Measuring Circulating Tumor Deoxyribonucleic Acid Tumor Fraction to Guide Early 177Lu-PSMA-617 Treatment Discontinuation in Patients With Metastatic Castration-Resistant Prostate Cancer, DYNAMO Trial

Dynamic Assessments of Molecular Response to Guide Early 177Lu-PSMA-617 Treatment Discontinuation: The DYNAMO Study

This clinical trial studies whether measuring circulating tumor deoxyribonucleic acid (ctDNA) tumor fraction (TF) can be used to help guide the early stopping (discontinuation) of lutetium Lu 177 vipivotide tetraxetan (177Lu-PSMA-617) in patients with castration-resistant prostate cancer that has spread from where it first started (primary site) to other places in the body (metastatic). Many types of tumors tend to lose cells or release different types of cellular products including their deoxyribonucleic acid, which is referred to as ctDNA, into the bloodstream before changes can be seen on scans. Health care providers can measure the level of ctDNA in blood or other bodily fluids to determine which patients are at higher risk for the disease to grow, spread, or get worse or come back after a period of improvement. ctDNA TF is a type of ctDNA measurement. Research has shown ctDNA TF may be a promising way to predict which patients will respond to 177Lu-PSMA-617 treatment. Measuring ctDNA TF may help doctors identify which patients may benefit from changing treatments sooner, which may be an effective way to guide early 177Lu-PSMA-617 treatment discontinuation in patients with metastatic castration-resistant prostate cancer.

Study Overview

• Status: Not yet recruiting
• Conditions: Stage IVB Prostate Cancer AJCC v8; Metastatic Castration-Resistant Prostate Adenocarcinoma
• Intervention / Treatment: Drug: Docetaxel; Procedure: Computed Tomography; Procedure: Biospecimen Collection; Procedure: PSMA PET Scan; Drug: Lutetium Lu 177 Vipivotide Tetraxetan; Procedure: Single Photon Tomography and Computed Tomography Scan; Procedure: Cell-free Circulating Tumor DNA Assay

Detailed Description

OUTLINE:

CYCLES 1 AND 2: Patients receive 177Lu-PSMA-617 intravenously (IV) over 20-30 minutes on day 1 of each cycle. Cycles repeat every 6 weeks for up to 2 cycles in the absence of disease progression or unacceptable toxicity. Patients also undergo blood sample collection with ctDNA TF testing at baseline and C2D1. Patients with undetectable ctDNA TF (< 3%) on C2D1 continue to receive 177Lu-PSMA-617 as above in the absence of disease progression or unacceptable toxicity. Patients with detectable ctDNA TF (≥ 3%) on C2D1 are randomized to 1 of 2 arms.

CYCLE 3+ ARM I: Starting with cycle 3, patients receive 177Lu-PSMA-617 IV over 20-30 minutes on day 1 of each cycle. Cycles repeat every 6 weeks in the absence of disease progression or unacceptable toxicity.

CYCLE 3+ ARM II: Starting with cycle 3, patients receive docetaxel IV on day 1 of each cycle. Cycles repeat every 3 weeks in the absence of disease progression or unacceptable toxicity.

Additionally, all patients undergo PSMA positron emission tomography (PET) during screening, single photon emission computed tomography (SPECT)/computed tomography (CT) on study, and additional blood sample collection as well as CT throughout the study.

After completion of study treatment, patients are followed up every 12 weeks for up to 1 year.

• Study Type: Interventional
• Enrollment (Estimated): 64
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Michael Schweizer, MD; Phone Number: 206-606-6252; Email: schweize@uw.edu

Study Locations

• United States
  • Washington
    • Seattle, Washington, United States, 98109
      • Fred Hutch/University of Washington Cancer Consortium
      • Principal Investigator: Michael Schweizer, MD
      • Contact: Michael Schweizer, MD; Phone Number: 206-606-6252; Email: schweize@uw.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Willing and able to provide informed consent
• Adult males ≥ 18 years age
• History of histologically confirmed adenocarcinoma of the prostate without evidence of neuroendocrine or small cell differentiation. If histology is not available, patients must have metastatic disease typical of prostate cancer (i.e., involving bone or pelvic lymph nodes or para-aortic lymph nodes)
• Evidence of metastatic disease on bone scan or CT scan

