Bleeding severity as an important outcome in childhood immune thrombocytopenia

Flow cytometric measurement of platelet-associated immunoglobulin in children with newly diagnosed Immune Thrombocytopenia

OBJECTIVE

To explore the clinical utility of measuring platelet-associated immunoglobulin (PAIG) at the time of diagnosis in children with immune thrombocytopenia (ITP).

METHODS

PAIG was measured by flow cytometry using fluorescent murine anti-IgG and anti-IgM. In a cohort of 88 children with ITP, the assay was performed within 15 days of diagnosis and before any treatment in 68 cases. We reviewed the results and examined the relation of isotype profile and degree of elevation to clinical manifestations and course of disease.

RESULTS

PAIG was elevated in 74%, with raised IgM being more frequent than IgG (63% vs. 44%, P = 0.04) and with isotype profile depending on symptom onset. Platelet counts at presentation were similar in all subgroups, but mucosal bleeding was less frequent in PAIG-negative patients compared to the positive groups (5.5% vs. 34%, P = 0.03). Duration of thrombocytopenia was similar in negative and positive cases, but during follow-up, significant bleeding events occurred less frequently in PAIG-negative patients (0% vs. 14%, P = 0.18).

CONCLUSION

Approximately one-quarter of children are PAIG-negative, and these children have milder bleeding tendency at diagnosis and lower morbidity during follow-up. Raised PAIG possibly may cause some degree of platelet dysfunction.

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.

Romiplostim in children with chronic immune thrombocytopenia (ITP): the French experience

A minority of children with chronic immune thrombocytopenia (ITP) require therapeutic intervention to prevent haemorrhagic risk. This retrospective national study evaluated romiplostim in childhood non-responsive or refractory chronic ITP. Between 2009 and 2012, 10 patients whose Buchanan score was 3-4 were treated with romiplostim. The median duration of thrombocytopenia was 1·9 years (0·8-15). The median duration of romiplostim treatment was 9 months (3-36). A response was observed in 5/10 patients (one complete, four partial). No serious adverse effect was noticed. The long-term benefit/risk balance of this innovative treatment is currently recorded by Centre de Référence National des Cytopénies Auto-immunes de l'Enfant.