The treatment for primary immune thrombocytopenia with romiplostim in adult and paediatric patients: use experience at a Spanish university hospital

What is known and objective: Primary immune thrombocytopenia (ITP) is characterized by accelerated platelet destruction, as well as suboptimal platelet production. Thrombopoietin (TPO) receptor agonists bind to and activate human TPO receptor, and have been shown to increase platelet counts. In this study, we assessed the effectiveness and safety of long-term administration of TPO agonist romiplostim in adult and paediatric patients. Methods: This is a retrospective observational study that included every ITP patient (adults and children) who received romiplostim since its inclusion in our institutional formulary. Data on patients' demographics, romiplostim doses, platelet counts, use of rescue medication and concurrent therapies were collected. Outcomes for effectiveness evaluation were proportion of patients who achieved a platelet response (platelet count >50 x 10(9) per litre and double the platelet count at baseline on any scheduled visit, excluding counts obtained within 8 weeks after receipt of rescue medications), proportion of patients who achieved a durable response (platelet responses during 6 or more weeks of the last 8 weeks of treatment), proportion of patients needing rescue medication, proportion of patients able to stop or reduce concurrent treatment and mean number of weekly platelet responses. Safety was assessed on the basis of the incidence of adverse events documented on the patients' medical records. Results and discussion: This study enrolled ten adults and four paediatric patients. None of the paediatric patients and one adult patient had been splenectomized (contraindicated in the other adults). In the adult population, eight achieved a response at least once during treatment, and 1 achieved a durable response. Four patients needed rescue medication (mostly intravenous immunoglobulins). Three patients were able to stop concurrent ITP therapies, and the mean number of weekly platelet responses was 6. All four paediatric patients achieved a response at least once during treatment, and three achieved durable responses. Three patients needed rescue medication. The only patient who was receiving concurrent ITP medication was able to stop it, and the mean number of weekly platelet responses was 25. No serious adverse events were registered during treatment in either population.