Presurgical Trial of Denosumab in Breast Cancer

Breast cancer is the most common cancer among women, affecting one in eight women, and is the
second leading cause of mortality from cancer. Bone metastases are a frequent complication of
breast cancer, and the mechanism of breast cancer metastases to bone is an ongoing area of
research.. Receptor activator of NF-kB (RANK) and its ligand (RANKL) have been identified and
characterized for its role in bone remodeling. RANKL is a member of the tumor necrosis factor
(TNF) family of cytokines that binds to its receptor RANK to control osteoclast
differentiation, activation, and survival. RANK protein expression is not only found on
osteoclasts and dendritic cells but also on T cells and mammary epithelial cells. RANK and
RANKL is important for lymph node and thymus formation as well as lactating mammary gland
development during pregnancy. Furthermore, the RANK/RANKL axis has been linked to progestin
driven breast carcinomas and bone metastases.

RANK is expressed in 6-57% of invasive human breast cancers (depending upon the parameters
for defining positivity and antibodies utilized for immunohistochemistry (IHC)), and RANKL
driven hormone (progesterone -dependent proliferation, survival, and nonproliferative
expansion of mammary stem cells may contribute to breast cancer initiation, progression, and
recurrence.

We hypothesize that denosumab can inhibit RANKL signaling in early breast tumors which
express RANK, inhibiting pro-metastatic mechanisms and reducing immunosuppression in the
tumor microenvironment. This will be tested in a pre-surgical clinical trial (Phase 0) to
evaluate and select the pharmacodynamics markers of RANKL inhibition in breast cancer.

Inclusion Criteria:

- Patients must have histologically confirmed invasive breast cancer (stages I-III) who
have undergone core needle biopsy (clinically or radiographically at least T1c to
allow adequate residual cancer tissue at surgery) and will be scheduled for surgical
resection (i.e. segmental excision or mastectomy).

- Archival tissue freshly cut from core biopsy must be available; patients who had a
diagnostic core biopsy at an outside institution are eligible as long as it is
confirmed that tumor specimens in paraffin blocks (preferred) or ≥ 25 unstained
slides, with an associated pathology report, are available.

- Female, Age ≥18 years (pre or postmenopausal).

- Signed informed consent

- Serum calcium or albumin-adjusted serum calcium ≥2.0mmol/L (8.0mg/dL) and ≤ 2.9 mmol/L
(11.5mg/dL)

- Patients with reproductive potential must be willing to use, in combination with her
partner, 2 acceptable methods of effective contraception or practice sexual abstinence
throughout the study and continue for 5 months after study duration. Subjects who are
surgically sterile (eg, history of bilateral tubal ligation, hysterectomy) or whose
sexual partner is sterile (eg, history of vasectomy) are not required to use
additional contraceptive measures.

Exclusion Criteria:

- Consideration for neoadjuvant therapy

- Serious infections including a history of active Hepatitis B, Hepatitis C or HIV

- Subject has known sensitivity to any of the products to be administered during the
study (e.g.., mammalian derived products, calcium, or vitamin D)

- Subject is pregnant or breast feeding, or planning to become pregnant/breastfeed while
on study through 5 months after the end of treatment

- Patients have prior history or current evidence of osteonecrosis or osteomyelitis of
the jaw, evidence of untreated local gum or oral infection, or non-healed dental or
oral surgery

- Patients with active dental or jaw conditions which require oral surgery/dental
procedures, including tooth extraction for the course of the study