FDA expands approval of Promacta

The FDA today expanded the improved indications for eltrombopag to include treatment of patients with severe aplastic anemia who demonstrated an insufficient response to immunosuppressive therapy, according to the agent’s manufacturer.

Eltrombopag (Promacta, GlaxoSmithKline), an oral thrombopoietin receptor agonist, already had been approved for treatment of thrombocytopenia in patients with chronic hepatitis C, as well as those with chronic immune thrombocytopenia who demonstrated insufficient response to immunoglobulins, corticosteroids or splenectomy.

In patients with severe aplastic anemia, bone marrow does not make sufficient numbers of white blood cells, red blood cells and platelets. Eltrombopag increases the production of blood cells by inducing the proliferation and differentiation of bone marrow stem cells.

The FDA had granted eltrombopag breakthrough therapy designation for this indication in January, and it granted priority review status in April.

The FDA based its approval in part on results of a phase 2 study conducted by the National Heart, Lung and Blood Institute at NIH. The single-arm, open-label trial included 43 patients with severe aplastic anemia who had insufficient response to immunosuppressive therapy.

Results showed 17 patients (40%) demonstrated hematologic response in at least one lineage — red blood cells, white blood cells or platelets — after week 12. During the study’s extension phase, eight patients demonstrated multi-lineage response. Four of them tapered off treatment but maintained the response throughout a median follow-up of 8.1 months (range, 7.2-10.6).

Ninety-one percent of patients had been platelet transfusion-dependent at baseline. Among responders, the median platelet transfusion-free period was 200 days (range, 8-1,096). Eighty-six percent of patients had been red blood cell transfusion-dependent at baseline. Among responders, the median red blood cell transfusion-free period was 208 days (range, 15-1,082).

The most frequently reported adverse events in eltrombopag-treated patients were nausea (33%), fatigue (28%), cough (23%), diarrhea (21%) and headache (21%).

“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, GlaxoSmithKline’s president of oncology, said in a press release. “Through collaboration with the National Institutes of Health, whose studies demonstrate the potential for Promacta to achieve a hematologic 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.”