LBA20 MRI-GUIDED TRANSURETHRAL ULTRASOUND ABLATION (TULSA) IN PATIENTS WITH LOCALIZED PROSTATE CANCER: PRELIMINARY RESULTS OF TACT PIVOTAL STUDY

Abstract

INTRODUCTION AND OBJECTIVES: MRI-guided transurethral ultrasound ablation (TULSA) is a minimally-invasive technology for ablation of benign and malignant prostate tissue. The transurethral device emits directional ultrasound to ablate a volume shaped to patient-specific anatomy using active MRI thermometry feedback control. We report preliminary results from the TULSAPRO Ablation Clinical Trial (TACT) Pivotal study of the safety and efficacy of whole-gland ablation for patients (pts) with localized prostate cancer (PCa). METHODS: TACT intended to enroll 110 pts with biopsyproven organ-confined PCa, aged 45-80, ≤ cT2b, PSA ≤ 15 ng/ml, Gleason Score (GS) ≤ 3+4, across 13 centers in USA, Canada, and Europe. MRI-guided TULSA was delivered with intent of wholegland ablation to the target boundary traced at the prostate capsule. The primary efficacy endpoint was the proportion of pts achieving a PSA reduction ≥ 75%, with secondary endpoints of 12-month (mo) biopsy and prostate volume reduction. The primary safety endpoint was the frequency and severity of adverse events (AE) in the first 12 mo. Secondary quality of life (QoL) endpoints include urinary incontinence (pads), erectile dysfunction (IIEF-5), IIEF-15, IPSS and EPIC-50. RESULTS: TACT enrolled 115 pts from Sep 2016 to Feb 2018. Pre-treatment median (IQR) age was 64 (59-69) years, PSA 6.5 (5.0- 8.3) ng/ml, with 39% GS6 and 61% GS7, 34% low-risk and 66% intermediate- risk (D'Amico). There was no rectal injury or fistula, no urinary incontinence > Grade 1, and no Grade ≥ 4 AE. Serious attributable AEs included 2 pts with urinary retention (catheterization/ antibiotics), 2 UTI and 1 epididymitis (medications/antibiotics), 1 urine extravasation into abdomen (catheterization/drainage), 1 ileus (medication), and 1 DVT (heparin), all resolved. Of the first 100 evaluable pts, median PSA reduction was 93% (nadir 0.44 ng/ml), with 96% of pts (96/ 100) meeting the endpoint of ≥ 75% reduction. The number of pts with 12-mo QoL data is not yet large enough to assess. Treatment time was 55 (41-70) min. Targeted prostate volumes ranged from 15-88 cc with spatial ablation precision 0.1±1.4 mm. Conformal ablation was confirmed qualitatively in all cases by post-treatment contrastenhanced MRI. CONCLUSIONS: Preliminary results of the TACT Pivotal study of MRI-guided TULSA for whole-gland ablation in patients with localized PCa showed that 96% of patients met the primary efficacy criteria of ≥ 75% PSA reduction, and the median PSA reduction was 93% from baseline. There was a high degree of safety and low rate of adverse events.