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

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).

Status

Active, not recruiting

Phases

Phase 1Phase 2

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT06590857

Acronym

TRACY-1

Enrollment

Registered

2024-09-19

Start date

2024-07-19

Completion date

2033-01-01

Last updated

2026-03-18

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Metastatic Breast Cancer, HER2-negative Breast Cancer, ER+ Breast Cancer, Advanced Breast Cancer

Keywords

Actinium, Alpha-Emitter, SSTR+ MBC, ER+, HER2-, MBC, RYZ101, 225Ac, Targeted Radiotherapy, Radiopharmaceutical, SSTR+ ABC, ER+, HER2-, ABC

Brief summary

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

Interventions

DRUGRYZ101

Ac-225

Study design

Allocation

NON_RANDOMIZED

Intervention model

SEQUENTIAL

Primary purpose

TREATMENT

Masking

NONE

Eligibility

Sex/Gender

ALL

Age

18 Years to No maximum

Healthy volunteers

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.

Design outcomes

Primary

Measure	Time frame	Description
Dose Escalation	6 weeks of RYZ101 treatment	Incidence rate of DLTs during the first 6 weeks of RYZ101 treatment
Expansion	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

Countries

Canada, South Korea, United States

Contacts

STUDY_DIRECTORPetrus de Jong, MD, PhD

RayzeBio, Inc.

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Mar 19, 2026