Dose Optimization of Rosuvastatin in Early Stage and Metastatic Estrogen Receptor Positive Breast Cancer Patients on Endocrine Therapy

Inclusion Criteria:

- Women with ER+/PR+ HER2-negative breast cancer initiating neoadjuvant endocrine
therapy with curative intent OR initiating endocrine therapy for the treatment of
metastatic breast cancer with a biopsy accessible primary breast tumor

- The patients may start any FDA approved endocrine therapy (with which they have not
been previously treated) at week 4 of the trial except for tamoxifen

- Palbociclib can be started at week 4, if indicated

- Patients with metastatic disease currently on endocrine therapy must be willing to
stop endocrine therapy for 2 weeks prior to starting the study and to switch to a new
endocrine therapy on the study (at week 4)

- Intact breast tumor present and size measuring at least 1cm at enrollment

- Post-menopausal at enrollment (age ≥ 60, age ≤ 60 and amenorrhea for ≥12 months in
the absence of chemotherapy, tamoxifen, ovarian suppression and FSH/estradiol in the
post-menopausal range)

- ECOG ≤ 2

- Can be on other endocrine therapy if willing to change a different endocrine therapy
agent for the trial

- Must have at least one FDA approved endocrine therapy option with which the patient
has not received prior treatment

- Life expectancy > 12 weeks

- Laboratory criteria: normal renal function: creatinine < 1.5 x upper limit of normal
(ULN)), liver function: bilirubin < 2 x ULN, transaminases < 2 x ULN and blood
counts: WBC ≥ 2.0, Neutrophils ≥1250, platelets ≥50,000, Hemoglobin ≥ 8.

- Age > 18 years

- Patients must have the ability to give informed consent.

- Patients must have a signed informed consent form prior to enrollment on study. -

Exclusion Criteria:

- Statin use in the last 6 months

- Patient has been treated with all FDA approved endocrine therapies or has been
treated with all FDA approved endocrine therapies except for tamoxifen (tamoxifen is
excluded from the trial)

- Active liver disease with elevated transaminases > 2x ULN

- Known hypersensitivity to rosuvastatin

- Any history of any other cancer (except non-melanoma skin cancer or carcinoma in-situ
of the cervix) unless the patient has been in remission and off all other cancer
therapy for at least 3 years.

- Patients should have no significant psychiatric illness or medical illness that would
preclude the ability to comply with the protocol.

- Patients currently taking medications with known rosuvastatin interactions including
cyclosporine, gemfibrozil, lopinavir/ritonavir, atazanavir/ritonavir, coumarin
anticoagulants, colchicine, fenofibrates, and niacin.