Study Evaluating Dosimetry, Randomized Dose Optimization, Dose Escalation and Efficacy of Ac-225 Rosopatamab Tetraxetan in Participants With PSMA PET-Positive Castration-Resistant Prostate Cancer (CRPC)

July 16, 2026 updated by: Convergent Therapeutics

A Phase 2, Open-label Study Evaluating Dosimetry, Randomized Dose Optimization, Dose Escalation and Efficacy of Ac-225 Rosopatamab Tetraxetan in Participants With PSMA PET-Positive Castration-Resistant Prostate Cancer

This is a four-part study evaluating the safety and efficacy of a PSMA-directed radioantibody (rosopatamab tetraxetan, conjugated to either In-111 or Ac-225). Part 1 will consist of one administration of In-111-rosopatamab tetraxetan to characterize the biodistribution of the radioantibody to target organs and prostate cancer lesions. Participants then will be enrolled into either Part 2 (Dose Optimization) or Part 3 (Dose Escalation and Expansion) depending on their prior treatment history. Part 4 will be an extended regimen in dose escalation and expansion. Participants qualifying for Part 2 will be randomized to receive Ac-225 rosopatamab tetraxetan in a single fractionated cycle (dose administration on Day 1 and Day 15) at either 45 or 60 kBq/Kg. Participants qualifying for Part 3 must have received prior Lu-177-PSMA-radioligand therapy and will receive Ac-225 rosopatamab tetraxetan in a single fractionated cycle at 45, 55, or 60 kBq/Kg. Dose limiting toxicities (DLTs) will be monitored in Part 3 to determine the recommended phase 2 dose (RP2D), and the study may enroll additional participants to be treated with the RP2D dose level. Participants qualifying for Part 4 will initially receive two doses (dose administration on Day 1 and Day 15) at the dose level selected in Part 2, followed by a single third dose of Ac-225 rosopatamab tetraxetan administered approximately 12 weeks after completion of the Part 2 fractionated dosing regimen. The starting dose level for Part 4 will be 22 kBq/kg (or fixed activity equivalent). Dose limiting toxicities (DLTs) will be monitored following administration of the third dose in Part 4 to determine the recommended phase 2 dose (RP2D) of a third dose of Ac-225 rosopatamab tetraxetan. Participants enrolled into any part will attend study visits which will include blood samples, electrocardiogram (ECG), radiographic imaging, and physical examinations along with other assessments.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
93

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • California
      • San Diego, California, United States, 92093
        • Recruiting
        • University of California San Diego
        • Principal Investigator:
          • Rana McKay, MD
    • Massachusetts
      • Boston, Massachusetts, United States, 02215
        • Recruiting
        • Dana-Farber Cancer Institute
        • Principal Investigator:
          • Praful Ravi, MB, BChir, MRCP
    • Missouri
      • St Louis, Missouri, United States, 63130
        • Recruiting
        • Washington University in St. Louis
        • Principal Investigator:
          • Vikas Prasad, MD, PhD
    • Nebraska
      • Omaha, Nebraska, United States, 68130-5606
        • Recruiting
        • X Cancer Omaha / Urology Cancer Center
        • Principal Investigator:
          • Luke Nordquist, MD
    • New York
      • New York, New York, United States, 10065
        • Recruiting
        • Memorial Sloan Kettering Cancer Center
        • Principal Investigator:
          • Anis Hamid, MD
      • New York, New York, United States, 10016
        • Recruiting
        • Laura & Isaac Perlmutter Cancer Center
        • Principal Investigator:
          • David Wise, MD
      • New York, New York, United States, 10065
        • Recruiting
        • New York Presbyterian/Weill Cornell Medical Center
        • Principal Investigator:
          • Cora Sternberg, MD
    • North Carolina
      • Durham, North Carolina, United States, 27710
        • Recruiting
        • Duke University Medical Center
        • Principal Investigator:
          • Daniel George, MD
    • Ohio
      • Cleveland, Ohio, United States, 44195
        • Recruiting
        • The Cleveland Clinic Foundation
        • Principal Investigator:
          • Shilpa Gupta, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Progressive CRPC defined as castrate levels of testosterone and progressing by at least one of the following criteria:

    1. Serum PSA progression as defined by PCWG3 (rising PSA consisting of two consecutive increases measured at least 3 weeks apart, of a rise of >25%, and with an absolute rise of 2.0 ng/mL.
    2. Soft tissue progression defined as a ≥20% increase in the sum of the diameter (short axis for nodal lesions and long axis for non-nodal lesions) of all target lesions based on the smallest sum of the diameter since the previous treatment was started or the appearance of one or more new lesions by CT/magnetic resonance imaging (MRI)
    3. Progression of bone disease defined by PCWG3 as evaluable disease or new bone lesions by bone scan
    4. Identification of new soft tissue or bone lesions on PSMA PET imaging

  • Metastatic disease defined as either or both of the following:

