Difficulty in recruitment. PDCO in the Day 30 summary report agrred to remove the PK study in children <1 year of age.

The purpose of this study is to find out more about darbepoetin alfa in children less than 1 year of age with anemia (a decrease in red blood cells) due to kidney failure. This study will see if darbepoetin alfa is safe and well tolerated and whether it causes any side effects by taking blood samples and checking vital signs (heart rate, body temperature, and blood pressure tests) at specific times throughout the study. In addition, the study will evaluate the amount of darbepoetin alfa in the blood over time and look at special markers in the blood to evaluate how darbepoetin alfa works on anemia.

Darbepoetin alfa is approved by the United States Food and Drug Administration (FDA) and European Medicines Agency (EMA) for use in adults, but not for all ages of pediatric subjects. Therefore, studies need to be conducted in pediatric subjects (children) to determine the appropriate dose to use in younger children.

Inclusion Criteria:

• Girls and boys between birth and < 1 year of age at the time of enrollment
• Body weight ≥ 3 kg at screening and enrollment
• Diagnosis of chronic kidney disease stage 3 to 5 with an estimated Glomerular Filtration Rate < 60 mL/min/1.73m2 without dialysis using the updated Schwartz Equation at screening; OR on dialysis at screening
• Hemoglobin ≤ 9.0 g/dL within 7 days prior to enrollment
• Transferrin saturation ≥ 20% at screening

Exclusion Criteria:

• Premature girls and boys (< 37 weeks of gestation, counting from the first day of the mother's last menstrual period)
• Peritoneal dialysis subjects with an episode of peritonitis within 30 days prior to enrollment
• History of cardiovascular events or thromboembolism
• History of upper or lower gastrointestinal bleeding
• History of seizures
• Active liver disease or history of liver disease
• Uncontrolled hypertension defined as stage 2 hypertension or greater. This is defined as a systolic or diastolic blood pressure value greater than the 99th percentile + 5 mmHg for a subject's age
• Major surgery 12 weeks prior to enrollment
• Red blood cell transfusions 12 weeks prior to enrollment
• Use of any erythropoiesis-stimulating agent within 12 weeks prior to enrollment
• Currently receiving antibiotic therapy for systemic infection within 4 weeks prior to enrollment
• Current or prior use of immunosuppressants (excluding low-dose corticosteroids, defined as ≤ 0.5 mg/kg per day prednisone or equivalent for ≤ 5 days)
• Subject is receiving a dose higher than 0.5 mg/kg per day of prednisone (or equivalent dose of another corticosteroid) for > 5 days within 4 weeks prior to enrollment
• Receiving or has received any investigational drug (or is currently using an investigational device) within the 30 days or 5 half-lives (whichever is longer) prior to enrollment
• Subject has known hypersensitivity to darbepoetin alfa, r-HuEPO, or to any of the excipients