Prostate Specific Membrane Antigen (PSMA) Imaging for Detection of Residual and Metastatic Prostate Cancer

May 11, 2026 updated by: Washington University School of Medicine

Optimizing PSMA Imaging for Enhanced Detection of Residual and Metastatic Prostate Cancer in Low PSA Recurrence (OPERA) Study

This is a randomized, open-label, pilot study assessing the impact of a short course of bicalutamide on PSMA expression in patients with prostate cancer belonging to the intermediate unfavorable or high risk group, who have low levels of PSA. Adult patients with biochemically recurrent prostate cancer (BCR PCa) who have a PSA of less than 1.0 ng/mL and who have undergone complete prostatectomy and/or will be undergoing radiotherapy, in combination with standard of care bicalutamide, will be recruited to this study. Patients will be randomized in a 1:1 ratio into Group A (baseline PSMA PET/CT only with bicalutamide standard of care) or Group B (baseline PSMA PET/CT and an additional PSMA PET/CT after 2 weeks of bicalutamide).

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

20

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Vikas Prasad, MD, PhD
  • Phone Number: 314-632-2812
  • Email: pvikas@wustl.edu

Study Locations

  • United States
    • Missouri
      • St Louis, Missouri, United States, 63110
        • Washington University School of Medicine
        • Principal Investigator:
          • Vikas Prasad, MD, PhD
        • Contact:
        • Sub-Investigator:
          • Farrokh Dehdashti, MD
        • Sub-Investigator:
          • Jeff Michalski, MD
        • Sub-Investigator:
          • Jingqin (Rosy) Luo, PhD
        • Sub-Investigator:
          • Jade Tao, PhD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Histologically or cytologically confirmed biochemically recurrent prostate cancer, with original diagnosis no more than 2 years from date of consent.
  • Intermediate unfavorable or high-risk prostate cancer.
  • All patients under consideration for radiation therapy, either at the time of first recurrence or in salvage radiation therapy will be included.
  • Patients who have started bicalutamide up to a maximum of 3 days prior to randomization will be allowed to be on protocol. Otherwise, a washout period of at least 42 days will be required.
  • Biological males, at least 18 years of age.
  • Prostate specific antigen (PSA) < 1.0 ng/mL.
  • Agreement to adhere to Lifestyle Considerations throughout study duration
  • Ability to understand and willingness to sign an IRB approved written informed consent document.

Exclusion Criteria:

  • Patients currently on androgen deprivation therapy (ADTs).
  • Currently receiving any other investigational agents.
  • A history of allergic reactions attributed to compounds of similar chemical or biologic composition to POSLUMA, furosemide, bicalutamide, or other agents used in the study.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Group A: Baseline PSMA PET/CT only with standard of care bicalutamide

Patients will undergo baseline PSMA PET/CT (PET1) with 18F-rhPSMA-7.3 (F-18 flotufolastat, Posluma). After the 18F-rhPSMA-7.3 injection, patients will undergo research imaging consisting of 5 minutes of PET imaging, followed by routine imaging at 60 minutes after 18F-rhPSMA-7.3 injection. Patients will have blood collected for PROSTest and PSA within 1 day of completion of PET1.

Following PET1, patients will initiate standard of care bicalutamide for a minimum of 14 days, with the first dose taken the day after PET1. Patients will undergo a 90 day follow-up visit (relative to PET1) for collection of blood for PROSTest and PSA.
Drug: Bicalutamide
Bicalutamide is a non-steroidal androgen receptor inhibitor administered as a once a day pill taken orally. This is given as standard of care.
Other Names:
  • Casodex
Device: Prostate-specific membrane antigen Positron Emission Tomography-Computed Tomography
Patients will undergo prostate-specific membrane antigen Positron Emission Tomography-Computed Tomography (PSMA PET-CT) imaging. Each PSMA PET-CT session will consist of 5 minutes of dynamic imaging conducted via the Biograph Vision Quadra PET-CT, a whole-body PET-CT scanner.
Other Names:
  • PSMA PET-CT
Drug: 18F-rhPSMA-7.3
Radioactive diagnostic agent for intravenous use.
Other Names:
  • Polsuma
  • Flotufolastat F-18
Diagnostic test: PROSTest
PROSTest is a novel, blood-based qPCR assay that assesses gene expression to diagnose PCa and predict patient outcomes to different treatments.
Experimental: Group B: PSMA PET/CT after 2 weeks of standard of care bicalutamide

Patients will undergo baseline PSMA PET/CT (PET1) with 18F-rhPSMA-7.3 (F-18 flotufolastat, Posluma). After the 18F-rhPSMA-7.3 injection, patients will undergo research imaging consisting of 5 minutes of PET imaging, followed by routine imaging at 60 minutes after 18F-rhPSMA-7.3 injection.

