Romiplostim

12.1 Mechanism of Action Nplate increases platelet production through binding and activation of the TPO receptor, a mechanism analogous to endogenous TPO.

1 INDICATIONS AND USAGE Nplate is a thrombopoietin receptor agonist indicated for the treatment of thrombocytopenia in: Adult patients with immune thrombocytopenia (ITP) who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. ( 1.1 ) Pediatric patients 1 year of age and older with ITP for at least 6 months who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. ( 1.1 ) Nplate is indicated to increase survival in adults and in pediatric patients (including term neonates) acutely exposed to myelosuppressive doses of radiation (Hematopoietic Syndrome of Acute Radiation Syndrome [HS-ARS]). ( 1.2 ) Limitations of Use: Nplate is not indicated for the treatment of thrombocytopenia due to myelodysplastic syndrome (MDS) or any cause of thrombocytopenia other than ITP. Nplate should be used only in patients with ITP whose degree of thrombocytopenia and clinical condition increases the risk for bleeding. Nplate should not be used in an attempt to normalize platelet counts. ( 1 ) 1.1 Patients with Immune Thrombocytopenia (ITP) Nplate is indicated for the treatment of thrombocytopenia in: Adult patients with immune thrombocytopenia (ITP) who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. Pediatric patients 1 year of age and older with ITP for at least 6 months who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. 1.2 Patients with Hematopoietic Syndrome of Acute Radiation Syndrome Nplate is indicated to increase survival in adults and in pediatric patients (including term neonates) acutely exposed to myelosuppressive doses of radiation [see Clinical Studies (14.3) ] . Limitations of Use: Nplate is not indicated for the treatment of thrombocytopenia due to myelodysplastic syndrome (MDS) or any cause of thrombocytopenia other than ITP [see Warnings and Precautions ( 5.1 )] . Nplate should be used only in patients with ITP whose degree o