• Patient must have evidence of castration- resistant prostate cancer as evidenced by PSA progression (per Prostate Cancer Working Group 3 [PCWG3] criteria) and a castrate serum testosterone level (i.e., ≤ 50 mg/dL)

  • Serum/plasma PSA progression defined as 2 consecutive increases in PSA over a previous reference value measured at least 1 week prior. The minimal start value is 2.0 ng/mL
• Eastern Cooperative Oncology Group (ECOG) performance status 0-2
• Prior treatment and progression on at least one androgen receptor pathway inhibitor (ARPI), in either castration-sensitive or castration-resistant setting
• Eligible for treatment with either 177Lu-PSMA-617 or docetaxel as per their respective Food and Drug Administration (FDA) labels
• Absolute neutrophil count ≥ 1.5 x 10^9/L
• Platelet count ≥ 100 x 10^9/L
• Hemoglobin ≥ 9 g/dL
• Creatinine clearance ≥ 50 ml/min (calculated by Cockcroft-Gault formula)
• Total bilirubin ≤ 1.5 x upper limit of normal (ULN) except for patients with known Gilbert's syndrome (direct bilirubin ≤ 1.5 x ULN)
• Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 x ULN, unless liver metastases are present in which case they must be ≤ 5 x ULN. For patients with known Gilbert's Syndrome they must be ≤ 3 x ULN
• Able to comply with study requirements including provision of peripheral blood samples at specified time points for correlative studies

Exclusion Criteria:

• Evidence of serious and/or unstable pre-existing medical, psychiatric or other condition that could interfere with patient safety or provision of informed consent to participate in this study
• Evidence of metastatic neuroendocrine/small cell prostate cancer (NEPC). Note: baseline biopsy is not required
• Patients receiving any systemic therapy (aside from a luteinizing hormone-releasing hormone [LHRH] analogue) or radiotherapy within 2 weeks prior to study treatment
• Persistent toxicities (CTCAE grade > 2) from prior cancer therapy, excluding alopecia and stable neuropathy
• Patients considered a poor medical risk due to a serious, uncontrolled medical disorder or active, uncontrolled infection. Examples include, but are not limited to uncontrolled seizure disorder, unstable spinal cord compression, superior vena cava syndrome, or any psychiatric disorder that prohibits obtaining informed consent
• Patients who are known to be serologically positive for human immunodeficiency virus (HIV) and a CD4 count < 200
• Patients with known active hepatitis (i.e. hepatitis B or C). Prior hepatitis C infection is allowed as long as polymerase chain reaction (PCR) is negative
• Major surgery within 2 weeks of starting study treatment and patients must have recovered from any effects of any major surgery
• Serious cardiac disorder, including but not limited to uncontrolled ventricular arrhythmia, recent (within 12 months) myocardial infarction, resting electrocardiogram (ECG) indicating Fridericia's corrected QT interval prolongation > 500ms, or congenital long QT syndrome
• Prior systemic chemotherapy with taxane chemotherapy, including in hormone sensitive setting (e.g. docetaxel or cabazitaxel)

• Brain metastases or active epidural disease (treated epidural disease is permitted)

  • Note: baseline brain imaging is not required
• Contraindication to prednisone therapy including poorly controlled diabetes mellitus

