First-in-class treatment option available for severe aplastic anemia patients who had insufficient responses to immunosuppressive therapy.
The FDA on Tuesday announced the approval of GlaxoSmithKline’s application for a new drug for previously treated patients with severe aplastic anemia (SAA).
Eltrombopag (Promacta) is a once-daily drug for SAA patients who had insufficient responses to immunosuppressive therapy (IST). Eltrombopag acts as an oral thrombopoietin receptor agonist that helps to induce the proliferation and differentiation of stem cells in bone marrow, thereby increasing the production of blood cells.
“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,” said GlaxoSmithKline President of Oncology Paolo Paoletti, MD, in a press release.
Eltrombopag was granted Breakthrough Therapy designation from the FDA in January 2014 and was given a priority review in April 2014. The approval by the FDA followed an investigator-sponsored Phase II single-arm, open-label trial of 43 patients by the National Institutes of Health (NIH).
The patients received eltrombopag at an initial once-daily dose of 50 mg for a period of 2 weeks, after which the dosage increased over 2-week periods up to a maximum once-daily dose of 150 mg. The primary endpoint for the trial was a haematologic response that was assessed after 12 weeks of treatment.
After 12 weeks, 40% of the patients experienced a haematologic response in at least 1 lineage of platelets, red blood cells, or white blood cells, the researchers noted.
During the extension phase of the study, 8 patients achieved a multi-lineage response, while 4 of them were able to maintain the response after tapering off treatment with a median follow up of 8.1 months and a range of 7.2 to 10.6 months.
At baseline, 91% of patients were platelet transfusion dependent and 86% of patients were red blood cell transfusion dependent. The platelet transfusion-free period ranged from 8 days to 1096 days in responders, with a median of 200 days, while the red blood cell transfusion-free period ranged from 15 days to 1082 days, with a median of 208 days.
The most common adverse events in patients who received Promacta were nausea, fatigue, cough, diarrhea, and headache. Additionally, 8 patients showed a new cytogenetic abnormality, with 5 patients experiencing complex changes to chromosome 7.
“Through collaboration with the NIH, 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 said.