Long-term Study of Romiplostim in Thrombocytopenic Pediatric Patients With Immune Thrombocytopenia (ITP)

Inclusion Criteria:

• Diagnosis of primary ITP according to The American Society of Hematology (ASH)Guidelines at least 6 months before screening, regardless of splenectomy status
• Age ≥ 1 year and < 18 years of age
• Refractory to prior ITP therapy, relapsed after at prior ITP therapy, or be ineligiblefor other therapies. Examples of prior therapy include: corticosteroids, intravenousImmunoglobulin (IVIG), anti-D immunoglobulin, platelet transfusions.
• Platelet count ≤ 30 x10^9/L or is experiencing uncontrolled bleeding
• Has provided informed consent before any study-specific procedure;
• Adequate hematologic, renal, and liver function during screening:
• Hemoglobin > 10.0 g/dL
• Serum creatinine ≤ 1.5 x the upper limit of normal (ULN)
• Total serum bilirubin ≤ 1.5 x the ULN
• Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 3.0 x theULN
• For the EU, Switzerland and Turkey protocol supplement, subject must agree to ascheduled bone marrow biopsy and aspirate at Year 1 or Year 2 following romiplostimtreatment and any unscheduled biopsies if clinically indicated
• For the EU, Switzerland and Turkey protocol supplement, a reticulin grade of 0, 1, 2,or 3 according to the modified Bauermeister grading scale, as assessed by centrallaboratory from a bone marrow biopsy performed within 1 year prior to planned firstdose of romiplostim or consent to a pre-treatment bone marrow biopsy and aspirateprior to planned first dose of romiplostim

Exclusion Criteria:

• History of a bone marrow stem cell disorder (Any abnormal bone marrow findings otherthan those typical of ITP must be approved by Amgen before a subject may be enrolled)
• Prior bone marrow transplant or peripheral blood progenitor cell transplant
• Active or prior malignancy except non-melanoma skin cancers within the last 5 years
• History of myelodysplastic syndrome
• History of bleeding diathesis
• History of congenital thrombocytopenia
• History of Hepatitis B, Hepatitis C or human immunodeficiency virus (HIV)
• History of systemic lupus erythematosus, Evans syndrome, or autoimmune neutropenia
• History of antiphospholipid antibody syndrome or known positive for lupusanticoagulant
• History of disseminated intravascular coagulation, hemolytic uremic syndrome, orthrombotic thrombocytopenic purpura
• History of venous thromboembolism or thrombotic events
• Previous use of romiplostim or previous use of eltrombopag within 4 weeks ofenrollment
• Previous use of pegylated recombinant human megakaryocyte growth and developmentfactor (PEG-rHuMGDF), recombinant human thrombopoietin (rHuTPO) or any other plateletproducing agent
• Rituximab (for any indication) or 6-mercaptopurine within 8 weeks of enrollment, oranticipated use at any time during the study
• Splenectomy within 4 weeks of the screening visit
• Alkylating agents within 8 weeks before the screening visit or anticipated use duringthe time of the proposed study
• Vaccinations known to decrease platelet counts within 8 weeks before the screeningvisit
• Currently enrolled in another investigational device or drug study, or less than 30days since ending investigational study
• Will have investigational procedures while enrolled on study
• Female subject of child bearing potential (defined as having first menses) not willingto use, in combination with her partner highly effective methods of birth controlduring treatment and for 1 month after the end of treatment
• Subject is pregnant or breast feeding, or might become pregnant within 1 month afterthe end of treatment
• Subject has known hypersensitivity to any recombinant Escherichia coli derived product (eg, Infergen®, Neupogen®, somatropin, and Actimmune®)
• Has previously enrolled into this study
• Will not be available for protocol-required study visits or procedures, to the best ofthe subject's and investigator's knowledge
• Any kind of disorder that, may compromise the subject to give written informed consentand/or to comply with all required study procedures