A Study of FG-3246 in Participants With Metastatic Castration-Resistant Prostate Cancer (mCRPC)

May 19, 2026 updated by: Kyntra Bio

A Phase 2 Dose Optimization Trial Evaluating a CD46-Targeted Antibody-Drug Conjugate (FG-3246) in Patients With Metastatic Castration-Resistant Prostate Cancer

The purpose of this study is to evaluate the safety, efficacy, tolerability, and pharmacokinetics (PK) of FG-3246, a cluster of differentiation 46 (CD46) targeting antibody-drug conjugate (ADC), in the treatment of participants with mCRPC who have progressed following treatment with one prior second-generation androgen receptor signaling inhibitor (ARSI) in any setting and no prior taxane therapy in the mCRPC setting.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

75

Phase

  • 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 Backup

Study Locations

  • United States
    • Arizona
      • Goodyear, Arizona, United States, 85338
        • Recruiting
        • Western Regional Medical Center - City of Hope Phoenix Goodyear
        • Contact:
      • Scottsdale, Arizona, United States, 85258
        • Recruiting
        • HonorHealth Research Institute
      • Tucson, Arizona, United States, 85719
        • Recruiting
        • The University of Arizona Cancer Center - North Campus
        • Contact:
    • California
      • Los Angeles, California, United States, 90073
        • Recruiting
        • VA Greater Los Angeles Healthcare System
        • Contact:
      • Los Angeles, California, United States, 90095
      • San Francisco, California, United States, 94158
        • Recruiting
        • University of California San Francisco
        • Contact:
    • Connecticut
      • New Haven, Connecticut, United States, 06519
        • Recruiting
        • New Haven Hospital - Yale Cancer Center
        • Contact:
    • Florida
      • Aventura, Florida, United States, 33180
      • Hialeah, Florida, United States, 33013
    • Georgia
      • Atlanta, Georgia, United States, 30322
        • Recruiting
        • Winship Cancer Institute, Emory University
        • Contact:
    • Louisiana
      • New Orleans, Louisiana, United States, 70112
        • Recruiting
        • East Jefferson General Hospital Metairie
        • Contact:
    • New Mexico
      • Albuquerque, New Mexico, United States, 87109
        • Recruiting
        • New Mexico Oncology Hematology Consultants, Ltd.
        • Contact:
    • North Carolina
      • Durham, North Carolina, United States, 27710
        • Recruiting
        • Duke University Medical Center - Duke Cancer Center
        • Contact:
    • Ohio
      • Cleveland, Ohio, United States, 44106
        • Recruiting
        • University Hospitals Cleveland Medical Center
        • Contact:
    • South Carolina
      • Myrtle Beach, South Carolina, United States, 29572
    • Texas
      • Dallas, Texas, United States, 75390
      • Houston, Texas, United States, 77030
    • Virginia
      • Charlottesville, Virginia, United States, 22908
    • Washington
      • Seattle, Washington, United States, 98195
        • Recruiting
        • University of Washington Medical Center
        • Contact:
      • Seattle, Washington, United States, 98109
        • Recruiting
        • Fred Hutchinson Cancer Center
        • Contact:

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

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Key Inclusion Criteria:

  • Participant must have histological, and/or cytological confirmation of prostate adenocarcinoma on all prior tumor biopsies.
  • Participant with soft tissue disease and a safely accessible soft tissue tumor lesion(s) must agree to biopsy of a primary or metastatic lesion during screening. Alternatively, participant may provide a suitable archival biopsy of a primary or metastatic lesion.
  • Participant must have serum testosterone levels <50 nanograms (ng)/deciliter (dL) during screening.
  • Participant is required to have progressed on no more than one prior treatment with a second generation ARSI (abiraterone acetate, enzalutamide, apalutamide, or darolutamide) initiated in either the castration-sensitive or castration-resistant setting.
  • Participant must have progressive mCRPC following last treatment at screening.
  • Participant must have ≥1 metastatic lesion that is present on baseline Computed Tomography (CT), Magnetic Resonance Imaging (MRI), or bone scan obtained ≤28 days prior to randomization.
  • Participant must have adequate organ function during screening.

Key Exclusion Criteria:

  • Participant has received previous treatment with a therapeutic targeting CD46.
  • Participant has small cell neuroendocrine carcinoma (pure or mixed) on any prior histologic evaluation of primary or metastatic lesion.
  • Participant has progressed on more than one prior second-generation ARSI in any setting or has received more than two prior second-generation ARSIs in any setting.
  • Participants must not have received recent anticancer treatments before enrollment. Ongoing supportive or hormonal therapies are allowed if they were started well before randomization and are continued without change.
  • Participant has received any prior radiation therapy within 14 days prior to randomization.
  • Participant has a known actionable mutation or gene alteration, for example, BRCA1 mutation, for which approved therapies are available, for example, PARP inhibitors, unless these therapies are not appropriate for the participant as determined by the investigator or the participant refuses such therapy.
  • Participant has National Cancer institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) ≥Grade 2 peripheral neuropathy at the time of screening from any etiology.
  • Participant has received any prior chemotherapy; however, one prior taxane-based chemotherapy in the castration-sensitive setting is allowed if completed >12 months before randomization.
  • Participant has known hypersensitivity to the components of FG-3246 or its analogs or a history of allergic or anaphylactic reaction to human, humanized, or chimeric monoclonal antibodies.
  • Participant has diagnosis with any other malignancy in the past 5 years, except for adequately treated basal cell or squamous cell carcinoma of the skin.
  • Participant requires treatment with a strong cytochrome P450 3A4 (CYP3A4) inhibitor or inducer drug that cannot be safely discontinued.

