Safety and Efficacy of Paricalcitol Capsules in Decreasing Serum Parathyroid Hormone Levels in Children 10-16 With Chronic Kidney Disease (CKD)

The study consists of two parts. Part I is an open-label single-dose, non-fasting,
multicenter study to evaluate the pharmacokinetics of paricalcitol capsules in 12 pediatric
subjects ages 10 to 16 years with Chronic Kidney Disease Stages 3 and 4. Part II of this
study will be conducted as a 12 week randomized double-blind, placebo-controlled study,
followed by 12 weeks open-label treatment. Subjects active or enrolled under amendment 5
will enter a Follow-Up period and have study visits every 4 weeks until the final subject
reaches Week 24. The objective of this multicenter study is to evaluate the safety and
efficacy of paricalcitol capsules in decreasing serum intact parathyroid hormone levels to
the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative target goals in
36 pediatric subjects ages 10 to 16 years with Chronic Kidney Disease Stages 3 and 4.

Inclusion Criteria:

- Subject has Chronic Kidney Disease Stage 3 or 4 as determined by estimated Glomerular
Filtration Rate (15 to 59 mL/min/1.73 m2) at Screening.

- Subject is not expected to begin dialysis for at least 6 months (in the opinion of
the investigator).

- For entry into the Washout Period (for subjects who are currently on a VDRA and need
to complete a 2 to 4 week washout), the subject must satisfy the following criteria
based on the Screening laboratory values:

- estimated Glomerular Filtration Rate between 15 to 59 mL/min/1.73 m2 (estimate
by the Schwartz formula as outlined in Section 5.3.1.2).

- iPTH measurement that is greater than or equal to 60 pg/mL (Stage 3 subjects) or
greater than or equal to 90 pg/mL (Stage 4 subjects).

- An adjusted serum calcium value greater than or equal to 8.2 mg/dL (2.05 mmol/L)
to less than or equal to 10.5 mg/dL (2.63 mmol/L).

- A serum phosphorus value greater than or equal to 2.0 mg/dL (0.65 mmol/L but
less than or equal to 6.0 mg/dL (1.94 mmol/L).

- For entry into the Treatment Phase (Vitamin D Receptor Activator naïve subjects and
those that have completed a 4 week washout), the subject must have:

- iPTH measurement that is greater than or equal to 75 pg/mL (Stage 3 subjects) or
greater than or equal to 110 pg/mL (Stage 4 subjects).

- An adjusted serum calcium value greater than or equal to 8.4 mg/dL (2.10 mmol/L)
but less than or equal to 10.2 mg/dL (2.55 mmol/L).

- A serum phosphorus value greater than or equal to 2.5 mg/dL (0.81 mmol/L) but
less than or equal to 5.8 mg/dL (1.87 mmol/L).

- Must have 25-hydroxyvitamin D levels ≥ 30 ng/mL prior to washout, if not VDRA
naïve, or treatment in Part II of the study.

Exclusion Criteria:

- All subjects that have had a small bowel transplant will be excluded from the study.

- Subject has had acute kidney failure within 12 weeks of the Screening Phase (defined
as an acute rise in serum creatinine).

- Subject has had symptomatic or significant hypocalcemia requiring active Vitamin D
therapy (for example, calcitriol, paricalcitol, doxercalciferol or alfacalcidol)
within 6 months prior to the Screening Phase.

- Subject has a history of active kidney stones (6 months prior to screening).

- Subject has chronic gastrointestinal disease, which in the investigator's opinion may
cause significant gastrointestinal malabsorption.

- Subject is taking maintenance calcitonin, bisphosphonates, cinacalcet,
glucocorticoids in an equivalent dose of greater than 5 mg prednisone daily, or other
drugs known to affect calcium or bone metabolism within 4 weeks prior to Treatment.