Treatment of Children with Persistent and Chronic Idiopathic Thrombocytopenic Purpura: 4 Infusions of Rituximab and Three 4-Day Cycles of Dexamethasone.

OBJECTIVES: To assess initial and long-term outcome of children with persistent/chronic idiopathic thrombocytopenic purpura (ITP) treated with 4 infusions of rituximab and three 4-day cycles of dexamethasone (4R+3Dex) including cohorts with most benefit and/or treatment associated toxicity. STUDY DESIGN: All pediatric patients with ITP at Weill-Cornell who received 4R+3Dex were included in this retrospective study. Duration was median time from first rituximab infusion to treatment failure. Patient cohort included 33 children ages 1-18 years with persistent/chronic ITP; 19 were female, 10 of whom were adolescents. Every patient had failed more than 1 and usually several ITP treatments. RESULTS: Children were treated with rituximab, 375 mg/m2 weekly for 4 weeks and three 4-day courses of dexamethasone 28 mg/m2 (40 mg max). Average age of nonresponders was 7.75 years, and initial responders averaged 12.7 years (P = .0073); 30% maintained continuing response at 60 months or last check-up. Eight of the 10 patients who underwent remission were female with ITP <24 months prior to initiating 4R+3Dex. All responding male patients except 2 relapsed. CONCLUSIONS: Durable unmaintained ITP remission after 4R+3Dex was seen almost exclusively in female adolescents with <24 months duration of ITP. This provides a new therapeutic paradigm for a subpopulation with hard-to-treat chronic ITP. The pathophysiology of ITP underlying this distinction requires further elucidation.

Thrombopoietic agents for the treatment of persistent and chronic immune thrombocytopenia in children.

OBJECTIVES: To determine the safety, tolerability, or efficacy of 2 licensed thrombopoietic agents in children with persistent and chronic immune thrombocytopenia (ITP). STUDY DESIGN: Retrospective analysis approved by the institutional review board of children with ITP not on-study who received thrombopoietin (TPO) therapy; 21 received romiplostim (11 at Children's Hospital of Orange County, 10 at Weill Cornell Medical Center) and 12 received eltrombopag (all at Weill Cornell Medical Center). Primary response measures were platelet counts ≥ 50 × 10(9)/L or ≥ 20 × 10(9)/L above baseline for 2 consecutive weeks and 50% of platelet counts ≥ 50 × 10(9)/L. Duration of treatment and adverse events, including bone marrow myelofibrosis (MF) consensus grades, were tabulated. RESULTS: Twenty-seven of 33 (82%) patients responded to TPO agents, 18 of 21 to romiplostim, and 9 of 12 to eltrombopag, after an average of 3.6 previous ITP therapies. These 27 patients had platelet counts ≥ 50 × 10(9)/L and ≥ 20 × 10(9)/L above baseline for 2 consecutive weeks; 26 had 50% of platelet counts ≥ 50 × 10(9)/L. Duration of romiplostim use ranged from 6 to 44 months (11/18 ongoing) and of eltrombopag 23 to 53 months (7/12 ongoing). One patient on eltrombopag experienced a provoked deep-vein thrombosis at site of ankle fracture. No other serious drug-related adverse events occurred. Among 24 bone marrows, 10 after greater than 2 years of therapy, 23 were normal (MF grades 0-1); 1 was MF-2. CONCLUSION: Retrospective analysis of off-study use of TPO agents in children with mainly chronic ITP showed increases in platelet counts in more than 4 of 5 children. The long-term use of TPO agents, up to 53 months, without tachyphylaxis supports their efficacy. These agents appear safe, effective, and tolerable in children with chronic ITP.

Chronic immune thrombocytopenic purpura in children: assessment of rituximab treatment.

OBJECTIVES: This study examined the efficacy and safety of rituximab in children with chronic immune thrombocytopenic purpura. STUDY DESIGN: Twenty-four patients, 2 to 19 years of age, with platelet counts <30,000/mcL (microliter 2), received 375 mg/m 2 rituximab in 4 weekly doses. Platelet response was characterized as complete (CR) if a count >150,000/mcL was achieved; partial (PR) if 50,000 to 150,000/mcL; minimal (MR) if the count increased by >20,000/mcL to a peak count >30,000/mcL but <50,000/mcL; or no response (NR). RESULTS: Fifteen of 24 patients (63%) achieved a CR lasting 4 to 30 months, 9 of which are ongoing. Two had PRs lasting 4 and 6 months; 2 had MRs lasting 5 and 8 months, and 5 did not respond. Pruritus, urticaria, and throat tightness (but no respiratory distress) occurred with the first infusion in a small number of children. Three patients had serum sickness after the first, second, and third infusions, respectively. No increased frequency or severity of infections was seen, although immunoglobulin levels decreased to below the normal range in 6 of 14 cases. CONCLUSIONS: Rituximab may be a useful treatment for chronic immune thrombocytopenic purpura in children with a >50% CR rate lasting an average of 13 months, with 9 of 15 CRs ongoing (8 lasted 6 months or longer). There was no substantial toxicity other than transient serum sickness.