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WASHINGTON -- Results from a long-term follow-up of the pivotal TACT trial showed that MRI-guided transurethral ultrasound ablation (TULSA) was effective and durable in men with localized prostate cancer.

The median prostate-specific antigen (PSA) level at 5 years was 0.63 ng/mL -- a 90% reduction from the median PSA at baseline, reported Scott Eggener, MD, of the University of Chicago, during the Society of Urologic Oncology annual meeting.

Biochemical recurrence-free survival and overall survival rates at 5 years were 86% and 99%, respectively.

"For many men, the results oncologically and functionally are durable," Eggener told 番茄社区app. "Obviously with more time, there are going to be patients who fall off from a cancer standpoint, but the side effect profile is more or less maintained, and there are some patients who required salvage therapy, but that rate was relatively low."

Eggener emphasized that the study evaluated TULSA as whole-gland therapy, "but is now being evaluated, offered, and applied for people with focal therapy."

TULSA uses ultrasound to thermally coagulate tissue under real-time MRI guidance. Feedback from closed-loop MRI thermometry automatically controls treatment parameters to match tissue response in the prescribed ablation volume.

"While the pivotal study represents early experience with TULSA, the risk of failure is mitigated by modern protocols," Eggener and colleagues noted. "Such protocols include best practices for screening for intraprostatic calcifications that can lead to undertreatment, refined strategies for device positioning, and thermal dose escalation to address undertreatment that is visible on intraprocedural imaging."

At 5 years, 92% of patients recovered pad-free continence, and 87% preserved erections sufficient for penetration.

"The continence data from the very beginning has been very strong," Eggener said. As for the erectile function data, he pointed out that while the majority of men maintained their baseline erections, there is a subset of men when TULSA is applied as whole-gland therapy -- as it was in this trial -- who will have new erectile dysfunction requiring medications or other interventions.

"But the key piece for reporting it and for talking to patients is that TULSA is largely being applied as focal therapy now," he pointed out. "So, by definition when it is applied as focal therapy, there is an extraordinarily high likelihood that the rates of erectile dysfunction will be lower than reported for whole-gland therapy."

Eggener said that the ongoing randomized phase III of radical prostatectomy versus focal TULSA, which was informed by TACT, is enrolling.

"Emphasizing that it was whole-gland therapy, the early signs as far as gland decrease and PSA went above and beyond the expectations for our primary endpoint," he added. "Ultimately, where we're going to get the best data is head-to-head against standard of care."

The phase II took place across 13 sites in five countries and included 115 men with organ-confined prostate cancer who underwent a single whole-gland TULSA treatment that spared the prostatic urethra and urinary sphincter.

Results from the study showed effective tissue ablation and PSA reductions, with low rates of toxicity and residual disease.

At baseline, patients' median age was 65, and median PSA was 6.3 ng/mL. Most of the men (72 0f 115) had ≥Grade Group 2 disease. Of the included men, 25 had received salvage treatment: 10 underwent prostatectomy, 11 received radiotherapy, three received androgen deprivation therapy, and one underwent surgery and received radiation, all without unexpected complications.

As for safety, there were no grade ≥4 adverse events (AEs), rectal injury, or fistula. Grade 3 AEs occurred in nine men with resolution before 1 year, and in two men with onset and resolution in the second year, including genitourinary infection, stricture, retention, urethral calculi, pain, urinoma, and lower urinary tract symptoms.

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