NCT05435495 · University of California, San Francisco
Mechanisms of Resistance to PSMA Radioligand Therapy
What this study is about
This is a conducted at multiple hospitals, correlative study to existing Lutetium based prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) trials and uses.
View original scientific description
This is a multicenter, correlative study to existing Lutetium based prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) trials and uses.
Interventions
PROCEDURE
Single-photon emission computed tomography
Imaging procedure
PROCEDURE
Blood Draw
Blood draw for future research tests (45-60 mL).
PROCEDURE
Tumor Biopsy
Guided biopsy of lesion
Primary outcome measures
Mean whole body tumor absorbed dose (WB Dose) across all metastatic lesions
Time frame: Up to 6 months
The unit density sphere model will be implemented using OLINDA, a second-generation personal computer software for internal dose assessment in nuclear medicine to measure mean dose across all metastatic lesions. This approach uses the three time-point SPECT/CTs to create a whole-body dose map, which can then be segmented. Using OLINDA, the total dose to each tumor will be calculated as the integral of activity over time estimated out to 500 hours. Dose will be calculated in gray (Gy).
Median PORTOS score
Time frame: Up to 6 months
PORTOS is a gene signature that predicts salvage radiation success. A PORTOS score of zero (called a "low" PORTOS) means it predicts no benefit from salvage radiotherapy. A PORTOS greater than zero (called a "high" PORTOS score) predicts a benefit from salvage radiation.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Initiating treatment with Lutetium based PSMA-targeted RLT.
- Participants must have a PSMA-avid lesion that is accessible to biopsy. Biopsy of newly emerging radiographic metastases is desired and preferable to the biopsy of previously existing lesions whenever possible. Newly emerging lesions are defined as those that are absent on a previous scan, or those demonstrating unequivocal progression since initiation of the last treatment. Biopsies will be performed according to local institutional standards.
- Patients on warfarin, aspirin, or other anti-coagulants are eligible provided they are deemed able to tolerate discontinuation of anti-coagulation for at least five days prior to the biopsy. Conversion to low molecular weight heparin prior to biopsy is permitted per local standard operating procedures, provided there is approval by the interventional radiologist or the PI.
- Age \>=18 years.
- Ability to understand and the willingness to sign a written informed consent document.
Exclusion criteria
- Patients with significant congenital or acquired bleeding disorders (eg von Wildebrand's disease, acquired bleeding factor inhibitors).
- Patients who are not able to undergo additional study related imaging procedures.
Where
- Los Angeles, California
- San Francisco, California
- New York, New York
Collaborators
National Cancer Institute (NCI), Prostate Cancer Foundation
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Mar 18, 2026 · Source of record for eligibility and locations