Study to Determine Treatment Effects of Denosumab in Patients With Breast Cancer Receiving Aromatase Inhibitor Therapy

Inclusion Criteria for Double Blinded Phase:

• Histologically or cytologically confirmed adenocarcinoma of the breast;
• Female subjects with non-metastatic disease who are estrogen receptor (ER) and/or progesterone receptor (PR) positive, and who have completed their treatment pathway;
• Subjects who are currently on, or will initiate an approved non-steroidal aromatase inhibitor therapy (eg, anastrazole) in the adjuvant setting;
• Postmenopausal woman, defined as a woman fulfilling any one of the following criteria:
• Having undergone a bilateral oophorectomy;
• Age ≥ 60 years;
• Aged < 60 years meeting the following requirements:
• Follicle-stimulating hormone (FSH) and estradiol in the postmenopausal range;
• A negative pregnancy test within 7 days prior to randomization. Subjects who have undergone a hysterectomy do not require a pregnancy test.
• More criteria may apply.

Exclusion Criteria for Double Blinded Phase:

• Aromatase inhibitor therapy for more than 24 months;
• Prior or concurrent treatment with Selective Estrogen Receptor Modulators (eg, tamoxifen);
• Evidence of metastatic disease;
• Current or prior intravenous (IV) bisphosphonate administration;
• Oral bisphosphonate treatment greater than or equal to 3 years continuously OR greater than 3 months but less than 3 years unless there was a washout period of at least 1 year prior to randomization OR any use during the 3-month period prior to randomization;
• Prior administration of denosumab;
• Known liver or renal deficiency;
• Recurrence of the primary malignancy (e.g., during the allowed interval of pretreatment with aromatase inhibitor);
• Diagnosis of any second non-breast malignancy within the last 5 years, except for adequately treated basal cell or squamous cell skin cancer, or for in situ carcinoma of the cervix uteri;
• Any kind of disorder that compromises the ability to give written informed consent and/or comply with study procedures.

Inclusion Criteria to Receive Open-label Phase Denosumab:

• Obtain signed and dated written informed consent prior to performing any study-specific procedure;
• Subjects currently taking an approved non-steroidal AIT (eg, anastrazole) or who have completed or discontinued AIT within 12 months prior to participation in the OLP;
• Randomized to placebo arm during the double-blind phase (as determined by unblinding procedures);

Exclusion Criteria to Receive Open-label Phase Denosumab:

• Current or prior IV bisphosphonate administration;
• Subjects meeting the following criteria for oral bisphosphonate treatment:
• Greater than or equal to 3 years continuously,
• Greater than 3 months but less than 3 years unless subject has had a washout period of at least 1 year prior to participation in the OLP,
• Any use during the 3-month period prior to participation in the OLP;
• Prior or concurrent treatment with SERMs (eg, tamoxifen);
• Subjects who ended treatment with investigational product (IP) prematurely in the double-blind phase; Treatment with commercial denosumab (Prolia or Xgeva) prior to participation in the OLP.

Eligibility for ZA substudy Inclusion Criteria

• Obtain signed and dated written informed consent prior to performing any substudy-specific procedure
• Subjects that received OLP denosumab and completed OLP treatment
• Last OLP denosumab administration no longer than 9 months ago Exclusion Criteria
• Current or prior ZA administration.
• Subjects who ended treatment with investigational product (IP) prematurely in the double-blind phase and OL phase
• Known sensitivity or intolerance to any of the products to be administered during the substudy (eg, ZA, calcium or vitamin D)
• Known history of any of the following conditions either by subject self report or chart review
• Paget's disease (bone), Cushing's disease, hyperprolactinemia or other active metabolic bone disease
• Known history of hypocalcemia
• Major surgery, or significant traumatic injury occurring within 4 weeks prior to randomization