Early Magnetic Resonance Imaging Response of the Dominant Intraprostatic Lesion After Online Adaptive Stereotactic Body Radiotherapy for Localized Prostate Cancer and Correlation with Prostate Specific Antigen Response

Recruiting

• Conditions: Prostate Carcinoma; Localized Prostate Adenocarcinoma; Stereotactic Body Radiotherapy; Stereotactic Radiotherapy; Magnetic Resonance Imaging; Multiparametric MRI

• Registration Number: NCT06822491
• Lead Sponsor: University of Zurich

Brief Summary

The aim of this phase II study is to determine the early multiparametric magnetic resonance imaging response of the dominant intraprostatic lesion and correlate these findings with prostate specific antigen response in patients with intermediate to (very) high risk localized prostate cancer treated with online adaptive stereotactic radiotherapy without intraprostatic fiducial markers.

Detailed Description

Background: Stereotactic body radiotherapy (SBRT) is an established standard of care treatment for localized prostate cancer. Recent pathological studies suggest the presence of a dominant intraprostatic lesion (DIL) within the prostate, which serve as a central driver of tumor aggressiveness and recurrence after treatment. Prostate-specific antigen (PSA) monitoring is the cornerstone of follow-up, though time to PSA nadir after SBRT can extend to 3 years.

Methods: This phase II observational study aims to evaluate the correlation between PSA response and early multiparametric magnetic resonance imaging (mpMRI) changes of the DIL(s) at 6- or 9-months following online adaptive SBRT for intermediate to (very) high risk localized prostate cancer. The primary outcome is the achievement of local control as assessed by mpMRI at 6 months post-SBRT or, if necessary, at 9 months post-SBRT (in case of image non complete response at 6 months). A complete imaging response is defined as the disappearance of all morphological and functional mpMRI changes of PIRADS (Prostate Imaging Reporting and Data System) ≥3 lesion(s) correlating with Gleason ≥7a pathology. No confirmatory biopsies will be conducted. The required sample size for this study will be 28 patients, assuming a complete response rate of 80% at 6 months, targeting an acceptable margin of error with 95% confidence, and a margin of error of 15%.

Study Timeline

• Study Start: 2024-08-20
• Status Verified: 2025-02
• Study First Submitted: 2025-02-06
• Study First Submitted QC: 2025-02-06
• Last Update Submitted: 2025-02-06
• Study First Posted: 2025-02-12
• Last Update Posted: 2025-02-12
• Primary Completion: 2026-06
• Study Completion: 2031-06

Recruitment & Eligibility

• Status: RECRUITING
• Sex: Male
• Target Recruitment: 28

Inclusion Criteria

• Patients with histologically confirmed localized prostate cancer who are planned for CT- or MRI-adaptive SBRT for prostate cancer;
• Presence of PIRADS ≥3 lesion(s) in a mpMRI correlating with Gleason ≥7 score at diagnosis;
• Intermediate to (very) high risk localized prostate cancer (≤ cT3b and cN0);
• ECOG performance status of 0-2;
• Age ≥ 18 years;
• PSMA PET ≤3 months is compulsory for high-risk prostate cancer (as part of clinical routine);
• Written informed consent.
• Willingness and ability to comply with schedule

Exclusion Criteria

• Previous (≤10 years) local therapy of the prostate including transurethral resection of the prostate (TURP),
• Contraindication for MRI;
• Previous (≤10 years) radiotherapy in the pelvis;
• Lymph node metastases or distant metastases (i.e. no localized prostate cancer);
• Participation in a clinical trial which might influence the results of this project;
• Claustrophobic anxiety;
• Uncontrolled intercurrent illness;
• Relation to investigator (family or professional)

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Multiparametric magnetic resonance imaging local control of the dominant intraprostatic lesion	6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.	To study multiparametric magnetic resonance imaging (mpMRI) local control of Prostate Imaging Reporting and Data System (PIRADS) ≥3 lesion(s) after SBRT. An image complete response is defined as disappearance of all morphological and functional PIRADS ≥3 lesion(s) correlating with Gleason ≥7a pathology in mpMRI.
Correlation of early prostate-specific antigen response with early multiparametric magnetic resonance imaging changes	6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.	To correlate early prostate-specific antigen response with early multiparametric magnetic resonance imaging changes of the PIRADS ≥3 lesion(s) correlating with Gleason ≥7a pathology

Secondary Outcome Measures

Name	Time	Method
Correlation of late prostate-specific antigen response with early multiparametric magnetic resonance imaging changes	Yearly (up to 5 years post SBRT)	To correlate late prostate-specific antigen response with early multiparametric magnetic resonance imaging changes of the PIRADS ≥3 lesion(s) correlating with Gleason ≥7a pathology
Correlation of genitourinary and gastrointestinal toxicity with early multiparametric magnetic resonance imaging changes	6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.	Correlating genitourinary and/or gastrointestinal toxicity (according to common terminology criteria for adverse events \[CTCAE\] version 5.0) with structural and/or functional changes of the prostate and/or surrounding organs on early multiparametric magnetic resonance imaging
Correlation of prostate quality of life with early multiparametric magnetic resonance imaging changes	6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.	Quality of life (according to EPIC-26) and relation to early structural and/or functional changes of the prostate and/or surrounding organs on multiparametric magnetic resonance imaging
To evaluate prostate volume change during and after adaptive prostate SBRT and to correlate to treatment toxicity.	Intra-treatment (within 1 week before the last fraction of SBRT) and 6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.	To evaluate prostate volume change intra-treatment and after adaptive prostate SBRT and to correlate to treatment toxicity.
Exploratory image analysis	6 months after SBRT. In cases with image non-complete response at 6 months, 3 months later (in total 9 months after SBRT) an additional mpMRI will be performed.	Quantitative imaging features will be used to predict outcome and side effects on the different images.

Trial Locations

Locations (1)

University Hospital Zurich; 🇨🇭 Zurich, Switzerland