Alternative Dosing of Exemestane Before Surgery in Treating Postmenopausal Patients With Stage 0-II Estrogen Positive Breast Cancer

We have conducted an international, multicenter, pre-surgical double-blind non-inferiority phase IIb study in which a total of 180 participants have been randomized to receive either exemestane 25 mg/day (Exemestane 25 mg QD) or 25 mg/ three times a week (Exemestane 25 mg TIW) or a single dose of 25 mg/week (Exemestane 25 mg QW) for a minimum of 4 up to 6 weeks. Participants were stratified by center and BMI (<25 kg/m2 vs >25 kg/m2).

Participants were histologically confirmed ER-positive (ER >10%) primary breast cancer patients who were candidates for breast surgery. Postmenopausal women younger than 76 years of age with cT0-2, cN0-1, Mx or women with larger tumors who refuse neo-adjuvant therapy before surgery were eligible. No previous treatment for breast cancer was allowed.

Complete physical exam and safety lab tests have been performed at baseline and at the end of treatment (28+1, 35+1, 42+1 days). Phone contact occurred on day 1 and a week before surgery (+3 days). Participants experiencing persistent adverse events (certainly, probably, and possibly treatment-related) have been monitored 20-30 days after study completion.

Biomarkers: blood samples were collected at baseline and the end of treatment (fasting blood for biomarkers collected prior to randomization and either on the day of surgery or the day before; fasting strongly recommended but not mandated), tissue samples collected from the diagnostic or research biopsy and at the time of surgery.

Inclusion criteria

• Postmenopausal women (postmenopausal: age >= 60 years, or amenorrhea >= 12 months, or bilateral oophorectomy, or - in women with hysterectomy only - follicle stimulating hormone [FSH] in the menopausal levels as per local institutional guidelines if < 60 years old) with histologically-confirmed estrogen receptor (ER)-positive (>= 10%) primary breast cancer stage cT0-2, cN0-1, Mx; women with larger tumors who refuse chemotherapy (chemo) and/or endocrine neoadjuvant therapy can be eligible
• Eastern Cooperative Oncology Group (ECOG) performance status =< 1 (Karnofsky >= 70%)
• Leukocytes >= 3,000/microliter
• Absolute neutrophil count >= 1,500/microliter
• Platelets >= 100,000/microliter
• Total bilirubin =< 2 x institutional upper limit of normal (ULN)
• Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase [SGOT])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase [SGPT]) =< 1.5 x institutional ULN
• Serum creatinine =< 1.5 times institutional ULN
• Ability to understand and the willingness to sign a written informed consent document

Exclusion criteria

• Body mass index (BMI) < 18.5 Kg/m^2
• Previous treatment for breast cancer including chemotherapy, endocrine therapy and radiotherapy; women with prior ductal breast carcinoma in situ (DCIS) who were treated with surgery only and whose treatment ended >= 2 years prior to enrollment are eligible for the trial
• Women who are planned to receive neoadjuvant therapy
• Participants may not be receiving investigational agents
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to exemestane
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements
• Other co-existing invasive malignancies (with the exclusion of basal cell carcinoma or skin squamous cell carcinoma) diagnosed during the last 2 years before randomization
• History of severe osteoporosis (T score =< -4 either spine or hip), or presence of vertebral fracture
• Use of systemic hormone replacement therapy (HRT) in the last 30 days prior to the randomization; the use of non-systemic estrogen (such as vaginal estrogen use) is allowed
• Use of any chemopreventive agents (selective estrogen receptor modulators [SERM]) in the last 3 months
• Concomitant use of CYP3A4 inducer medication (rifampicin, phenytoin, carbamazepine, phenobarbital, and St. John's wort)