Eltrombopag in combination with immunosuppressive therapy in pediatric severe aplastic anemia: phase 2 ESCALATE trial.

Severe aplastic anemia (SAA) is a rare, life-threatening disease with acquired pancytopenia and hypocellular bone marrow. ESCALATE evaluated eltrombopag in combination with immunosuppressive therapy (IST) in pediatric patients (aged 1 to <18 years) with relapsed/refractory (R/R) or treatment-naïve SAA. The eltrombopag starting dose was 25 mg/d for patients aged 1 to <6 years and 50 mg/d for patients aged 6 to <18 years; dose modifications (maximum dose, 150 mg/d) were allowed to achieve a target platelet count of 50 × 109/L to 200 × 109/L. Eltrombopag was administered with cyclosporine A, with or without horse antithymocyte globulin, for 26 weeks and could be extended if clinically beneficial. Fifty-one patients were treated (R/R SAA, n = 14; treatment-naïve SAA, n = 37). Data were analyzed overall and as 2 cohorts: R/R and treatment-naïve cohorts. The overall response rate (ORR; per North American Pediatric Aplastic Anemia Consortium criteria) at 26 weeks was 54.9% in both cohorts combined and 71.4% and 48.6% in the R/R and treatment-naïve cohorts, respectively; most responders had sustained responses after discontinuing eltrombopag. Among baseline transfusion-dependent patients, 66.7% and 76.7% achieved red blood cell and platelet transfusion independence, respectively, with rates of 70% and 80% for the R/R cohort and 65.6% and 75.8% for the treatment-naïve cohort, respectively. The most common treatment-related adverse events were abnormalities in liver function tests, including increased bilirubin (43.1%), alanine aminotransferase (37.3%), and aspartate aminotransferase (33.3%). Eltrombopag with IST showed a trend toward a favorable ORR in the R/R cohort, with no new safety signals. This trial was registered at www.clinicaltrials.gov as #NCT03025698.