NCT06374459 · Washington University School of Medicine
Zunsemetinib in Combination With Capecitabine in Patients With Hormone Receptor-Positive and HER2-Negative Metastatic Breast Cancer With Bone Metastasis
What this study is about
This is a phase Ib/II study evaluating the safety and effectiveness of zunsemetinib (ATI-450) with capecitabine in patients with hormone receptor-positive and HER2-negative (HR+/HER2-) metastatic breast cancer (MBC).
View original scientific description
This is a phase Ib/II study evaluating the safety and efficacy of zunsemetinib (ATI-450) with capecitabine in patients with hormone receptor-positive and HER2-negative (HR+/HER2-) metastatic breast cancer (MBC).
Interventions
DRUG
Zumsemetinib
Patients should take zunsemetinib at approximately the same times every day, with or without food with 8 oz of water.
DRUG
Capecitabine
Patients should take capecitabine at approximately the same times every day, within 30 minutes after a meal.
DRUG
Zoledronic acid
Standard of care. Will receive zoledronic acid or denosumab.
DRUG
Denosumab
Standard of care. Will receive zoledronic acid or denosumab.
Primary outcome measures
Number of participants with adverse events (Phase Ib only)
Time frame: From start of treatment through 30 days after end of treatment (estimated to be 11 months)
Recommended phase II dose of zunsemetinib (Phase Ib only)
Time frame: Through end of 1st cycle (each cycle is 21 days)
Number of participants with dose-limiting toxicities (Phase Ib only)
Time frame: Through end of 1st cycle (each cycle is 21 days)
Percent change in serum CTX (Phase II only)
Time frame: Baseline and Day 1 of week 7
Progression-free survival (PFS) (Phase II only)
Time frame: From start of treatment through completion of follow-up (estimated to be 3 years and 10 months)
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- for both Phase Ib and Phase II:
- Hormone receptor-positive, HER2-negative metastatic breast cancer.
- Measurable or non-measurable but evaluable disease by RECIST v1.1.
- Candidate for capecitabine treatment per physician decision. See below phase-specific eligibility criteria for further guidance.
- No more than one prior chemotherapy for metastatic disease.
- Patient must have received prior endocrine therapy with CDK4/6 inhibitor.
- If patient is on denosumab or zoledronic acid prior to enrollment, patient must have been on the regimen for at least 6 months prior to study. However, a washout of 3 weeks is required prior to C1D1.
- At least 18 years of age.
- ECOG performance status 0, 1, or 2
- Life expectancy of at least 12 weeks.
- Adequate bone marrow and organ function as defined below:
- Leukocytes ≥ 3 K/cumm
- Absolute neutrophil count (ANC) ≥ 1.5 K/cumm
- Platelets ≥ 100 K/cumm
- Total bilirubin ≤ 1.5 x IULN (or total bilirubin ≤ 3 mg/dL if patie
Where
- Westwood, Kansas
- Rochester, Minnesota
- St Louis, Missouri
Collaborators
United States Department of Defense, Aclaris Therapeutics, Inc.
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Apr 20, 2026 · Source of record for eligibility and locations