    1. Parts 1, 2, 3, and 4: Documented M1 disease on conventional imaging (CT/MRI of the chest/abdomen/pelvis and/or Technetium 99m [99mTc] whole-body bone scan)
    2. Parts 1, 2, and 4 only: Identification of bone lesion(s), extra-pelvic soft tissue lesion(s), or visceral metastases on PSMA PET imaging with an FDA-approved imaging agent
  • PSMA PET-positive disease, defined as at least one PSMA-positive metastatic lesion and no PSMA-negative lesions
  • Progression following treatment with ADT and at least one ARSI (e.g., enzalutamide, apalutamide, darolutamide, and/or abiraterone acetate)
  • The standard of care use (in the setting of metastatic CRPC with significant burden of active bone metastases) of antiresorptive bone-targeted agents (e.g., zoledronic acid, denosumab) is required for all participants without a contraindication, for at least 4 weeks prior to administration of Ac-225 rosopatamab tetraxetan.
  • Participants with HIV are eligible if they are well-controlled (i.e, an undetectable HIV viral load (<50 copies/mL) within 6 months of enrollment and a stable ART regimen for at least 6 months prior to enrollment) and at low risk for HIV-related illness

Part 3 Only:

  • Prior treatment with Lu-177-PSMA-radioligand therapy
  • Prior treatment with up to only one taxane-based chemotherapy regimen is allowed

Exclusion Criteria:

  • Superscans by nuclear medicine/99mTc bone scan
  • A known malignancy that is progressing or has required active treatment within the past 3 years other than CRPC, which is expected to alter life expectancy or may interfere with CRPC disease assessment
  • Prior platinum-based chemotherapy
  • Prior PARP inhibitors (e.g., olaparib or rucaparib)
  • Prior treatment with Radium-223, Actinium-225, Strontium-89, Samarium-153, Rheunium-186, or Rhenium-188
  • Participants receiving anti-coagulants or anti-platelet drugs (e.g., aspirin or nonsteroidal anti-inflammatory drugs [NSAIDs]) who cannot discontinue use if platelet count decreases to <50,000

Part 2 and 4 Only:

  • Prior chemotherapy for CRPC. Prior taxane chemotherapy for HSPC is allowed if discontinued ≥1 year prior to randomization
  • Prior radiopharmaceutical therapy (e.g., Ra-223, Lu-177-PSMA-617, or Lu-177-PSMA-I&T)
  • Prior PSMA-targeted therapy, except for bispecific or CAR-T therapies

Part 3 Only:

  • Prior PSMA-targeted therapy (e.g., antibody-drug conjugates or CAR-T therapy), except for Lu-177-PSMA-radioligand therapy and bispecific or CAR-T therapies

