MRI-guided focused ultrasound focal therapy for patients with intermediate-risk prostate cancer: a phase 2b, multicentre study.

Background: Men with grade group 2 or 3 prostate cancer are often considered ineligible for active surveillance; some patients with grade group 2 prostate cancer who are managed with active surveillance will have early disease progression requiring radical therapy. This study aimed to investigate whether MRI-guided focused ultrasound focal therapy can safely reduce treatment burden for patients with localised grade group 2 or 3 intermediate-risk prostate cancer.
Methods: In this single-arm, multicentre, phase 2b study conducted at eight health-care centres in the USA, we recruited men aged 50 years and older with unilateral, MRI-visible, primary, intermediate-risk, previously untreated prostate adenocarcinoma (prostate-specific antigen ≤20 ng/mL, grade group 2 or 3; tumour classification ≤T2) confirmed on combined biopsy (combining MRI-targeted and systematic biopsies). MRI-guided focused ultrasound energy, sequentially titrated to temperatures sufficient for tissue ablation (about 60-70°C), was delivered to the index lesion and a planned margin of 5 mm or more of normal tissue, using real-time magnetic resonance thermometry for intraoperative monitoring. Co-primary outcomes were oncological outcomes (absence of grade group 2 and higher cancer in the treated area at 6-month and 24-month combined biopsy; when 24-month biopsy data were not available and grade group 2 or higher cancer had occurred in the treated area at 6 months, the 6-month biopsy results were included in the final analysis) and safety (adverse events up to 24 months) in all patients enrolled in the study. This study is registered with ClinicalTrials.gov, NCT01657942, and is no longer recruiting.
Findings: Between May 4, 2017, and Dec 21, 2018, we assessed 194 patients for eligibility and treated 101 patients with MRI-guided focused ultrasound. Median age was 63 years (IQR 58-67) and median concentration of prostate-specific antigen was 5·7 ng/mL (IQR 4·2-7·5). Most cancers were grade group 2 (79 [78%] of 101). At 24 months, 78 (88% [95% CI 79-94]) of 89 men had no evidence of grade group 2 or higher prostate cancer in the treated area. No grade 4 or grade 5 treatment-related adverse events were reported, and only one grade 3 adverse event (urinary tract infection) was reported. There were no treatment-related deaths.
Interpretation: 24-month biopsy outcomes show that MRI-guided focused ultrasound focal therapy is safe and effectively treats grade group 2 or 3 prostate cancer. These results support focal therapy for select patients and its use in comparative trials to determine if a tissue-preserving approach is effective in delaying or eliminating the need for radical whole-gland treatment in the long term.
Funding: Insightec and the National Cancer Institute.
Competing Interests: Declaration of interests BE attends the medical advisory board of Insightec as an unpaid consultant, and has previously received consulting funds from Myriad Genetics. CMT reports consulting funds from Profound. DDS reports consulting funds from OPKO Health and Steba. ASK is on the medical advisory board of Insightec, Profound, and Janssen, and has received consulting funds from Advantagene DSMC, Bristol Myers Squibb, Merck, Bayer, and General Electric. Q-DT reports consulting funds from Astellas, Bayer, Intuitive Surgical, and Janssen. JCD is the Chief Clinical Officer for Ajax Health and Cordis Accelco and has equity interests in Cordis; is on the advisory board and has ownership or equity interests in Serpex Health and Adient Medical; and serves as the past chair of the Society of Interventional Radiology Foundation. OA has ownership or equity interests in Ezra AI. AJV is named on a patent for a statistical method to detect prostate cancer that has been commercialised by OPKO Health (from which he receives royalties and stock options) and has received consulting funds from Insightec and Steba. PTS is named on a patent for a statistical method to detect prostate cancer that has been commercialised by OPKO Health (from which he receives royalties and stock options) and chairs the medical advisory board of Insightec as an unpaid consultant. DS is the medical director and founder of Sperling Prostate Center, a private facility for prostate cancer treatment in Delray Beach, FL, USA. LAM has collaborative and research agreements with Philips Healthcare and Biobot Surgical. GAS is on the medical advisory board of miR Scientific. PG is on the medical advisory boards of Insightec and SonALASense and has ownership or equity interests in SonALASense. All other authors declare no competing interests.
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