Refractory idiopathic immune thrombocytopenic purpura in children: current and future treatment options

Prognostic Factors for Immune Thrombocytopenia Outcome in Greek Children: A Retrospective Single-Centered Analysis

Immune thrombocytopenia (ITP) in children has a varied course and according to duration is distinguished as newly diagnosed (<3 months), persistent (3-12), and chronic (>12) types. Several studies have evaluated the prognostic factors for the progression of the disease, but similar works have yet to be performed in Greece. We aimed to identify prognostic markers for the three forms of the disease in 57 Greek children during a 13-year period. Information regarding age, gender, preceding infection, bleeding type, duration of symptoms and platelets at diagnosis, treatment, disease course, and immunological markers was recorded. 39 children had newly diagnosed, 4 persistent, and 14 chronic disease. Chronic ITP children were more likely to be of age > 10 years (p = 0.015) and have gradual initiation of the disease (p = 0.001), platelets > 10 × 10⁹/L (p = 0.01), and impaired immunological markers (p < 0.003) compared to newly diagnosed/persistent groups. Recent history of infection was found mainly in the newly diagnosed/persistent group (p = 0.013). None of the children exhibited severe spontaneous bleeding. Conclusion. Even though ITP in children usually has a self-limited course, with rare serious bleeding complications, the chronic form of the disease is characterized by different predictive parameters, which can be used in clinical practice.

Long-term use of the thrombopoietin-mimetic romiplostim in children with severe chronic immune thrombocytopenia (ITP)

BACKGROUND

Treatment of chronic severe pediatric ITP is not well studied. In a phase 1/2 12-16-week study, 15/17 romiplostim-treated patients achieved platelet counts ≥50 × 10⁹ /L, and romiplostim treatment was well tolerated. In a subsequent open-label extension (≤109 weeks), 20/22 patients received romiplostim; all achieved platelet counts >50 × 10⁹ /L. Twelve patients continued in a second extension (≤127 weeks). Longitudinal data from start of romiplostim treatment through the two extensions were evaluated to investigate the safety and efficacy of long-term romiplostim treatment in chronic severe pediatric ITP.

PROCEDURE

Patients received weekly subcutaneous romiplostim, adjusted by 1 µg/kg/week to maintain platelet counts (50-200 × 10⁹ /L, maximum dose 10 µg/kg). Bone marrow examinations were not required.

RESULTS

At baseline, patients were median age 10.0 years; median ITP duration 2.4 years; median platelet count 13 × 10⁹ /L; 73% were male; and 36% had prior splenectomy. Median romiplostim treatment duration was 167 weeks (Q1, Q3: 78,227 weeks), and median average weekly dose was 5.4 µg/kg (Q1, Q3: 4.3, 8.0 µg/kg). Seven patients discontinued treatment: four withdrew consent, two were noncompliant, and one received alternative therapy. None withdrew because of adverse events (AEs). After the first 12 weeks, median platelet counts remained >50 × 10⁹ /L. Eight (36.4%) patients received rescue medication, and 14 (63.6%) used concurrent ITP therapy. Seven patients (31.8%) reported serious AEs, and two (9.1%) reported life-threatening AEs (both thrombocytopenia); there were no serious AEs attributed to treatment and no fatalities.

CONCLUSIONS

Long-term romiplostim treatment in this small cohort increased and maintained platelet counts for over 4 years in children with ITP with good tolerability and without significant toxicity. Pediatr Blood Cancer 2015;62:208-213. © 2014. The Authors. Pediatr Blood & Cancer published by Wiley Periodicals, Inc.

The long-term impact of rituximab for childhood immune thrombocytopenia

Rituximab administered at standard doses induces universal B-cell depletion. It shows good efficacy in patients with a variety of autoimmune diseases and has been licensed for use in rheumatoid arthritis. Despite prolonged B-cell depletion, side effects appear to be minimal. The use of B-cell depletion in children in whom the immune system is more immature may have other unknown complications, although the literature remains sparse. This review summarizes the available studies of rituximab in children with immune thrombocytopenia and assesses some of the short-term and potential long-term consequences of B-cell depletion. Overall, rituximab appears well-tolerated in children. The incidence of serum sickness may be higher than it is in adults, but infections remain infrequent and occur mostly in patients with an underlying predisposition to infections. Finally, although data remain limited, it is recommended to perform vaccinations before administration of rituximab or after B-cell return.