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Part 1: 148 ± 37 MBq In-111 rosopatamab tetraxetan
Biological: In-111 rosopatamab tetraxetan
A single dose of 148 ± 37 MBq In-111 rosopatamab tetraxetan will be administered as an IV infusion over a period of 10 minutes.
Experimental: Part 2: 45 kBq/kg Ac-225 rosopatamab tetraxetan
Biological: 45 kBq/kg Ac-225 rosopatamab tetraxetan
45 kBq/kg Ac-225 rosopatamab tetraxetan will be administered as an IV infusion over a period of 10 minutes. Doses will be given two weeks apart for a total of two doses.
Experimental: Part 2: 60 kBq/kg Ac-225 rosopatamab tetraxetan
Biological: 60 kBq/kg Ac-225 rosopatamab tetraxetan
60 kBq/kg Ac-225 rosopatamab tetraxetan will be administered as an IV infusion over a period of 10 minutes. Doses will be given two weeks apart for a total of two doses.
Experimental: Part 3: Dose Escalation and Expansion
Participants previously treated with Lu-177-PSMA-radioligand therapy will be assigned to receive one of the three dose levels (45 kBq/kg, 55 kBq/kg, or 60 kBq/kg, or equivalent fixed dose activity) depending on the dose limiting toxicities (DLTs) observed.
Biological: 45 kBq/kg or equivalent fixed dose activity Ac-225 rosopatamab tetraxetan
45 kBq/kg Ac-225 rosopatamab tetraxetan will be administered as an IV infusion over a period of 10 minutes. Doses will be given two weeks apart for a total of two doses.
Biological: 55 kBq/kg or equivalent fixed dose activity Ac-225 rosopatamab tetraxetan
55 kBq/kg Ac-225 rosopatamab tetraxetan will be administered as an IV infusion over a period of 10 minutes. Doses will be given two weeks apart for a total of two doses.
Biological: 60 kBq/kg or equivalent fixed dose activity Ac-225 rosopatamab tetraxetan
60 kBq/kg Ac-225 rosopatamab tetraxetan will be administered as an IV infusion over a period of 10 minutes. Doses will be given two weeks apart for a total of two doses.
Experimental: Part 4: Dose Escalation and Expansion
Participants will initially receive two doses of the Part 2 selected dose level, followed by a single third dose of Ac-225 rosopatamab tetraxetan approximately 12 weeks after the completion of the Part 2 fractionated dosing regimen. Participants will be assigned to receive one of the three dose levels (22 kBq/kg, 34 kBq/kg, or 45 kBq/kg, or equivalent fixed dose activity) depending on the dose limiting toxicities (DLTs) observed.
Biological: Single dose 22 kBq/kg or equivalent fixed dose activity Ac-225 rosopatamab tetraxetan
22 kBq/kg Ac-225 rosopatamab tetraxetan will be administered as an IV infusion over a period of 10 minutes. A single dose will be given.
Biological: Single dose 34 kBq/kg or equivalent fixed dose activity Ac-225 rosopatamab tetraxetan
34 kBq/kg Ac-225 rosopatamab tetraxetan will be administered as an IV infusion over a period of 10 minutes. A single dose will be given.
Biological: Single dose 45 kBq/kg or equivalent fixed dose activity Ac-225 rosopatamab tetraxetan
45 kBq/kg Ac-225 rosopatamab tetraxetan will be administered as an IV infusion over a period of 10 minutes. A single dose will be given.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Part 1: Visual evaluation on whole body planar scans (days 1 and 4) with comparison to reference scans for the presence of radiolabeled rosopatamab textraxetan in organs of interest (e.g., liver, circulation, spleen) to determine biodistribution
Time Frame: Day 1 and Day 4
Day 1 and Day 4
Part 2: Incidence of Adverse Events (AEs) and Serious Adverse Events (SAEs) overall, by severity, and leading to discontinuation of study intervention
Time Frame: Screening through Week 12
Screening through Week 12
Part 2: Proportion of participants who achieve a greater than or equal to 50% decline in prostate-specific antigen (PSA50)
Time Frame: Through end of study (approximately 3 years) or until PSA progression as defined by PCWG3 criteria
Through end of study (approximately 3 years) or until PSA progression as defined by PCWG3 criteria
Part 3: Incidence of Adverse Events (AEs) and Serious Adverse Events (SAEs) overall, by severity, and leading to discontinuation of study intervention
Time Frame: Screening through Week 12
Screening through Week 12
Part 3: Determine the recommended Phase 2 dose (RP2D) of Ac-225 rosopatamab tetraxetan
Time Frame: Day 1 through 6 weeks
Day 1 through 6 weeks
Part 3 (Participants treated at RP2D): Proportion of participants who achieve a greater than or equal to 50% decline in prostate-specific antigen (PSA50)
Time Frame: Through end of study (approximately 3 years) or until PSA progression as defined by PCWG3 criteria
Through end of study (approximately 3 years) or until PSA progression as defined by PCWG3 criteria
Part 4: Incidence of AEs and SAEs overall, by severity, by relationship to study drug, and leading to discontinuation of study intervention
Time Frame: Screening through Week 12
Screening through Week 12
Part 4: Determine the recommended Phase 2 dose (RP2D) of Ac-225 rosopatamab tetraxetan
Time Frame: Through end of study (approximately 3 years)
Through end of study (approximately 3 years)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
Part 2: Determine the clearance of rosopatamab tetraxetan and Ac-225 rosopatamab tetraxetan via measurement of whole blood and serum levels at specified serial timepoints
Time Frame: Through Week 8
Through Week 8
Part 2: Radioactivity levels of Ac-225 rosopatamab tetraxetan
Time Frame: Through Day 21
Through Day 21
Part 2: Biochemical progression-free survival (bPFS) as assessed by the Prostate Cancer Working Group 3 (PCWG3)
Time Frame: Through end of study (approximately 3 years) or until disease progression
Through end of study (approximately 3 years) or until disease progression
Part 3: Proportion of participants who achieve PSA50
Time Frame: Through end of study (approximately 3 years)
Through end of study (approximately 3 years)
Part 3: Determine the clearance of rosopatamab tetraxetan and Ac-225 rosopatamab tetraxetan from the circulation via measurement in the serum at specified serial timepoints
Time Frame: Through Week 8
Through Week 8
Part 2: Radiation dosimetry of Ac-225 rosopatamab tetraxetan: Absorbed radiation dose (expressed as Gy/MBq) in normal organs
Time Frame: Day 1 through Day 15
Day 1 through Day 15
Part 3: Radioactivity levels of Ac-225 rosopatamab tetraxetan
Time Frame: Through Week 8
Through Week 8
Part 4: Proportion of participants who achieve PSA50
Time Frame: Through end of study (approximately 3 years)
Through end of study (approximately 3 years)
Part 4: Biochemical progression-free survival (bPFS) as assessed by the Prostate Cancer Working Group 3 (PCWG3)
Time Frame: Through end of study (approximately 3 years) or until disease progression
Through end of study (approximately 3 years) or until disease progression

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Convergent Therapeutics

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
August 6, 2024

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
April 20, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 20, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
July 31, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 7, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
August 12, 2024

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 20, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 16, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • CONVERGE-01

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

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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