AUA 2020: Pivotal Trial of MRI-Guided Transurethral Ultrasound Ablation in Men with Localized Prostate Cancer: Two-Year Follow-Up

(UroToday.com) Prostate cancer is the most common non-cutaneous malignancy among men in the western world, with the vast majority of men having clinically localized disease at the time of diagnosis. For patients with low-risk disease, active surveillance is widely accepted. For patients opting for active treatment, currently accepted treatments including radical prostatectomy and radiotherapy provide good cancer control as evidenced by very high 5-year cancer-specific survival. However, each is associated with significant toxicity. Thus, there has been much ongoing work to identify treatments that provide cancer control with a lower toxicity profile. One such approach is prostate ablation. MRI-guided transurethral ultrasound ablation (TULSA) is a novel minimally-invasive procedure for prostate ablation. In a podium presentation at the American Urologic Association Virtual Annual Meeting, Dr. Eggener and colleagues presented the two-year results of the multicenter TULSA-PRO Ablation Clinical Trial (TACT).

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To summarize the methodology, the authors enrolled 115 men with low and intermediate-risk clinically localized prostate cancer: organ-confined prostate cancer (≤T2b, PSA ≤15 ng/ml, Gleason Grade Group 1-2). These patients were accrued and treated at 13 centers in the United States, Europe, and Canada. Patients received whole-gland prostate ablation with sparing of the urethra and urinary sphincter. The primary endpoints were safety and PSA reduction at one year. Secondary endpoints included one-year prostate volume reduction, mpMRI changes, and 10-core biopsy positivity. At two-years, the authors assessed outcomes including adverse events, quality of life (IPSS, IIEF, EPIC), and PSA stability.

Among the 115 patients, median (IQR) age was 65 (59-69) years. Disease characteristics were consistent with intermediate-risk disease in most: median PSA was 6.3 (4.6-7.9) ng/ml, with Grade Group ≥2 (GG2+) disease in 72/115 men (63%). The median ablation zone was 40 (32-50) cc with 98% thermal coverage and ±1.4 mm spatial precision on MRI thermometry. Median treatment time was 51 (39-66) min.

Assessing the primary safety endpoint, the authors found transient grade 3 adverse events in 9 men (8%), all of which resolved by 1 year. There were no rectal injuries or Grade ≥ 4 events.

Assessing secondary endpoints, they found median prostate volume decreased from 37 to 3 cc on MRI at 1 year and GG2 disease was eliminated in 54/68 (79%) men with 72/111 (65%) had no evidence of any cancer. Salvage radical prostatectomy was performed in three men with residual disease on biopsy.

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PSA and quality of life data are immature with available data on 48 of 115 patients. Median PSA decreased 95% to a nadir of 0.30 ng/ml which subsequently rose to a small degree over time (0.53 ng/ml at one year and 0.68 ng/ml at 2 years). Median IPSS was unchanged from 7 to 6 at one year and 5 (n=47) at two years. Moderate urinary incontinence (Grade 2, pads) was reported by 3 patients (2.6%) at one year, with no new incontinence at two years. The rate of moderate erectile dysfunction (Grade 2, responding to PDE5) was 23% at one year, with one new onset at two years. Median change in IIEF-5 recovered from -3 at one year to -1 (n=46) at two years. Erections sufficient for penetration (IIEF Q2 ≥ 2) were maintained by 69/92 (75%) at one year, and for the patient subset with two-year follow-up, by 25/37 (68%) and 23/37 (62%) at one and two years, respectively.

In this two-year follow-up on the TACT trial of MRI-guided transurethral ultrasound ablation (TULSA) in men with localized prostate cancer, the authors have shown the feasibility of this approach as well as its relatively low toxicity and stable quality of life.

Authors: Scott Eggener*, Michael Koch, David Penson, Christian Pavlovich, Joseph Chin, Yair Lotan, Steven Raman, Gencay Hatiboglu, Aytekin Oto, James Relle, Jurgen Fütterer, Marc Serrallach, Axel Heidenreich, Masoom Haider, David Bonekamp, Temel Tirkes, Sandeep Arora, Allan Pantuck, Gregory Zagaja, Michiel Sedelaar, Katarzyna Macura, Daniel Costa, Thorsten Persigehl, Andrei Purysko, and Laurence Klotz

Written by: Christopher J.D. Wallis, Urologic Oncology Fellow, Vanderbilt University Medical Center Contact: @WallisCJD on Twitter at the 2020 American Urological Association (AUA) Annual Meeting, Virtual Experience #AUA20, June 27- 28, 2020
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