This is a prospective, single-center, single-arm Phase I study evaluating GPRC5D-targeted PET/CT imaging in patients with plasma cell disorders, including multiple myeloma. Participants will undergo GPRC5D-targeted PET/CT, 18F-FDG PET/CT, and 68Ga-BCMA PET/CT within 5 days whenever feasible for head-to-head comparison of lesion detection and disease assessment. The study aims to evaluate the safety, feasibility, biodistribution, and diagnostic performance of GPRC5D-targeted PET/CT and to compare its imaging characteristics with currently available molecular imaging modalities in plasma cell disorders.
This is a prospective, single-center, single-arm Phase I interventional imaging study designed to evaluate the safety, feasibility, biodistribution, and diagnostic performance of GPRC5D-targeted PET/CT imaging in patients with plasma cell disorders, including multiple myeloma. GPRC5D is a novel therapeutic and molecular imaging target that is highly expressed on malignant plasma cells while showing limited expression in normal tissues. Recent advances in GPRC5D-targeted immunotherapies have demonstrated promising clinical activity in multiple myeloma, highlighting the potential value of GPRC5D-directed molecular imaging for disease detection, tumor burden evaluation, treatment selection, therapeutic response assessment and prognostic evaluation. Current standard molecular imaging with 18F-FDG PET/CT has several limitations in multiple myeloma, including reduced sensitivity in lesions with low hexokinase-2 expression and limited specificity due to inflammatory uptake.Therefore, development of novel imaging approaches targeting alternative plasma cell antigens may improve disease evaluation and provide complementary biological information. In this study, eligible participants will undergo GPRC5D-targeted PET/CT imaging together with standard molecular imaging examinations, including 18F-FDG PET/CT and 68Ga-BCMA PET/CT. Whenever feasible, all imaging studies will be completed within 5 days to minimize interval changes in disease status and enable direct head-to-head comparison among imaging modalities. Imaging findings from GPRC5D-targeted PET/CT will be compared with 18F-FDG PET/CT and 68Ga-BCMA PET/CT with respect to lesion detectability, disease distribution, tumor uptake characteristics, and overall disease assessment. The study will also evaluate tracer biodistribution, radiation dosimetry, image quality, and safety of the GPRC5D-targeted radiotracer. The results of this study may help establish GPRC5D-targeted PET/CT as a novel molecular imaging tool for plasma cell disorders and support future development of GPRC5D-directed theranostic strategies in multiple myeloma.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
50
Participants with plasma cell disorders, including multiple myeloma, will undergo GPRC5D-targeted PET/CT imaging following intravenous administration of the investigational GPRC5D-targeted radiotracer. Participants will also undergo 18F-FDG PET/CT and 68Ga-BCMA PET/CT within 5 days whenever feasible for intra-individual head-to-head comparison of lesion detection and disease assessment. Safety, biodistribution, tracer uptake characteristics, and imaging performance will be evaluated.
Peking University First Hospital
Beijing, Beijing Municipality, China
Diagnostic Accuracy of GPRC5D-Targeted PET/CT for Detection of Disease Lesions
Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and inter-reader agreement between independent readers for identification of disease lesions in participants with plasma cell disorders, compared with standard reference assessments and with 18F-FDG PET/CT and 68Ga-BCMA PET/CT.
Time frame: Within 5 days after completion of all PET/CT imaging examinations
Incidence and Severity of Adverse Events Following GPRC5D-Targeted Radiotracer Administration
Number of participants experiencing adverse events and severity of adverse events following administration of the GPRC5D-targeted radiotracer, graded according to the Common Terminology Criteria for Adverse Events (CTCAE) version 6.0.
Time frame: From radiotracer administration to 30 days after PET/CT imaging
Concordance Between Imaging Findings and Clinical Disease Assessment
Concordance between GPRC5D-targeted PET/CT findings and clinical, laboratory, and conventional imaging assessments of disease status.
Time frame: From imaging to 1 months of clinical follow-up
Tumor-to-Background Ratio on GPRC5D-Targeted PET/CT
Tumor-to-background ratio (TBR), maximum standardized uptake value (SUVmax), and mean standardized uptake value (SUVmean) of disease lesions identified on GPRC5D-targeted PET/CT.
Time frame: At the time of image interpretation within 5 days after imaging
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