What is the role of eltrombopag in the treatment of aplastic anemia?

Updated: Jan 29, 2021
  • Author: Sameer Bakhshi, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

Eltrobombopag (Promacta) is an oral thrombopoietin receptor agonist that was approved in 2014 for patients with severe aplastic anemia that failed to respond adequately to at least one prior immunosuppressive therapy (IST) regimen. Eltrombopag probably acts in aplastic anemia by stimulating the small number of residual stem cells in these patients' bone marrow. Approval of eltrombopag for this indication was supported by a phase II study in which 41% of patients experienced a hematologic response in at least one lineage (ie, platelets, red blood cells, neutrophils) after 12 weeks of treatment. [106, 107]  In the extension phase of the study, three patients achieved a multi-lineage response. Four of those patients subsequently tapered off treatment and maintained the response (median followup 8.1 months, range 7.2-10.6 months). [106, 107]

Eltrombopag has also shown benefit as first-line therapy. Townsley et al combined standard IST with eltrombopag in previously untreated patients with severe aplastic anemia, using three different regimens. The best response was noted in patients receiving eltrombopag from day 1 to 6 months, along with horse ATG on days 1 to 4 and daily cyclosporine from day 1 to 6 months. In this cohort, at 6 months, complete responses were seen in 58% of patients and hematologic responses in 94%. This compared with 10% and 66% rates, respectively, observed in a historical cohort treated with IST alone. In addition, the improved blood counts were accompanied by increased marrow cellularity and hematopoietic progenitor numbers. No additional increase in risk of clonal evolution (15%) was noted with the addition of eltrombopag to ATG and cyclosporine. [108]

Geng et al reported on upfront use of eltrombopag in two pediatric patients with non-severe aplastic anemia. Both patients achieved hematologic response with eltrombopag monotherapy. [109]

In  2018, the FDA expanded approval for eltrombopag to include use as first-line therapy, in combination with standard IST, for adult and pediatric patients 2 years and older with severe aplastic anemia. [110]


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