FDA posts Promacta briefing documents

Ligand (NASDAQ:LGND) was off $1.29 (36%) to $2.30 on Wednesday after FDA posted briefing documents ahead of Friday's Oncologic Drugs Advisory Committee meeting to discuss an NDA from partner GlaxoSmithKline (LSE:GSK; NYSE:GSK) for Promacta eltrombopag. GlaxoSmithKline is seeking approval of the oral small molecule thrombopoietin (TPO) receptor agonist for the short-term treatment of previously treated patients with chronic idiopathic thrombocytopenic purpura (ITP) to increase platelet counts.

Although FDA stated in the documents that the data appear to support short-term use of Promacta to treat ITP, the agency expressed concern about the lack of long-term safety data given the likelihood of extended use for a chronic disease. FDA also questioned whether a short-term treatment indication is viable given the known risk of a decrease in platelet count below pre-treatment levels following discontinuation of Promacta, as well as whether it would be possible to design a RiskMAP to address these issues. ...