• Biochemical markers (i.e., serum parathyroid hormone [PTH], bone-specific alkaline phosphatase, and osteocalcin) that are surrogates for fracture risk and are associated with increased bone pain, morbidity, and mortality from prostate cancer [ Designated as safety issue: No ]
  

• Markers of bone resorption (i.e., tartrate resistant acid phosphatase [TRAP], cross-linked C-telopeptide of type I collagen [ICPT], and osteoprotegerin [OPG]) [ Designated as safety issue: No ]
  

OBJECTIVES:

Primary

• To explore the relationship between paricalcitol therapy and markers of bone formation in patients with androgen-refractory, advanced prostate cancer with bone metastases.

Secondary

• To explore the relationship between paricalcitol therapy and markers of bone resorption in these patients.

OUTLINE: Patients receive oral paricalcitol once daily for 10 weeks in the absence of unacceptable toxicity.

Patients undergo blood sample collection periodically to determine markers of bone formation and resorption by ELISA; parathyroid hormone (PTH) levels by immunometric assay; prostate-specific antigen (PSA) levels by immunoassay; and 25-hydroxyvitamin D and 1,25(OH)_2D levels by radioimmunoassay.

Patients also undergo a bone densitometry (DEXA scan) at baseline and at 10 weeks to assess changes in bone strength.

After completion of study treatment, patients are followed every 6 months for 1 year.

DISEASE CHARACTERISTICS:

• 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

PATIENT CHARACTERISTICS:

• 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

• No underlying metabolic bone disease or vitamin D deficiency

  • 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
• No history of hypercalcemia
• No concurrent uncontrolled illness or co-morbid condition (including psychiatric illness) that would interfere with study compliance

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• 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
• No concurrent ergocalciferol supplementation
• No concurrent chemotherapy or hormonal therapy
• No other concurrent investigational or commercial agents for the malignancy