The widespread use of prostate specific antigen (PSA) testing had led to an increase in the diagnosis of prostate cancer. Men with low- to intermediate-risk, localized prostate cancer (PCa) have multiple management options including active surveillance or definitive therapy with radiotherapy or radical prostatectomy.1,2 Although these more invasive treatment options have impressive clinical efficacy outcomes, many patients can develop debilitating adverse events (AEs) such as urinary incontinence or impotence that have a significant impact on their quality of life (QoL). Therefore, there is significant research interest in developing effective, yet less invasive, treatment options that will minimize AEs in these patients. One such therapy with accumulating data and research interest is magnetic resonance imaging (MRI)-guided transurethral ultrasound ablation (TULSA). 

MRI-guided TULSA uses a transurethral catheter to precisely apply ultrasound and MRI-guided thermotherapy to ablate cancerous tissue within the prostate gland. It is performed under direct visualization and considered minimally invasive. It is an outpatient procedure, completed within a radiology/MRI unit with minimal recovery time. A temperature algorithm helps control and provide constant feedback during the procedure in order to minimize damage to surrounding tissue and organs. 

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Recently, data on 1-year outcomes from the TULSA PRO Ablation Clinical Trial (TACT) were presented again at the Radiology Society of North America (RSNA) Annual Meeting, of which the original abstract was presented at the May 2019 American Urologic Association (AUA) Annual Meeting.3,4 At 1 year of follow-up, this abstract included the longest-term data to date. 

The study (ClinicalTrials.gov Identifier: NCT02766543) included 115 men with localized PCa who were recruited across 13 centers in 3 countries. Localized prostate cancer was considered (<T2b, PSA < 15 ng/mL and Gleason Grade Group (GGG) 1-2). The median patient age and median PSA was 65 years and 6.3 ng/mL, respectively. 

The goal of treatment was whole-gland ablation with sparing of the urethra and urinary sphincter. Primary end points included frequency and severity of AEs and proportion of men achieving a PSA reduction of at least 75%. Secondary end points included 1-year biopsy results, prostate volume reduction, and QoL measures. 

With respect to safety end points, only 8% of men had grade 3 AEs, which included infections, strictures, urinary retention, and pain. No patients had grade 4 or higher AEs or rectal injuries. Only 1% of patients reported incontinence at 1 year, with 4% reporting an increase in daily leakage and 8% utilizing a pad. At 1 year follow-up, 20% of patients had grade 2 erectile dysfunction and 75% of patients reported being able to maintain erections sufficient for penetration. 

The primary efficacy end point of PSA reduction of at least 75% was met in 96% of patients, with a median PSA reduction of 95%. Median perfused prostate volume decreased from 41 cc to 4 cc. Median treatment delivery time was 51 minutes. Of the 68 patients with pretreatment GGG2 on biopsy, 79% of patients were free of GGG2 on their 1-year biopsy.  A total of 111 patients had 1-year biopsy data, of which 65% had no evidence of cancer. 

The authors concluded that MRI-guided TULSA was both safe and effective in patients with localized PCa. This data is in line with the previous, smaller phase 1 study.1 It will be interesting to see if additional safety data are available from this TULSA PRO study, especially any data on grade 1 and grade 2 AEs. In addition, future studies could aim to directly compare both the safety and efficacy of MRI-TULSA to other PCa treatment options. This could lead to the increased incorporation of MRI-TULSA into treatment protocols in the future. It is important to note that access to this technology and physicians with the appropriate training along with insurance coverage could be potential challenges in the future. 

Disclosure: The study being discussed was funded by Profound Medical.

References

1. Chin JL, Billia M, and Roethke MC, et al. Magnetic resonance imaging-guided transurethral ultrasound ablation of prostate tissue in Patients with localized prostate cancer: a prospective phase 1 clinical trial. Eur Urol. 2016;70(3):447-455.

2. Hatiboglu G, Popeneciu V, Bonekamp D, et al. Magnetic resonance imaging-guided transurethral ultrasound ablation of prostate tissue in patients with localized prostate cancer: single-center evaluation of 6-month treatment safety and functional outcomes of intensified treatment parameters [published online May 6, 2019]. World J Urol. doi: 10.1007/s00345-019-02784-w

3. Eggener SE. Pivotal trial of MRI-guided transurethral ultrasound ablation in men with localized prostate cancer. Presented at: American Urological Association’s (AUA) 2019 Annual Meeting; May 3–6, 2019; Chicago, IL. Abstract LBA-26. 

4. Eggener SE et al. Pivotal trial of MRI-guided transurethral ultrasound ablation in men with localized prostate cancer. Presented at: 105th Scientific Assembly and Annual Meeting of the Radiology Society of North America Annual Meeting (RSNA) 2019; December 2, 2019; Chicago, IL. Abstract SSC07-07. 

This article originally appeared on Cancer Therapy Advisor