NOTE: Other protocol-defined inclusion/exclusion may apply.

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: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: FG-3246 1.8 mg/kg
Participants will receive FG-3246 1.8 milligrams (mg)/kilogram (kg) administered via intravenous (IV) infusion on Day 1 of each 21-day treatment cycle (every 3 weeks [Q3W]) until radiographic progression, unacceptable safety and tolerability, participant or investigator decision to stop treatment, other withdrawal criteria are met, or sponsor decision to close the study.
Drug: FG-3246
FG-3246 will be administered per schedule specified in the arm description.
Other Names:
  • FOR46
Experimental: FG-3246 2.4 mg/kg
Participants will receive FG-3246 2.4 mg/kg administered via IV infusion on Day 1 of each 21-day treatment cycle (Q3W) until radiographic progression, unacceptable safety and tolerability, participant or investigator decision to stop treatment, other withdrawal criteria are met, or sponsor decision to close the study.
Drug: FG-3246
FG-3246 will be administered per schedule specified in the arm description.
Other Names:
  • FOR46
Experimental: FG-3246 2.7 mg/kg
Participants will receive FG-3246 2.7 mg/kg administered via IV infusion on Day 1 of each 21-day treatment cycle (Q3W) until radiographic progression, unacceptable safety and tolerability, participant or investigator decision to stop treatment, other withdrawal criteria are met, or sponsor decision to close the study.
Drug: FG-3246
FG-3246 will be administered per schedule specified in the arm description.
Other Names:
  • FOR46

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Radiographic Progression-free Survival (rPFS) By Investigator Assessment Per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 and Prostate Cancer Clinical Trials Working Group 3 (PCWG3) Criteria
Time Frame: Until radiographic progression is noted (up to approximately 25 months)
Until radiographic progression is noted (up to approximately 25 months)
Number of Participants With Treatment-emergent Adverse Events (TEAEs)
Time Frame: From first dose until 28 days after last dose (up to approximately 25 months)
From first dose until 28 days after last dose (up to approximately 25 months)
Maximum Plasma Concentration (Cmax) of FG-3246, Total Anti-cluster of Differentiation 46 Antibody (CD46), and Free Monomethyl Auristatin E (MMAE)
Time Frame: Within each 21 day treatment cycle from Cycle 1 through 28 days post last dose (up to approximately 25 months)
Within each 21 day treatment cycle from Cycle 1 through 28 days post last dose (up to approximately 25 months)

Secondary Outcome Measures

Outcome Measure
Time Frame
rPFS Rate at 6 Months (rPFS6) Per RECIST v1.1 and PCWG3 Criteria
Time Frame: Month 6
Month 6
rPFS Rate at 12 Months (rPFS12) Per RECIST v1.1 and PCWG3 Criteria
Time Frame: Month 12
Month 12
Confirmed Objective Response Rate (ORR) Per RECIST v1.1 and PCWG3 Criteria
Time Frame: From first dose up to approximately 25 months
From first dose up to approximately 25 months
Duration of Response (DoR) Per RECIST v1.1 and PCWG3 Criteria
Time Frame: From first dose up to approximately 25 months
From first dose up to approximately 25 months
Confirmed PSA50 Response Rate: Percentage of Participants Achieving a Decline in Prostate-specific Antigen (PSA) ≥50% From Baseline
Time Frame: Up to approximately 25 months
Up to approximately 25 months
Confirmed PSA90 Response Rate: Percentage of Participants Achieving a Decline in PSA ≥90% From Baseline
Time Frame: Up to approximately 25 months
Up to approximately 25 months
Composite Response Rate (CRR) Per RECIST 1.1 and PCWG3 Criteria
Time Frame: Up to approximately 25 months
Up to approximately 25 months
PSA Progression-free Survival (PFS)
Time Frame: Up to approximately 25 months
Up to approximately 25 months
Disease Control Rate (DCR) per RECIST 1.1 and PCWG3 Criteria
Time Frame: Up to approximately 25 months
Up to approximately 25 months
Clinical Benefit Rate (CBR) per RECIST 1.1 and PCWG3 Criteria
Time Frame: Up to approximately 25 months
Up to approximately 25 months
Time to First Symptomatic Skeletal-related Event (SSRE)
Time Frame: Up to approximately 25 months
Up to approximately 25 months
Overall Survival (OS)
Time Frame: Until death or up to approximately 25 months
Until death or up to approximately 25 months
Percentage of Participants Who Develop Anti-drug Antibodies (ADA) and Neutralizing Antibody (NAb) Against FG-3246
Time Frame: Within each 21 day treatment cycle from Cycle 1 through 28 days post last dose (up to approximately 25 months)
Within each 21 day treatment cycle from Cycle 1 through 28 days post last dose (up to approximately 25 months)

Collaborators and Investigators

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

Sponsor

Kyntra Bio

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)

February 22, 2026

Primary Completion (Estimated)

March 31, 2028

Study Completion (Estimated)

March 31, 2028

Study Registration Dates

First Submitted

February 19, 2025

First Submitted That Met QC Criteria

February 19, 2025

First Posted (Actual)

February 24, 2025

Study Record Updates

Last Update Posted (Actual)

May 22, 2026

Last Update Submitted That Met QC Criteria

May 19, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • FGCL-3246-112

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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