Eltrombopag preferentially expands haematopoietic multipotent progenitors in human aplastic anaemia

Summary Eltrombopag has been added to first‐line treatment of immune aplastic anaemia (AA), resulting in higher responses. We analysed marrow samples of AA patients who responded to immunosuppressive therapy (IST) alone or in combination with eltrombopag for the composition of the haematopoietic stem and progenitor cell (HSPC) compartment. The number of CD34 + cells and multipotent progenitors was higher in patients treated with eltrombopag ( P < 0·005; P < 0·05; respectively), but not the number of stem cells. No aberrant phenotype was observed. These results indicate that eltrombopag augments CD34 + cells in vivo and preferentially expands multipotent progenitors, but not stem cells.