A Study of Terbium 161 (161Tb)-RAD402 in Participants With CRPC

NCT07259213 | Recruiting Phase 1 DMC

• 1 other identifier: RAD402-AU-101
• Study Type: interventional
• Target: 73
• Locations: 1 country
• Sites: 2

Brief Summary

A Phase 1/2a Study to Evaluate the Safety, Tolerability, Whole-Body Distribution, and Preliminary Clinical Activity of 161Tb-RAD402, a Radiolabeled Anti-KLK3 Monoclonal Antibody Targeting Free Prostate-Specific Antigen, in Participants with Castration-Resistant Prostate Cancer (CRPC).

Conditions

Castration-resistant Prostate Cancer

Outcome Measures

Primary Outcomes (3)

• Incidence of treatment emergent adverse events of 161Tb RAD402 (phase 1) (Safety)

  As defined per Common Terminology Criteria for Adverse Events (CTCAE) v5.0

  6 weeks

• Recommended dose(s) of 161Tb RAD402 for future exploration (phase 1)

  Incidence of dose-limiting toxicities (DLTs) during the first 6 weeks following the first 161Tb RAD402 injection

  6 weeks

• Preliminary anti-tumor activity, as defined by biochemical response, in participants who are treated with 161Tb RAD402 at the RP2D (phase 2a)

  Proportion of participants who achieve a ≥50% decline in prostate-specific antigen (PSA) 50

  Up to 30 weeks

Secondary Outcomes (11)

• Preliminary anti-tumor activity of 161Tb RAD402 (phase 1)

  Up to 30 weeks

• Preliminary anti-tumor activity of 161Tb RAD402 as defined by biochemical response (phase 1)

  Up to 30 weeks

• Pharmacokinetics of 161Tb RAD402 (phase 1)

  120 hours

• Radiation dosimetry of 161Tb RAD402 (phase 1)

  120 hours

• Biodistribution of 161Tb RAD402 (phase 1)

  120 hours

Study Arms (1)

161Tb RAD402

EXPERIMENTAL

Single-arm, open-label study of 161Tb RAD402 consisting of Phase 1 Dose Escalation and Phase 2 Dose Expansion study parts.

Drug: 161Tb RAD402

Interventions

161Tb RAD402 DRUG

161Tb RAD402 administered at treatment doses

161Tb RAD402

Eligibility Criteria

• Age: 18 Years+
• Gender Eligibility Details: Individuals' gender of male physical characteristics is the primary criterion for inclusion.
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Willing and able to provide informed consent prior to start of any study procedures and assessments and must be willing to comply with all study procedures.
• Male participants ≥ 18 years of age.
• Participants with a documented history of histopathologically confirmed locally advanced or metastatic CRPC defined as follows:
• Progressive CRPC defined as castrate levels of testosterone and progressing by at least one of the following criteria:
• Serum PSA increase \>25% and \>2.0 ng/ml above nadir, confirmed by progression at 2 timepoints at least 3 weeks apart (PCWG3)
• 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 computed tomography (CT)/ magnetic resonance imaging (MRI).
• Progression of bone disease defined by PCWG3 as evaluable disease or new bone lesions by bone scan (if metastatic disease).
• Identification of new soft tissue or bone lesions on PSMA PET imaging.
• If metastatic disease, metastatic disease defined as either or both of the following:
• Documented M1 disease on conventional imaging (CT/MRI of the chest/abdomen/pelvis and/or Technetium 99m \[99mTc\] whole-body bone scan)
• Identification of bone lesion(s), extra-pelvic soft tissue lesion(s), or visceral metastases on PSMA PET imaging with an FDA-approved imaging agent (e.g., Gallium-68 (68Ga)-PSMA-11)
• PSMA PET-positive disease, defined as at least one PSMA-positive metastatic lesion PSMA PET-positive lesions are defined as uptake greater than that of liver parenchyma in one or more extra-pelvic metastatic lesions of any size in any organ system using an FDA-approved PSMA PET imaging agent.
• Progression following treatment with androgen deprivation therapy (ADT) and at least one androgen receptor signaling inhibitor (ARSI) (e.g., enzalutamide, apalutamide, darolutamide, and/or abiraterone acetate). If a participant is currently on ADT, they should continue ADT for the duration of their participation in the study but will not be permitted to start a new therapy or ADT regimen. If a participant has progressed on an ARSI, they will have the option to remain on the same ARSI or discontinue therapy.
• Prior definitive and palliative external beam radiation therapy and stereotactic body radiation therapy is allowed.
• Note: Participants with extended external beam radiation therapy to the axial skeleton, which in the opinion of the Investigator may pose a risk for increased myelotoxicity, will be discussed with the Sponsor to determine eligibility.