Diagnosis, pathophysiology and management of children with refractory immune thrombocytopenic purpura

PURPOSE OF REVIEW

Refractory immune thrombocytopenic purpura is infrequent in children, but carries substantial morbidity and even mortality. Management of these children is controversial despite the availability of several treatment options as these strategies have not been directly compared and there are many definitions for refractory immune thrombocytopenic purpura. This review will provide an update on the pathogenesis, diagnosis and treatment options for children with severe, acute and chronic refractory immune thrombocytopenic purpura.

RECENT FINDINGS

Recent studies have demonstrated a number of immunologic alterations (dominant proinflammatory state, inadequate thrombopoiesis, and various B and T lymphocyte disturbances) in the pathogenesis of chronic immune thrombocytopenic purpura. New agents that target certain of these mechanisms (e.g. anti-CD20 monoclonal antibody, thrombopoietic agents) have shown promising results in recent clinical trials, primarily but not solely in adults.

SUMMARY

Management of refractory immune thrombocytopenic purpura often requires multiple agents that may provide only short-term benefit. Lack of clear views about the use of these medications, their unwanted side effects and an inability to specifically target a particular patient's disease all lead to frustration among patients, family and the physicians. Better understanding of pathogenesis with the availability of newer therapies with different mechanisms of effect should, however, allow improved management of these patients.

Low rate of long-lasting remissions after successful treatment of immune thrombocytopenic purpura with rituximab

Idiopathic thrombocytopenic purpura (ITP), also known as immune thrombocytopenic purpura, is thought to be caused primarily by the production of autoantibodies directed against platelet surface glycoproteins. Treatment of an acute ITP episode can be difficult, and relapses are common. Recent studies have shown that the anti-CD20 antibody rituximab is effective in the treatment of relapsed and refractory patients. We report the results of a retrospective analysis of rituximab treatment in 14 patients with immune thrombocytopenic purpura. Nine of these patients had a refractory disease, and five patients had a relapse of the thrombocytopenia. The median time since last treatment was 10 days (range 1-470 days). All patients were previously treated with one to seven different regimens, and four had undergone splenectomy. Rituximab was administered at the standard dose of 375 mg/m(2) once per week with a median of 4 infusions (range 2-4). The overall response rate was 64%; 7 of 14 patients (50%) achieved a complete remission (platelet levels > 100 x 10(9)/l), 2 of 14 patients (14%) had a partial remission (platelets > 50 x 10(9)/l), and 5 patients did not respond. The median time to response was 2 weeks (range 1-4) after the first infusion. Responding patients stayed in remission for a median period of 8 weeks (range 10 days-36 months). Three patients (21%) remained in remission after 26 to 156 weeks of follow-up. All of the four splenectomized patients achieved a complete remission after rituximab therapy, and two of them are still in remission after 26 and 156 weeks observation. Our data confirm that rituximab is well tolerated and effective in refractory and relapsed immune thrombocytopenias; however, response duration was short, and only about one fifth of our patients enjoyed a long-lasting remission.

Chronic refractory ITP in children: beyond splenectomy

Idiopathic (or immune) thrombocytopenic purpura (ITP) is a relatively common hematologic condition, but one that the hematology community has failed to reach a consensus on with regard to treatment. In patients with chronic refractory ITP, there is even less agreement about treatment approaches, as this population represents a small, but challenging, fraction of the total cases of ITP. The aim of this article is to review the treatment options available for children with chronic refractory ITP, including a review of the benefits versus risks, rate of remission, and areas of ongoing and future research.

Immunologic manipulation for the threatened fetus

Management of the pregnant woman with the antiphospholipid syndrome (APLS) has improved over the last 10 years. The recurrent pregnancy loss that is associated with this disease is managed with prophylactic low dose aspirin and heparin therapy. This therapy leads to a 40% absolute risk reduction in pregnancy loss. However, many women still fail to deliver a live infant despite this therapy so immunologic manipulation of the mother's disease in this group needs to be considered. Intravenous immunoglobulin and plasma exchange may have a role. New immunosuppressive drugs such as tacrolimus have yet to be tried. Monoclonal antibodies to B cells, B-cell growth factors, complement proteins and integrin molecules, all of which appear to play a role in the disease process, may also offer patients some hope. Similarly, biologics such as C1 esterase inhibitor protein, cell surface complement regulator proteins or interleukin-3 need to be tried given their efficacy in models of antibody-induced cell injury.