Daratumumab in children with advanced idiopathic thrombocytopenic purpura

Most children with idiopathic thrombocytopenic purpura (ITP) respond to initial therapy but some do not and some responders relapse. How to treat these children is controversial. Proposed interventions include IGIV, anti-CD20 antibodies like rituximab, immune suppressive drugs, splenectomy, thrombopoietin receptor agonists like eltrombopag, romiplostim, and hetrombopag and even umbilical cord blood cell–derived mesenchymal stromal cell infusions.1–6 These interventions are effective in some children but relapses are common. Recently, Sun et al7 from the National Clinical Research Center for Blood Diseases, Tianjin, China, the Blood Diseases Hospital, Tianjin, China, and the State Key Laboratory of Experimental Hematology, Tianjin, China, published a Phase-2 study of daratumumab in 20 children with advanced ITP. Therapy was safe and effective. Median time to platelet response was 1 week (Interquartile Range [IQR] 1–2 weeks). There were responses within 8 weeks in 18 children including 17 failing prior to rituximab. It is curious to see such rapid responses from targeting plasma cells given the 3-week half-life of IgG. The authors should explain how this occurs. Another issue is how often daratumumab therapy might be needed for sustained responses. Finally, it is interesting to speculate whether there might be roles for bi-specific antibodies and anti–B-cell maturation antigen (BCMA) chimeric antigen receptor (CAR)-T-cells which might have more sustained responses. These encouraging data from Sun et al7 offer a promising approach to children with ITP failing other interventions. We anxiously await confirmation of these exciting results from larger series. AUTHOR CONTRIBUTIONS R.P.G. developed the typescript, takes responsibility for the content, and agrees to submit for publication.