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Cycles 1 and 2 (177Lu-PSMA-617, ctDNA testing); Patients receive 177Lu-PSMA-617 IV over 20-30 minutes on day 1 of each cycle. Cycles repeat every 6 weeks for up to 2 cycles in the absence of disease progression or unacceptable toxicity. Patients also undergo blood sample collection with ctDNA TF testing at baseline and C2D1. Patients with undetectable ctDNA TF (< 3%) on C2D1 continue to receive 177Lu-PSMA-617 as above in the absence of disease progression or unacceptable toxicity. Patients with detectable ctDNA TF (≥ 3%) on C2D1 are randomized to 1 of 2 arms. Additionally, patients undergo PSMA PET during screening, SPECT/CT on study, and additional blood sample collection as well as CT throughout the study.	Procedure: Computed Tomography; Undergo CT; Other Names: CT; CAT; CAT Scan; Computed Axial Tomography; Computerized Axial Tomography; Computerized Tomography; CT Scan; tomography; Computerized axial tomography (procedure); Computerized Tomography (CT) scan; Diagnostic CAT Scan; Diagnostic CAT Scan Service Type; Procedure: Biospecimen Collection; Undergo blood sample collection; Other Names: Biological Sample Collection; Biospecimen Collected; Specimen Collection; Sample Collection; Procedure: PSMA PET Scan; Undergo PSMA PET; Other Names: PSMA PET; Prostate-specific Membrane Antigen PET; PSMA-Positron emission tomography; Drug: Lutetium Lu 177 Vipivotide Tetraxetan; Given IV; Other Names: 177Lu-labeled PSMA-617; 177Lu-PSMA-617; Pluvicto; Lu177-PSMA-617; Lutetium-177-PSMA-617; AAA 617; AAA-617; AAA617; Lutetium Lu 177-PSMA-617; Procedure: Single Photon Tomography and Computed Tomography Scan; Undergo SPECT/CT; Other Names: SPECT/CT; SPECT/CT SCAN; Procedure: Cell-free Circulating Tumor DNA Assay; Undergo ctDNA TF testing; Other Names: Signatera; ctDNA Assay
Active Comparator: Cycle 3+ Arm I (177Lu-PSMA-617); Starting with cycle 3, patients receive 177Lu-PSMA-617 IV over 20-30 minutes on day 1 of each cycle. Cycles repeat every 6 weeks in the absence of disease progression or unacceptable toxicity. Additionally, patients undergo PSMA PET during screening, SPECT/CT on study, and additional blood sample collection as well as CT throughout the study.	Procedure: Computed Tomography; Undergo CT; Other Names: CT; CAT; CAT Scan; Computed Axial Tomography; Computerized Axial Tomography; Computerized Tomography; CT Scan; tomography; Computerized axial tomography (procedure); Computerized Tomography (CT) scan; Diagnostic CAT Scan; Diagnostic CAT Scan Service Type; Procedure: Biospecimen Collection; Undergo blood sample collection; Other Names: Biological Sample Collection; Biospecimen Collected; Specimen Collection; Sample Collection; Procedure: PSMA PET Scan; Undergo PSMA PET; Other Names: PSMA PET; Prostate-specific Membrane Antigen PET; PSMA-Positron emission tomography; Drug: Lutetium Lu 177 Vipivotide Tetraxetan; Given IV; Other Names: 177Lu-labeled PSMA-617; 177Lu-PSMA-617; Pluvicto; Lu177-PSMA-617; Lutetium-177-PSMA-617; AAA 617; AAA-617; AAA617; Lutetium Lu 177-PSMA-617; Procedure: Single Photon Tomography and Computed Tomography Scan; Undergo SPECT/CT; Other Names: SPECT/CT; SPECT/CT SCAN
Active Comparator: Cycle 3+ Arm II (docetaxel); Starting with cycle 3, patients receive docetaxel IV on day 1 of each cycle. Cycles repeat every 3 weeks in the absence of disease progression or unacceptable toxicity. Additionally, patients undergo PSMA PET during screening, SPECT/CT on study, and additional blood sample collection as well as CT throughout the study.	Drug: Docetaxel; Given IV; Other Names: Taxotere; Docecad; RP56976; Taxotere Injection Concentrate; RP 56976; RP-56976; Procedure: Computed Tomography; Undergo CT; Other Names: CT; CAT; CAT Scan; Computed Axial Tomography; Computerized Axial Tomography; Computerized Tomography; CT Scan; tomography; Computerized axial tomography (procedure); Computerized Tomography (CT) scan; Diagnostic CAT Scan; Diagnostic CAT Scan Service Type; Procedure: Biospecimen Collection; Undergo blood sample collection; Other Names: Biological Sample Collection; Biospecimen Collected; Specimen Collection; Sample Collection; Procedure: PSMA PET Scan; Undergo PSMA PET; Other Names: PSMA PET; Prostate-specific Membrane Antigen PET; PSMA-Positron emission tomography; Procedure: Single Photon Tomography and Computed Tomography Scan; Undergo SPECT/CT; Other Names: SPECT/CT; SPECT/CT SCAN