Patients will have blood collected for PROSTest and PSA within 1 day of completion of PET1. Following PET1, patients will initiate standard of care bicalutamide for a minimum of 14 days, with the first dose taken the day after PET1 and will undergo a research PSMA PET/CT (PET2) on Day 14 (±3 days). The research PSMA PET/CT (PET2) will follow the same imaging procedures as the baseline PET. Patients will undergo a 90 day follow-up visit (relative to PET1) for collection of blood for PROSTest and PSA.
Drug: Bicalutamide
Bicalutamide is a non-steroidal androgen receptor inhibitor administered as a once a day pill taken orally. This is given as standard of care.
Other Names:
  • Casodex
Device: Prostate-specific membrane antigen Positron Emission Tomography-Computed Tomography
Patients will undergo prostate-specific membrane antigen Positron Emission Tomography-Computed Tomography (PSMA PET-CT) imaging. Each PSMA PET-CT session will consist of 5 minutes of dynamic imaging conducted via the Biograph Vision Quadra PET-CT, a whole-body PET-CT scanner.
Other Names:
  • PSMA PET-CT
Drug: 18F-rhPSMA-7.3
Radioactive diagnostic agent for intravenous use.
Other Names:
  • Polsuma
  • Flotufolastat F-18
Diagnostic test: PROSTest
PROSTest is a novel, blood-based qPCR assay that assesses gene expression to diagnose PCa and predict patient outcomes to different treatments.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Group B only: Lesion detection rates between PET1 and PET2.
Time Frame: Baseline and 14 days after start of bicalutamide treatment (total estimated time 14 days)
Differences in lesion detection rates between Group B PET1 and PET2 will be analyzed by McNemar's test. Lesion detection rates will be reported by Group B patients at PET1 and PET2 scans and by the two scan sets (first 5 minutes and at 60 minutes post 18F-rhPSMA-7.3 injection).
Baseline and 14 days after start of bicalutamide treatment (total estimated time 14 days)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Group A and B: Number of lesions detected on early scan versus delayed scan
Time Frame: At baseline and 14 days after start of bicalutamid treatment (total estimated time is 14 days)
The total number of lesions detected per patient will be summarized as counts. The number of lesions will be summarized by descriptive statistics for all patients at PET1, Group A patients at PET1, Group B patients at PET1, and Group B patients at PET2 and for each, by the two scan sets (early scan = first 5 minutes and at delayed scan = 60 minutes post 18F-rhPSMA-7.3 injection).
At baseline and 14 days after start of bicalutamid treatment (total estimated time is 14 days)
Group A and B: Correlation between PSA response and PROSTest after radiation therapy
Time Frame: Through day 90
The correlation between PSA response and PROSTest after radiation therapy will be analyzed in Group A versus Group B. The results will be reported as a two-sample t-test or Wilcoxon sum rank test.
Through day 90
Group A and B: Comparison of PSA response in patients who are treated with radiation vs. those treated with radiation
Time Frame: Through day 90
The comparison of PSA response will be analyzed in patients who are treated with radiation based on results of the PET2 versus those treated with radiation based on the results of PET1. The comparison will be reported as the results of a two-sample t-test or Wilcoxon sum rank test.
Through day 90
Group B only: Correlation between PSA kinetics and detection rates between PET1 and PET2
Time Frame: Through day 90
The correlation between PSA kinetics and detection rates will be reported as the results of a two sample t-test or Wilcoxon sum rank test for each timepoint, PET1 and PET2.
Through day 90
Group B only: Correlation between PROSTest results and detection rates of PET1 and PET2
Time Frame: 14 days after start of bicalutamide treatment (total estimated time 14 days)
Correlation between PROSTest results and detection rates of PET1 and PET2 will be reported as two sample t-test or Wilcoxon sum rank test. Results will be reported for PET1 and PET2.
14 days after start of bicalutamide treatment (total estimated time 14 days)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Washington University School of Medicine

Collaborators

The Society of Nuclear Medicine and Molecular Imaging

Investigators

  • Principal Investigator: Vikas Prasad, MD, PhD, Washington University School of Medicine

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

June 30, 2026

Primary Completion (Estimated)

July 14, 2027

Study Completion (Estimated)

September 30, 2027

Study Registration Dates

First Submitted

May 11, 2026

First Submitted That Met QC Criteria

May 11, 2026

First Posted (Actual)

May 18, 2026

Study Record Updates

Last Update Posted (Actual)

May 18, 2026

Last Update Submitted That Met QC Criteria

May 11, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 26-x105

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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