The Value of GRPR PET Imaging for Diagnosis and Staging in Prostate Cancer

January 16, 2026 updated by: First Affiliated Hospital of Fujian Medical University

The Value of Gastrin-Releasing Peptide Receptor (GRPR) PET Imaging for Diagnosis and Staging in Prostate Cancer

The gastrin-releasing peptide receptor (GRPR) is highly expressed in prostate cancer (77%-100%). Numerous studies have confirmed that GRPR PET imaging has emerged as a significant molecular imaging modality in prostate cancer, particularly serving as a complementary tool to PSMA PET for addressing cases with negative or insufficient PSMA expression. It demonstrates substantial value in initial staging (especially in intermediate- and high-risk patients), detecting sites of biochemical recurrence, assessing metastatic lesions (notably in mCRPC), and guiding treatment decisions. 68Ga-G21 and 68Ga-G23 are two novel molecular probes targeting GRPR. This study aims to evaluate their biodistribution and diagnostic performance in prostate cancer and compare them with 68Ga-PSMA-11 PET imaging.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

The gastrin-releasing peptide receptor (GRPR), also known as the bombesin receptor subtype BB2, is a G protein-coupled receptor containing seven transmembrane domains. Its endogenous ligand, gastrin-releasing peptide (GRP), exhibits high homology at the C-terminal peptide sequence with bombesin (BBN), a 14-amino-acid peptide derived from amphibians. GRP regulates a series of physiological processes including cell proliferation, differentiation, and metabolism by activating GRPR and its downstream phospholipase C signaling pathway. Studies have shown that GRPR is highly expressed in various malignant tumors and their metastases, such as gastrinoma (100%), prostate cancer (77%-100%), glioma (85%), gastrointestinal stromal tumors (84%), and breast cancer (62%-71.9%), and is closely associated with tumor growth, invasion, and metastasis. Owing to its widespread and high expression across multiple tumor types, GRPR has emerged as a pan-cancer target of significant clinical value, demonstrating strong potential for applications in the fields of precise tumor diagnosis and targeted therapy. Numerous studies have confirmed that GRPR PET imaging has emerged as a significant molecular imaging modality in prostate cancer, particularly serving as a complementary tool to PSMA PET for addressing cases with negative or insufficient PSMA expression. It demonstrates substantial value in initial staging (especially in intermediate- and high-risk patients), detecting sites of biochemical recurrence, assessing metastatic lesions (notably in mCRPC), and guiding treatment decisions. 68Ga-G21 and 68Ga-G23 are two novel molecular probes targeting GRPR. This study aims to evaluate their biodistribution and diagnostic performance in prostate cancer and compare them with 68Ga-PSMA-11 PET imaging.

Study Type

Interventional

Enrollment (Estimated)

6

Phase

  • Phase 2
  • Phase 1

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

Study Contact Backup

Study Locations

  • China
    • Fujian
      • Fuzhou, Fujian, China, 350005
        • Recruiting
        • Department of Nuclear Medicine, First Affiliated Hospital of Fujian Medical University
        • Contact:
        • Contact:

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:

  • confirmed treated or untreated prostate cancer patients;
  • signed written consent.

Exclusion Criteria:

  • known allergy against PSMA;
  • any medical condition that in the opinion of the investigator may significantly interfere with study compliance.

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
Experimental: 68Ga-G21 PET imaging
Intravenous injection of one dosage of 111-148 MBq (3-4 mCi) 68Ga-G21. Tracer of 68Ga-G21 will be used to image lesions of prostate cancer by PET imaging.
Drug: 68Ga-G21
Intravenous injection of one dosage of 111-148 MBq (3-4 mCi) 68Ga-G21. Tracer of 68Ga-G21 will be used to image lesions of prostate cancer by PET imaging.
Experimental: 68Ga-G23 PET imaging
Intravenous injection of one dosage of 111-148 MBq (3-4 mCi) 68Ga-G23. Tracer of 68Ga-G23 will be used to image lesions of prostate cancer by PET imaging.
Drug: 68Ga-G23
Intravenous injection of one dosage of 111-148 MBq (3-4 mCi) 68Ga-G23. Tracer of 68Ga-G23 will be used to image lesions of prostate cancer by PET imaging.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of participants with Imaging Emergent Adverse Events
Time Frame: From enrollment till 7 days safety follow-up
The distribution of adverse events (AE) will be done via the analysis of frequencies for imaging emergent Adverse Event, through the monitoring of relevant clinical and laboratory safety parameters.
From enrollment till 7 days safety follow-up
Dosimetry data
Time Frame: through study completion, an average of 3 months
Calculate the absorbed dose of 68Ga-G21 and 68Ga-G23 in normal organs.
through study completion, an average of 3 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Diagnostic value
Time Frame: through study completion, an average of 3 months
Sensitivity and Specificity of 68Ga-G21 and 68Ga-G23 PET imaging for prostate cancer in comparison with 68Ga-PSMA-11 PET imaging.
through study completion, an average of 3 months

Collaborators and Investigators

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

Sponsor

First Affiliated Hospital of Fujian Medical University

Investigators

  • Principal Investigator: Weibing Miao, MD, First Affiliated Hospital of Fujian Medical University

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 (Actual)

December 20, 2025

Primary Completion (Estimated)

December 31, 2026

Study Completion (Estimated)

December 31, 2027

Study Registration Dates

First Submitted

January 16, 2026

First Submitted That Met QC Criteria

January 16, 2026

First Posted (Actual)

January 23, 2026

Study Record Updates

Last Update Posted (Actual)

January 23, 2026

Last Update Submitted That Met QC Criteria

January 16, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • FirstAHFujian-GRPR PET Imaging

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

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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