You may not qualify if:

• Prostate cancer with known significant sarcomatoid, or spindle cell, or neuroendocrine small cell components, or metastasis of other cancer to the prostate.
• History of prior organ transplant (other than corneal transplant)
• Any other known, active malignancy except for non-melanoma skin cancer or adequately treated non-muscle-invasive urothelial carcinoma of the bladder (i.e. tumor in situ (Tis), tumor grade a (Ta) and low-grade tumor grade 1 (T1) tumors). Participants with a history of malignancies of low recurrence potential who have received curative-intent therapy may be approved on a case-by-case basis in discussion with the Sponsor, if it is determined not to put the participant at an increased risk of adverse drug effects and/or interfere with the integrity of the study outcome.
• Have any medical condition that would, in the Investigator's judgment, prevent the participant's full participation in the clinical study due to safety concerns or compliance with clinical study procedures such as participants with severe claustrophobia who are unresponsive to oral anxiolytics, participants with low back pain who cannot lie comfortably on an imaging table, participants who are hyperactive or hyperkinetic such that they cannot tolerate lying still for multiple time point imaging procedures, etc.
• Residual toxicity ≥ Grade 2 from prior anti-cancer therapy (except alopecia and peripheral sensory neuropathy).
• History of uncontrolled allergic reactions and/or known or expected hypersensitivity to protein therapeutics, 161Tb-RAD402, or any of its excipients.
• Inadequate organ functions as reflected in laboratory parameters:
• Estimated glomerular filtration rate (eGFR) \< 50 mL/min adjusted for body surface area (BSA) using the Chronic Kidney Disease Epidemiology Collaboration formula
• Platelet count of \< 100 x 109/L
• Absolute neutrophil count (ANC) \< 1.5 x 109/L
• Hemoglobin \< 9 g/dL
• Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \> 3 x upper limit of normal (ULN), or \> 5 x ULN for participants with known liver metastases
• Total bilirubin \> 1.5 x ULN, except for participants with documented Gilbert's syndrome who are eligible if total bilirubin ≤ 3 x ULN
• For participants not taking warfarin or other anticoagulants: International Normalised Ratio (INR) ≤1.5 or PT ≤1.5 x ULN; and either partial thromboplastin time or activated partial thromboplastin time (PTT or aPTT) ≤1.5 x ULN. Participants taking warfarin must be on a stable dose that results in a stable INR \<3.5. Among participants receiving other anticoagulant therapy, PT or aPTT must be within the intended therapeutic range of the anticoagulant.
• Participants requiring blood product transfusion within 2 weeks of first dose of 161Tb-RAD402 are not eligible to participate.

Sponsors & Collaborators

• Radiopharm Theranostics, Ltd: lead

Study Sites (2)

Wollongong Hospital

Wollongong, New South Wales, 2500, Australia

RECRUITING

Icon Cancer Centre Hollywood

Nedlands, Western Australia, 6009, Australia

RECRUITING

Central Study Contacts

Dimitris Voliotis, MD

CONTACT

646-535-5017; dv@radiopharmtheranostics.com

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: November 15, 2025
• First Posted: December 2, 2025
• Study Start: March 5, 2026
• Primary Completion (Estimated): November 30, 2028
• Study Completion (Estimated): March 30, 2029
• Last Updated: April 1, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

AU (2)