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

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.