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

Fujian Medical University (FJMU)

Status and phase: Enrolling; Phase 2; Phase 1

Conditions: Prostate Cancer (Adenocarcinoma)

Treatments: Drug: 68Ga-G23; Drug: 68Ga-G21

Study type: Interventional

Funder types: Other

Identifiers

NCT07363382

FirstAHFujian-GRPR PET Imaging

Details and patient eligibility

About

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.

Full 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.

Enrollment: 6 estimated patients

Sex: Male

Ages: 18 to 90 years old

Volunteers: No Healthy Volunteers

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.

Trial design

Primary purpose: Diagnostic

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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6 participants in 2 patient groups

68Ga-G21 PET imaging

Experimental group

Description:

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.

Treatment:

Drug: 68Ga-G21

68Ga-G23 PET imaging

Experimental group

Description:

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.

Treatment:

Drug: 68Ga-G23