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Abstract
Introduction The oligometastatic (OM) disease hypothesis of an intermediate metastatic state with limited distant disease deposits amenable for curative therapies remains debatable. Over a third of prostate cancer (PCa) patients treated with radical prostatectomy and postoperative radiotherapy experience disease recurrence; these patients are considered incurable by current standards. Often the recurrence cannot be localised by conventional imaging (CT and bone scan). Combined anatomical imaging with CT and/or MR with positron emission tomography (PET) using a novel second-generation prostate-specific membrane antigen (PSMA) probe, [18F]DCFPyL, is a promising imaging modality to unveil disease deposits in these patients. A new and earlier molecularly defined oligorecurrent (OR) state may be amenable to focal-targeted ablative curative-intent therapies, such as stereotactic ablative radiotherapy (SABR) or surgery, thereby significantly delaying or completely avoiding the need for palliative therapies in men with recurrent PCa after maximal local treatments.
Methods and analysis This ongoing single-institution phase II study will enrol up to 75 patients total, to include up to 37 patients with response-evaluable disease, who have rising prostate-specific antigen (range 0.4–3.0 ng/mL) following maximal local therapies with no evidence of disease on conventional imaging. These patients will undergo [18F]DCFPyL PET-MR/CT imaging to detect disease deposits, which will then be treated with SABR or surgery. The primary endpoints are performance of [18F]DCFPyL PET-MR/CT, and treatment response rates following SABR or surgery. Demographics and disease characteristics will be summarised and analysed descriptively. Response rates will be described with waterfall plots and proportions.
Ethics and dissemination Ethics approval was obtained from the institutional Research Ethics Board. All patients will provide written informed consent. [18F]DCFPyL has approval from Health Canada. The results of the study will be disseminated by the principal investigator. Patients will not be identifiable as individuals in any publication or presentation of this study.
Trial registration numbers NCT03160794
- radiation oncology
- radiation oncology
- radiology & imaging
- prostate disease
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Footnotes
Twitter @r_glicksman, @aleberlin2
Contributors Initial draft of the protocol and critical review of the manuscript: RMG, UR, JV, PWC, NEF, RGB, DG, AF, RH, TS, DH, CC, MG, PW, AB, SB, DV, DAJ and AB. Initial draft of the manuscript: RMG and AB. All authors read and approved the final manuscript.
Funding This work was supported by: (1) Terry Fox Canadian Comprehensive Cancer Centre Network (TF4CN) Pilot Project, Terry Fox Research Institute (TFRI); (2) Abbvie CARO Uro-Oncologic Radiation Awards (ACURA); (3) Astellas Prostate Cancer Innovation Fund, University of Toronto and (4) The Princess Margaret Cancer Foundation. The funding bodies have no role in study design, collection, management, analysis, interpretation of data, writing the manuscript or decision to submit the report for publication.
Competing interests UM declares a competing interest with Point Biopharm Inc. as a consultant.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting or dissemination plans of this research.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.