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Mechanisms of Resistance to PSMA Radioligand Therapy

Mechanisms of Resistance to PSMA Radioligand Therapy: Radiation Resistance Versus Dose

Status
Recruiting
Phases
Unknown
Study type
Observational
Source
ClinicalTrials.gov
Registry ID
NCT05435495
Enrollment
125
Registered
2022-06-28
Start date
2021-10-21
Completion date
2026-12-31
Last updated
2026-03-18

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Prostate Cancer

Keywords

Radioligand Therapy

Brief summary

This is a multicenter, correlative study to existing Lutetium based prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) trials and uses.

Detailed description

PRIMARY OBJECTIVES: I. To determine the relationship between whole body tumor absorbed dose and response Lutetium based prostate-specific membrane antigen-targeted radioligand therapy (177Lu-PSMA-RLT). II. To determine the relationship between Post-Operative Radiation Therapy Outcomes Score (PORTOS) score and response to 177Lu-PSMA-RLT. III. To determine the relative importance of radiation dose (whole body tumor absorbed dose) and radiation sensitivity (PORTOS score) as a marker of response to 177Lu-PSMA-RLT. EXPLORATORY OBJECTIVES: I. To develop novel signature of radiation sensitivity. II. To evaluate tumor biopsies to understand mechanisms of resistance. III. To understand utility of post-cycle 4 single-photon emission computed tomography (SPECT/CT) to evaluate treatment response. Study participants will undergo a biopsy and blood draw prior to the initiation of planned therapy, as well as SPECT/CT imaging performed after the first and fourth treatments. One SPECT/CT scan will be performed 24 (+/- 6) after the first treatment, and after the fourth treatment, a 24 +/- 6-hour post-treatment SPECT/CT will be performed. Additionally, study participants may choose to undergo optional biopsy and blood draw at time of progression.

Interventions

PROCEDUREBlood Draw

Blood draw for future research tests (45-60 mL).

PROCEDURETumor Biopsy

Guided biopsy of lesion

Sponsors

University of California, San Francisco
Lead SponsorOTHER
National Cancer Institute (NCI)
CollaboratorNIH
Prostate Cancer Foundation
CollaboratorOTHER

Study design

Observational model
COHORT
Time perspective
PROSPECTIVE

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

1. Initiating treatment with Lutetium based PSMA-targeted RLT. 2. 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. 3. 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. 4. Age \>=18 years. 5. Ability to understand and the willingness to sign a written informed consent document.

Exclusion criteria

1. Patients with significant congenital or acquired bleeding disorders (eg von Wildebrand's disease, acquired bleeding factor inhibitors). 2. Patients who are not able to undergo additional study related imaging procedures.

Design outcomes

Primary

MeasureTime frameDescription
Mean whole body tumor absorbed dose (WB Dose) across all metastatic lesionsUp to 6 monthsThe 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 scoreUp to 6 monthsPORTOS 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.

Countries

United States

Contacts

CONTACTMaya Aslam
Maya.Aslam@ucsf.edu(415) 514-8987
PRINCIPAL_INVESTIGATORThomas Hope, MD

University of California, San Francisco

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Mar 19, 2026