This is a single center, pilot, cross-sectional imaging study investigating the use of gallium-68 citrate PET in participants with metastatic castration-resistant prostate cancer who are planning to undergo a metastatic tumor biopsy on protocol NCT02432001 (CC#125519). The study population will consist of participants with metastatic castration-resistant prostate cancer who are undergoing a metastatic tumor biopsy as part of clinical protocol NCT02432001 (CC#125519), with evidence of resistance to androgen signaling inhibition.
Primary Objective: I. To determine the association between maximum average of standard uptake value (SUVmax-ave) of target metastatic lesions on gallium-68 citrate PET with MYC amplification determined from analysis of circulating tumor DNA. Secondary Objectives: I. To determine the accuracy rate, sensitivity, specificity of gallium citrate PET in the detection of metastatic lesions as compared to standard staging scans including cross-sectional imaging of the abdomen/pelvis and whole body bone scan. II. To determine the optimal dose of gallium-68 citrate and timing of scan post-injection to maximize tumor-to-background signal. III. To characterize the safety profile of gallium-68 citrate. Outline: The study will involve gallium-68 PET scan obtained on a single day, followed by optional tumor biopsy within 6 weeks of gallium scan. There will be optional follow up gallium-68 citrate PET scan to assess response to treatment that will be completed within 12 weeks of baseline gallium citrate PET.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
39
Given via IV at time of imaging
Imaging procedure
University of California, San Francisco
San Francisco, California, United States
Mean maximum Standardized Uptake Value (SUVmax)
The mean and standard deviation of SUVmax of gallium-68 citrate (across all metastatic lesions per participant) will be reported.
Time frame: Day of imaging (1 day)
Mean maximum Standardized Uptake Value (SUVmax-ave)
The mean and standard deviation of SUVmax-ave of gallium-68 citrate across all participants in the study cohort will be descriptively reported.
Time frame: Day of imaging (1 day)
Correlation between SUVmax and MYC gene expression
For participants who undergo optional tumor biopsy, with evaluable RNA sequencing data: Correlation between SUVmax on Gallium-68 Citrate PET and MYC gene expression level, reported as the Pearson correlation coefficient. The coefficient correlation has a value between +1 and -1, where 1 is total positive linear correlation, 0 is no linear correlation, and -1 is total negative linear correlation.
Time frame: Day of imaging (1 day)
Correlation between SUVmax and transferrin receptor gene expression
For participants who undergo optional tumor biopsy, with evaluable RNA sequencing data: Correlation between SUVmax on Gallium-68 Citrate PET and transferrin receptor gene expression level, reported as the Pearson correlation coefficient. The coefficient correlation has a value between +1 and -1, where 1 is total positive linear correlation, 0 is no linear correlation, and -1 is total negative linear correlation.
Time frame: Day of imaging (1 day)
Mean SUVmax-ave percent change from baseline
For participants who undergo optional follow up gallium-68 citrate PET scan, the mean percent change from baseline in SUVmax-ave will be descriptively reported.
Time frame: Up to 12 weeks
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Sensitivity of gallium-68 PET
Using as a cut-off to define a positive lesion on gallium-68 citrate PET as a lesion with SUV at least 1.5 times higher than mediastinal blood pool, the sensitivity value of gallium-68 PET will be descriptively reported on a lesion-per-lesion basis, using as reference standard staging scans including CT or MRI of the chest/abdomen/pelvis and whole body bone scan.
Time frame: Day of imaging (1 day)
Specificity of gallium-68 PET
Using as a cut-off to define a positive lesion on gallium-68 citrate PET as a lesion with SUV at least 1.5 times higher than mediastinal blood pool, the specificity of gallium-68 PET will be descriptively reported on a lesion-per-lesion basis, using as reference standard staging scans including CT or MRI of the chest/abdomen/pelvis and whole body bone scan.
Time frame: Day of imaging (1 day)
Positive predictive value (PPV) of gallium-68 PET
Using as a cut-off to define a positive lesion on gallium-68 citrate PET as a lesion with SUV at least 1.5 times higher than mediastinal blood pool, the positive predictive value of gallium-68 PET will be descriptively reported on a lesion-per-lesion basis, using as reference standard staging scans including CT or MRI of the chest/abdomen/pelvis and whole body bone scan.
Time frame: Day of imaging (1 day)
Number of participants with reported treatment-emergent adverse events
The frequency and severity of adverse events following gallium-68 citrate injection will be descriptively reported, using CTCAE version 4.03.
Time frame: Up to 12 weeks