Thrombopoietin receptor agonists for treatment of new and relapsed immune thrombocytopenia in children-A single-centre experience

ABSTRACT

Immune thrombocytopenia (ITP) is the most common bleeding disorder in paediatrics. ITP is usually a self-limiting disorder;however, it can be associated with significant and life-threatening bleeding. Outside the context of the COVID-19 pandemic, the first-line treatment for newly diagnosed or relapsed ITP is corticosteroids or intravenous immunoglobulin (IVIg). Treatment of ITP in the COVID-19 era became more challenging due to the shortage of IVIg, the continuous fear of immunosuppression, and the need for hospital contact. Because of these additional burdens, NHS England established a rapid policy in February 2021 to aid clinicians in offering the best care and advice to ITP patients. This policy recommended the use of thrombopoietin receptor agonists (TPO RAs) as first-line therapy for new or relapsed ITP in adults and children over the age of 1 year. TPO RAs including eltrombopag and romiplostim have been shown to be safe and effective in chronic ITP in children. Data on its safety and efficacy in acute ITP are limited. We conducted a retrospective observational study at Birmingham Children's Hospital between February 2021 and December 2021. The study aimed to assess the response to TPO RAs as first-line therapy in newly diagnosed or relapsed paediatric ITP patients. Eleven paediatric patients were included, nine were acute ITP and two had relapse of chronic ITP. All patients had baseline platelet count less than 10 × 10 9 /l. They presented with either moderate, severe or life-threatening bleeding requiring rescue treatment with steroids and/or IVIG. The 11 patients were commenced on eltrombopag. Two patients did not tolerate dietary restrictions with eltrombopag, and therefore they were switched to romiplostim. Nine out of the 11 patients who continued on TPO RAs had good and sustained response to TPO RAs with a platelet count more than 50 × 109 /l. No adverse events to the treatment have been reported during the study period. Four patients stopped treatment after sustained platelet count more than 200 × 10 9 /l, and they are currently off treatment for 4-9 months without rebound thrombocytopenia. Two out of the 11 patients did not respond to TPO RAs. One of them had poor response to romiplostim and hence it was discontinued, after a maximum dose of 10 mcg/Kg. This child then received rituximab and is currently stable with a platelet count of >50 × 10 9 /l. The clinical trials of using TPO RAs in the setting of acute ITP are still ongoing. However, after the current recommendations of their use in acute ITP, we expect TPO RAs to be increasingly brought forward in the management pathway of ITP. Although we are unable to quantify, but this NHS England policy has had a significant positive impact on the need for rescue therapy, hospital admissions, need for IVIG, in this cohort of patients. Further studies would be helpful to confirm these initial observations..