Trial of 225Ac-DOTATATE (RYZ101) in Subjects With ER+, HER2-negative Unresectable or Metastatic Breast Cancer Expressing SSTRs. (TRACY-1)

March 16, 2026 updated by: RayzeBio, Inc.

Phase 1b/2 Open-label Trial of 225Ac-DOTATATE (RYZ101) in Subjects With Estrogen Receptor-positive (ER+), Human Epidermal Growth Factor Receptor 2 (HER2)-Negative, Locally Advanced and Unresectable or Metastatic Breast Cancer Expressing Somatostatin Receptors (SSTRs) and Progressed After Antibody-drug Conjugates and/or Chemotherapy (TRACY-1).

Phase 1b/2 open-label trial of 225Ac-DOTATATE (RYZ101) in subjects with ER+, HER2-negative unresectable or metastatic breast cancer expressing SSTRs.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

16

Phase

  • Phase 2
  • Phase 1

Contacts and Locations

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

Study Locations

  • Canada
    • British Columbia
      • Victoria, British Columbia, Canada, V8R 6V5
        • Research Facility
    • Ontario
      • Toronto, Ontario, Canada, M4N 3M5
        • Research Facility
      • Toronto, Ontario, Canada, M5G 2M9
        • Research Facility
    • Quebec
      • Québec, Quebec, Canada, G1S 4L8
        • Research Facility
  • South Korea
    • Seoul
      • Seoul, Seoul, South Korea, 03080
        • Research Facility
      • Seoul, Seoul, South Korea, 05505
        • Research Facility
  • United States
    • Arizona
      • Phoenix, Arizona, United States, 85054
        • Research Facility
    • California
      • Irvine, California, United States, 92618
        • Research Facility
      • San Diego, California, United States, 92093
        • Research Facility
      • Santa Monica, California, United States, 90404
        • Research Facility
    • Colorado
      • Longmont, Colorado, United States, 80504
        • Research Facility
    • Florida
      • Jacksonville, Florida, United States, 32224
        • Research Facility
    • Georgia
      • Atlanta, Georgia, United States, 30322
        • Research Facility
    • Indiana
      • Indianapolis, Indiana, United States, 46202
        • Research Facility
    • Massachusetts
      • Boston, Massachusetts, United States, 02215
        • Research Facility
    • Michigan
      • Detroit, Michigan, United States, 48202
        • Research Facility
    • Minnesota
      • Rochester, Minnesota, United States, 55905
        • Research Facility
    • Missouri
      • St Louis, Missouri, United States, 63130
        • Research Facility
    • Nebraska
      • Omaha, Nebraska, United States, 68124
        • Research Facility
    • New Mexico
      • Albuquerque, New Mexico, United States, 87109
        • Research Facility
    • New York
      • Buffalo, New York, United States, 14203
        • Research Facility
      • New York, New York, United States, 10016
        • Research Facility
      • New York, New York, United States, 10021
        • Research Facility
    • Ohio
      • Cleveland, Ohio, United States, 44195
        • Research Facility
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19104
        • Research Facility
      • Pittsburgh, Pennsylvania, United States, 15213
        • Research Facility
    • Texas
      • Dallas, Texas, United States, 75246
        • Research Facility
      • Houston, Texas, United States, 77024
        • Research Facility
    • Utah
      • Salt Lake City, Utah, United States, 84132
        • Research Facility
    • Virginia
      • Norfolk, Virginia, United States, 23502
        • Research Facility
    • Washington
      • Seattle, Washington, United States, 98109
        • Research Facility

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

Inclusion Criteria

Subjects must meet all the following criteria for enrollment in the study:

  • Eastern Cooperative Oncology Group performance status ≤2.
  • Histologically confirmed, ER+, HER2-negative, locally advanced and unresectable or metastatic breast cancer not amenable to treatment with curative intent.
  • At least one RECIST v1.1-measurable tumor lesion that is SSTR-PET positive (defined as maximum standard uptake value (SUVmax) higher than liver mean standard uptake value (SUVmean) on SSTR-PET imaging) and at least 80% of RECIST v1.1measurable tumor lesions are SSTR-PET positive
  • Sufficient renal function, as evidenced by eGFR ≥60 mL/min/1.73m2 calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation
  • Adequate hematologic and hepatic function

Exclusion Criteria

Subjects who meet any of the following criteria will be excluded from the study:

  • Prior radiopharmaceutical therapy, including radioembolization.
  • Any toxicities from prior treatments that have not recovered to CTCAE Grade ≤1, except for alopecia.
  • Significant cardiovascular disease
  • Known active uncontrolled or symptomatic central nervous system (CNS) metastases, carcinomatous meningitis, spinal cord compression, or leptomeningeal disease.
  • History of hypersensitivity or allergy to 225Ac, 68Ga, 64Cu, octreotate, or any of the excipients of DOTATATE imaging agents.
  • Prior or concurrent malignancy whose natural history or treatment has the potential to interfere with the study safety or efficacy assessments.
  • Pregnancy or lactation.

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
Intervention / Treatment
Experimental: Dose Escalation

RYZ101 Dose Level -1

RYZ101 Dose Level 1

RYZ101 Dose Level 2

RYZ101 Dose Level 3
Drug: RYZ101
Ac-225
Experimental: Expansion
RYZ101 RP2D Regimen
Drug: RYZ101
Ac-225

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Dose Escalation
Time Frame: 6 weeks of RYZ101 treatment
Incidence rate of DLTs during the first 6 weeks of RYZ101 treatment
6 weeks of RYZ101 treatment
Expansion
Time Frame: Up to approximately 5 years after the last subject has completed RYZ101 treatment
Overall Response Rate, defined as rate of subjects achieving a Complete Response or Partial Response as determined by BICR using RECIST v1.1
Up to approximately 5 years after the last subject has completed RYZ101 treatment

Collaborators and Investigators

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

Sponsor

RayzeBio, Inc.

Investigators

  • Study Director: Petrus de Jong, MD, PhD, RayzeBio, Inc.

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)

July 19, 2024

Primary Completion (Estimated)

October 1, 2028

Study Completion (Estimated)

January 1, 2033

Study Registration Dates

First Submitted

September 3, 2024

First Submitted That Met QC Criteria

September 10, 2024

First Posted (Actual)

September 19, 2024

Study Record Updates

Last Update Posted (Actual)

March 18, 2026

Last Update Submitted That Met QC Criteria

March 16, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • RYZ101-201

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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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