Tirzepatide for Weight Loss Intervention in Early-Stage Hormone Receptor Positive/HER2 Negative Breast Cancer

This clinical trial aims to evaluate the effectiveness of tirzepatide in achieving a 5% or more body weight reduction in patients undergoing adjuvant treatment for hormone receptor-positive, HER2-negative (HR+/Her2-) breast cancer. The study will also assess the safety and tolerability of tirzepatide, its feasibility based on discontinuation rates, and completion of treatment. Secondary objectives include evaluating 3-year invasive disease-free survival (IDFS) and distant relapse-free survival (DRFS), changes in BMI and body fat distribution, metabolic markers, and circulating tumor DNA (ctDNA).

The primary objective of this clinical trial is to determine the proportion of patients who achieve a 5% or greater reduction in body weight by the end of the study treatment with tirzepatide, during adjuvant treatment for hormone receptor-positive, HER2-negative (HR+/Her2-) breast cancer. Secondary objectives include assessing the safety and tolerability of tirzepatide for weight loss during this treatment. The feasibility of using tirzepatide for weight loss intervention will be evaluated through discontinuation rates and completion of the treatment course. Additionally, the trial will determine the 3-year invasive disease-free survival (IDFS) and 3-year distant relapse-free survival (DRFS) with the use of tirzepatide. The study will also assess changes in Body Mass Index (BMI), body fat distribution (measured via Waist/Hip Ratio (WHR) and waist circumference), and obesity-related metabolic markers (including Blood Pressure, fasting insulin, fasting blood glucose, HgbA1c, cholesterol, LDL, HDL, triglycerides, IGF1, estrogen, and testosterone). Finally, the trial will monitor for circulating tumor DNA (ctDNA) and assess changes when using tirzepatide for weight loss in the adjuvant treatment of HR+/Her2- breast cancer. Quality of Life assessments will be obtained and exploratory objectives investigating adipokines (adiponectin, leptin) and their receptors, metabolomic pathways and immune cell metabolism will be conducted.

Eligibility Criteria:
Inclusion Criteria:

* Consent: Be willing and able to provide written informed consent for the trial.
* Age: Male or Female patients aged 18 years or older.
* Breast Cancer Diagnosis: Have hormone receptor-positive (HR+), HER2-negative (HER2-) breast cancer previously diagnosed by biopsy. HR status is defined as estrogen receptor (ER) \>10% and/or progesterone receptor (PR) \>10%; HER2 status is defined as immunohistochemistry (IHC) 0 or 1+ or IHC 2+, fluorescence in situ hybridization (FISH) negative.
* Stage: Have previously untreated early-stage, clinical or anatomic stage I, II, or III hormone receptor-positive breast cancer.
* Definitive Treatment: Have had definitive treatment with curative intent for breast cancer, including surgery, chemotherapy, and radiotherapy as indicated.
* Body Mass Index (BMI): Have a BMI of 30 kg/m² or more, or a BMI of 27 kg/m² or more with one weight-related complication (e.g., hypertension, type 2 diabetes, dyslipidemia, obstructive sleep apnea, or cardiovascular disease).
* Performance Status: Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2.
* Cardiac Function: Have a left ventricular ejection fraction (LVEF) of 50% or greater, or greater than the institution's lower limit of normal (LLN), as assessed by echocardiogram (ECHO) or multigated acquisition (MUGA) scan performed at screening.
* Organ Function: Demonstrate adequate organ function in screening labs.
* Tumor Specimens: Have archived biopsy or surgical tumor specimens available as tumor blocks or unstained slides.

Exclusion Criteria:

* Other Clinical Studies: Is currently enrolled, or will enroll in, a different clinical study in which investigational therapeutic procedures are performed or investigational therapies are administered while participating in this study.
* Stage IV Breast Cancer: Have stage IV, metastatic breast cancer.
* Cancer Type: Have HER2-positive or triple-negative breast cancer.
* Active Malignancy: Have a concomitant active malignancy.
* Performance Status: Have an Eastern Cooperative Oncology Group (ECOG) performance status greater than 2.
* Body Mass Index: Have a BMI of less than 27 kg/m².
* Type 1 Diabetes Mellitus: Have type 1 diabetes mellitus.
* Gastric Emptying Abnormality: Have a known clinically important gastric emptying abnormality (e.g., severe gastroparesis or gastric outlet obstruction) or chronically took drugs that directly affect gastrointestinal motility.