The phase 2 VIOLETTE trial (NCT04582656) evaluating organ-based tracking fusion (OBT-Fusion) technology in focal ablation of the prostate using microwave needles has completed enrollment and released interim results, according to Koelis, the technology's developer. The findings suggest a potential for precise and safe management of localized, intermediate-risk prostate cancer.
The VIOLETTE trial utilized the Koelis Trinity® fusion imaging system, which creates a 3D map of the prostate and records identified lesions using OBT-Fusion technology. Researchers assessed the system's effectiveness in targeted microwave ablation.
Key Findings from the Interim Analysis
Interim results from the first 37 patients showed that ablation covered over 100% of the tumor in treated individuals. Dynamic contrast-enhanced MRI (DCE-MRI) revealed non-vascularized prostatic tissue in 97% of patients seven days post-procedure. The median pain level reported was 0/10 on a visual analog scale two hours after the procedure, and all treated patients recovered spontaneous micturition and were discharged on the same day. Furthermore, a stable decrease in prostate-specific antigen (PSA) and PSA density was observed after a one-month follow-up.
Safety and Adverse Events
The trial reported no significant impact on urinary or sexual function. Among the 37 patients, 58 adverse events (AEs) were observed in 22 patients, with 5 being classified as severe. However, all severe AEs resolved by the time of the analysis.
Trial Design and Patient Eligibility
The VIOLETTE trial enrolled 76 patients across multiple centers in France. To be eligible, patients were required to be between 45 and 76 years old with a life expectancy exceeding 10 years, have intermediate-risk prostate cancer (T1c or T2a clinical stage, Gleason score of 3+4), and a PSA level below 20 ng/mL. Exclusion criteria included prior prostate surgery, radiotherapy, pelvic trauma, acute prostatitis, cancer within the past 5 years, active hormonal manipulation or androgen supplements, severe benign prostatic hyperplasia (BPH)-related urinary tract symptoms, and a tumor's largest axis exceeding 12 mm on MRI.
The procedure involved targeted ablation of the index tumor with microwaves, administered either transperineally or transrectally. The primary outcome was the proportion of patients showing no evidence of cancer on targeted biopsy. Secondary outcomes included the proportion requiring radical salvage treatment, time to radical salvage treatment, the proportion with any cancer in the untreated area, the proportion undergoing treatment for cancer in the untreated area, and urine flow.
Expert Commentary
Professor Barry-Delongchamps, the principal investigator of the VIOLETTE trial from Cochin Hospital, stated, "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."
Antoine Leroy, PhD, founder and CEO of Koelis, added, "Prostate care is undergoing a profound shift globally. At Koelis, we believe precision imaging can transform the lives of millions of patients. As we work to become the preferred partner for urologists worldwide, we are proud that the VIOLETTE trial demonstrates Koelis’ leading role in enabling focal therapy for prostate cancer."
