Recruiting

Phase 2

CapecitabineAdaptive Therapy With Capecitabine for Treatment of Metastatic ER Positive, HER2 Negative Breast Cancer

Sponsor:

Mayo Clinic

Code:

NCT06525766

Conditions

Anatomic Stage IV Breast Cancer AJCC v8

Estrogen-receptor-positive Breast Cancer

Metastatic HER2-Negative Breast Carcinoma

Metastatic Breast Cancer

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Interventions

Biospecimen Collection

Bone Scan

Capecitabine

Computed Tomography

Magnetic Resonance Imaging

Study Details

Brief summary:

This phase II trial evaluates the effect of capecitabine on tumor response using imaging and tumor markers to adjust dose (adaptive therapy) in patients with estrogen receptor (ER) positive, HER2 negative breast cancer that has spread from where it first started to other areas in the body (metastatic). Capecitabine is in a class of medications called antimetabolites. It is taken up by tumor cells and breaks down into fluorouracil, a substance that kills tumor cells. Adaptive therapy with capecitabine based on tumor burden response may slow or stop the growth of tumor cells in patients with metastatic ER positive, HER2 negative breast cancer.

Conditions

Anatomic Stage IV Breast Cancer AJCC v8

Estrogen-receptor-positive Breast Cancer

Metastatic HER2-Negative Breast Carcinoma

Metastatic Breast Cancer

Study ID

NCT06525766

Start date

Oct 1, 2025

Status verified date

May, 2026

Completion date

Oct 15, 2030

Anticipated

Primary completion date

Oct 15, 2030

Anticipated

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Inclusion Criteria:

PRE-REGISTRATION: Provide written informed consent Note: Pre-registration should occur prior to screening research blood draws being completed
PRE-REGISTRATION: Provider anticipates the patient will begin on capecitabine within 14 days or has started capecitabine within the past 42 days and has had a maximum of two cycles Note: Pre-registration should occur prior to screening research blood draws being completed

REGISTRATION - INCLUSION CRITERIA

Age ≥ 18 years
Histological confirmation of estrogen-receptor positive (ER+), HER2-negative overexpression or amplification negative as per American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines, metastatic breast cancer
Measurable disease. Bone only disease allowed if associated with soft tissue component that is measurable by Response Evaluation Criteria is Solid Tumors (RECIST) 1.1 criteria
Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0, 1 or 2
Hemoglobin ≥ 9.0 g/dL (obtained ≤ 14 days prior to registration), no transfusions allowed ≤ 14 days prior to registration
Absolute neutrophil count (ANC) ≥ 1500/mm\^3 (obtained ≤ 14 days prior to registration)
Platelet count ≥ 100,000/mm\^3 (obtained ≤ 14 days prior to registration)
Total bilirubin ≤ 1.5 x upper limit of normal (ULN) (obtained ≤ 14 days prior to registration)
Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3 x ULN (≤ 5 x ULN for patients with liver involvement) (obtained ≤ 14 days prior to registration)
Calculated creatinine clearance ≥ 30 ml/min using the Cockcroft-Gault formula (obtained ≤ 14 days prior to registration)
Negative serum or urine pregnancy test done ≤ 7 days prior to registration, for persons of childbearing potential only. NOTE: If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required
Provide written informed consent
Ability to complete questionnaire(s) by themselves or with assistance
Willingness to provide mandatory blood specimens for correlative research
Ability to undergo re-staging CT scans as required by the protocol

Note: for patients who have had up to two cycles of capecitabine prior to joining the study, they must have had their initial CT imaging completed within 28 days of their first dose of capecitabine
Willing to return to enrolling institution at the specified frequency for follow-up (during the active monitoring phase of the study)
Cohort 2 only: Stable disease, partial or complete response on imaging after beginning capecitabine

Exclusion Criteria:

Prior chemotherapy or use of antibody drug conjugate in the metastatic setting

Note - Cohort 2 only: Patients can have had up to two cycles of capecitabine before joining the study
Any of the following, because this study involves an agent that has known genotoxic, mutagenic and teratogenic effects:

Pregnant persons
Nursing persons
Persons of childbearing potential who are unwilling to employ adequate contraception
Any of the following prior therapies:

Major surgery ≤ 3 weeks prior to registration
Radiation therapy ≤ 2 weeks prior to registration
Evidence of visceral crisis or impending cord compression
Evidence of uncontrolled brain metastasis requiring whole brain irradiation or intervention
Uncontrolled intercurrent illness including, but not limited to:

ongoing or active infection
symptomatic congestive heart failure
unstable angina pectoris
uncontrolled cardiac arrhythmia
chronic oxygen dependence
respiratory failure
or psychiatric illness/social situations that would limit compliance with study requirements
Receiving any other investigational agent which would be considered as a treatment for the primary neoplasm
Other active malignancy ≤ 3 years prior to registration. EXCEPTIONS: Non-melanotic skin cancer or carcinoma-in-situ of the cervix
If there is a history of prior malignancy, they must not be receiving other cancer specific treatment. Except for antiestrogen treatment (aromatase inhibitors or selective estrogen modulators) for their cancer are permitted if they meet other eligibility criteria. Denosumab and zoledronic acid, are permitted as established adjunct therapies per guidelines
History of myocardial infarction ≤ 6 months prior to registration, or congestive heart failure requiring use of ongoing maintenance therapy for life-threatening ventricular arrhythmias
Patients known to have certain homozygous or compound heterozygous dihydropyrimidine dehydrogenase (DPYD) variants that result in complete absence of deoxypyridinoline (DPD) activity. Test results do not need to be available prior to registration
History of severe hypersensitivity reactions to fluorouracil or capecitabine

Study Design

Enrollment

35 participants

Anticipated

Intervention Model

Single group

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Treatment (capecitabine)

See Detailed Description.

Interventions

Biospecimen Collection

Undergo blood sample collection

Bone Scan

Undergo bone scan

Capecitabine

Given PO

Computed Tomography

Undergo CT

Magnetic Resonance Imaging

Undergo MRI

Questionnaire Administration

Ancillary studies

Primary outcome measure

Ability to achieve adaptive therapy (AT) [ Time Frame: Up to 5 years ]

Central Contacts and Locations

Central contacts

Clinical Trials Referral Office

855-776-0015 mayocliniccancerstudies@mayo.edu

Locations

Mayo Clinic in Arizona

Recruiting

Scottsdale, Arizona, United States, 85259

Contacts

Clinical Trials Referral Office

855-776-0015 mayocliniccancerstudies@mayo.edu

Principal Investigator:

Lida A. Mina, M.D.

More Information

Sponsor

Mayo Clinic

Last update posted

Aug 12, 2026

Last verified

May, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by Mayo Clinic on 2026-08-12.