Ligand Pharmaceuticals Incorporated announced that its partner GlaxoSmithKline has received approval of a supplemental New Drug Application (sNDA) for the once-daily use of Promacta®/Revolade™ (eltrombopag) in patients with severe aplastic anemia (SAA) who have had an insufficient response to immunosuppressive therapy (IST). SAA is a blood disorder where the bone marrow fails to make enough red blood cells, white blood cells and platelets. Eltrombopag, an oral thrombopoietin (TPO) receptor agonist, works by helping to induce proliferation and differentiation of bone marrow stem cells to increase production of blood cells.

Promacta gained Breakthrough Therapy designation status from the FDA in January 2014 and Priority Review in April 2014. Yesterday’s approval by the FDA is based on results from an investigator-sponsored Phase II study (09-H-0154) conducted by the National Heart, Lung and Blood Institute (NHLBI) at the National Institutes of Health (NIH). The study demonstrated a hematologic response in SAA patients treated with eltrombopag who had an insufficient response to IST:
•Forty per cent (95% CI, 25, 56) of patients (N=17) experienced a hematologic response in at least one lineage – platelets, red blood cells (RBC), or white blood cells (ANC) – after Week 12. 1◦In the extension phase, eight patients achieved a multi-lineage response; four of these patients subsequently tapered off treatment and maintained the response (median follow up 8.1 months, range 7.2-10.6 months).

•Ninety-one per cent of patients were platelet transfusion-dependent at baseline; the platelet transfusion-free period in responders ranged from eight to 1,096 days (median 200 days).
•Eighty-six per cent of patients were RBC-transfusion dependent at baseline; the RBC transfusion-free period in responders ranged from 15 to 1,082 days (median 208 days).