2 DOSAGE AND ADMINISTRATION Patients with Immune Thrombocytopenia (ITP) Recommended Initial Dose: 1 mcg/kg once weekly as a subcutaneous injection. Adjust dose based on platelet response. ( 2.1 ) Patients acutely exposed to myelosuppressive doses of radiation Recommended Dose: 10 mcg/kg administered once as a subcutaneous injection. Administer the dose as soon as possible after suspected or confirmed exposure to myelosuppressive doses of radiation. ( 2.2 ) See Full Prescribing Information for instructions on reconstitution, preparation, and administration. ( 2.3 ) Reconstitution and Dilution of Nplate Single Dose Vials 2.1 Patients with Immune Thrombocytopenia (ITP) Use the lowest dose of Nplate to achieve and maintain a platelet count ≥ 50 × 10 9 /L as necessary to reduce the risk for bleeding. Administer Nplate as a weekly subcutaneous injection with dose adjustments based upon the platelet count response. The prescribed Nplate dose may consist of a very small volume (e.g., 0.15 mL). Administer Nplate only with a syringe that contains 0.01 mL graduations. Discontinue Nplate if the platelet count does not increase to a level sufficient to avoid clinically important bleeding after 4 weeks of Nplate therapy at the maximum weekly dose of 10 mcg/kg [see Warnings and Precautions ( 5.3 )] . Obtain complete blood counts (CBCs), including platelet counts, weekly during the dose adjustment phase of Nplate therapy and then monthly following establishment of a stable Nplate dose. Obtain CBCs, including platelet counts, weekly for at least 2 weeks following discontinuation of Nplate. For Adult Patients with ITP The initial dose of Nplate is 1 mcg/kg. Actual body weight at initiation of treatment should always be used when calculating the initial dose. In adults, future dose adjustments are based on changes in platelet counts only. Adjust the weekly dose of Nplate by increments of 1 mcg/kg until the patient achieves a platelet count ≥ 50 × 10 9 /L as necessary to reduce the risk for bleeding; do not exceed a maximum weekly dose of 10 mcg/kg. In clinical studies, most adult patients who responded to Nplate achieved and maintained platelet counts ≥ 50 × 10 9 /L with a median dose of 2-3 mcg/kg. Adjust the dose as follows for adult patients: If the platelet count is < 50 × 10 9 /L, increase the dose by 1 mcg/kg. If platelet count is > 200 × 10 9 /L and ≤ 400 × 10 9 /L for 2 consecutive weeks, reduce the dose by 1 mcg/kg. If platelet count is > 400 × 10 9 /L, do not dose. Continue to assess the platelet count weekly. After the platelet count has fallen to < 200 × 10 9 /L, resume Nplate at a dose reduced by 1 mcg/kg. For Pediatric Patients with ITP The initial dose of Nplate is 1 mcg/kg. Actual body weight at initiation of treatment should always be used when calculating initial dose. In pediatric patients, future dose adjustments are based on changes in platelet counts and changes in body weight. Reassessment of body weight is recommended every 12 weeks. Adjust the weekly dose of Nplate by increments of 1 mcg/kg until the patient achieves a platelet count ≥ 50 × 10 9 /L as necessary to reduce the risk for bleeding; do not exceed a maximum weekly dose of 10 mcg/kg. In a pediatric placebo-controlled clinical study, the median of the most frequent dose of Nplate received by patients during weeks 17 through 24 was 5.5 mcg/kg. Adjust the dose as follows for pediatric patients: If the platelet count is < 50 × 10 9 /L, increase the dose by 1 mcg/kg. If platelet count is > 200 × 10 9 /L and ≤ 400 × 10 9 /L for 2 consecutive weeks, reduce the dose by 1 mcg/kg. If platelet count is > 400 × 10 9 /L, do not dose. Continue to assess the platelet count weekly. After the platelet count has fallen to < 200 × 10 9 /L, resume Nplate at a dose reduced by 1 mcg/kg. 2.2 Patients with Hematopoietic Syndrome of Acute Radiation Syndrome For Adult and Pediatric Patients (including term neonates) The recommended dose of Nplate is 10 mcg/kg administered once as a subcutaneous injection. Administer the dose as soon as possible after suspected or confirmed exposure to radiation levels greater than 2 gray (Gy). Administer Nplate regardless of whether a complete blood count (CBC) can be obtained. Estimate a patient's absorbed whole body radiation dose (i.e., level of radiation exposure) based on information from public health authorities, biodosimetry if available, or clinical findings such as time to onset of vomiting or lymphocyte depletion kinetics. 2.3 Preparation and Administration To mitigate against medication errors (both overdose and underdose), ensure that these preparation and administration instructions are followed. Use aseptic technique. Only administer subcutaneously [see Overdosage ( 10 )] . Nplate is supplied in single-dose vials as a sterile, preservative-free, white lyophilized powder that must be reconstituted as outlined in Table 1 and administered using a syringe with 0.01 mL graduations. Calculation of Patient Dose Multiply the pa

