FDA OKs Eltrombopag (Promacta) for Severe Aplastic Anemia

Megan Brooks


August 26, 2014

The US Food and Drug Administration (FDA) has approved a supplemental new drug application for eltrombopag (Promacta, GlaxoSmithKline) for use in patients with severe aplastic anemia who fail to respond adequately to immunosuppressive therapy, the company said.

Eltrombopag, an oral thrombopoietin receptor agonist, induces the proliferation and differentiation of bone marrow stem cells to increase production of blood cells.

The FDA approval is based on results of a phase 2 study conducted by the National Heart, Lung and Blood Institute, involving 43 patients with severe aplastic anemia who have had an insufficient response to at least 1 prior immunosuppressive therapy.

Eltrombopag was administered at an initial dose of 50 mg once daily for 2 weeks and increased over the course of 2-week periods to a maximum dose of 150 mg once daily. The primary endpoint was hematologic response, which was initially assessed after 12 weeks. Treatment was discontinued after 16 weeks if no hematologic response was observed.

With eltrombopag, 40% of patients experienced a hematologic response in platelets, red blood cells, or white blood cells after week 12.

In an extension phase, 8 patients achieved a multilineage response. Four of these patients subsequently tapered off treatment and maintained the response during a median follow-up of 8.1 months.

The most common adverse reactions were nausea (33%), fatigue (28%), cough (23%), diarrhea (21%), and headache (21%).

Patients in the study had bone marrow aspirates evaluated for cytogenetic abnormalities. Eight patients had a new cytogenetic abnormality, including 5 patients who had complex changes in chromosome 7. "If new cytogenetic abnormalities are observed, discontinuation of Promacta should be considered," the company said in a news release.

"FDA approval of Promacta addresses a significant treatment need for this very rare but serious blood disorder in those who have failed current treatment options," Paolo Paoletti, MD, president of GlaxoSmithKline Oncology, said in the release.

In the United States, approximately 300 to 600 new cases of severe aplastic anemia are identified each year.

"Through collaboration with the National Institutes of Health, whose studies demonstrate the potential for Promacta to achieve a haematologic response in at least one lineage — red blood cells, platelets, or white blood cells — patients now have a treatment option where one didn't previously exist," Dr. Paoletti added.

Eltrombopag is also approved in the United States for the treatment of thrombocytopenia in patients with chronic immune (idiopathic) thrombocytopenia refractory to other treatments and in patients with chronic hepatitis C, when needed, to allow the initiation and maintenance of interferon-based therapy.


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