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number and proportion among those recruited with detectable circulating tumor deoxyribonucleic acid (ctDNA) tumor fraction who undergo randomization	Will be analyzed descriptively. Among patients who initiate lutetium Lu 177 vipivotide tetraxetan and undergo cycle (C) 2 day (D) 1 ctDNA tumor fraction assessment, the number (and proportion among those recruited) with detectable ctDNA tumor fraction who undergo randomization will be reported with a two-sided 95% Wilson confidence interval.	Up to 2 cycles (Cycle length = 6 weeks)
Number of patients screened, enrolled, evaluable for C2D1 ctDNA tumor fraction and for who cycle 3 is administered	Will report the number of patients screened, enrolled, evaluable for C2D1 (week 13) ctDNA tumor fraction, classified as having detectable versus undetectable ctDNA tumor fraction, and for who cycle 3 is administered. Reasons for failure to undergo C1D28 ctDNA assessment or randomization will be tabulated.	Up to cycle 3 administration (Cycle length = 6 weeks)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Radiographic progression free survival (PFS)	Will be estimated in the subset of patients who undergo randomization. Disease progression assessed per modified Response Evaluation Criteria in Solid Tumors criteria or the Prostate Cancer Working Group 3 criteria for bone lesions. Clinical progression as determined by the treating physician. Will be estimated using the Kaplan-Meier method. Differences between groups will be evaluated using the log-rank test and the hazard ratio from a Cox regression model with treatment group as the predictor variable following assessment of proportional hazards. Will also visualize PFS point estimates and 95% confidence interval (CI) bands over time and report median and 95% CIs of PFS for each group.	From randomization to disease progression, clinical progression, or death, whichever occurs first, assessed up to 1 year
Overall survival	Will be estimated in the subset of patients who undergo randomization. Will be estimated using the Kaplan-Meier method. Differences between groups will be evaluated using the log-rank test and the hazard ratio from a Cox regression model with treatment group as the predictor variable following assessment of proportional hazards.	From the start of treatment until death from any cause, assessed up to 1 year
Prostate-specific antigen (PSA) PFS	Will be estimated in the subset of patients who undergo randomization. Will be estimated using the Kaplan-Meier method. Differences between groups will be evaluated using the log-rank test and the hazard ratio from a Cox regression model with treatment group as the predictor variable following assessment of proportional hazards.	From the start of treatment until PSA progression, assessed up to 1 year
Proportion of patients with a ≥ 50% decline in PSA from baseline (PSA50) response rate	Will be estimated in the subset of patients who undergo randomization. Will be reported as a percentage with 95% CI calculated using Wilson's method. Changes in PSA from baseline, with patients achieving PSA50, may be visualized using waterfall plots.	Up to 1 year
Duration of response	Will be estimated in the subset of patients who undergo randomization.	From the time measurement criteria are met for complete response or partial response (whichever is first recorded) until the first date that recurrent or progressive disease is objectively documented, assessed up to 1 year

Collaborators and Investigators

• Sponsor: University of Washington
• Collaborators: Institute for Prostate Cancer Research (IPCR)
• Investigators: Principal Investigator: Michael Schweizer, MD, Fred Hutch/University of Washington Cancer Consortium

Study record dates

Study Major Dates

• Study Start (Estimated): December 1, 2026
• Primary Completion (Estimated): July 5, 2029
• Study Completion (Estimated): July 5, 2029

Study Registration Dates

• First Submitted: June 25, 2026
• First Submitted That Met QC Criteria: July 6, 2026
• First Posted (Actual): July 13, 2026

Study Record Updates

• Last Update Posted (Actual): July 13, 2026
• Last Update Submitted That Met QC Criteria: July 6, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Genital Neoplasms, Male; Urogenital Neoplasms; Neoplasms by Site; Neoplasms; Genital Diseases, Male; Prostatic Diseases; Male Urogenital Diseases; Prostatic Neoplasms; Organic Chemicals; Investigative Techniques; Clinical Laboratory Techniques; Diagnostic Techniques and Procedures; Diagnosis; Hydrocarbons; Cycloparaffins; Hydrocarbons, Alicyclic; Hydrocarbons, Cyclic; Terpenes; Hydrolases; Enzymes; Enzymes and Coenzymes; Taxoids; Cyclodecanes; Diterpenes; Peptide Hydrolases; Metalloproteases; Carboxypeptidases; Exopeptidases; Metalloexopeptidases; Docetaxel; Pluvicto; Specimen Handling; Glutamate Carboxypeptidase II
• Other Study ID Numbers: RG1126448; NCI-2026-03971 (Registry Identifier: CTRP (Clinical Trial Reporting Program)); FHIRB0021269 (Other Identifier: Fred Hutch/University of Washington Cancer Consortium)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: Yes