Inclusion Criteria

Inclusion:

- Histologically or cytologically confirmed advanced adenocarcinoma of the prostate

- Radiographically proven bone metastasis from prostate cancer

- Androgen refractory disease (including anti-androgen withdrawal)

- Secondary hyperparathyroidism, defined as two parathyroid hormone (PTH) values > 70
pg/mL, 14 days apart

- ECOG performance status 0-2

- Leukocytes ≥ 3,000/μL

- Absolute neutrophil count ≥ 1,500/μL

- Platelets ≥ 100,000/μL

- Total bilirubin normal

- AST/ALT ≤ 2.5 times upper limit of normal

- Creatinine clearance ≥ 60 mL/min

- Calcium normal

- 25-hydroxyvitamin D (25-OHD) ≥ 20 ng/mL

- 1,25(OH)_2D normal

- Patients with serum 25-OHD indicative of vitamin D insufficiency are eligible
provided they are treated with ergocalciferol to raise 25-OHD levels to 20 ng/mL
prior to paricalcitol therapy

- More than 8 weeks since prior bisphosphonates

- More than 2 weeks since prior palliative radiotherapy

- More than 4 weeks since other prior therapy

- No more than one prior taxane-containing chemotherapy regimen for metastatic disease

- Multiple lines of prior therapy with hormonal agents allowed

- Concurrent corticosteroids allowed provided the dose remains stable during the study
period

Exclusion:

- Underlying metabolic bone disease or vitamin D deficiency

- History of hypercalcemia

- Concurrent uncontrolled illness or co-morbid condition (including psychiatric
illness) that would interfere with study compliance

- Concurrent ergocalciferol supplementation

- Concurrent chemotherapy or hormonal therapy

- Concurrent investigational or commercial agents for the malignancy