Curative-intent Metastasis-directed Therapies for Molecularly-defined Oligorecurrent Prostate Cancer: A Prospective Phase II Trial Testing the Oligometastasis Hypothesis.

The hypothesis of a curable oligometastatic prostate cancer (PCa) state remains to be clinically-proven. Conventional imaging often fails to localize early recurrences, hampering the potential for radical approaches.

We hypothesize that prostate-specific membrane antigen (PSMA)-targeted PET-MR/CT allows for earlier detection and localization of oligorecurrent-PCa, unveiling a molecularly-defined state amenable to curative-intent metastasis-directed treatment (MDT).

Single-institution single-arm phase-two study. Patients with rising PSA (0.4-3.0 ng/mL) after maximal local therapy (radical prostatectomy and post-operative radiotherapy), negative conventional staging, and no prior salvage hormonal therapy (HT) were eligible.

All patients underwent [18F]DCFPyL PET-MR/CT. Patients with molecularly-defined oligorecurrent-PCa had MDT (stereotactic ablative body radiotherapy [SABR] or surgery) without HT.

Primary endpoint was biochemical response (complete, i.e. biochemical 'no evidence of disease' [bNED], or partial response [100% or ≥50% PSA decline from baseline, respectively]) after MDT. Simon's two-stage design was employed (null and alternate hypotheses <5% and >20% response rate, respectively), with α and β of 0.1.

Seventy-two patients were enrolled (May/2017-July/2019). Thirty-eight (53%) had PSMA-detected oligorecurrent-PCa amenable for MDT. Thirty-seven (51%) agreed to MDT: 10 and 27 underwent surgery and SABR, respectively. Median follow-up was 15.9 months (IQR 9.8-19.1). Of patients receiving MDT, the overall response rate was 60%, including 22% rendered bNED. One (2.7%) grade 3 toxicity (intra-operative ureteric injury) was observed.

PSMA-defined oligorecurrent-PCa can be rendered bNED, a necessary step towards cure, in 1 of 5 patients receiving MDT alone. Randomized trials are justified to determine if MDT +/- systemic agents can expand the curative therapeutic armamentarium for PCa.

We studied men treated for prostate cancer with rising PSA. We found PSMA imaging detected recurrent cancer in three-quarters of patients, and targeted treatment to these areas significantly decreased PSA in half of patients.

European urology. 2021 Mar 05 [Epub ahead of print]

Rachel M Glicksman, Ur Metser, Douglass Vines, John Valliant, Zhihui Liu, Peter W Chung, Robert G Bristow, Antonio Finelli, Robert Hamilton, Neil E Fleshner, Nathan Perlis, Alexandre R Zlotta, David Green, Andrew Bayley, Joelle Helou, Srinivas Raman, Girish Kulkarni, Charles Catton, Tony Lam, Rosanna Chan, Padraig Warde, Mary Gospodarowicz, David A Jaffray, Alejandro Berlin

University of Toronto, Department of Radiation Oncology, 149 College Street, Unit 504, Toronto, Ontario, M5T 1P5, Canada., Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, 263 McCaul Street, 4th floor, Toronto, Ontario, M5T 1W7, Canada., University of Toronto, Department of Radiation Oncology, 149 College Street, Unit 504, Toronto, Ontario, M5T 1P5, Canada; Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, 700 University Avenue, 7th floor, Toronto, Ontario, M5G 1Z5, Canada., Centre for Probe Development and Commercialization, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, Canada., Department of Biostatistics, Princess Margaret Cancer Centre, University Health Network, 610 University Avenue, Toronto, Ontario, M5G 2M9, Canada; Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, M5T 3M7, Canada., Manchester Cancer Research Centre, University of Manchester, 555 Wilmslow Road, Manchester, M20 4GJ, United Kingdom., Department of Surgical Oncology, Division of Urology, University Health Network, University of Toronto, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada., University of Toronto, Department of Radiation Oncology, 149 College Street, Unit 504, Toronto, Ontario, M5T 1P5, Canada; Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, 700 University Avenue, 7th floor, Toronto, Ontario, M5G 1Z5, Canada; TECHNA Institute, University Health Network, University of Toronto, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada., Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, 700 University Avenue, 7th floor, Toronto, Ontario, M5G 1Z5, Canada., TECHNA Institute, University Health Network, University of Toronto, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada; Divisions of Radiation Oncology and Diagnostic Radiology, MD Anderson Cancer Centre, 1515 Holcombe Boulevard, Houston, Texas, 77030, United States., University of Toronto, Department of Radiation Oncology, 149 College Street, Unit 504, Toronto, Ontario, M5T 1P5, Canada; Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, 700 University Avenue, 7th floor, Toronto, Ontario, M5G 1Z5, Canada; TECHNA Institute, University Health Network, University of Toronto, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada. Electronic address: .

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