Risedronate to Prevent Skeletal Related Events in Patients With Metastatic Prostate Cancer Commencing Hormonal Therapy

Risedronate is an orally administered pyridinyl bisphosphonate that is 36 times more potent than pamidronate and 72 times more potent than clodronate. Four randomized, double-blind trials have been carried out in patients with postmenopausal osteoporosis. In 2 of these studies, vertebral fracture incidence was reduced by a daily dose of 5 mg risedronate by up to 65% and 49% relative to placebo after 1 and 3 years, respectively. In these trials, risedronate improved lumbar spine, femoral neck, and femoral trochanter bone mineral density (BMD) at 6 months. In addition, preclinical studies have shown that risedronate is more potent than pamidronate and clodronate in inhibiting adhesion of prostate cancer cells to bone and preventing tumor cell invasion. The incidence of osteoporosis in prostate cancer patients has been well established; therefore, it is advantageous to assess the efficacy of oral bisphosphonate therapy.

OUTLINE: This is a randomized, placebo-controlled, double-blind, multicenter, 2 arm study.

The study population will consist of prostate cancer patients with metastatic bone disease for whom androgen-deprivation therapy is planned. After stratification based on the patient's age, performance status, and severity of metastatic disease, the patients will be randomized at a 1:1 ratio to the following treatment arms:

* Daily oral risedronate combined with androgen deprivation
* Daily oral placebo combined with androgen deprivation

Initial clinical evaluation will be performed during the 2-week screening period. While patients receive per-protocol treatment, study assessments will be performed every 4 weeks during the first 3 months, and every 12 weeks thereafter.

Performance Status: Eastern Cooperative Oncology Group (ECOG) 0 to 2

Life Expectancy: At least 12 weeks

Hematopoietic:

* Absolute neutrophil count (ANC) \> 1,000/mm3
* Platelet count \> 100,000/mm3
* international normalized ratio (INR) \< 1.5 x upper limit of normal unless on therapeutic anticoagulation
* Partial thromboplastin time (PTT) \< 1.5 x upper limit of normal unless on therapeutic anticoagulation

Hepatic:

* Bilirubin \< 1.5 mg/dL
* Alanine transaminase (ALT) \< 2.5 x upper limit of normal

Renal:

* Creatinine clearance of \> 30 mL/min (by Cockcroft-Gault)

Cardiovascular:

* No significant history of uncontrolled cardiac disease (i.e., uncontrolled hypertension, unstable angina, and congestive heart failure).

Pulmonary:

* Not specified

Calcium:

* Corrected serum calcium = (4.0 g/dL - actual albumin g/dL)x 0.8 + serum calcium

Eligibility Criteria:
Inclusion Criteria:

* Histologically or cytologically confirmed adenocarcinoma of the prostate with metastatic bone disease (by CT, MRI or bone scan) with plans to start or be \< 30 days from beginning androgen deprivation therapy. Patients with lymph node or visceral metastases only are not eligible
* Patients may receive palliative radiation therapy at the investigators discretion during the first 4 weeks of beginning protocol therapy.

Exclusion Criteria:

* No neuroendocrine, small cell or transitional cell cancer of the prostate No abnormal bone metabolism (i.e., Paget's disease, untreated hyperthyroidism, untreated hyperprolactinemia, untreated Cushing's disease).
* No use of calcitonin within 14 days before being registered for protocol therapy or any previous use of bisphosphonates.
* No major surgery within 4 weeks of registration to protocol therapy.
* No adjuvant chemotherapy within 6 months of registration to protocol therapy.
* No previous chemotherapy for metastatic disease.
* No hormonal therapy in the adjuvant setting within 12 months of registration to protocol therapy; previous hormonal therapy must not have exceeded 6 months.
* No prior history of malignancy in the past 5 years with the exception of basal cell and squamous cell carcinoma of the skin.
* No history of allergy or drug reactions to bisphosphonates.