the remaining patients. The authors note that further follow-up and inclusions are needed to confirm the initially reported findings.

They wrote, “The evaluation of the primary outcome will be crucial to confirm the relevance of the technique.”

The primary objective for the study is treatment efficacy, as assessed by no evidence of ISUP grade 2 or higher cancer on targeted biopsy at 12-month follow-up. Secondary outcomes include safety, urinary and sexual outcomes, PSA kinetics, and treatment zone shape on MRI at day 7 and months 6 and 12.³

References

1. Delongchamps NB, Peltier A, Potiron E, et al. Targeted microwave ablation of localised prostate cancer: Initial results of VIOLETTE trial. BJUI Compass. 2024.doi:10.1002/bco2.444

2. KOELIS announces the first interim results of the VIOLETTE trial which evaluates the use of OBT-Fusion technology in focal ablation of the prostate by microwave needles. News release. Koelis. November 20, 2024. Accessed November 21, 2024. https://www.globenewswire.com/news-release/2024/11/20/2984493/0/en/KOELIS-announces-the-first-interim-results-of-the-VIOLETTE-trial-which-evaluates-the-use-of-OBT-Fusion-technology-in-focal-ablation-of-the-prostate-by-microwave-needles.html

3. Efficacy assessment of a novel 3D cartography-based targeted focal microwave therapy in men with localized intermediate-risk prostate cancer (VIOLETTE). ClinicalTrials.gov. Last updated August 6, 2021. Accessed November 21, 2024. https://clinicaltrials.gov/study/NCT04582656