6 ADVERSE REACTIONS The following clinically significant adverse reactions are discussed in greater detail in other sections: Progression of Myelodysplastic Syndromes [see Warnings and Precautions ( 5.1 )] Thrombotic/Thromboembolic Complications [see Warnings and Precautions ( 5.2 )] Loss of Response to Nplate [see Warnings and Precautions ( 5.3 )] In adult patients, the most common adverse reactions (≥ 5% higher patient incidence in Nplate versus placebo) are arthralgia, dizziness, insomnia, myalgia, pain in extremity, abdominal pain, shoulder pain, dyspepsia, and paresthesia. Headache was the most commonly reported adverse reaction that did not occur at ≥ 5% higher patient incidence in Nplate versus placebo. ( 6.1 ) In pediatric patients, the most common adverse reactions (≥ 25%) are: contusion, upper respiratory tract infection, and oropharyngeal pain. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Amgen Inc. at 1-800-77-AMGEN (1-800-772-6436) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Adults The data described below reflect Nplate exposure to 271 adult patients with ITP, aged 18 to 88, of whom 62% were female. Nplate was studied in two randomized, placebo-controlled, double-blind studies that were identical in design, with the exception that Study 1 evaluated non-splenectomized patients with ITP and Study 2 evaluated splenectomized patients with ITP. Data are also reported from an open-label, single-arm study in which patients received Nplate over an extended period of time. Overall, Nplate was administered to 114 patients for at least 52 weeks and 53 patients for at least 96 weeks. In the placebo-controlled studies, headache was the most commonly reported adverse drug reaction, occurring in 35% of patients receiving Nplate and 32% of patients receiving placebo. For those patients receiving Nplate, 14 (48%) of headaches were mild, 9 (31%) were moderate, and 6 (21%) were severe. Table 3 presents adverse drug reactions from Studies 1 and 2 with a ≥ 5% higher patient incidence in Nplate versus placebo. Table 3. Adverse Reactions Identified in Two Placebo-Controlled Studies Adverse Reactions by Body System Nplate (%) (n = 84) Placebo (%) (n = 41) Musculoskeletal and Connective Tissue Disorders Arthralgia 22 (26%) 8 (20%) Myalgia 12 (14%) 1 (2%) Pain in Extremity 11 (13%) 2 (5%) Shoulder Pain 7 (8%) 0 Nervous System Disorders Dizziness 14 (17%) 0 Paresthesia 5 (6%) 0 Psychiatric Disorders Insomnia 13 (16%) 3 (7%) Gastrointestinal Disorders Abdominal pain 9 (11%) 0 Dyspepsia 6 (7%) 0 MedDRA version 9 is used. Among 291 adult patients with ITP who received Nplate in the single-arm extension study, the incidence rates of the adverse reactions occurred in a pattern similar to those reported in the placebo-controlled clinical studies. The safety profile of Nplate was similar across patients, regardless of ITP duration. The following adverse reactions (at least 5% incidence and at least 5% more frequent with Nplate compared with placebo or standard of care) occurred in Nplate patients with ITP duration up to 12 months: bronchitis, sinusitis, vomiting, arthralgia, myalgia, headache, dizziness, diarrhea, upper respiratory tract infection, cough, nausea and oropharyngeal pain. The adverse reaction of thrombocytosis occurred with an incidence of 2% in adults with ITP duration up to 12 months. Bone Marrow Reticulin Formation and Collagen Fibrosis Nplate administration may increase the risk for development or progression of reticulin fiber formation within the bone marrow. This formation may improve upon discontinuation of Nplate. In a clinical trial, one patient with ITP and hemolytic anemia developed marrow fibrosis with collagen during Nplate therapy. An open-label clinical trial prospectively evaluated changes in bone marrow reticulin formation and collagen fibrosis in adult patients with ITP treated with Nplate or a non-US approved romiplostim product. Patients were administered romiplostim by SC injection once weekly for up to 3 years. Based on cohort assignment at time of study enrollment, patients were evaluated for bone marrow reticulin and collagen at year 1 (cohort 1), year 2 (cohort 2), or year 3 (cohort 3) in comparison to the baseline bone marrow at start of the trial. Patients were evaluated for bone marrow reticulin formation and collagen fibrosis using the modified Bauermeister grading scale. From the total of 169 patients enrolled in the 3 cohorts, 132 (78%) patients were evaluable for bone marrow collagen fibrosis and 131 (78%) patients were evaluable for bone marrow reticulin formation. Two percent (2/132) of patients (both from cohort 3) developed Grade 4 findings (presence of collagen). There w

7 DRUG INTERACTIONS Nplate may be used with other medical ITP therapies, such as corticosteroids, danazol, azathioprine, intravenous immunoglobulin (IVIG), and anti-D immunoglobulin [see Clinical Studies ( 14.1 )] .